IMediaSource: Improve shared memory buffer transfer
Bug: 29125703
Change-Id: Icf1180dee65f6504e6c10dd4d5b28a8e441f67d1
diff --git a/include/media/IMediaSource.h b/include/media/IMediaSource.h
index 524e7aa..7a7599d 100644
--- a/include/media/IMediaSource.h
+++ b/include/media/IMediaSource.h
@@ -18,14 +18,17 @@
#define IMEDIA_SOURCE_BASE_H_
+#include <map>
+
#include <binder/IInterface.h>
+#include <binder/IMemory.h>
+#include <media/stagefright/MediaBuffer.h>
#include <media/stagefright/MediaErrors.h>
namespace android {
struct MediaSource;
class MetaData;
-class MediaBuffer;
class MediaBufferGroup;
class IMediaSource : public IInterface {
@@ -56,7 +59,7 @@
// a) not request a seek
// b) not be late, i.e. lateness_us = 0
struct ReadOptions {
- enum SeekMode {
+ enum SeekMode : int32_t {
SEEK_PREVIOUS_SYNC,
SEEK_NEXT_SYNC,
SEEK_CLOSEST_SYNC,
@@ -72,6 +75,7 @@
void clearSeekTo();
bool getSeekTo(int64_t *time_us, SeekMode *mode) const;
+ // TODO: remove this if unused.
void setLateBy(int64_t lateness_us);
int64_t getLateBy() const;
@@ -79,6 +83,11 @@
void clearNonBlocking();
bool getNonBlocking() const;
+ // Used to clear all non-persistent options for multiple buffer reads.
+ void clearNonPersistent() {
+ clearSeekTo();
+ }
+
private:
enum Options {
kSeekTo_Option = 1,
@@ -98,21 +107,26 @@
// A result of INFO_FORMAT_CHANGED indicates that the format of this
// MediaSource has changed mid-stream, the client can continue reading
// but should be prepared for buffers of the new configuration.
+ //
+ // TODO: consider removing read() in favor of readMultiple().
virtual status_t read(
MediaBuffer **buffer, const ReadOptions *options = NULL) = 0;
- // Returns a vector of new buffers of data. The vector size could be
- // <= |maxNumBuffers|. Used for buffers with small size
- // since all buffer data are passed back by binder, not shared memory.
+ // Returns a vector of new buffers of data, where the new buffers are added
+ // to the end of the vector.
// Call blocks until an error is encountered, or the end of the stream is
// reached, or format change is hit, or |kMaxNumReadMultiple| buffers have
// been read.
- // End of stream is signalled by a result of ERROR_END_OF_STREAM.
+ // End of stream is signaled by a result of ERROR_END_OF_STREAM.
// A result of INFO_FORMAT_CHANGED indicates that the format of this
// MediaSource has changed mid-stream, the client can continue reading
// but should be prepared for buffers of the new configuration.
+ //
+ // ReadOptions may be specified. Persistent options apply to all reads;
+ // non-persistent options (e.g. seek) apply only to the first read.
virtual status_t readMultiple(
- Vector<MediaBuffer *> *buffers, uint32_t maxNumBuffers = 1) = 0;
+ Vector<MediaBuffer *> *buffers, uint32_t maxNumBuffers = 1,
+ const ReadOptions *options = nullptr) = 0;
// Returns true if |readMultiple| is supported, otherwise false.
virtual bool supportReadMultiple() = 0;
@@ -148,20 +162,92 @@
}
virtual status_t readMultiple(
- Vector<MediaBuffer *> * /* buffers */, uint32_t /* maxNumBuffers = 1 */) {
+ Vector<MediaBuffer *> * /* buffers */, uint32_t /* maxNumBuffers = 1 */,
+ const ReadOptions * /* options = nullptr */) {
return ERROR_UNSUPPORTED;
}
virtual bool supportReadMultiple() {
return false;
}
+
+ static const size_t kBinderMediaBuffers = 4; // buffers managed by BnMediaSource
+
protected:
virtual ~BnMediaSource();
private:
- MediaBufferGroup *mGroup;
-};
+ uint32_t mBuffersSinceStop; // Buffer tracking variable
+ std::unique_ptr<MediaBufferGroup> mGroup;
+
+ // To prevent marshalling IMemory with each read transaction, we cache the IMemory pointer
+ // into a map.
+ //
+ // This is converted into an index, which is used to identify the associated memory
+ // on the receiving side. We hold a reference to the IMemory here to ensure it doesn't
+ // change underneath us.
+
+ struct IndexCache {
+ IndexCache() : mIndex(0) { }
+
+ // Returns the index of the IMemory stored in cache or 0 if not found.
+ uint64_t lookup(const sp<IMemory> &mem) {
+ auto p = mMemoryToIndex.find(mem.get());
+ if (p == mMemoryToIndex.end()) {
+ return 0;
+ }
+ if (MediaBuffer::isDeadObject(p->second.first)) {
+ // this object's dead
+ ALOGW("Attempting to lookup a dead IMemory");
+ (void)mMemoryToIndex.erase(p);
+ return 0;
+ }
+ ALOGW_IF(p->second.first.get() != mem.get(), "Mismatched buffers without reset");
+ return p->second.second;
+ }
+
+ // Returns the index of the IMemory stored in the index cache.
+ uint64_t insert(const sp<IMemory> &mem) {
+ auto p = mMemoryToIndex.find(mem.get());
+ if (p == mMemoryToIndex.end()) {
+ if (mIndex == UINT64_MAX) {
+ ALOGE("Index overflow");
+ mIndex = 1; // skip overflow condition and hope for the best
+ } else {
+ ++mIndex;
+ }
+ (void)mMemoryToIndex.emplace(// C++11 mem.get(), std::make_pair(mem, mIndex))
+ std::piecewise_construct,
+ std::forward_as_tuple(mem.get()), std::forward_as_tuple(mem, mIndex));
+ return mIndex;
+ }
+ ALOGW("IMemory already inserted into cache");
+ return p->second.second;
+ }
+
+ void reset() {
+ mMemoryToIndex.clear();
+ mIndex = 0;
+ }
+
+ void gc() {
+ for (auto it = mMemoryToIndex.begin(); it != mMemoryToIndex.end(); ) {
+ if (MediaBuffer::isDeadObject(it->second.first)) {
+ it = mMemoryToIndex.erase(it);
+ } else {
+ ++it;
+ }
+ }
+ }
+
+ private:
+ uint64_t mIndex;
+ // C++14 unordered_map erase on iterator is stable; C++11 has no guarantee.
+ // Could key on uintptr_t instead of IMemory *
+ std::map<IMemory *, std::pair<sp<IMemory>, uint64_t>> mMemoryToIndex;
+ } mIndexCache;
+};
} // namespace android
diff --git a/include/media/stagefright/MediaBuffer.h b/include/media/stagefright/MediaBuffer.h
index 18b80e3..55b1f58 100644
--- a/include/media/stagefright/MediaBuffer.h
+++ b/include/media/stagefright/MediaBuffer.h
@@ -18,6 +18,8 @@
#define MEDIA_BUFFER_H_
+#include <atomic>
+#include <list>
#include <media/stagefright/foundation/MediaBufferBase.h>
#include <pthread.h>
@@ -60,6 +62,12 @@
MediaBuffer(const sp<ABuffer> &buffer);
+ MediaBuffer(const sp<IMemory> &mem) :
+ MediaBuffer((uint8_t *)mem->pointer() + sizeof(SharedControl), mem->size()) {
+ // delegate and override mMemory
+ mMemory = mem;
+ }
+
// Decrements the reference count and returns the buffer to its
// associated MediaBufferGroup if the reference count drops to 0.
virtual void release();
@@ -91,9 +99,44 @@
int refcount() const;
+ bool isDeadObject() const {
+ return isDeadObject(mMemory);
+ }
+
+ static bool isDeadObject(const sp<IMemory> &memory) {
+ if (memory.get() == nullptr || memory->pointer() == nullptr) return false;
+ return reinterpret_cast<SharedControl *>(memory->pointer())->isDeadObject();
+ }
+
protected:
+ // MediaBuffer remote releases are handled through a
+ // pending release count variable stored in a SharedControl block
+ // at the start of the IMemory.
+
+ // Returns old value of pending release count.
+ inline int32_t addPendingRelease(int32_t value) {
+ return getSharedControl()->addPendingRelease(value);
+ }
+
+ // Issues all pending releases (works in parallel).
+ // Assumes there is a MediaBufferObserver.
+ inline void resolvePendingRelease() {
+ if (mMemory.get() == nullptr) return;
+ while (addPendingRelease(-1) > 0) {
+ release();
+ }
+ addPendingRelease(1);
+ }
+
+ // true if MediaBuffer is observed (part of a MediaBufferGroup).
+ inline bool isObserved() const {
+ return mObserver != nullptr;
+ }
+
virtual ~MediaBuffer();
+ sp<IMemory> mMemory;
+
private:
friend class MediaBufferGroup;
friend class OMXDecoder;
@@ -105,7 +148,6 @@
void claim();
MediaBufferObserver *mObserver;
- MediaBuffer *mNextBuffer;
int mRefCount;
void *mData;
@@ -119,12 +161,57 @@
MediaBuffer *mOriginal;
- void setNextBuffer(MediaBuffer *buffer);
- MediaBuffer *nextBuffer();
-
MediaBuffer(const MediaBuffer &);
MediaBuffer &operator=(const MediaBuffer &);
- sp<IMemory> mMemory;
+
+ // SharedControl block at the start of IMemory.
+ struct SharedControl {
+ enum {
+ FLAG_DEAD_OBJECT = (1 << 0),
+ };
+
+ // returns old value
+ inline int32_t addPendingRelease(int32_t value) {
+ return std::atomic_fetch_add_explicit(
+ &mPendingRelease, (int_least32_t)value, std::memory_order_seq_cst);
+ }
+
+ inline int32_t getPendingRelease() const {
+ return std::atomic_load_explicit(&mPendingRelease, std::memory_order_seq_cst);
+ }
+
+ inline void setPendingRelease(int32_t value) {
+ std::atomic_store_explicit(
+ &mPendingRelease, (int_least32_t)value, std::memory_order_seq_cst);
+ }
+
+ inline bool isDeadObject() const {
+ return (std::atomic_load_explicit(
+ &mFlags, std::memory_order_seq_cst) & FLAG_DEAD_OBJECT) != 0;
+ }
+
+ inline void setDeadObject() {
+ (void)std::atomic_fetch_or_explicit(
+ &mFlags, (int_least32_t)FLAG_DEAD_OBJECT, std::memory_order_seq_cst);
+ }
+
+ inline void clear() {
+ std::atomic_store_explicit(
+ &mFlags, (int_least32_t)0, std::memory_order_seq_cst);
+ std::atomic_store_explicit(
+ &mPendingRelease, (int_least32_t)0, std::memory_order_seq_cst);
+ }
+
+ private:
+ // Caution: atomic_int_fast32_t is 64 bits on LP64.
+ std::atomic_int_least32_t mFlags;
+ std::atomic_int_least32_t mPendingRelease;
+ int32_t unused[6]; // additional buffer space
+ };
+
+ inline SharedControl *getSharedControl() const {
+ return reinterpret_cast<SharedControl *>(mMemory->pointer());
+ }
};
} // namespace android
diff --git a/include/media/stagefright/MediaBufferGroup.h b/include/media/stagefright/MediaBufferGroup.h
index 7ca3fa1..d1f59f4 100644
--- a/include/media/stagefright/MediaBufferGroup.h
+++ b/include/media/stagefright/MediaBufferGroup.h
@@ -29,7 +29,7 @@
class MediaBufferGroup : public MediaBufferObserver {
public:
- MediaBufferGroup();
+ MediaBufferGroup(size_t growthLimit = 0);
~MediaBufferGroup();
void add_buffer(MediaBuffer *buffer);
@@ -45,6 +45,11 @@
status_t acquire_buffer(
MediaBuffer **buffer, bool nonBlocking = false, size_t requestedSize = 0);
+ size_t buffers() const { return mBuffers.size(); }
+
+ // freeBuffers is the number of free buffers allowed to remain.
+ void gc(size_t freeBuffers = 0);
+
protected:
virtual void signalBufferReturned(MediaBuffer *buffer);
@@ -53,8 +58,8 @@
Mutex mLock;
Condition mCondition;
-
- MediaBuffer *mFirstBuffer, *mLastBuffer;
+ size_t mGrowthLimit; // Do not automatically grow group larger than this.
+ std::list<MediaBuffer *> mBuffers;
MediaBufferGroup(const MediaBufferGroup &);
MediaBufferGroup &operator=(const MediaBufferGroup &);