svn merge -r113003:119136 svn+ssh://svn.lindenlab.com/svn/linden/branches/login-api/login-api-2 svn+ssh://svn.lindenlab.com/svn/linden/branches/login-api/login-api-3

12 files changed, 1869 insertions, 50 deletions

diff --git a/indra/llcommon/CMakeLists.txt b/indra/llcommon/CMakeLists.txt
index 694f3d5de8..d3d75f78df 100644
--- a/indra/llcommon/CMakeLists.txt
+++ b/indra/llcommon/CMakeLists.txt
@@ -33,6 +33,8 @@ set(llcommon_SOURCE_FILES
     llerror.cpp
     llerrorthread.cpp
     llevent.cpp
+    lleventcoro.cpp
+    lleventfilter.cpp
     llevents.cpp
     llfasttimer.cpp
     llfile.cpp
@@ -118,6 +120,8 @@ set(llcommon_HEADER_FILES
     llerrorlegacy.h
     llerrorthread.h
     llevent.h
+    lleventcoro.h
+    lleventfilter.h
     llevents.h
     lleventemitter.h
     llextendedstatus.h
@@ -223,3 +227,5 @@ target_link_libraries(
     )
 
 ADD_BUILD_TEST(lllazy llcommon)
+ADD_BUILD_TEST(lleventfilter llcommon)
+ADD_BUILD_TEST(coroutine llcommon)
diff --git a/indra/llcommon/lleventcoro.cpp b/indra/llcommon/lleventcoro.cpp
new file mode 100644
index 0000000000..cea5a1eda3
--- /dev/null
+++ b/indra/llcommon/lleventcoro.cpp
@@ -0,0 +1,118 @@
+/**
+ * @file   lleventcoro.cpp
+ * @author Nat Goodspeed
+ * @date   2009-04-29
+ * @brief  Implementation for lleventcoro.
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "lleventcoro.h"
+// STL headers
+#include <map>
+// std headers
+// external library headers
+// other Linden headers
+#include "llsdserialize.h"
+#include "llerror.h"
+
+std::string LLEventDetail::listenerNameForCoro(const void* self)
+{
+    typedef std::map<const void*, std::string> MapType;
+    static MapType memo;
+    MapType::const_iterator found = memo.find(self);
+    if (found != memo.end())
+    {
+        // this coroutine instance has called us before, reuse same name
+        return found->second;
+    }
+    // this is the first time we've been called for this coroutine instance
+    std::string name(LLEventPump::inventName("coro"));
+    memo[self] = name;
+    return name;
+}
+
+void LLEventDetail::storeToLLSDPath(LLSD& dest, const LLSD& rawPath, const LLSD& value)
+{
+    if (rawPath.isUndefined())
+    {
+        // no-op case
+        return;
+    }
+
+    // Arrange to treat rawPath uniformly as an array. If it's not already an
+    // array, store it as the only entry in one.
+    LLSD path;
+    if (rawPath.isArray())
+    {
+        path = rawPath;
+    }
+    else
+    {
+        path.append(rawPath);
+    }
+
+    // Need to indicate a current destination -- but that current destination
+    // needs to change as we step through the path array. Where normally we'd
+    // use an LLSD& to capture a subscripted LLSD lvalue, this time we must
+    // instead use a pointer -- since it must be reassigned.
+    LLSD* pdest = &dest;
+
+    // Now loop through that array
+    for (LLSD::Integer i = 0; i < path.size(); ++i)
+    {
+        if (path[i].isString())
+        {
+            // *pdest is an LLSD map
+            pdest = &((*pdest)[path[i].asString()]);
+        }
+        else if (path[i].isInteger())
+        {
+            // *pdest is an LLSD array
+            pdest = &((*pdest)[path[i].asInteger()]);
+        }
+        else
+        {
+            // What do we do with Real or Array or Map or ...?
+            // As it's a coder error -- not a user error -- rub the coder's
+            // face in it so it gets fixed.
+            LL_ERRS("lleventcoro") << "storeToLLSDPath(" << dest << ", " << rawPath << ", " << value
+                                   << "): path[" << i << "] bad type " << path[i].type() << LL_ENDL;
+        }
+    }
+
+    // Here *pdest is where we should store value.
+    *pdest = value;
+}
+
+LLSD errorException(const LLEventWithID& result, const std::string& desc)
+{
+    // If the result arrived on the error pump (pump 1), instead of
+    // returning it, deliver it via exception.
+    if (result.second)
+    {
+        throw LLErrorEvent(desc, result.first);
+    }
+    // That way, our caller knows a simple return must be from the reply
+    // pump (pump 0).
+    return result.first;
+}
+
+LLSD errorLog(const LLEventWithID& result, const std::string& desc)
+{
+    // If the result arrived on the error pump (pump 1), log it as a fatal
+    // error.
+    if (result.second)
+    {
+        LL_ERRS("errorLog") << desc << ":" << std::endl;
+        LLSDSerialize::toPrettyXML(result.first, LL_CONT);
+        LL_CONT << LL_ENDL;
+    }
+    // A simple return must therefore be from the reply pump (pump 0).
+    return result.first;
+}
diff --git a/indra/llcommon/lleventcoro.h b/indra/llcommon/lleventcoro.h
new file mode 100644
index 0000000000..7232d1780f
--- /dev/null
+++ b/indra/llcommon/lleventcoro.h
@@ -0,0 +1,542 @@
+/**
+ * @file   lleventcoro.h
+ * @author Nat Goodspeed
+ * @date   2009-04-29
+ * @brief  Utilities to interface between coroutines and events.
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLEVENTCORO_H)
+#define LL_LLEVENTCORO_H
+
+#include <boost/coroutine/coroutine.hpp>
+#include <boost/coroutine/future.hpp>
+#include <boost/optional.hpp>
+#include <string>
+#include <stdexcept>
+#include "llevents.h"
+#include "llerror.h"
+
+/**
+ * Like LLListenerOrPumpName, this is a class intended for parameter lists:
+ * accept a <tt>const LLEventPumpOrPumpName&</tt> and you can accept either an
+ * <tt>LLEventPump&</tt> or its string name. For a single parameter that could
+ * be either, it's not hard to overload the function -- but as soon as you
+ * want to accept two such parameters, this is cheaper than four overloads.
+ */
+class LLEventPumpOrPumpName
+{
+public:
+    /// Pass an actual LLEventPump&
+    LLEventPumpOrPumpName(LLEventPump& pump):
+        mPump(pump)
+    {}
+    /// Pass the string name of an LLEventPump
+    LLEventPumpOrPumpName(const std::string& pumpname):
+        mPump(LLEventPumps::instance().obtain(pumpname))
+    {}
+    /// Pass string constant name of an LLEventPump. This override must be
+    /// explicit, since otherwise passing <tt>const char*</tt> to a function
+    /// accepting <tt>const LLEventPumpOrPumpName&</tt> would require two
+    /// different implicit conversions: <tt>const char*</tt> -> <tt>const
+    /// std::string&</tt> -> <tt>const LLEventPumpOrPumpName&</tt>.
+    LLEventPumpOrPumpName(const char* pumpname):
+        mPump(LLEventPumps::instance().obtain(pumpname))
+    {}
+    /// Unspecified: "I choose not to identify an LLEventPump."
+    LLEventPumpOrPumpName() {}
+    operator LLEventPump& () const { return *mPump; }
+    LLEventPump& getPump() const { return *mPump; }
+    operator bool() const { return mPump; }
+    bool operator!() const { return ! mPump; }
+
+private:
+    boost::optional<LLEventPump&> mPump;
+};
+
+/// This is an adapter for a signature like void LISTENER(const LLSD&), which
+/// isn't a valid LLEventPump listener: such listeners should return bool.
+template <typename LISTENER>
+class LLVoidListener
+{
+public:
+    LLVoidListener(const LISTENER& listener):
+        mListener(listener)
+    {}
+    bool operator()(const LLSD& event)
+    {
+        mListener(event);
+        // don't swallow the event, let other listeners see it
+        return false;
+    }
+private:
+    LISTENER mListener;
+};
+
+/// LLVoidListener helper function to infer the type of the LISTENER
+template <typename LISTENER>
+LLVoidListener<LISTENER> voidlistener(const LISTENER& listener)
+{
+    return LLVoidListener<LISTENER>(listener);
+}
+
+namespace LLEventDetail
+{
+    /**
+     * waitForEventOn() permits a coroutine to temporarily listen on an
+     * LLEventPump any number of times. We don't really want to have to ask
+     * the caller to label each such call with a distinct string; the whole
+     * point of waitForEventOn() is to present a nice sequential interface to
+     * the underlying LLEventPump-with-named-listeners machinery. So we'll use
+     * LLEventPump::inventName() to generate a distinct name for each
+     * temporary listener. On the other hand, because a given coroutine might
+     * call waitForEventOn() any number of times, we don't really want to
+     * consume an arbitrary number of generated inventName()s: that namespace,
+     * though large, is nonetheless finite. So we memoize an invented name for
+     * each distinct coroutine instance (each different 'self' object). We
+     * can't know the type of 'self', because it depends on the coroutine
+     * body's signature. So we cast its address to void*, looking for distinct
+     * pointer values. Yes, that means that an early coroutine could cache a
+     * value here, then be destroyed, only to be supplanted by a later
+     * coroutine (of the same or different type), and we'll end up
+     * "recognizing" the second one and reusing the listener name -- but
+     * that's okay, since it won't collide with any listener name used by the
+     * earlier coroutine since that earlier coroutine no longer exists.
+     */
+    std::string listenerNameForCoro(const void* self);
+
+    /**
+     * Implement behavior described for postAndWait()'s @a replyPumpNamePath
+     * parameter:
+     *
+     * * If <tt>path.isUndefined()</tt>, do nothing.
+     * * If <tt>path.isString()</tt>, @a dest is an LLSD map: store @a value
+     *   into <tt>dest[path.asString()]</tt>.
+     * * If <tt>path.isInteger()</tt>, @a dest is an LLSD array: store @a
+     *   value into <tt>dest[path.asInteger()]</tt>.
+     * * If <tt>path.isArray()</tt>, iteratively apply the rules above to step
+     *   down through the structure of @a dest. The last array entry in @a
+     *   path specifies the entry in the lowest-level structure in @a dest
+     *   into which to store @a value.
+     *
+     * @note
+     * In the degenerate case in which @a path is an empty array, @a dest will
+     * @em become @a value rather than @em containing it.
+     */
+    void storeToLLSDPath(LLSD& dest, const LLSD& path, const LLSD& value);
+} // namespace LLEventDetail
+
+/**
+ * Post specified LLSD event on the specified LLEventPump, then wait for a
+ * response on specified other LLEventPump. This is more than mere
+ * convenience: the difference between this function and the sequence
+ * @code
+ * requestPump.post(myEvent);
+ * LLSD reply = waitForEventOn(self, replyPump);
+ * @endcode
+ * is that the sequence above fails if the reply is posted immediately on
+ * @a replyPump, that is, before <tt>requestPump.post()</tt> returns. In the
+ * sequence above, the running coroutine isn't even listening on @a replyPump
+ * until <tt>requestPump.post()</tt> returns and @c waitForEventOn() is
+ * entered. Therefore, the coroutine completely misses an immediate reply
+ * event, making it wait indefinitely.
+ *
+ * By contrast, postAndWait() listens on the @a replyPump @em before posting
+ * the specified LLSD event on the specified @a requestPump.
+ *
+ * @param self The @c self object passed into a coroutine
+ * @param event LLSD data to be posted on @a requestPump
+ * @param requestPump an LLEventPump on which to post @a event. Pass either
+ * the LLEventPump& or its string name. However, if you pass a
+ * default-constructed @c LLEventPumpOrPumpName, we skip the post() call.
+ * @param replyPump an LLEventPump on which postAndWait() will listen for a
+ * reply. Pass either the LLEventPump& or its string name. The calling
+ * coroutine will wait until that reply arrives. (If you're concerned about a
+ * reply that might not arrive, please see also LLEventTimeout.)
+ * @param replyPumpNamePath specifies the location within @a event in which to
+ * store <tt>replyPump.getName()</tt>. This is a strictly optional convenience
+ * feature; obviously you can store the name in @a event "by hand" if desired.
+ * @a replyPumpNamePath can be specified in any of four forms:
+ * * @c isUndefined() (default-constructed LLSD object): do nothing. This is
+ *   the default behavior if you omit @a replyPumpNamePath.
+ * * @c isInteger(): @a event is an array. Store <tt>replyPump.getName()</tt>
+ *   in <tt>event[replyPumpNamePath.asInteger()]</tt>.
+ * * @c isString(): @a event is a map. Store <tt>replyPump.getName()</tt> in
+ *   <tt>event[replyPumpNamePath.asString()]</tt>.
+ * * @c isArray(): @a event has several levels of structure, e.g. map of
+ *   maps, array of arrays, array of maps, map of arrays, ... Store
+ *   <tt>replyPump.getName()</tt> in
+ *   <tt>event[replyPumpNamePath[0]][replyPumpNamePath[1]]...</tt> In other
+ *   words, examine each array entry in @a replyPumpNamePath in turn. If it's an
+ *   <tt>LLSD::String</tt>, the current level of @a event is a map; step down to
+ *   that map entry. If it's an <tt>LLSD::Integer</tt>, the current level of @a
+ *   event is an array; step down to that array entry. The last array entry in
+ *   @a replyPumpNamePath specifies the entry in the lowest-level structure in
+ *   @a event into which to store <tt>replyPump.getName()</tt>.
+ */
+template <typename SELF>
+LLSD postAndWait(SELF& self, const LLSD& event, const LLEventPumpOrPumpName& requestPump,
+                 const LLEventPumpOrPumpName& replyPump, const LLSD& replyPumpNamePath=LLSD())
+{
+    // declare the future
+    boost::coroutines::future<LLSD> future(self);
+    // make a callback that will assign a value to the future, and listen on
+    // the specified LLEventPump with that callback
+    std::string listenerName(LLEventDetail::listenerNameForCoro(&self));
+    LLTempBoundListener connection(
+        replyPump.getPump().listen(listenerName,
+                                   voidlistener(boost::coroutines::make_callback(future))));
+    // skip the "post" part if requestPump is default-constructed
+    if (requestPump)
+    {
+        // If replyPumpNamePath is non-empty, store the replyPump name in the
+        // request event.
+        LLSD modevent(event);
+        LLEventDetail::storeToLLSDPath(modevent, replyPumpNamePath, replyPump.getPump().getName());
+        LL_DEBUGS("lleventcoro") << "postAndWait(): coroutine " << listenerName
+                                 << " posting to " << requestPump.getPump().getName()
+                                 << ": " << modevent << LL_ENDL;
+        requestPump.getPump().post(modevent);
+    }
+    LL_DEBUGS("lleventcoro") << "postAndWait(): coroutine " << listenerName
+                             << " about to wait on LLEventPump " << replyPump.getPump().getName()
+                             << LL_ENDL;
+    // trying to dereference ("resolve") the future makes us wait for it
+    LLSD value(*future);
+    LL_DEBUGS("lleventcoro") << "postAndWait(): coroutine " << listenerName
+                             << " resuming with " << value << LL_ENDL;
+    // returning should disconnect the connection
+    return value;
+}
+
+/// Wait for the next event on the specified LLEventPump. Pass either the
+/// LLEventPump& or its string name.
+template <typename SELF>
+LLSD waitForEventOn(SELF& self, const LLEventPumpOrPumpName& pump)
+{
+    // This is now a convenience wrapper for postAndWait().
+    return postAndWait(self, LLSD(), LLEventPumpOrPumpName(), pump);
+}
+
+/// return type for two-pump variant of waitForEventOn()
+typedef std::pair<LLSD, int> LLEventWithID;
+
+namespace LLEventDetail
+{
+    /**
+     * This helper is specifically for the two-pump version of waitForEventOn().
+     * We use a single future object, but we want to listen on two pumps with it.
+     * Since we must still adapt from (the callable constructed by)
+     * boost::coroutines::make_callback() (void return) to provide an event
+     * listener (bool return), we've adapted LLVoidListener for the purpose. The
+     * basic idea is that we construct a distinct instance of WaitForEventOnHelper
+     * -- binding different instance data -- for each of the pumps. Then, when a
+     * pump delivers an LLSD value to either WaitForEventOnHelper, it can combine
+     * that LLSD with its discriminator to feed the future object.
+     */
+    template <typename LISTENER>
+    class WaitForEventOnHelper
+    {
+    public:
+        WaitForEventOnHelper(const LISTENER& listener, int discriminator):
+            mListener(listener),
+            mDiscrim(discriminator)
+        {}
+        // this signature is required for an LLEventPump listener
+        bool operator()(const LLSD& event)
+        {
+            // our future object is defined to accept LLEventWithID
+            mListener(LLEventWithID(event, mDiscrim));
+            // don't swallow the event, let other listeners see it
+            return false;
+        }
+    private:
+        LISTENER mListener;
+        const int mDiscrim;
+    };
+
+    /// WaitForEventOnHelper type-inference helper
+    template <typename LISTENER>
+    WaitForEventOnHelper<LISTENER> wfeoh(const LISTENER& listener, int discriminator)
+    {
+        return WaitForEventOnHelper<LISTENER>(listener, discriminator);
+    }
+} // namespace LLEventDetail
+
+/**
+ * This function waits for a reply on either of two specified LLEventPumps.
+ * Otherwise, it closely resembles postAndWait(); please see the documentation
+ * for that function for detailed parameter info.
+ *
+ * While we could have implemented the single-pump variant in terms of this
+ * one, there's enough added complexity here to make it worthwhile to give the
+ * single-pump variant its own straightforward implementation. Conversely,
+ * though we could use preprocessor logic to generate n-pump overloads up to
+ * BOOST_COROUTINE_WAIT_MAX, we don't foresee a use case. This two-pump
+ * overload exists because certain event APIs are defined in terms of a reply
+ * LLEventPump and an error LLEventPump.
+ *
+ * The LLEventWithID return value provides not only the received event, but
+ * the index of the pump on which it arrived (0 or 1).
+ *
+ * @note
+ * I'd have preferred to overload the name postAndWait() for both signatures.
+ * But consider the following ambiguous call:
+ * @code
+ * postAndWait(self, LLSD(), requestPump, replyPump, "someString");
+ * @endcode
+ * "someString" could be converted to either LLSD (@a replyPumpNamePath for
+ * the single-pump function) or LLEventOrPumpName (@a replyPump1 for two-pump
+ * function).
+ *
+ * It seems less burdensome to write postAndWait2() than to write either
+ * LLSD("someString") or LLEventOrPumpName("someString").
+ */
+template <typename SELF>
+LLEventWithID postAndWait2(SELF& self, const LLSD& event,
+                           const LLEventPumpOrPumpName& requestPump,
+                           const LLEventPumpOrPumpName& replyPump0,
+                           const LLEventPumpOrPumpName& replyPump1,
+                           const LLSD& replyPump0NamePath=LLSD(),
+                           const LLSD& replyPump1NamePath=LLSD())
+{
+    // declare the future
+    boost::coroutines::future<LLEventWithID> future(self);
+    // either callback will assign a value to this future; listen on
+    // each specified LLEventPump with a callback
+    std::string name(LLEventDetail::listenerNameForCoro(&self));
+    LLTempBoundListener connection0(
+        replyPump0.getPump().listen(name + "a",
+                               LLEventDetail::wfeoh(boost::coroutines::make_callback(future), 0)));
+    LLTempBoundListener connection1(
+        replyPump1.getPump().listen(name + "b",
+                               LLEventDetail::wfeoh(boost::coroutines::make_callback(future), 1)));
+    // skip the "post" part if requestPump is default-constructed
+    if (requestPump)
+    {
+        // If either replyPumpNamePath is non-empty, store the corresponding
+        // replyPump name in the request event.
+        LLSD modevent(event);
+        LLEventDetail::storeToLLSDPath(modevent, replyPump0NamePath,
+                                       replyPump0.getPump().getName());
+        LLEventDetail::storeToLLSDPath(modevent, replyPump1NamePath,
+                                       replyPump1.getPump().getName());
+        LL_DEBUGS("lleventcoro") << "postAndWait2(): coroutine " << name
+                                 << " posting to " << requestPump.getPump().getName()
+                                 << ": " << modevent << LL_ENDL;
+        requestPump.getPump().post(modevent);
+    }
+    LL_DEBUGS("lleventcoro") << "postAndWait2(): coroutine " << name
+                             << " about to wait on LLEventPumps " << replyPump0.getPump().getName()
+                             << ", " << replyPump1.getPump().getName() << LL_ENDL;
+    // trying to dereference ("resolve") the future makes us wait for it
+    LLEventWithID value(*future);
+    LL_DEBUGS("lleventcoro") << "postAndWait(): coroutine " << name
+                             << " resuming with (" << value.first << ", " << value.second << ")"
+                             << LL_ENDL;
+    // returning should disconnect both connections
+    return value;
+}
+
+/**
+ * Wait for the next event on either of two specified LLEventPumps.
+ */
+template <typename SELF>
+LLEventWithID
+waitForEventOn(SELF& self,
+               const LLEventPumpOrPumpName& pump0, const LLEventPumpOrPumpName& pump1)
+{
+    // This is now a convenience wrapper for postAndWait2().
+    return postAndWait2(self, LLSD(), LLEventPumpOrPumpName(), pump0, pump1);
+}
+
+/**
+ * Helper for the two-pump variant of waitForEventOn(), e.g.:
+ *
+ * @code
+ * LLSD reply = errorException(waitForEventOn(self, replyPump, errorPump),
+ *                             "error response from login.cgi");
+ * @endcode
+ *
+ * Examines an LLEventWithID, assuming that the second pump (pump 1) is
+ * listening for an error indication. If the incoming data arrived on pump 1,
+ * throw an LLErrorEvent exception. If the incoming data arrived on pump 0,
+ * just return it. Since a normal return can only be from pump 0, we no longer
+ * need the LLEventWithID's discriminator int; we can just return the LLSD.
+ *
+ * @note I'm not worried about introducing the (fairly generic) name
+ * errorException() into global namespace, because how many other overloads of
+ * the same name are going to accept an LLEventWithID parameter?
+ */
+LLSD errorException(const LLEventWithID& result, const std::string& desc);
+
+/**
+ * Exception thrown by errorException(). We don't call this LLEventError
+ * because it's not an error in event processing: rather, this exception
+ * announces an event that bears error information (for some other API).
+ */
+class LLErrorEvent: public std::runtime_error
+{
+public:
+    LLErrorEvent(const std::string& what, const LLSD& data):
+        std::runtime_error(what),
+        mData(data)
+    {}
+    virtual ~LLErrorEvent() throw() {}
+
+    LLSD getData() const { return mData; }
+
+private:
+    LLSD mData;
+};
+
+/**
+ * Like errorException(), save that this trips a fatal error using LL_ERRS
+ * rather than throwing an exception.
+ */
+LLSD errorLog(const LLEventWithID& result, const std::string& desc);
+
+/**
+ * Certain event APIs require the name of an LLEventPump on which they should
+ * post results. While it works to invent a distinct name and let
+ * LLEventPumps::obtain() instantiate the LLEventPump as a "named singleton,"
+ * in a certain sense it's more robust to instantiate a local LLEventPump and
+ * provide its name instead. This class packages the following idiom:
+ *
+ * 1. Instantiate a local LLCoroEventPump, with an optional name prefix.
+ * 2. Provide its actual name to the event API in question as the name of the
+ *    reply LLEventPump.
+ * 3. Initiate the request to the event API.
+ * 4. Call your LLEventTempStream's wait() method to wait for the reply.
+ * 5. Let the LLCoroEventPump go out of scope.
+ */
+class LLCoroEventPump
+{
+public:
+    LLCoroEventPump(const std::string& name="coro"):
+        mPump(name, true)           // allow tweaking the pump instance name
+    {}
+    /// It's typical to request the LLEventPump name to direct an event API to
+    /// send its response to this pump.
+    std::string getName() const { return mPump.getName(); }
+    /// Less typically, we'd request the pump itself for some reason.
+    LLEventPump& getPump() { return mPump; }
+
+    /**
+     * Wait for an event on this LLEventPump.
+     *
+     * @note
+     * The other major usage pattern we considered was to bind @c self at
+     * LLCoroEventPump construction time, which would avoid passing the
+     * parameter to each wait() call. But if we were going to bind @c self as
+     * a class member, we'd need to specify a class template parameter
+     * indicating its type. The big advantage of passing it to the wait() call
+     * is that the type can be implicit.
+     */
+    template <typename SELF>
+    LLSD wait(SELF& self)
+    {
+        return waitForEventOn(self, mPump);
+    }
+
+    template <typename SELF>
+    LLSD postAndWait(SELF& self, const LLSD& event, const LLEventPumpOrPumpName& requestPump,
+                     const LLSD& replyPumpNamePath=LLSD())
+    {
+        return ::postAndWait(self, event, requestPump, mPump, replyPumpNamePath);
+    }
+
+private:
+    LLEventStream mPump;
+};
+
+/**
+ * Other event APIs require the names of two different LLEventPumps: one for
+ * success response, the other for error response. Extend LLCoroEventPump
+ * for the two-pump use case.
+ */
+class LLCoroEventPumps
+{
+public:
+    LLCoroEventPumps(const std::string& name="coro",
+                     const std::string& suff0="Reply",
+                     const std::string& suff1="Error"):
+        mPump0(name + suff0, true),   // allow tweaking the pump instance name
+        mPump1(name + suff1, true)
+    {}
+    /// request pump 0's name
+    std::string getName0() const { return mPump0.getName(); }
+    /// request pump 1's name
+    std::string getName1() const { return mPump1.getName(); }
+    /// request both names
+    std::pair<std::string, std::string> getNames() const
+    {
+        return std::pair<std::string, std::string>(mPump0.getName(), mPump1.getName());
+    }
+
+    /// request pump 0
+    LLEventPump& getPump0() { return mPump0; }
+    /// request pump 1
+    LLEventPump& getPump1() { return mPump1; }
+
+    /// waitForEventOn(self, either of our two LLEventPumps)
+    template <typename SELF>
+    LLEventWithID wait(SELF& self)
+    {
+        return waitForEventOn(self, mPump0, mPump1);
+    }
+
+    /// errorException(wait(self))
+    template <typename SELF>
+    LLSD waitWithException(SELF& self)
+    {
+        return errorException(wait(self), std::string("Error event on ") + getName1());
+    }
+
+    /// errorLog(wait(self))
+    template <typename SELF>
+    LLSD waitWithLog(SELF& self)
+    {
+        return errorLog(wait(self), std::string("Error event on ") + getName1());
+    }
+
+    template <typename SELF>
+    LLEventWithID postAndWait(SELF& self, const LLSD& event,
+                              const LLEventPumpOrPumpName& requestPump,
+                              const LLSD& replyPump0NamePath=LLSD(),
+                              const LLSD& replyPump1NamePath=LLSD())
+    {
+        return postAndWait2(self, event, requestPump, mPump0, mPump1,
+                            replyPump0NamePath, replyPump1NamePath);
+    }
+
+    template <typename SELF>
+    LLSD postAndWaitWithException(SELF& self, const LLSD& event,
+                                  const LLEventPumpOrPumpName& requestPump,
+                                  const LLSD& replyPump0NamePath=LLSD(),
+                                  const LLSD& replyPump1NamePath=LLSD())
+    {
+        return errorException(postAndWait(self, event, requestPump,
+                                          replyPump0NamePath, replyPump1NamePath),
+                              std::string("Error event on ") + getName1());
+    }
+
+    template <typename SELF>
+    LLSD postAndWaitWithLog(SELF& self, const LLSD& event,
+                            const LLEventPumpOrPumpName& requestPump,
+                            const LLSD& replyPump0NamePath=LLSD(),
+                            const LLSD& replyPump1NamePath=LLSD())
+    {
+        return errorLog(postAndWait(self, event, requestPump,
+                                    replyPump0NamePath, replyPump1NamePath),
+                        std::string("Error event on ") + getName1());
+    }
+
+private:
+    LLEventStream mPump0, mPump1;
+};
+
+#endif /* ! defined(LL_LLEVENTCORO_H) */
diff --git a/indra/llcommon/lleventfilter.cpp b/indra/llcommon/lleventfilter.cpp
new file mode 100644
index 0000000000..74133781be
--- /dev/null
+++ b/indra/llcommon/lleventfilter.cpp
@@ -0,0 +1,149 @@
+/**
+ * @file   lleventfilter.cpp
+ * @author Nat Goodspeed
+ * @date   2009-03-05
+ * @brief  Implementation for lleventfilter.
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "lleventfilter.h"
+// STL headers
+// std headers
+// external library headers
+#include <boost/bind.hpp>
+// other Linden headers
+#include "llerror.h"                // LL_ERRS
+#include "llsdutil.h"               // llsd_matches()
+
+LLEventFilter::LLEventFilter(LLEventPump& source, const std::string& name, bool tweak):
+    LLEventStream(name, tweak)
+{
+    source.listen(getName(), boost::bind(&LLEventFilter::post, this, _1));
+}
+
+LLEventMatching::LLEventMatching(const LLSD& pattern):
+    LLEventFilter("matching"),
+    mPattern(pattern)
+{
+}
+
+LLEventMatching::LLEventMatching(LLEventPump& source, const LLSD& pattern):
+    LLEventFilter(source, "matching"),
+    mPattern(pattern)
+{
+}
+
+bool LLEventMatching::post(const LLSD& event)
+{
+    if (! llsd_matches(mPattern, event).empty())
+        return false;
+
+    return LLEventStream::post(event);
+}
+
+LLEventTimeoutBase::LLEventTimeoutBase():
+    LLEventFilter("timeout")
+{
+}
+
+LLEventTimeoutBase::LLEventTimeoutBase(LLEventPump& source):
+    LLEventFilter(source, "timeout")
+{
+}
+
+void LLEventTimeoutBase::actionAfter(F32 seconds, const Action& action)
+{
+    setCountdown(seconds);
+    mAction = action;
+    if (! mMainloop.connected())
+    {
+        LLEventPump& mainloop(LLEventPumps::instance().obtain("mainloop"));
+        mMainloop = mainloop.listen(getName(), boost::bind(&LLEventTimeoutBase::tick, this, _1));
+    }
+}
+
+class ErrorAfter
+{
+public:
+    ErrorAfter(const std::string& message): mMessage(message) {}
+
+    void operator()()
+    {
+        LL_ERRS("LLEventTimeout") << mMessage << LL_ENDL;
+    }
+
+private:
+    std::string mMessage;
+};
+
+void LLEventTimeoutBase::errorAfter(F32 seconds, const std::string& message)
+{
+    actionAfter(seconds, ErrorAfter(message));
+}
+
+class EventAfter
+{
+public:
+    EventAfter(LLEventPump& pump, const LLSD& event):
+        mPump(pump),
+        mEvent(event)
+    {}
+
+    void operator()()
+    {
+        mPump.post(mEvent);
+    }
+
+private:
+    LLEventPump& mPump;
+    LLSD mEvent;
+};
+
+void LLEventTimeoutBase::eventAfter(F32 seconds, const LLSD& event)
+{
+    actionAfter(seconds, EventAfter(*this, event));
+}
+
+bool LLEventTimeoutBase::post(const LLSD& event)
+{
+    cancel();
+    return LLEventStream::post(event);
+}
+
+void LLEventTimeoutBase::cancel()
+{
+    mMainloop.disconnect();
+}
+
+bool LLEventTimeoutBase::tick(const LLSD&)
+{
+    if (countdownElapsed())
+    {
+        cancel();
+        mAction();
+    }
+    return false;                   // show event to other listeners
+}
+
+LLEventTimeout::LLEventTimeout() {}
+
+LLEventTimeout::LLEventTimeout(LLEventPump& source):
+    LLEventTimeoutBase(source)
+{
+}
+
+void LLEventTimeout::setCountdown(F32 seconds)
+{
+    mTimer.setTimerExpirySec(seconds);
+}
+
+bool LLEventTimeout::countdownElapsed() const
+{
+    return mTimer.hasExpired();
+}
diff --git a/indra/llcommon/lleventfilter.h b/indra/llcommon/lleventfilter.h
new file mode 100644
index 0000000000..fe1a631c6b
--- /dev/null
+++ b/indra/llcommon/lleventfilter.h
@@ -0,0 +1,186 @@
+/**
+ * @file   lleventfilter.h
+ * @author Nat Goodspeed
+ * @date   2009-03-05
+ * @brief  Define LLEventFilter: LLEventStream subclass with conditions
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLEVENTFILTER_H)
+#define LL_LLEVENTFILTER_H
+
+#include "llevents.h"
+#include "stdtypes.h"
+#include "lltimer.h"
+#include <boost/function.hpp>
+
+/**
+ * Generic base class
+ */
+class LLEventFilter: public LLEventStream
+{
+public:
+    /// construct a standalone LLEventFilter
+    LLEventFilter(const std::string& name="filter", bool tweak=true):
+        LLEventStream(name, tweak)
+    {}
+    /// construct LLEventFilter and connect it to the specified LLEventPump
+    LLEventFilter(LLEventPump& source, const std::string& name="filter", bool tweak=true);
+
+    /// Post an event to all listeners
+    virtual bool post(const LLSD& event) = 0;
+};
+
+/**
+ * Pass through only events matching a specified pattern
+ */
+class LLEventMatching: public LLEventFilter
+{
+public:
+    /// Pass an LLSD map with keys and values the incoming event must match
+    LLEventMatching(const LLSD& pattern);
+    /// instantiate and connect
+    LLEventMatching(LLEventPump& source, const LLSD& pattern);
+
+    /// Only pass through events matching the pattern
+    virtual bool post(const LLSD& event);
+
+private:
+    LLSD mPattern;
+};
+
+/**
+ * Wait for an event to be posted. If no such event arrives within a specified
+ * time, take a specified action. See LLEventTimeout for production
+ * implementation.
+ *
+ * @NOTE This is an abstract base class so that, for testing, we can use an
+ * alternate "timer" that doesn't actually consume real time.
+ */
+class LLEventTimeoutBase: public LLEventFilter
+{
+public:
+    /// construct standalone
+    LLEventTimeoutBase();
+    /// construct and connect
+    LLEventTimeoutBase(LLEventPump& source);
+
+    /// Callable, can be constructed with boost::bind()
+    typedef boost::function<void()> Action;
+
+    /**
+     * Start countdown timer for the specified number of @a seconds. Forward
+     * all events. If any event arrives before timer expires, cancel timer. If
+     * no event arrives before timer expires, take specified @a action.
+     *
+     * This is a one-shot timer. Once it has either expired or been canceled,
+     * it is inert until another call to actionAfter().
+     *
+     * Calling actionAfter() while an existing timer is running cheaply
+     * replaces that original timer. Thus, a valid use case is to detect
+     * idleness of some event source by calling actionAfter() on each new
+     * event. A rapid sequence of events will keep the timer from expiring;
+     * the first gap in events longer than the specified timer will fire the
+     * specified Action.
+     *
+     * Any post() call cancels the timer. To be satisfied with only a
+     * particular event, chain on an LLEventMatching that only passes such
+     * events:
+     *
+     * @code
+     * event                                                 ultimate
+     * source ---> LLEventMatching ---> LLEventTimeout  ---> listener
+     * @endcode
+     *
+     * @NOTE
+     * The implementation relies on frequent events on the LLEventPump named
+     * "mainloop".
+     */
+    void actionAfter(F32 seconds, const Action& action);
+
+    /**
+     * Like actionAfter(), but where the desired Action is LL_ERRS
+     * termination. Pass the timeout time and the desired LL_ERRS @a message.
+     *
+     * This method is useful when, for instance, some async API guarantees an
+     * event, whether success or failure, within a stated time window.
+     * Instantiate an LLEventTimeout listening to that API and call
+     * errorAfter() on each async request with a timeout comfortably longer
+     * than the API's time guarantee (much longer than the anticipated
+     * "mainloop" granularity).
+     *
+     * Then if the async API breaks its promise, the program terminates with
+     * the specified LL_ERRS @a message. The client of the async API can
+     * therefore assume the guarantee is upheld.
+     *
+     * @NOTE
+     * errorAfter() is implemented in terms of actionAfter(), so all remarks
+     * about calling actionAfter() also apply to errorAfter().
+     */
+    void errorAfter(F32 seconds, const std::string& message);
+
+    /**
+     * Like actionAfter(), but where the desired Action is a particular event
+     * for all listeners. Pass the timeout time and the desired @a event data.
+     * 
+     * Suppose the timeout should only be satisfied by a particular event, but
+     * the ultimate listener must see all other incoming events as well, plus
+     * the timeout @a event if any:
+     * 
+     * @code
+     * some        LLEventMatching                           LLEventMatching
+     * event  ---> for particular  ---> LLEventTimeout  ---> for timeout
+     * source      event                                     event \
+     *       \                                                      \ ultimate
+     *        `-----------------------------------------------------> listener
+     * @endcode
+     * 
+     * Since a given listener can listen on more than one LLEventPump, we can
+     * set things up so it sees the set union of events from LLEventTimeout
+     * and the original event source. However, as LLEventTimeout passes
+     * through all incoming events, the "particular event" that satisfies the
+     * left LLEventMatching would reach the ultimate listener twice. So we add
+     * an LLEventMatching that only passes timeout events.
+     *
+     * @NOTE
+     * eventAfter() is implemented in terms of actionAfter(), so all remarks
+     * about calling actionAfter() also apply to eventAfter().
+     */
+    void eventAfter(F32 seconds, const LLSD& event);
+
+    /// Pass event through, canceling the countdown timer
+    virtual bool post(const LLSD& event);
+
+    /// Cancel timer without event
+    void cancel();
+
+protected:
+    virtual void setCountdown(F32 seconds) = 0;
+    virtual bool countdownElapsed() const = 0;
+
+private:
+    bool tick(const LLSD&);
+
+    LLBoundListener mMainloop;
+    Action mAction;
+};
+
+/// Production implementation of LLEventTimoutBase
+class LLEventTimeout: public LLEventTimeoutBase
+{
+public:
+    LLEventTimeout();
+    LLEventTimeout(LLEventPump& source);
+
+protected:
+    virtual void setCountdown(F32 seconds);
+    virtual bool countdownElapsed() const;
+
+private:
+    LLTimer mTimer;
+};
+
+#endif /* ! defined(LL_LLEVENTFILTER_H) */
diff --git a/indra/llcommon/llevents.cpp b/indra/llcommon/llevents.cpp
index eb380ba7c8..7e3c6964dc 100644
--- a/indra/llcommon/llevents.cpp
+++ b/indra/llcommon/llevents.cpp
@@ -38,6 +38,7 @@
 #pragma warning (pop)
 #endif
 // other Linden headers
+#include "stringize.h"
 
 /*****************************************************************************
 *   queue_names: specify LLEventPump names that should be instantiated as
@@ -256,6 +257,12 @@ LLEventPump::~LLEventPump()
 // static data member
 const LLEventPump::NameList LLEventPump::empty;
 
+std::string LLEventPump::inventName(const std::string& pfx)
+{
+    static long suffix = 0;
+    return STRINGIZE(pfx << suffix++);
+}
+
 LLBoundListener LLEventPump::listen_impl(const std::string& name, const LLEventListener& listener,
                                          const NameList& after,
                                          const NameList& before)
diff --git a/indra/llcommon/llevents.h b/indra/llcommon/llevents.h
index 2f6515a4cb..20061f09c6 100644
--- a/indra/llcommon/llevents.h
+++ b/indra/llcommon/llevents.h
@@ -19,7 +19,6 @@
 #include <map>
 #include <set>
 #include <vector>
-#include <list>
 #include <deque>
 #include <stdexcept>
 #include <boost/signals2.hpp>
@@ -28,13 +27,9 @@
 #include <boost/enable_shared_from_this.hpp>
 #include <boost/utility.hpp>        // noncopyable
 #include <boost/optional/optional.hpp>
-#include <boost/ptr_container/ptr_vector.hpp>
 #include <boost/visit_each.hpp>
 #include <boost/ref.hpp>            // reference_wrapper
 #include <boost/type_traits/is_pointer.hpp>
-#include <boost/utility/addressof.hpp>
-#include <boost/preprocessor/repetition/enum_params.hpp>
-#include <boost/preprocessor/iteration/local.hpp>
 #include <boost/function.hpp>
 #include <boost/static_assert.hpp>
 #include "llsd.h"
@@ -111,6 +106,9 @@ typedef LLStandardSignal::slot_type LLEventListener;
 /// Result of registering a listener, supports <tt>connected()</tt>,
 /// <tt>disconnect()</tt> and <tt>blocked()</tt>
 typedef boost::signals2::connection LLBoundListener;
+/// Storing an LLBoundListener in LLTempBoundListener will disconnect the
+/// referenced listener when the LLTempBoundListener instance is destroyed.
+typedef boost::signals2::scoped_connection LLTempBoundListener;
 
 /**
  * A common idiom for event-based code is to accept either a callable --
@@ -255,13 +253,61 @@ namespace LLEventDetail
 } // namespace LLEventDetail
 
 /*****************************************************************************
+*   LLEventTrackable
+*****************************************************************************/
+/**
+ * LLEventTrackable wraps boost::signals2::trackable, which resembles
+ * boost::trackable. Derive your listener class from LLEventTrackable instead,
+ * and use something like
+ * <tt>LLEventPump::listen(boost::bind(&YourTrackableSubclass::method,
+ * instance, _1))</tt>. This will implicitly disconnect when the object
+ * referenced by @c instance is destroyed.
+ *
+ * @note
+ * LLEventTrackable doesn't address a couple of cases:
+ * * Object destroyed during call
+ *   - You enter a slot call in thread A.
+ *   - Thread B destroys the object, which of course disconnects it from any
+ *     future slot calls.
+ *   - Thread A's call uses 'this', which now refers to a defunct object.
+ *     Undefined behavior results.
+ * * Call during destruction
+ *   - @c MySubclass is derived from LLEventTrackable.
+ *   - @c MySubclass registers one of its own methods using
+ *     <tt>LLEventPump::listen()</tt>.
+ *   - The @c MySubclass object begins destruction. <tt>~MySubclass()</tt>
+ *     runs, destroying state specific to the subclass. (For instance, a
+ *     <tt>Foo*</tt> data member is <tt>delete</tt>d but not zeroed.)
+ *   - The listening method will not be disconnected until
+ *     <tt>~LLEventTrackable()</tt> runs.
+ *   - Before we get there, another thread posts data to the @c LLEventPump
+ *     instance, calling the @c MySubclass method.
+ *   - The method in question relies on valid @c MySubclass state. (For
+ *     instance, it attempts to dereference the <tt>Foo*</tt> pointer that was
+ *     <tt>delete</tt>d but not zeroed.)
+ *   - Undefined behavior results.
+ * If you suspect you may encounter any such scenario, you're better off
+ * managing the lifespan of your object with <tt>boost::shared_ptr</tt>.
+ * Passing <tt>LLEventPump::listen()</tt> a <tt>boost::bind()</tt> expression
+ * involving a <tt>boost::weak_ptr<Foo></tt> is recognized specially, engaging
+ * thread-safe Boost.Signals2 machinery.
+ */
+typedef boost::signals2::trackable LLEventTrackable;
+
+/*****************************************************************************
 *   LLEventPump
 *****************************************************************************/
 /**
  * LLEventPump is the base class interface through which we access the
  * concrete subclasses LLEventStream and LLEventQueue.
+ *
+ * @NOTE
+ * LLEventPump derives from LLEventTrackable so that when you "chain"
+ * LLEventPump instances together, they will automatically disconnect on
+ * destruction. Please see LLEventTrackable documentation for situations in
+ * which this may be perilous across threads.
  */
-class LLEventPump: boost::noncopyable
+class LLEventPump: public LLEventTrackable
 {
 public:
     /**
@@ -364,10 +410,22 @@ public:
      * themselves. listen() can throw any ListenError; see ListenError
      * subclasses.
      *
-     * If (as is typical) you pass a <tt>boost::bind()</tt> expression,
-     * listen() will inspect the components of that expression. If a bound
-     * object matches any of several cases, the connection will automatically
-     * be disconnected when that object is destroyed.
+     * The listener name must be unique among active listeners for this
+     * LLEventPump, else you get DupListenerName. If you don't care to invent
+     * a name yourself, use inventName(). (I was tempted to recognize e.g. ""
+     * and internally generate a distinct name for that case. But that would
+     * handle badly the scenario in which you want to add, remove, re-add,
+     * etc. the same listener: each new listen() call would necessarily
+     * perform a new dependency sort. Assuming you specify the same
+     * after/before lists each time, using inventName() when you first
+     * instantiate your listener, then passing the same name on each listen()
+     * call, allows us to optimize away the second and subsequent dependency
+     * sorts.
+     *
+     * If (as is typical) you pass a <tt>boost::bind()</tt> expression as @a
+     * listener, listen() will inspect the components of that expression. If a
+     * bound object matches any of several cases, the connection will
+     * automatically be disconnected when that object is destroyed.
      *
      * * You bind a <tt>boost::weak_ptr</tt>.
      * * Binding a <tt>boost::shared_ptr</tt> that way would ensure that the
@@ -429,6 +487,9 @@ public:
     /// query
     virtual bool enabled() const { return mEnabled; }
 
+    /// Generate a distinct name for a listener -- see listen()
+    static std::string inventName(const std::string& pfx="listener");
+
 private:
     friend class LLEventPumps;
     /// flush queued events
@@ -503,48 +564,9 @@ private:
 };
 
 /*****************************************************************************
-*   LLEventTrackable and underpinnings
+*   Underpinnings
 *****************************************************************************/
 /**
- * LLEventTrackable wraps boost::signals2::trackable, which resembles
- * boost::trackable. Derive your listener class from LLEventTrackable instead,
- * and use something like
- * <tt>LLEventPump::listen(boost::bind(&YourTrackableSubclass::method,
- * instance, _1))</tt>. This will implicitly disconnect when the object
- * referenced by @c instance is destroyed.
- *
- * @note
- * LLEventTrackable doesn't address a couple of cases:
- * * Object destroyed during call
- *   - You enter a slot call in thread A.
- *   - Thread B destroys the object, which of course disconnects it from any
- *     future slot calls.
- *   - Thread A's call uses 'this', which now refers to a defunct object.
- *     Undefined behavior results.
- * * Call during destruction
- *   - @c MySubclass is derived from LLEventTrackable.
- *   - @c MySubclass registers one of its own methods using
- *     <tt>LLEventPump::listen()</tt>.
- *   - The @c MySubclass object begins destruction. <tt>~MySubclass()</tt>
- *     runs, destroying state specific to the subclass. (For instance, a
- *     <tt>Foo*</tt> data member is <tt>delete</tt>d but not zeroed.)
- *   - The listening method will not be disconnected until
- *     <tt>~LLEventTrackable()</tt> runs.
- *   - Before we get there, another thread posts data to the @c LLEventPump
- *     instance, calling the @c MySubclass method.
- *   - The method in question relies on valid @c MySubclass state. (For
- *     instance, it attempts to dereference the <tt>Foo*</tt> pointer that was
- *     <tt>delete</tt>d but not zeroed.)
- *   - Undefined behavior results.
- * If you suspect you may encounter any such scenario, you're better off
- * managing the lifespan of your object with <tt>boost::shared_ptr</tt>.
- * Passing <tt>LLEventPump::listen()</tt> a <tt>boost::bind()</tt> expression
- * involving a <tt>boost::weak_ptr<Foo></tt> is recognized specially, engaging
- * thread-safe Boost.Signals2 machinery.
- */
-typedef boost::signals2::trackable LLEventTrackable;
-
-/**
  * We originally provided a suite of overloaded
  * LLEventTrackable::listenTo(LLEventPump&, ...) methods that would call
  * LLEventPump::listen(...) and then pass the returned LLBoundListener to
diff --git a/indra/llcommon/llsdutil.cpp b/indra/llcommon/llsdutil.cpp
index 0202a033c3..643720cebe 100644
--- a/indra/llcommon/llsdutil.cpp
+++ b/indra/llcommon/llsdutil.cpp
@@ -46,6 +46,11 @@
 #endif
 
 #include "llsdserialize.h"
+#include "stringize.h"
+
+#include <map>
+#include <set>
+#include <boost/range.hpp>
 
 // U32
 LLSD ll_sd_from_U32(const U32 val)
@@ -313,3 +318,261 @@ BOOL compare_llsd_with_template(
 
 	return TRUE;
 }
+
+/*****************************************************************************
+*   Helpers for llsd_matches()
+*****************************************************************************/
+// raw data used for LLSD::Type lookup
+struct Data
+{
+    LLSD::Type type;
+    const char* name;
+} typedata[] =
+{
+#define def(type) { LLSD::type, #type + 4 }
+    def(TypeUndefined),
+    def(TypeBoolean),
+    def(TypeInteger),
+    def(TypeReal),
+    def(TypeString),
+    def(TypeUUID),
+    def(TypeDate),
+    def(TypeURI),
+    def(TypeBinary),
+    def(TypeMap),
+    def(TypeArray)
+#undef  def
+};
+
+// LLSD::Type lookup class into which we load the above static data
+class TypeLookup
+{
+    typedef std::map<LLSD::Type, std::string> MapType;
+
+public:
+    TypeLookup()
+    {
+        for (const Data *di(boost::begin(typedata)), *dend(boost::end(typedata)); di != dend; ++di)
+        {
+            mMap[di->type] = di->name;
+        }
+    }
+
+    std::string lookup(LLSD::Type type) const
+    {
+        MapType::const_iterator found = mMap.find(type);
+        if (found != mMap.end())
+        {
+            return found->second;
+        }
+        return STRINGIZE("<unknown LLSD type " << type << ">");
+    }
+
+private:
+    MapType mMap;
+};
+
+// static instance of the lookup class
+static const TypeLookup sTypes;
+
+// describe a mismatch; phrasing may want tweaking
+const std::string op(" required instead of ");
+
+// llsd_matches() wants to identify specifically where in a complex prototype
+// structure the mismatch occurred. This entails passing a prefix string,
+// empty for the top-level call. If the prototype contains an array of maps,
+// and the mismatch occurs in the second map in a key 'foo', we want to
+// decorate the returned string with: "[1]['foo']: etc." On the other hand, we
+// want to omit the entire prefix -- including colon -- if the mismatch is at
+// top level. This helper accepts the (possibly empty) recursively-accumulated
+// prefix string, returning either empty or the original string with colon
+// appended.
+static std::string colon(const std::string& pfx)
+{
+    if (pfx.empty())
+        return pfx;
+    return pfx + ": ";
+}
+
+// param type for match_types
+typedef std::vector<LLSD::Type> TypeVector;
+
+// The scalar cases in llsd_matches() use this helper. In most cases, we can
+// accept not only the exact type specified in the prototype, but also other
+// types convertible to the expected type. That implies looping over an array
+// of such types. If the actual type doesn't match any of them, we want to
+// provide a list of acceptable conversions as well as the exact type, e.g.:
+// "Integer (or Boolean, Real, String) required instead of UUID". Both the
+// implementation and the calling logic are simplified by separating out the
+// expected type from the convertible types.
+static std::string match_types(LLSD::Type expect, // prototype.type()
+                               const TypeVector& accept, // types convertible to that type
+                               LLSD::Type actual,        // type we're checking
+                               const std::string& pfx)   // as for llsd_matches
+{
+    // Trivial case: if the actual type is exactly what we expect, we're good.
+    if (actual == expect)
+        return "";
+
+    // For the rest of the logic, build up a suitable error string as we go so
+    // we only have to make a single pass over the list of acceptable types.
+    // If we detect success along the way, we'll simply discard the partial
+    // error string.
+    std::ostringstream out;
+    out << colon(pfx) << sTypes.lookup(expect);
+
+    // If there are any convertible types, append that list.
+    if (! accept.empty())
+    {
+        out << " (";
+        const char* sep = "or ";
+        for (TypeVector::const_iterator ai(accept.begin()), aend(accept.end());
+             ai != aend; ++ai, sep = ", ")
+        {
+            // Don't forget to return success if we match any of those types...
+            if (actual == *ai)
+                return "";
+            out << sep << sTypes.lookup(*ai);
+        }
+        out << ')';
+    }
+    // If we got this far, it's because 'actual' was not one of the acceptable
+    // types, so we must return an error. 'out' already contains colon(pfx)
+    // and the formatted list of acceptable types, so just append the mismatch
+    // phrase and the actual type.
+    out << op << sTypes.lookup(actual);
+    return out.str();
+}
+
+// see docstring in .h file
+std::string llsd_matches(const LLSD& prototype, const LLSD& data, const std::string& pfx)
+{
+    // An undefined prototype means that any data is valid.
+    // An undefined slot in an array or map prototype means that any data
+    // may fill that slot.
+    if (prototype.isUndefined())
+        return "";
+    // A prototype array must match a data array with at least as many
+    // entries. Moreover, every prototype entry must match the
+    // corresponding data entry.
+    if (prototype.isArray())
+    {
+        if (! data.isArray())
+        {
+            return STRINGIZE(colon(pfx) << "Array" << op << sTypes.lookup(data.type()));
+        }
+        if (data.size() < prototype.size())
+        {
+            return STRINGIZE(colon(pfx) << "Array size " << prototype.size() << op
+                             << "Array size " << data.size());
+        }
+        for (LLSD::Integer i = 0; i < prototype.size(); ++i)
+        {
+            std::string match(llsd_matches(prototype[i], data[i], STRINGIZE('[' << i << ']')));
+            if (! match.empty())
+            {
+                return match;
+            }
+        }
+        return "";
+    }
+    // A prototype map must match a data map. Every key in the prototype
+    // must have a corresponding key in the data map; every value in the
+    // prototype must match the corresponding key's value in the data.
+    if (prototype.isMap())
+    {
+        if (! data.isMap())
+        {
+            return STRINGIZE(colon(pfx) << "Map" << op << sTypes.lookup(data.type()));
+        }
+        // If there are a number of keys missing from the data, it would be
+        // frustrating to a coder to discover them one at a time, with a big
+        // build each time. Enumerate all missing keys.
+        std::ostringstream out;
+        out << colon(pfx);
+        const char* init = "Map missing keys: ";
+        const char* sep = init;
+        for (LLSD::map_const_iterator mi = prototype.beginMap(); mi != prototype.endMap(); ++mi)
+        {
+            if (! data.has(mi->first))
+            {
+                out << sep << mi->first;
+                sep = ", ";
+            }
+        }
+        // So... are we missing any keys?
+        if (sep != init)
+        {
+            return out.str();
+        }
+        // Good, the data block contains all the keys required by the
+        // prototype. Now match the prototype entries.
+        for (LLSD::map_const_iterator mi2 = prototype.beginMap(); mi2 != prototype.endMap(); ++mi2)
+        {
+            std::string match(llsd_matches(mi2->second, data[mi2->first],
+                                           STRINGIZE("['" << mi2->first << "']")));
+            if (! match.empty())
+            {
+                return match;
+            }
+        }
+        return "";
+    }
+    // A String prototype can match String, Boolean, Integer, Real, UUID,
+    // Date and URI, because any of these can be converted to String.
+    if (prototype.isString())
+    {
+        static LLSD::Type accept[] =
+        {
+            LLSD::TypeBoolean,
+            LLSD::TypeInteger,
+            LLSD::TypeReal,
+            LLSD::TypeUUID,
+            LLSD::TypeDate,
+            LLSD::TypeURI
+        };
+        return match_types(prototype.type(),
+                           TypeVector(boost::begin(accept), boost::end(accept)),
+                           data.type(),
+                           pfx);
+    }
+    // Boolean, Integer, Real match each other or String. TBD: ensure that
+    // a String value is numeric.
+    if (prototype.isBoolean() || prototype.isInteger() || prototype.isReal())
+    {
+        static LLSD::Type all[] =
+        {
+            LLSD::TypeBoolean,
+            LLSD::TypeInteger,
+            LLSD::TypeReal,
+            LLSD::TypeString
+        };
+        // Funny business: shuffle the set of acceptable types to include all
+        // but the prototype's type. Get the acceptable types in a set.
+        std::set<LLSD::Type> rest(boost::begin(all), boost::end(all));
+        // Remove the prototype's type because we pass that separately.
+        rest.erase(prototype.type());
+        return match_types(prototype.type(),
+                           TypeVector(rest.begin(), rest.end()),
+                           data.type(),
+                           pfx);
+    }
+    // UUID, Date and URI match themselves or String.
+    if (prototype.isUUID() || prototype.isDate() || prototype.isURI())
+    {
+        static LLSD::Type accept[] =
+        {
+            LLSD::TypeString
+        };
+        return match_types(prototype.type(),
+                           TypeVector(boost::begin(accept), boost::end(accept)),
+                           data.type(),
+                           pfx);
+    }
+    // We don't yet know the conversion semantics associated with any new LLSD
+    // data type that might be added, so until we've been extended to handle
+    // them, assume it's strict: the new type matches only itself. (This is
+    // true of Binary, which is why we don't handle that case separately.) Too
+    // bad LLSD doesn't define isConvertible(Type to, Type from).
+    return match_types(prototype.type(), TypeVector(), data.type(), pfx);
+}
diff --git a/indra/llcommon/llsdutil.h b/indra/llcommon/llsdutil.h
index 501600f1d9..0752f8aff1 100644
--- a/indra/llcommon/llsdutil.h
+++ b/indra/llcommon/llsdutil.h
@@ -104,6 +104,61 @@ BOOL compare_llsd_with_template(
 	const LLSD& template_llsd,
 	LLSD& resultant_llsd);
 
+/**
+ * Recursively determine whether a given LLSD data block "matches" another
+ * LLSD prototype. The returned string is empty() on success, non-empty() on
+ * mismatch.
+ *
+ * This function tests structure (types) rather than data values. It is
+ * intended for when a consumer expects an LLSD block with a particular
+ * structure, and must succinctly detect whether the arriving block is
+ * well-formed. For instance, a test of the form:
+ * @code
+ * if (! (data.has("request") && data.has("target") && data.has("modifier") ...))
+ * @endcode
+ * could instead be expressed by initializing a prototype LLSD map with the
+ * required keys and writing:
+ * @code
+ * if (! llsd_matches(prototype, data).empty())
+ * @endcode
+ *
+ * A non-empty return value is an error-message fragment intended to indicate
+ * to (English-speaking) developers where in the prototype structure the
+ * mismatch occurred.
+ *
+ * * If a slot in the prototype isUndefined(), then anything is valid at that
+ *   place in the real object. (Passing prototype == LLSD() matches anything
+ *   at all.)
+ * * An array in the prototype must match a data array at least that large.
+ *   (Additional entries in the data array are ignored.) Every isDefined()
+ *   entry in the prototype array must match the corresponding entry in the
+ *   data array.
+ * * A map in the prototype must match a map in the data. Every key in the
+ *   prototype map must match a corresponding key in the data map. (Additional
+ *   keys in the data map are ignored.) Every isDefined() value in the
+ *   prototype map must match the corresponding key's value in the data map.
+ * * Scalar values in the prototype are tested for @em type rather than value.
+ *   For instance, a String in the prototype matches any String at all. In
+ *   effect, storing an Integer at a particular place in the prototype asserts
+ *   that the caller intends to apply asInteger() to the corresponding slot in
+ *   the data.
+ * * A String in the prototype matches String, Boolean, Integer, Real, UUID,
+ *   Date and URI, because asString() applied to any of these produces a
+ *   meaningful result.
+ * * Similarly, a Boolean, Integer or Real in the prototype can match any of
+ *   Boolean, Integer or Real in the data -- or even String.
+ * * UUID matches UUID or String.
+ * * Date matches Date or String.
+ * * URI matches URI or String.
+ * * Binary in the prototype matches only Binary in the data.
+ *
+ * @TODO: when a Boolean, Integer or Real in the prototype matches a String in
+ * the data, we should examine the String @em value to ensure it can be
+ * meaningfully converted to the requested type. The same goes for UUID, Date
+ * and URI.
+ */
+std::string llsd_matches(const LLSD& prototype, const LLSD& data, const std::string& pfx="");
+
 // Simple function to copy data out of input & output iterators if
 // there is no need for casting.
 template<typename Input> LLSD llsd_copy_array(Input iter, Input end)
diff --git a/indra/llcommon/tests/listener.h b/indra/llcommon/tests/listener.h
new file mode 100644
index 0000000000..fa12f944ef
--- /dev/null
+++ b/indra/llcommon/tests/listener.h
@@ -0,0 +1,139 @@
+/**
+ * @file   listener.h
+ * @author Nat Goodspeed
+ * @date   2009-03-06
+ * @brief  Useful for tests of the LLEventPump family of classes
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LISTENER_H)
+#define LL_LISTENER_H
+
+#include "llsd.h"
+#include <iostream>
+
+/*****************************************************************************
+*   test listener class
+*****************************************************************************/
+class Listener;
+std::ostream& operator<<(std::ostream&, const Listener&);
+
+/// Bear in mind that this is strictly for testing
+class Listener
+{
+public:
+    /// Every Listener is instantiated with a name
+    Listener(const std::string& name):
+        mName(name)
+    {
+//      std::cout << *this << ": ctor\n";
+    }
+/*==========================================================================*|
+    // These methods are only useful when trying to track Listener instance
+    // lifespan
+    Listener(const Listener& that):
+        mName(that.mName),
+        mLastEvent(that.mLastEvent)
+    {
+        std::cout << *this << ": copy\n";
+    }
+    virtual ~Listener()
+    {
+        std::cout << *this << ": dtor\n";
+    }
+|*==========================================================================*/
+    /// You can request the name
+    std::string getName() const { return mName; }
+    /// This is a typical listener method that returns 'false' when done,
+    /// allowing subsequent listeners on the LLEventPump to process the
+    /// incoming event.
+    bool call(const LLSD& event)
+    {
+//      std::cout << *this << "::call(" << event << ")\n";
+        mLastEvent = event;
+        return false;
+    }
+    /// This is an alternate listener that returns 'true' when done, which
+    /// stops processing of the incoming event.
+    bool callstop(const LLSD& event)
+    {
+//      std::cout << *this << "::callstop(" << event << ")\n";
+        mLastEvent = event;
+        return true;
+    }
+    /// ListenMethod can represent either call() or callstop().
+    typedef bool (Listener::*ListenMethod)(const LLSD&);
+    /**
+     * This helper method is only because our test code makes so many
+     * repetitive listen() calls to ListenerMethods. In real code, you should
+     * call LLEventPump::listen() directly so it can examine the specific
+     * object you pass to boost::bind().
+     */
+    LLBoundListener listenTo(LLEventPump& pump,
+                             ListenMethod method=&Listener::call,
+                             const LLEventPump::NameList& after=LLEventPump::empty,
+                             const LLEventPump::NameList& before=LLEventPump::empty)
+    {
+        return pump.listen(getName(), boost::bind(method, this, _1), after, before);
+    }
+    /// Both call() and callstop() set mLastEvent. Retrieve it.
+    LLSD getLastEvent() const
+    {
+//      std::cout << *this << "::getLastEvent() -> " << mLastEvent << "\n";
+        return mLastEvent;
+    }
+    /// Reset mLastEvent to a known state.
+    void reset(const LLSD& to = LLSD())
+    {
+//      std::cout << *this << "::reset(" << to << ")\n";
+        mLastEvent = to;
+    }
+
+private:
+    std::string mName;
+    LLSD mLastEvent;
+};
+
+std::ostream& operator<<(std::ostream& out, const Listener& listener)
+{
+    out << "Listener(" << listener.getName() /* << "@" << &listener */ << ')';
+    return out;
+}
+
+/**
+ * This class tests the relative order in which various listeners on a given
+ * LLEventPump are called. Each listen() call binds a particular string, which
+ * we collect for later examination. The actual event is ignored.
+ */
+struct Collect
+{
+    bool add(const std::string& bound, const LLSD& event)
+    {
+        result.push_back(bound);
+        return false;
+    }
+    void clear() { result.clear(); }
+    typedef std::vector<std::string> StringList;
+    StringList result;
+};
+
+std::ostream& operator<<(std::ostream& out, const Collect::StringList& strings)
+{
+    out << '(';
+    Collect::StringList::const_iterator begin(strings.begin()), end(strings.end());
+    if (begin != end)
+    {
+        out << '"' << *begin << '"';
+        while (++begin != end)
+        {
+            out << ", \"" << *begin << '"';
+        }
+    }
+    out << ')';
+    return out;
+}
+
+#endif /* ! defined(LL_LISTENER_H) */
diff --git a/indra/llcommon/tests/lleventfilter_test.cpp b/indra/llcommon/tests/lleventfilter_test.cpp
new file mode 100644
index 0000000000..28b909298e
--- /dev/null
+++ b/indra/llcommon/tests/lleventfilter_test.cpp
@@ -0,0 +1,276 @@
+/**
+ * @file   lleventfilter_test.cpp
+ * @author Nat Goodspeed
+ * @date   2009-03-06
+ * @brief  Test for lleventfilter.
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "lleventfilter.h"
+// STL headers
+// std headers
+// external library headers
+// other Linden headers
+#include "../test/lltut.h"
+#include "stringize.h"
+#include "listener.h"
+#include "tests/wrapllerrs.h"
+
+/*****************************************************************************
+*   Test classes
+*****************************************************************************/
+// Strictly speaking, we're testing LLEventTimeoutBase rather than the
+// production LLEventTimeout (using LLTimer) because we don't want every test
+// run to pause for some number of seconds until we reach a real timeout. But
+// as we've carefully put all functionality except actual LLTimer calls into
+// LLEventTimeoutBase, that should suffice. We're not not not trying to test
+// LLTimer here.
+class TestEventTimeout: public LLEventTimeoutBase
+{
+public:
+    TestEventTimeout():
+        mElapsed(true)
+    {}
+    TestEventTimeout(LLEventPump& source):
+        LLEventTimeoutBase(source),
+        mElapsed(true)
+    {}
+
+    // test hook
+    void forceTimeout(bool timeout=true) { mElapsed = timeout; }
+
+protected:
+    virtual void setCountdown(F32 seconds) { mElapsed = false; }
+    virtual bool countdownElapsed() const { return mElapsed; }
+
+private:
+    bool mElapsed;
+};
+
+/*****************************************************************************
+*   TUT
+*****************************************************************************/
+namespace tut
+{
+    struct filter_data
+    {
+        // The resemblance between this test data and that in llevents_tut.cpp
+        // is not coincidental.
+        filter_data():
+            pumps(LLEventPumps::instance()),
+            mainloop(pumps.obtain("mainloop")),
+            listener0("first"),
+            listener1("second")
+        {}
+        LLEventPumps& pumps;
+        LLEventPump& mainloop;
+        Listener listener0;
+        Listener listener1;
+
+        void check_listener(const std::string& desc, const Listener& listener, const LLSD& got)
+        {
+            ensure_equals(STRINGIZE(listener << ' ' << desc),
+                          listener.getLastEvent(), got);
+        }
+    };
+    typedef test_group<filter_data> filter_group;
+    typedef filter_group::object filter_object;
+    filter_group filtergrp("lleventfilter");
+
+    template<> template<>
+    void filter_object::test<1>()
+    {
+        set_test_name("LLEventMatching");
+        LLEventPump& driver(pumps.obtain("driver"));
+        listener0.reset(0);
+        // Listener isn't derived from LLEventTrackable specifically to test
+        // various connection-management mechanisms. But that means we have a
+        // couple of transient Listener objects, one of which is listening to
+        // a persistent LLEventPump. Capture those connections in local
+        // LLTempBoundListener instances so they'll disconnect
+        // on destruction.
+        LLTempBoundListener temp1(
+            listener0.listenTo(driver));
+        // Construct a pattern LLSD: desired Event must have a key "foo"
+        // containing string "bar"
+        LLEventMatching filter(driver, LLSD().insert("foo", "bar"));
+        listener1.reset(0);
+        LLTempBoundListener temp2(
+            listener1.listenTo(filter));
+        driver.post(1);
+        check_listener("direct", listener0, LLSD(1));
+        check_listener("filtered", listener1, LLSD(0));
+        // Okay, construct an LLSD map matching the pattern
+        LLSD data;
+        data["foo"] = "bar";
+        data["random"] = 17;
+        driver.post(data);
+        check_listener("direct", listener0, data);
+        check_listener("filtered", listener1, data);
+    }
+
+    template<> template<>
+    void filter_object::test<2>()
+    {
+        set_test_name("LLEventTimeout::actionAfter()");
+        LLEventPump& driver(pumps.obtain("driver"));
+        TestEventTimeout filter(driver);
+        listener0.reset(0);
+        LLTempBoundListener temp1(
+            listener0.listenTo(filter));
+        // Use listener1.call() as the Action for actionAfter(), since it
+        // already provides a way to sense the call
+        listener1.reset(0);
+        // driver --> filter --> listener0
+        filter.actionAfter(20,
+                           boost::bind(&Listener::call, boost::ref(listener1), LLSD("timeout")));
+        // Okay, (fake) timer is ticking. 'filter' can only sense the timer
+        // when we pump mainloop. Do that right now to take the logic path
+        // before either the anticipated event arrives or the timer expires.
+        mainloop.post(17);
+        check_listener("no timeout 1", listener1, LLSD(0));
+        // Expected event arrives...
+        driver.post(1);
+        check_listener("event passed thru", listener0, LLSD(1));
+        // Should have canceled the timer. Verify that by asserting that the
+        // time has expired, then pumping mainloop again.
+        filter.forceTimeout();
+        mainloop.post(17);
+        check_listener("no timeout 2", listener1, LLSD(0));
+        // Verify chained actionAfter() calls, that is, that a second
+        // actionAfter() resets the timer established by the first
+        // actionAfter().
+        filter.actionAfter(20,
+                           boost::bind(&Listener::call, boost::ref(listener1), LLSD("timeout")));
+        // Since our TestEventTimeout class isn't actually manipulating time
+        // (quantities of seconds), only a bool "elapsed" flag, sense that by
+        // forcing the flag between actionAfter() calls.
+        filter.forceTimeout();
+        // Pumping mainloop here would result in a timeout (as we'll verify
+        // below). This state simulates a ticking timer that has not yet timed
+        // out. But now, before a mainloop event lets 'filter' recognize
+        // timeout on the previous actionAfter() call, pretend we're pushing
+        // that timeout farther into the future.
+        filter.actionAfter(20,
+                           boost::bind(&Listener::call, boost::ref(listener1), LLSD("timeout")));
+        // Look ma, no timeout!
+        mainloop.post(17);
+        check_listener("no timeout 3", listener1, LLSD(0));
+        // Now let the updated actionAfter() timer expire.
+        filter.forceTimeout();
+        // Notice the timeout.
+        mainloop.post(17);
+        check_listener("timeout", listener1, LLSD("timeout"));
+        // Timing out cancels the timer. Verify that.
+        listener1.reset(0);
+        filter.forceTimeout();
+        mainloop.post(17);
+        check_listener("no timeout 4", listener1, LLSD(0));
+        // Reset the timer and then cancel() it.
+        filter.actionAfter(20,
+                           boost::bind(&Listener::call, boost::ref(listener1), LLSD("timeout")));
+        // neither expired nor satisified
+        mainloop.post(17);
+        check_listener("no timeout 5", listener1, LLSD(0));
+        // cancel
+        filter.cancel();
+        // timeout!
+        filter.forceTimeout();
+        mainloop.post(17);
+        check_listener("no timeout 6", listener1, LLSD(0));
+    }
+
+    template<> template<>
+    void filter_object::test<3>()
+    {
+        set_test_name("LLEventTimeout::eventAfter()");
+        LLEventPump& driver(pumps.obtain("driver"));
+        TestEventTimeout filter(driver);
+        listener0.reset(0);
+        LLTempBoundListener temp1(
+            listener0.listenTo(filter));
+        filter.eventAfter(20, LLSD("timeout"));
+        // Okay, (fake) timer is ticking. 'filter' can only sense the timer
+        // when we pump mainloop. Do that right now to take the logic path
+        // before either the anticipated event arrives or the timer expires.
+        mainloop.post(17);
+        check_listener("no timeout 1", listener0, LLSD(0));
+        // Expected event arrives...
+        driver.post(1);
+        check_listener("event passed thru", listener0, LLSD(1));
+        // Should have canceled the timer. Verify that by asserting that the
+        // time has expired, then pumping mainloop again.
+        filter.forceTimeout();
+        mainloop.post(17);
+        check_listener("no timeout 2", listener0, LLSD(1));
+        // Set timer again.
+        filter.eventAfter(20, LLSD("timeout"));
+        // Now let the timer expire.
+        filter.forceTimeout();
+        // Notice the timeout.
+        mainloop.post(17);
+        check_listener("timeout", listener0, LLSD("timeout"));
+        // Timing out cancels the timer. Verify that.
+        listener0.reset(0);
+        filter.forceTimeout();
+        mainloop.post(17);
+        check_listener("no timeout 3", listener0, LLSD(0));
+    }
+
+    template<> template<>
+    void filter_object::test<4>()
+    {
+        set_test_name("LLEventTimeout::errorAfter()");
+        WrapLL_ERRS capture;
+        LLEventPump& driver(pumps.obtain("driver"));
+        TestEventTimeout filter(driver);
+        listener0.reset(0);
+        LLTempBoundListener temp1(
+            listener0.listenTo(filter));
+        filter.errorAfter(20, "timeout");
+        // Okay, (fake) timer is ticking. 'filter' can only sense the timer
+        // when we pump mainloop. Do that right now to take the logic path
+        // before either the anticipated event arrives or the timer expires.
+        mainloop.post(17);
+        check_listener("no timeout 1", listener0, LLSD(0));
+        // Expected event arrives...
+        driver.post(1);
+        check_listener("event passed thru", listener0, LLSD(1));
+        // Should have canceled the timer. Verify that by asserting that the
+        // time has expired, then pumping mainloop again.
+        filter.forceTimeout();
+        mainloop.post(17);
+        check_listener("no timeout 2", listener0, LLSD(1));
+        // Set timer again.
+        filter.errorAfter(20, "timeout");
+        // Now let the timer expire.
+        filter.forceTimeout();
+        // Notice the timeout.
+        std::string threw;
+        try
+        {
+            mainloop.post(17);
+        }
+        catch (const WrapLL_ERRS::FatalException& e)
+        {
+            threw = e.what();
+        }
+        ensure_contains("errorAfter() timeout exception", threw, "timeout");
+        // Timing out cancels the timer. Verify that.
+        listener0.reset(0);
+        filter.forceTimeout();
+        mainloop.post(17);
+        check_listener("no timeout 3", listener0, LLSD(0));
+    }
+} // namespace tut
+
+/*****************************************************************************
+*   Link dependencies
+*****************************************************************************/
+#include "llsdutil.cpp"
diff --git a/indra/llcommon/tests/wrapllerrs.h b/indra/llcommon/tests/wrapllerrs.h
new file mode 100644
index 0000000000..1001ebc466
--- /dev/null
+++ b/indra/llcommon/tests/wrapllerrs.h
@@ -0,0 +1,56 @@
+/**
+ * @file   wrapllerrs.h
+ * @author Nat Goodspeed
+ * @date   2009-03-11
+ * @brief  Define a class useful for unit tests that engage llerrs (LL_ERRS) functionality
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_WRAPLLERRS_H)
+#define LL_WRAPLLERRS_H
+
+#include "llerrorcontrol.h"
+
+struct WrapLL_ERRS
+{
+    WrapLL_ERRS():
+        // Resetting Settings discards the default Recorder that writes to
+        // stderr. Otherwise, expected llerrs (LL_ERRS) messages clutter the
+        // console output of successful tests, potentially confusing things.
+        mPriorErrorSettings(LLError::saveAndResetSettings()),
+        // Save shutdown function called by LL_ERRS
+        mPriorFatal(LLError::getFatalFunction())
+    {
+        // Make LL_ERRS call our own operator() method
+        LLError::setFatalFunction(boost::bind(&WrapLL_ERRS::operator(), this, _1));
+    }
+
+    ~WrapLL_ERRS()
+    {
+        LLError::setFatalFunction(mPriorFatal);
+        LLError::restoreSettings(mPriorErrorSettings);
+    }
+
+    struct FatalException: public std::runtime_error
+    {
+        FatalException(const std::string& what): std::runtime_error(what) {}
+    };
+
+    void operator()(const std::string& message)
+    {
+        // Save message for later in case consumer wants to sense the result directly
+        error = message;
+        // Also throw an appropriate exception since calling code is likely to
+        // assume that control won't continue beyond LL_ERRS.
+        throw FatalException(message);
+    }
+
+    std::string error;
+    LLError::Settings* mPriorErrorSettings;
+    LLError::FatalFunction mPriorFatal;
+};
+
+#endif /* ! defined(LL_WRAPLLERRS_H) */