From ff5496239bffadaca111b1e4380a01447f85843a Mon Sep 17 00:00:00 2001
From: Nat Goodspeed <nat@lindenlab.com>
Date: Fri, 5 Nov 2021 12:33:31 -0400
Subject: SL-16202: Use WorkQueue::postTo() for texture create/post handshake.

That is, when LLViewerFetchedTexture::scheduleCreateTexture() wants to call
createTexture() on the LLImageGLThread, but postCreateTexture() on the main
thread, use the "mainloop" WorkQueue to set up the handshake.

Give ThreadPool a public virtual run() method so a subclass can override with
desired behavior. This necessitates a virtual destructor. Add accessors for
embedded WorkQueue (for post calls), ThreadPool name and width (in threads).

Allow LLSimpleton::createInstance() to forward arguments to the subject
constructor.

Make LLImageGLThread an LLSimpleton - that abstraction didn't yet exist at the
time LLImageGLThread was coded. Also derive from ThreadPool rather than
LLThread. Make it a single-thread "pool" with a very large queue capacity.
---
 indra/llrender/llimagegl.cpp | 22 +++++++++++-----------
 indra/llrender/llimagegl.h   | 11 ++++-------
 2 files changed, 15 insertions(+), 18 deletions(-)

(limited to 'indra/llrender')

diff --git a/indra/llrender/llimagegl.cpp b/indra/llrender/llimagegl.cpp
index 71c48801ac..1b6920fe3b 100644
--- a/indra/llrender/llimagegl.cpp
+++ b/indra/llrender/llimagegl.cpp
@@ -172,24 +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();
+    LLImageGLThread::createInstance(window);
 }
 
 //static 
 void LLImageGL::cleanupClass() 
 {
     LL_PROFILE_ZONE_SCOPED;
-    LLImageGLThread::sInstance->mFunctionQueue.close();
-    delete LLImageGLThread::sInstance;
-    LLImageGLThread::sInstance = nullptr;
+    LLImageGLThread::deleteSingleton();
 }
 
 //static
@@ -1532,8 +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");
@@ -2257,7 +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)
 {
     mFinished = false;
 
@@ -2266,9 +2264,11 @@ LLImageGLThread::LLImageGLThread(LLWindow* window)
 
 void LLImageGLThread::run()
 {
+    // We must perform setup on this thread before actually servicing our
+    // WorkQueue, likewise cleanup afterwards.
     mWindow->makeContextCurrent(mContext);
     gGL.init();
-    mFunctionQueue.runUntilClose();
+    ThreadPool::run();
     gGL.shutdown();
     mWindow->destroySharedContext(mContext);
 }
diff --git a/indra/llrender/llimagegl.h b/indra/llrender/llimagegl.h
index b9de481aae..27496def1d 100644
--- a/indra/llrender/llimagegl.h
+++ b/indra/llrender/llimagegl.h
@@ -37,6 +37,7 @@
 #include "llunits.h"
 #include "llthreadsafequeue.h"
 #include "llrender.h"
+#include "threadpool.h"
 #include "workqueue.h"
 
 class LLTextureAtlas ;
@@ -307,7 +308,7 @@ public:
 
 };
 
-class LLImageGLThread : public LLThread
+class LLImageGLThread : public LLSimpleton<LLImageGLThread>, LL::ThreadPool
 {
 public:
     LLImageGLThread(LLWindow* window);
@@ -316,19 +317,15 @@ public:
     template <typename CALLABLE>
     bool post(CALLABLE&& func)
     {
-        return mFunctionQueue.postIfOpen(std::forward<CALLABLE>(func));
+        return getQueue().postIfOpen(std::forward<CALLABLE>(func));
     }
 
     void run() override;
 
-    // Work Queue for background thread
-    LL::WorkQueue mFunctionQueue;
-
+private:
     LLWindow* mWindow;
     void* mContext;
     LLAtomicBool mFinished;
-
-    static LLImageGLThread* sInstance;
 };
 
 
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