5 files changed, 52 insertions, 4 deletions
diff --git a/indra/llcommon/lleventcoro.cpp b/indra/llcommon/lleventcoro.cpp
index 578a2b62c8..2d5f964deb 100755
--- a/indra/llcommon/lleventcoro.cpp
+++ b/indra/llcommon/lleventcoro.cpp
@@ -229,6 +229,28 @@ LLSD llcoro::postAndSuspend(const LLSD& event, const LLEventPumpOrPumpName& requ
     return value;
 }
 
+LLSD llcoro::suspendUntilEventOnWithTimeout(const LLEventPumpOrPumpName& suspendPumpOrName, 
+        F32 timeoutin, const LLSD &timeoutResult)
+{
+    /**
+     * The timeout pump is attached upstream of of the waiting pump and will 
+     * pass the timeout event through it.  We CAN NOT attach downstream since
+     * doing so will cause the suspendPump to fire any waiting events immediately 
+     * and they will be lost.  This becomes especially problematic with the 
+     * LLEventTimeout(pump) constructor which will also attempt to fire those
+     * events using the virtual listen_impl method in the not yet fully constructed
+     * timeoutPump.
+     */
+    LLEventTimeout timeoutPump;
+    LLEventPump &suspendPump = suspendPumpOrName.getPump();
+
+    LLTempBoundListener timeoutListener(timeoutPump.listen(suspendPump.getName(), 
+            boost::bind(&LLEventPump::post, &suspendPump, _1)));
+
+    timeoutPump.eventAfter(timeoutin, timeoutResult);
+    return llcoro::suspendUntilEventOn(suspendPump);
+}
+
 namespace
 {
 
diff --git a/indra/llcommon/lleventcoro.h b/indra/llcommon/lleventcoro.h
index 2105faf861..87926c692d 100755
--- a/indra/llcommon/lleventcoro.h
+++ b/indra/llcommon/lleventcoro.h
@@ -147,6 +147,11 @@ LLSD suspendUntilEventOn(const LLEventPumpOrPumpName& pump)
     return postAndSuspend(LLSD(), LLEventPumpOrPumpName(), pump);
 }
 
+/// Suspend the coroutine until an event is fired on the identified pump
+/// or the timeout duration has elapsed.  If the timeout duration 
+/// elapses the specified LLSD is returned.
+LLSD suspendUntilEventOnWithTimeout(const LLEventPumpOrPumpName& suspendPumpOrName, F32 timeoutin, const LLSD &timeoutResult);
+
 } // namespace llcoro
 
 /// return type for two-pump variant of suspendUntilEventOn()
diff --git a/indra/llcommon/lleventfilter.cpp b/indra/llcommon/lleventfilter.cpp
index d36a107254..64ab58adcd 100755
--- a/indra/llcommon/lleventfilter.cpp
+++ b/indra/llcommon/lleventfilter.cpp
@@ -39,9 +39,9 @@
 #include "llsdutil.h"               // llsd_matches()
 
 LLEventFilter::LLEventFilter(LLEventPump& source, const std::string& name, bool tweak):
-    LLEventStream(name, tweak)
+    LLEventStream(name, tweak),
+    mSource(source.listen(getName(), boost::bind(&LLEventFilter::post, this, _1)))
 {
-    source.listen(getName(), boost::bind(&LLEventFilter::post, this, _1));
 }
 
 LLEventMatching::LLEventMatching(const LLSD& pattern):
diff --git a/indra/llcommon/lleventfilter.h b/indra/llcommon/lleventfilter.h
index e822a664f5..66f3c14869 100755
--- a/indra/llcommon/lleventfilter.h
+++ b/indra/llcommon/lleventfilter.h
@@ -49,6 +49,9 @@ public:
 
     /// Post an event to all listeners
     virtual bool post(const LLSD& event) = 0;
+
+private:
+    LLTempBoundListener mSource;
 };
 
 /**
@@ -181,11 +184,23 @@ protected:
 private:
     bool tick(const LLSD&);
 
-    LLBoundListener mMainloop;
+    LLTempBoundListener mMainloop;
     Action mAction;
 };
 
-/// Production implementation of LLEventTimoutBase
+/**
+ * Production implementation of LLEventTimoutBase.
+ * 
+ * @NOTE: Caution should be taken when using the LLEventTimeout(LLEventPump &) 
+ * constructor to ensure that the upstream event pump is not an LLEventMaildrop
+ * or any other kind of store and forward pump which may have events outstanding.
+ * Using this constructor will cause the upstream event pump to fire any pending
+ * events and could result in the invocation of a virtual method before the timeout
+ * has been fully constructed. The timeout should instead be connected upstream
+ * from the event pump and attached using the listen method.
+ * See llcoro::suspendUntilEventOnWithTimeout() for an example.
+ */
+ 
 class LL_COMMON_API LLEventTimeout: public LLEventTimeoutBase
 {
 public:
diff --git a/indra/llcommon/llevents.h b/indra/llcommon/llevents.h
index 6175329a9d..ba4fcd766e 100755
--- a/indra/llcommon/llevents.h
+++ b/indra/llcommon/llevents.h
@@ -616,6 +616,12 @@ public:
  * a queue. Subsequent attaching listeners will receive stored events from the queue 
  * until a listener indicates that the event has been handled.  In order to receive 
  * multiple events from a mail drop the listener must disconnect and reconnect.
+ * 
+ * @NOTE: When using an LLEventMailDrop (or LLEventQueue) with a LLEventTimeout or
+ * LLEventFilter attaching the filter downstream using Timeout's constructor will
+ * cause the MailDrop to discharge any of it's stored events. The timeout should 
+ * instead be connected upstream using its listen() method.  
+ * See llcoro::suspendUntilEventOnWithTimeout() for an example.
  */
 class LL_COMMON_API LLEventMailDrop : public LLEventStream
 {