Reintroduce LLCoros::killreq() to request killing a named coroutine.

Make LLCoros constructor echo "LLApp" status-change events on new "LLCoros"
event pump.

Rename LLCoros::kill() to killreq() because this operation only registers a
request for the named coroutine to terminate next time it calls checkStop().
Add a new CoroData member to record the name of the coroutine requesting
termination. killreq() sets that and also posts "killreq" to "LLCoros".

Add an optional final-cleanup callback to LLCoros::checkStop(). Make
checkStop() check for a pending killreq() request as well as viewer
termination. Introduce new LLCoros::Killed exception for that case.

Introduce LLCoros::getStopListener(), with two overloads, to encapsulate some
of the messy logic to listen (perhaps temporarily) for viewer shutdown. Both
overloads are for use by code at the source end of a queue or promise or other
resource for which coroutines might still be waiting at viewer shutdown time.
One overload is specifically for when the caller knows the name of the one and
only coroutine that will wait on the resource (e.g. because the caller IS that
coroutine). That overload honors killreq().

Use getStopListener() to simplify the four existing places where we set up
such a listener. Add a fifth: also make WorkQueue listen for viewer shutdown
(resolving a TODO comment).

Remove LLLUAmanager::terminateScript(), getTerminationList() and the static
sTerminationList. In the Lua interrupt callback, instead of checking
sTerminationList, call LLCoros::checkStop().

Change LLFloaterLUAScripts terminate-script logic to call LLCoros::killreq()
instead of posting on "LLLua" and calling LLLUAmanager::terminateScript().

Drop LLApp::setStatus() posting to "LLLua" LLEventPump: the above makes that
moot.

1 files changed, 50 insertions, 17 deletions

diff --git a/indra/llcommon/llcoros.h b/indra/llcommon/llcoros.h
index fd878f20ad..61c0fef1c3 100644
--- a/indra/llcommon/llcoros.h
+++ b/indra/llcommon/llcoros.h
@@ -29,17 +29,18 @@
 #if ! defined(LL_LLCOROS_H)
 #define LL_LLCOROS_H
 
+#include "llevents.h"
 #include "llexception.h"
+#include "llinstancetracker.h"
+#include "llsingleton.h"
+#include "mutex.h"
 #include <boost/fiber/fss.hpp>
 #include <boost/fiber/future/promise.hpp>
 #include <boost/fiber/future/future.hpp>
-#include "mutex.h"
-#include "llsingleton.h"
-#include "llinstancetracker.h"
-#include <boost/function.hpp>
-#include <string>
 #include <exception>
+#include <functional>
 #include <queue>
+#include <string>
 
 // e.g. #include LLCOROS_MUTEX_HEADER
 #define LLCOROS_MUTEX_HEADER   <boost/fiber/mutex.hpp>
@@ -101,7 +102,7 @@ public:
     /// stuck with the term "coroutine."
     typedef boost::fibers::fiber coro;
     /// Canonical callable type
-    typedef boost::function<void()> callable_t;
+    typedef std::function<void()> callable_t;
 
     /**
      * Create and start running a new coroutine with specified name. The name
@@ -143,13 +144,13 @@ public:
     std::string launch(const std::string& prefix, const callable_t& callable);
 
     /**
-     * Abort a running coroutine by name. Normally, when a coroutine either
+     * Ask the named coroutine to abort. Normally, when a coroutine either
      * runs to completion or terminates with an exception, LLCoros quietly
      * cleans it up. This is for use only when you must explicitly interrupt
      * one prematurely. Returns @c true if the specified name was found and
      * still running at the time.
      */
-//  bool kill(const std::string& name);
+    bool killreq(const std::string& name);
 
     /**
      * From within a coroutine, look up the (tweaked) name string by which
@@ -251,15 +252,21 @@ public:
     /// thrown by checkStop()
     // It may sound ironic that Stop is derived from LLContinueError, but the
     // point is that LLContinueError is the category of exception that should
-    // not immediately crash the viewer. Stop and its subclasses are to notify
-    // coroutines that the viewer intends to shut down. The expected response
-    // is to terminate the coroutine, rather than abort the viewer.
+    // not immediately crash the viewer. Stop and its subclasses are to tell
+    // coroutines to terminate, e.g. because the viewer is shutting down. We
+    // do not want any such exception to crash the viewer.
     struct Stop: public LLContinueError
     {
         Stop(const std::string& what): LLContinueError(what) {}
     };
 
-    /// early stages
+    /// someone wants to kill this specific coroutine
+    struct Killed: public Stop
+    {
+        Killed(const std::string& what): Stop(what) {}
+    };
+
+    /// early shutdown stages
     struct Stopping: public Stop
     {
         Stopping(const std::string& what): Stop(what) {}
@@ -278,9 +285,31 @@ public:
     };
 
     /// Call this intermittently if there's a chance your coroutine might
-    /// continue running into application shutdown. Throws Stop if LLCoros has
-    /// been cleaned up.
-    static void checkStop();
+    /// still be running at application shutdown. Throws one of the Stop
+    /// subclasses if the caller needs to terminate. Pass a cleanup function
+    /// if you need to execute that cleanup before terminating.
+    /// Of course, if your cleanup function throws, that will be the exception
+    /// propagated by checkStop().
+    static void checkStop(callable_t cleanup={});
+
+    /// Call getStopListener() at the source end of a queue, promise or other
+    /// resource on which coroutines will wait, so that shutdown can wake up
+    /// consuming coroutines. @a caller should distinguish who's calling. The
+    /// passed @a cleanup function must close the queue, break the promise or
+    /// otherwise cause waiting consumers to wake up in an abnormal way. It's
+    /// advisable to store the returned LLBoundListener in an
+    /// LLTempBoundListener, or otherwise arrange to disconnect it.
+    static LLBoundListener getStopListener(const std::string& caller, LLVoidListener cleanup);
+
+    /// This getStopListener() overload is like the two-argument one, for use
+    /// when we know the name of the only coroutine that will wait on the
+    /// resource in question. Pass @a consumer as the empty string if the
+    /// consumer coroutine is the same as the calling coroutine. Unlike the
+    /// two-argument getStopListener(), this one also responds to
+    /// killreq(target).
+    static LLBoundListener getStopListener(const std::string& caller,
+                                           const std::string& consumer,
+                                           LLVoidListener cleanup);
 
     /**
      * Aliases for promise and future. An older underlying future implementation
@@ -312,6 +341,8 @@ private:
     static CoroData& get_CoroData(const std::string& caller);
     void saveException(const std::string& name, std::exception_ptr exc);
 
+    LLTempBoundListener mConn;
+
     struct ExceptionData
     {
         ExceptionData(const std::string& nm, std::exception_ptr exc):
@@ -335,8 +366,10 @@ private:
 
         // tweaked name of the current coroutine
         const std::string mName;
-        // set_consuming() state
-        bool mConsuming;
+        // set_consuming() state -- don't consume events unless specifically directed
+        bool mConsuming{ false };
+        // killed by which coroutine
+        std::string mKilledBy;
         // setStatus() state
         std::string mStatus;
         F64 mCreationTime; // since epoch