SL-16220: Add LL::ThreadPool class and a "General" instance.

ThreadPool bundles a WorkQueue with the specified number of worker threads to
service it. Each ThreadPool has a name that can be used to locate its
WorkQueue.

Each worker thread calls WorkQueue::runUntilClose().

ThreadPool listens on the "LLApp" LLEventPump for shutdown notification. On
receiving that, it closes its WorkQueue and then join()s each of its worker
threads for orderly shutdown.

Add a settings.xml entry "ThreadPoolSizes", the first LLSD-valued settings
entry to expect a map: pool name->size. The expectation is that usually code
instantiating a particular ThreadPool will have a default size in mind, but it
should check "ThreadPoolSizes" for a user override.

Make idle_startup()'s STATE_SEED_CAP_GRANTED state instantiate a "General"
ThreadPool. This is function-static for lazy initialization.

Eliminate LLMainLoopRepeater, which is completely unreferenced. Any potential
future use cases are better addressed by posting to the main loop's WorkQueue.

Eliminate llappviewer.cpp's private LLDeferredTaskList class, which
implemented LLAppViewer::addOnIdleCallback(). Make addOnIdleCallback() post
work to the main loop's WorkQueue instead.

1 files changed, 18 insertions, 0 deletions

diff --git a/indra/newview/llstartup.cpp b/indra/newview/llstartup.cpp
index 57c5074804..13e7fcb6e4 100644
--- a/indra/newview/llstartup.cpp
+++ b/indra/newview/llstartup.cpp
@@ -205,6 +205,9 @@
 
 #include "llstacktrace.h"
 
+#include "threadpool.h"
+
+
 #if LL_WINDOWS
 #include "lldxhardware.h"
 #endif
@@ -301,6 +304,18 @@ void callback_cache_name(const LLUUID& id, const std::string& full_name, bool is
 // local classes
 //
 
+void launchThreadPool()
+{
+    LLSD poolSizes{ gSavedSettings.getLLSD("ThreadPoolSizes") };
+    LLSD sizeSpec{ poolSizes["General"] };
+    LLSD::Integer size{ sizeSpec.isInteger()? sizeSpec.asInteger() : 3 };
+    LL_DEBUGS("ThreadPool") << "Instantiating General pool with "
+                            << size << " threads" << LL_ENDL;
+    // Use a function-static ThreadPool: static duration, but instantiated
+    // only on demand.
+    static LL::ThreadPool pool("General", size);
+}
+
 void update_texture_fetch()
 {
 	LLAppViewer::getTextureCache()->update(1); // unpauses the texture cache thread
@@ -1489,6 +1504,9 @@ bool idle_startup()
 		gAgentCamera.resetCamera();
 		display_startup();
 
+		// start up the ThreadPool we'll use for textures et al.
+		launchThreadPool();
+
 		// Initialize global class data needed for surfaces (i.e. textures)
 		LL_DEBUGS("AppInit") << "Initializing sky..." << LL_ENDL;
 		// Initialize all of the viewer object classes for the first time (doing things like texture fetches.