DRTVWR-546, SL-16220, SL-16094: Undo previous glthread branch revert.

Reverting a merge is sticky: it tells git you never want to see that branch
again. Merging the DRTVWR-546 branch, which contained the revert, into the
glthread branch undid much of the development work on that branch. To restore
it we must revert the revert.

This reverts commit 029b41c0419e975bbb28454538b46dc69ce5d2ba.

1 files changed, 15 insertions, 74 deletions

diff --git a/indra/llrender/llimagegl.cpp b/indra/llrender/llimagegl.cpp
index ed0e3fb345..894eb8c773 100644
--- a/indra/llrender/llimagegl.cpp
+++ b/indra/llrender/llimagegl.cpp
@@ -172,31 +172,19 @@ BOOL is_little_endian()
 	return (*c == 0x78) ;
 }
 
-LLImageGLThread* LLImageGLThread::sInstance = nullptr;
-
 //static 
 void LLImageGL::initClass(LLWindow* window, S32 num_catagories, BOOL skip_analyze_alpha /* = false */)
 {
     LL_PROFILE_ZONE_SCOPED;
 	sSkipAnalyzeAlpha = skip_analyze_alpha;
-    LLImageGLThread::sInstance = new LLImageGLThread(window);
-    LLImageGLThread::sInstance->start();
-}
-
-//static
-void LLImageGL::updateClass()
-{
-    LL_PROFILE_ZONE_SCOPED;
-    LLImageGLThread::sInstance->executeCallbacks();
+    LLImageGLThread::createInstance(window);
 }
 
 //static 
 void LLImageGL::cleanupClass() 
 {
     LL_PROFILE_ZONE_SCOPED;
-    LLImageGLThread::sInstance->mFunctionQueue.close();
-    delete LLImageGLThread::sInstance;
-    LLImageGLThread::sInstance = nullptr;
+    LLImageGLThread::deleteSingleton();
 }
 
 //static
@@ -504,6 +492,9 @@ void LLImageGL::init(BOOL usemipmaps)
 #endif
 
 	mCategory = -1;
+
+	// Sometimes we have to post work for the main thread.
+	mMainQueue = LL::WorkQueue::getInstance("mainloop");
 }
 
 void LLImageGL::cleanup()
@@ -1536,8 +1527,7 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_
     }
 
     //if we're on the image loading thread, be sure to delete old_texname and update mTexName on the main thread
-    if (LLImageGLThread::sInstance != nullptr && 
-        LLThread::currentID() == LLImageGLThread::sInstance->getID())
+    if (! on_main_thread())
     {
         {
             LL_PROFILE_ZONE_NAMED("cglt - sync");
@@ -1554,7 +1544,9 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_
         }
 
         ref();
-        LLImageGLThread::sInstance->postCallback([=]()
+        LL::WorkQueue::postMaybe(
+            mMainQueue,
+            [=]()
             {
                 LL_PROFILE_ZONE_NAMED("cglt - delete callback");
                 if (old_texname != 0)
@@ -2259,7 +2251,11 @@ void LLImageGL::resetCurTexSizebar()
 */  
 
 LLImageGLThread::LLImageGLThread(LLWindow* window)
-    : LLThread("LLImageGL"), mWindow(window)
+    // We want exactly one thread, but a very large capacity: we never want
+    // anyone, especially inner-loop render code, to have to block on post()
+    // because we're full.
+    : ThreadPool("LLImageGL", 1, 1024*1024)
+    , mWindow(window)
 {
     LL_PROFILE_ZONE_SCOPED;
     mFinished = false;
@@ -2268,61 +2264,6 @@ LLImageGLThread::LLImageGLThread(LLWindow* window)
     ThreadPool::start();
 }
 
-// post a function to be executed on the LLImageGL background thread
-
-bool LLImageGLThread::post(const std::function<void()>& func)
-{
-    try
-    {
-        mFunctionQueue.post(func);
-    }
-    catch (LLThreadSafeQueueInterrupt e)
-    {
-        return false;
-    }
-
-    return true;
-}
-
-//post a callback to be executed on the main thread
-
-bool LLImageGLThread::postCallback(const std::function<void()>& callback)
-{
-    try
-    {
-        if (!mCallbackQueue.tryPost(callback))
-        {
-            mPendingCallbackQ.push(callback);
-        }
-    }
-    catch (LLThreadSafeQueueInterrupt e)
-    {
-        //thread is closing, drop request
-        return false;
-    }
-
-    return true;
-}
-
-void LLImageGLThread::executeCallbacks()
-{
-    LL_PROFILE_ZONE_SCOPED;
-    //executed from main thread
-    mCallbackQueue.runPending();
-
-    while (!mPendingCallbackQ.empty())
-    {
-        if (mCallbackQueue.tryPost(mPendingCallbackQ.front()))
-        {
-            mPendingCallbackQ.pop();
-        }
-        else
-        {
-            break;
-        }
-    }
-}
-
 void LLImageGLThread::run()
 {
     LL_PROFILE_ZONE_SCOPED;
@@ -2330,7 +2271,7 @@ void LLImageGLThread::run()
     // WorkQueue, likewise cleanup afterwards.
     mWindow->makeContextCurrent(mContext);
     gGL.init();
-    mFunctionQueue.runUntilClose();
+    ThreadPool::run();
     gGL.shutdown();
     mWindow->destroySharedContext(mContext);
 }