SL-16182: Offload audio decoding from the main thread to the general work queue.

The work queue callback binds "this". This is deemed safe due to current dependencies, but see the associated comment in the return callback. There was some trial and error to get a this-binded lambda to compile.

Due to LLVorbisDecodeState writing to disk off-thread, limit audio decodes proportional to general worker thread count. Guess the thread count for now.

1 files changed, 214 insertions, 119 deletions

diff --git a/indra/llaudio/llaudiodecodemgr.cpp b/indra/llaudio/llaudiodecodemgr.cpp
index ff0aa6e76e..cc5abee08a 100644..100755
--- a/indra/llaudio/llaudiodecodemgr.cpp
+++ b/indra/llaudio/llaudiodecodemgr.cpp
@@ -35,6 +35,7 @@
 #include "llendianswizzle.h"
 #include "llassetstorage.h"
 #include "llrefcount.h"
+#include "workqueue.h"
 
 #include "llvorbisencode.h"
 
@@ -45,15 +46,13 @@
 
 extern LLAudioEngine *gAudiop;
 
-LLAudioDecodeMgr *gAudioDecodeMgrp = NULL;
-
 static const S32 WAV_HEADER_SIZE = 44;
 
 
 //////////////////////////////////////////////////////////////////////////////
 
 
-class LLVorbisDecodeState : public LLRefCount
+class LLVorbisDecodeState : public LLThreadSafeRefCount
 {
 public:
 	class WriteResponder : public LLLFSThread::Responder
@@ -532,146 +531,242 @@ void LLVorbisDecodeState::flushBadFile()
 
 class LLAudioDecodeMgr::Impl
 {
-	friend class LLAudioDecodeMgr;
-public:
-	Impl() {};
-	~Impl() {};
+    friend class LLAudioDecodeMgr;
+    LLAudioDecodeMgr::Impl();
+  public:
 
-	void processQueue(const F32 num_secs = 0.005);
+    void processQueue();
 
-protected:
-	std::deque<LLUUID> mDecodeQueue;
-	LLPointer<LLVorbisDecodeState> mCurrentDecodep;
+    void startMoreDecodes();
+    void enqueueFinishAudio(const LLUUID &decode_id, LLPointer<LLVorbisDecodeState>& decode_state);
+    void checkDecodesFinished();
+
+  protected:
+    std::deque<LLUUID> mDecodeQueue;
+    std::map<LLUUID, LLPointer<LLVorbisDecodeState>> mDecodes;
 };
 
+LLAudioDecodeMgr::Impl::Impl()
+{
+}
+
+// Returns the in-progress decode_state, which may be an empty LLPointer if
+// there was an error and there is no more work to be done.
+LLPointer<LLVorbisDecodeState> beginDecodingAndWritingAudio(const LLUUID &decode_id);
 
-void LLAudioDecodeMgr::Impl::processQueue(const F32 num_secs)
+// Return true if finished
+bool tryFinishAudio(const LLUUID &decode_id, LLPointer<LLVorbisDecodeState> decode_state);
+
+void LLAudioDecodeMgr::Impl::processQueue()
 {
-	LLUUID uuid;
+    // First, check if any audio from in-progress decodes are ready to play. If
+    // so, mark them ready for playback (or errored, in case of error).
+    checkDecodesFinished();
 
-	LLTimer decode_timer;
+    // Second, start as many decodes from the queue as permitted
+    startMoreDecodes();
+}
 
-	BOOL done = FALSE;
-	while (!done)
-	{
-		if (mCurrentDecodep)
-		{
-			BOOL res;
+void LLAudioDecodeMgr::Impl::startMoreDecodes()
+{
+    llassert_always(gAudiop);
+
+    LL::WorkQueue::ptr_t main_queue = LL::WorkQueue::getInstance("mainloop");
+    // *NOTE: main_queue->postTo casts this refcounted smart pointer to a weak
+    // pointer
+    LL::WorkQueue::ptr_t general_queue = LL::WorkQueue::getInstance("General");
+    llassert_always(main_queue);
+    llassert_always(general_queue);
+    // Set max decodes to double the thread count of the general work queue.
+    // This ensures the general work queue is full, but prevents theoretical
+    // buildup of buffers in memory due to disk writes once the
+    // LLVorbisDecodeState leaves the worker thread (see
+    // LLLFSThread::sLocal->write). This is probably as fast as we can get it
+    // without modifying/removing LLVorbisDecodeState, at which point we should
+    // consider decoding the audio during the asset download process.
+    // -Cosmic,2022-05-11
+    const size_t MAX_DECODES = 4 * 2;
+
+    while (!mDecodeQueue.empty() && mDecodes.size() < MAX_DECODES)
+    {
+        const LLUUID decode_id = mDecodeQueue.front();
+        mDecodeQueue.pop_front();
+
+        // Don't decode the same file twice
+        if (mDecodes.find(decode_id) != mDecodes.end())
+        {
+            continue;
+        }
+        if (gAudiop->hasDecodedFile(decode_id))
+        {
+            continue;
+        }
+
+        // Kick off a decode
+        mDecodes[decode_id] = LLPointer<LLVorbisDecodeState>(NULL);
+        main_queue->postTo(
+            general_queue,
+            [decode_id, this]() // Work done on general queue
+            {
+                LLPointer<LLVorbisDecodeState> decode_state = beginDecodingAndWritingAudio(decode_id);
+
+                if (!decode_state)
+                {
+                    // Audio decode has errored
+                    return decode_state;
+                }
+
+                // Disk write of decoded audio is now in progress off-thread
+                return decode_state;
+            },
+            [decode_id, this](LLPointer<LLVorbisDecodeState> decode_state) // Callback to main thread
+            mutable {
+                if (!gAudiop)
+                {
+                    // There is no LLAudioEngine anymore. This might happen if
+                    // an audio decode is enqueued just before shutdown.
+                    return;
+                }
+
+                // At this point, we can be certain that the pointer to "this"
+                // is valid because the lifetime of "this" is dependent upon
+                // the lifetime of gAudiop.
+
+                enqueueFinishAudio(decode_id, decode_state);
+            });
+    }
+}
 
-			// Decode in a loop until we're done or have run out of time.
-			while(!(res = mCurrentDecodep->decodeSection()) && (decode_timer.getElapsedTimeF32() < num_secs))
-			{
-				// decodeSection does all of the work above
-			}
+LLPointer<LLVorbisDecodeState> beginDecodingAndWritingAudio(const LLUUID &decode_id)
+{
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_MEDIA;
+
+    LL_DEBUGS() << "Decoding " << decode_id << " from audio queue!" << LL_ENDL;
+
+    std::string                    d_path       = gDirUtilp->getExpandedFilename(LL_PATH_CACHE, decode_id.asString()) + ".dsf";
+    LLPointer<LLVorbisDecodeState> decode_state = new LLVorbisDecodeState(decode_id, d_path);
+
+    if (!decode_state->initDecode())
+    {
+        return NULL;
+    }
+
+    // Decode in a loop until we're done
+    while (!decode_state->decodeSection())
+    {
+        // decodeSection does all of the work above
+    }
+
+    if (!decode_state->isDone())
+    {
+        // Decode stopped early, or something bad happened to the file
+        // during decoding.
+        LL_WARNS("AudioEngine") << decode_id << " has invalid vorbis data or decode has been canceled, aborting decode" << LL_ENDL;
+        decode_state->flushBadFile();
+        return NULL;
+    }
+
+    if (!decode_state->isValid())
+    {
+        // We had an error when decoding, abort.
+        LL_WARNS("AudioEngine") << decode_id << " has invalid vorbis data, aborting decode" << LL_ENDL;
+        decode_state->flushBadFile();
+        return NULL;
+    }
+
+    // Kick off the writing of the decoded audio to the disk cache.
+    // The receiving thread can then cheaply call finishDecode() again to check
+    // if writing has finished. Someone has to hold on to the refcounted
+    // decode_state to prevent it from getting destroyed during write.
+    decode_state->finishDecode();
+
+    return decode_state;
+}
 
-			if (mCurrentDecodep->isDone() && !mCurrentDecodep->isValid())
-			{
-				// We had an error when decoding, abort.
-				LL_WARNS("AudioEngine") << mCurrentDecodep->getUUID() << " has invalid vorbis data, aborting decode" << LL_ENDL;
-				mCurrentDecodep->flushBadFile();
-
-				if (gAudiop)
-				{
-					LLAudioData *adp = gAudiop->getAudioData(mCurrentDecodep->getUUID());
-					adp->setHasValidData(false);
-					adp->setHasCompletedDecode(true);
-				}
-
-				mCurrentDecodep = NULL;
-				done = TRUE;
-			}
+void LLAudioDecodeMgr::Impl::enqueueFinishAudio(const LLUUID &decode_id, LLPointer<LLVorbisDecodeState>& decode_state)
+{
+    // Assumed fast
+    if (tryFinishAudio(decode_id, decode_state))
+    {
+        // Done early!
+        auto decode_iter = mDecodes.find(decode_id);
+        llassert(decode_iter != mDecodes.end());
+        mDecodes.erase(decode_iter);
+        return;
+    }
+
+    // Not done yet... enqueue it
+    mDecodes[decode_id] = decode_state;
+}
 
-			if (!res)
-			{
-				// We've used up out time slice, bail...
-				done = TRUE;
-			}
-			else if (mCurrentDecodep)
-			{
-				if (gAudiop && mCurrentDecodep->finishDecode())
-				{
-					// We finished!
-					LLAudioData *adp = gAudiop->getAudioData(mCurrentDecodep->getUUID());
-					if (!adp)
-					{
-						LL_WARNS("AudioEngine") << "Missing LLAudioData for decode of " << mCurrentDecodep->getUUID() << LL_ENDL;
-					}
-					else if (mCurrentDecodep->isValid() && mCurrentDecodep->isDone())
-					{
-						adp->setHasCompletedDecode(true);
-						adp->setHasDecodedData(true);
-						adp->setHasValidData(true);
-
-						// At this point, we could see if anyone needs this sound immediately, but
-						// I'm not sure that there's a reason to - we need to poll all of the playing
-						// sounds anyway.
-						//LL_INFOS("AudioEngine") << "Finished the vorbis decode, now what?" << LL_ENDL;
-					}
-					else
-					{
-						adp->setHasCompletedDecode(true);
-						LL_INFOS("AudioEngine") << "Vorbis decode failed for " << mCurrentDecodep->getUUID() << LL_ENDL;
-					}
-					mCurrentDecodep = NULL;
-				}
-				done = TRUE; // done for now
-			}
-		}
+void LLAudioDecodeMgr::Impl::checkDecodesFinished()
+{
+    auto decode_iter = mDecodes.begin();
+    while (decode_iter != mDecodes.end())
+    {
+        const LLUUID& decode_id = decode_iter->first;
+        const LLPointer<LLVorbisDecodeState>& decode_state = decode_iter->second;
+        if (tryFinishAudio(decode_id, decode_state))
+        {
+            decode_iter = mDecodes.erase(decode_iter);
+        }
+        else
+        {
+            ++decode_iter;
+        }
+    }
+}
 
-		if (!done)
-		{
-			if (mDecodeQueue.empty())
-			{
-				// Nothing else on the queue.
-				done = TRUE;
-			}
-			else
-			{
-				LLUUID uuid;
-				uuid = mDecodeQueue.front();
-				mDecodeQueue.pop_front();
-				if (!gAudiop || gAudiop->hasDecodedFile(uuid))
-				{
-					// This file has already been decoded, don't decode it again.
-					continue;
-				}
-
-				LL_DEBUGS() << "Decoding " << uuid << " from audio queue!" << LL_ENDL;
-
-				std::string uuid_str;
-				std::string d_path;
-
-				LLTimer timer;
-				timer.reset();
-
-				uuid.toString(uuid_str);
-				d_path = gDirUtilp->getExpandedFilename(LL_PATH_CACHE,uuid_str) + ".dsf";
-
-				mCurrentDecodep = new LLVorbisDecodeState(uuid, d_path);
-				if (!mCurrentDecodep->initDecode())
-				{
-					mCurrentDecodep = NULL;
-				}
-			}
-		}
-	}
+bool tryFinishAudio(const LLUUID &decode_id, LLPointer<LLVorbisDecodeState> decode_state)
+{
+    // decode_state is a file write in progress unless finished is true
+    bool finished = decode_state && decode_state->finishDecode();
+    if (!finished)
+    {
+        return false;
+    }
+
+    llassert_always(gAudiop);
+
+    LLAudioData *adp = gAudiop->getAudioData(decode_id);
+    if (!adp)
+    {
+        LL_WARNS("AudioEngine") << "Missing LLAudioData for decode of " << decode_id << LL_ENDL;
+        return true;
+    }
+
+    bool valid = decode_state && decode_state->isValid();
+    // Mark current decode finished regardless of success or failure
+    adp->setHasCompletedDecode(true);
+    // Flip flags for decoded data
+    adp->setHasDecodeFailed(!valid);
+    adp->setHasDecodedData(valid);
+    // When finished decoding, there will also be a decoded wav file cached on
+    // disk with the .dsf extension
+    if (valid)
+    {
+        adp->setHasWAVLoadFailed(false);
+    }
+
+    return true;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 LLAudioDecodeMgr::LLAudioDecodeMgr()
 {
-	mImpl = new Impl;
+    mImpl = new Impl();
 }
 
 LLAudioDecodeMgr::~LLAudioDecodeMgr()
 {
-	delete mImpl;
+    delete mImpl;
+    mImpl = nullptr;
 }
 
-void LLAudioDecodeMgr::processQueue(const F32 num_secs)
+void LLAudioDecodeMgr::processQueue()
 {
-	mImpl->processQueue(num_secs);
+    mImpl->processQueue();
 }
 
 BOOL LLAudioDecodeMgr::addDecodeRequest(const LLUUID &uuid)
@@ -687,7 +782,7 @@ BOOL LLAudioDecodeMgr::addDecodeRequest(const LLUUID &uuid)
 	{
 		// Just put it on the decode queue.
 		LL_DEBUGS("AudioEngine") << "addDecodeRequest for " << uuid << " has local asset file already" << LL_ENDL;
-		mImpl->mDecodeQueue.push_back(uuid);
+        mImpl->mDecodeQueue.push_back(uuid);
 		return TRUE;
 	}