From f14dfaa7b961af138737d0e09cd80ae61a29c9aa Mon Sep 17 00:00:00 2001
From: beveloper <beveloper@nowhere.fake>
Date: Sun, 24 Oct 2004 17:15:50 +0000
Subject: [PATCH] Completed implementation of chunk caching. Playback from
 harddisk is now much better, crackling should be gone.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@9485 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 src/kits/media/ChunkCache.cpp     | 84 ++++++++++++++++++++++++++++++-
 src/kits/media/ChunkCache.h       | 25 ++++++++-
 src/kits/media/MediaExtractor.cpp |  2 +-
 3 files changed, 107 insertions(+), 4 deletions(-)

diff --git a/src/kits/media/ChunkCache.cpp b/src/kits/media/ChunkCache.cpp
index ff301e8a2d..c88570d542 100644
--- a/src/kits/media/ChunkCache.cpp
+++ b/src/kits/media/ChunkCache.cpp
@@ -1,38 +1,118 @@
+#include <Locker.h>
+
 #include "ChunkCache.h"
 #include "debug.h"
 
 
 ChunkCache::ChunkCache()
 {
+	fLocker = new BLocker("media chunk cache locker");
+
+	// fEmptyChunkCount must be one less than the real chunk count,
+	// because the buffer returned by GetNextChunk must be preserved
+	// until the next call of that function, and must not be overwritten.
+	fEmptyChunkCount = CHUNK_COUNT - 1;
+	fReadyChunkCount = 0;
+	fNeedsRefill = 1;
+
+	fGetWaitSem = create_sem(0, "media chunk cache sem");
+
+	fNextPut = &fChunkInfos[0];
+	fNextGet = &fChunkInfos[0];
+	
+	for (int i = 0; i < CHUNK_COUNT; i++) {
+		fChunkInfos[i].next = (i == CHUNK_COUNT -1) ? &fChunkInfos[0] : &fChunkInfos[i + 1];
+		fChunkInfos[i].buffer = NULL;
+		fChunkInfos[i].sizeUsed = 0;
+		fChunkInfos[i].sizeMax = 0;
+		fChunkInfos[i].err = B_ERROR;
+	}
 }
 
 
 ChunkCache::~ChunkCache()
 {
+	delete_sem(fGetWaitSem);
+	delete fLocker;
+	for (int i = 0; i < CHUNK_COUNT; i++) {
+		free(fChunkInfos[i].buffer);
+	}
 }
 
 
 void
 ChunkCache::MakeEmpty()
 {
+	fLocker->Lock();
+	fEmptyChunkCount = CHUNK_COUNT - 1;
+	fReadyChunkCount = 0;
+	atomic_or(&fNeedsRefill, 1);
+	fLocker->Unlock();
 }
 
 
 bool
 ChunkCache::NeedsRefill()
 {
-	return false;
+	return atomic_or(&fNeedsRefill, 0);
 }
 
 					
 status_t
 ChunkCache::GetNextChunk(void **chunkBuffer, int32 *chunkSize, media_header *mediaHeader)
 {
-	return B_ERROR;
+//	printf("ChunkCache::GetNextChunk: %p fEmptyChunkCount %ld, fReadyChunkCount %ld\n", fNextGet, fEmptyChunkCount, fReadyChunkCount);
+retry:
+	acquire_sem(fGetWaitSem);
+
+	fLocker->Lock();
+	if (fReadyChunkCount == 0) {
+		fLocker->Unlock();
+		printf("ChunkCache::GetNextChunk: %p retrying\n", fNextGet);
+		goto retry;
+	}
+	fEmptyChunkCount++;
+	fReadyChunkCount--;
+	atomic_or(&fNeedsRefill, 1);
+	fLocker->Unlock();
+	
+	*chunkBuffer = fNextGet->buffer;
+	*chunkSize = fNextGet->sizeUsed;
+	*mediaHeader = fNextGet->mediaHeader;
+	status_t err = fNextGet->err;
+	fNextGet = fNextGet->next;
+
+	return err;
 }
 
 
 void
 ChunkCache::PutNextChunk(void *chunkBuffer, int32 chunkSize, const media_header &mediaHeader, status_t err)
 {
+//	printf("ChunkCache::PutNextChunk: %p fEmptyChunkCount %ld, fReadyChunkCount %ld\n", fNextPut, fEmptyChunkCount, fReadyChunkCount);
+
+	if (err == B_OK) {
+		if (fNextPut->sizeMax < chunkSize) {
+//			printf("ChunkCache::PutNextChunk: %p resizing from %ld to %ld\n", fNextPut, fNextPut->sizeMax, chunkSize);
+			free(fNextPut->buffer);
+			fNextPut->buffer = malloc((chunkSize + 1024) & ~1023);
+			fNextPut->sizeMax = chunkSize;
+		}
+		memcpy(fNextPut->buffer, chunkBuffer, chunkSize);
+		fNextPut->sizeUsed = chunkSize;
+	}
+	
+	fNextPut->mediaHeader = mediaHeader;
+	fNextPut->err = err;
+
+	fNextPut = fNextPut->next;
+
+	fLocker->Lock();
+	fEmptyChunkCount--;
+	fReadyChunkCount++;
+	if (fEmptyChunkCount == 0)
+		atomic_and(&fNeedsRefill, 0);
+	fLocker->Unlock();
+
+	release_sem(fGetWaitSem);
 }
diff --git a/src/kits/media/ChunkCache.h b/src/kits/media/ChunkCache.h
index 3bcfb768a2..255dd57dd0 100644
--- a/src/kits/media/ChunkCache.h
+++ b/src/kits/media/ChunkCache.h
@@ -7,6 +7,17 @@ namespace BPrivate {
 namespace media {
 
 
+struct chunk_info
+{
+	chunk_info *	next;
+	void *			buffer;
+	int32			sizeUsed;
+	int32			sizeMax;
+	media_header	mediaHeader;
+	status_t		err;
+};
+
+
 class ChunkCache
 {
 public:
@@ -20,9 +31,21 @@ public:
 	void			PutNextChunk(void *chunkBuffer, int32 chunkSize, const media_header &mediaHeader, status_t err);
 	
 private:
-
+	enum { CHUNK_COUNT = 5 };
+	
+	chunk_info *	fNextPut;
+	chunk_info *	fNextGet;
+	chunk_info		fChunkInfos[CHUNK_COUNT];
+	
+	sem_id			fGetWaitSem;
+	int32			fEmptyChunkCount;
+	int32			fReadyChunkCount;
+	int32			fNeedsRefill;
+	
+	BLocker *		fLocker;
 };
 
+
 }; // namespace media
 }; // namespace BPrivate
 
diff --git a/src/kits/media/MediaExtractor.cpp b/src/kits/media/MediaExtractor.cpp
index ae5760cc0e..d9caadf737 100644
--- a/src/kits/media/MediaExtractor.cpp
+++ b/src/kits/media/MediaExtractor.cpp
@@ -63,7 +63,7 @@ MediaExtractor::MediaExtractor(BDataIO *source, int32 flags)
 	}
 	
 	// start extractor thread
-	fExtractorWaitSem = create_sem(0, "media extractor thread sem");
+	fExtractorWaitSem = create_sem(1, "media extractor thread sem");
 	fExtractorThread = spawn_thread(extractor_thread, "media extractor thread", 10, this);
 	resume_thread(fExtractorThread);  
 }