DRTVWR-476: Revert "Use LLThreadSafeQueue, not boost::fibers::buffered_channel."

This reverts commit bf8aea50.

Try boost::fibers::buffered_channel again with Boost 1.72.

indra/llmessage/llcoproceduremanager.cpp

@@ -33,7 +33,7 @@
 
 #include <chrono>
 
-#include "llthreadsafequeue.h"
+#include <boost/fiber/buffered_channel.hpp>
 
 #include "llexception.h"
 #include "stringize.h"
@@ -105,7 +105,10 @@ class LLCoprocedurePool: private boost::noncopyable
         CoProcedure_t mProc;
     };
 
-    typedef LLThreadSafeQueue<QueuedCoproc::ptr_t>  CoprocQueue_t;
+    // we use a buffered_channel here rather than unbuffered_channel since we want to be able to 
+    // push values without blocking,even if there's currently no one calling a pop operation (due to
+    // fiber running right now)
+    typedef boost::fibers::buffered_channel<QueuedCoproc::ptr_t>  CoprocQueue_t;
     // Use shared_ptr to control the lifespan of our CoprocQueue_t instance
     // because the consuming coroutine might outlive this LLCoprocedurePool
     // instance.
@@ -321,13 +324,14 @@ LLUUID LLCoprocedurePool::enqueueCoprocedure(const std::string &name, LLCoproced
     LLUUID id(LLUUID::generateNewID());
 
     LL_INFOS("CoProcMgr") << "Coprocedure(" << name << ") enqueuing with id=" << id.asString() << " in pool \"" << mPoolName << "\" at " << mPending << LL_ENDL;
-    auto pushed = mPendingCoprocs->tryPushFront(boost::make_shared<QueuedCoproc>(name, id, proc));
-    // We don't really have a lot of good options if tryPushFront() failed,
-    // perhaps because the consuming coroutines are gummed up or something. This
+    auto pushed = mPendingCoprocs->try_push(boost::make_shared<QueuedCoproc>(name, id, proc));
+    // We don't really have a lot of good options if try_push() failed,
+    // perhaps because the consuming coroutine is gummed up or something. This
     // method is probably called from code called by mainloop. If we toss an
     // llcoro::suspend() call here, we'll circle back for another mainloop
     // iteration, possibly resulting in being re-entered here. Let's avoid that.
-    LL_ERRS_IF(! pushed, "CoProcMgr") << "Enqueue failed" << LL_ENDL;
+    LL_ERRS_IF(pushed != boost::fibers::channel_op_status::success, "CoProcMgr")
+        << "Enqueue failed because queue is " << int(pushed) << LL_ENDL;
     ++mPending;
 
     return id;
@@ -339,19 +343,24 @@ void LLCoprocedurePool::coprocedureInvokerCoro(
     LLCoreHttpUtil::HttpCoroutineAdapter::ptr_t httpAdapter)
 {
     QueuedCoproc::ptr_t coproc;
+    boost::fibers::channel_op_status status;
     for (;;)
     {
         try
         {
-            LLCoros::TempStatus st("waiting for work");
-            coproc = pendingCoprocs->popBack();
+            LLCoros::TempStatus st("waiting for work for 10s");
+            status = pendingCoprocs->pop_wait_for(coproc, std::chrono::seconds(10));
         }
-        catch (const LLThreadSafeQueueError&)
+        if (status == boost::fibers::channel_op_status::closed)
         {
-            // queue is closed
             break;
         }
 
+        if(status == boost::fibers::channel_op_status::timeout)
+        {
+            LL_INFOS_ONCE() << "pool '" << mPoolName << "' stalled." << LL_ENDL;
+            continue;
+        }
         // we actually popped an item
         --mPending;