diff options
| -rw-r--r-- | include/private/surfaceflinger/SharedBufferStack.h | 4 | ||||
| -rw-r--r-- | libs/surfaceflinger_client/SharedBufferStack.cpp | 35 |
2 files changed, 13 insertions, 26 deletions
diff --git a/include/private/surfaceflinger/SharedBufferStack.h b/include/private/surfaceflinger/SharedBufferStack.h index 6ace5bc..39ef3a1 100644 --- a/include/private/surfaceflinger/SharedBufferStack.h +++ b/include/private/surfaceflinger/SharedBufferStack.h @@ -167,6 +167,7 @@ protected: SharedBufferStack* const mSharedStack; const int mNumBuffers; const int mIdentity; + int32_t computeTail() const; friend struct Update; friend struct QueueUpdate; @@ -259,8 +260,6 @@ private: friend struct Condition; friend struct DequeueCondition; friend struct LockCondition; - - int32_t computeTail() const; struct QueueUpdate : public UpdateBase { inline QueueUpdate(SharedBufferBase* sbb); @@ -288,6 +287,7 @@ private: }; int32_t tail; + int32_t undoDequeueTail; // statistics... nsecs_t mDequeueTime[NUM_BUFFER_MAX]; }; diff --git a/libs/surfaceflinger_client/SharedBufferStack.cpp b/libs/surfaceflinger_client/SharedBufferStack.cpp index f1aec8a..6745704 100644 --- a/libs/surfaceflinger_client/SharedBufferStack.cpp +++ b/libs/surfaceflinger_client/SharedBufferStack.cpp @@ -179,7 +179,7 @@ String8 SharedBufferBase::dump(char const* prefix) const char buffer[SIZE]; String8 result; SharedBufferStack& stack( *mSharedStack ); - int tail = (mNumBuffers + stack.head - stack.available + 1) % mNumBuffers; + int tail = computeTail(); snprintf(buffer, SIZE, "%s[ head=%2d, available=%2d, queued=%2d, tail=%2d ] " "reallocMask=%08x, inUse=%2d, identity=%d, status=%d\n", @@ -189,6 +189,12 @@ String8 SharedBufferBase::dump(char const* prefix) const return result; } +int32_t SharedBufferBase::computeTail() const +{ + SharedBufferStack& stack( *mSharedStack ); + return (mNumBuffers + stack.head - stack.available + 1) % mNumBuffers; +} + // ============================================================================ // conditions and updates // ============================================================================ @@ -297,32 +303,12 @@ ssize_t SharedBufferServer::StatusUpdate::operator()() { SharedBufferClient::SharedBufferClient(SharedClient* sharedClient, int surface, int num, int32_t identity) - : SharedBufferBase(sharedClient, surface, num, identity), tail(0) + : SharedBufferBase(sharedClient, surface, num, identity), + tail(0), undoDequeueTail(0) { tail = computeTail(); } -int32_t SharedBufferClient::computeTail() const -{ - SharedBufferStack& stack( *mSharedStack ); - // we need to make sure we read available and head coherently, - // w.r.t RetireUpdate. - int32_t newTail; - int32_t avail; - int32_t head; - do { - avail = stack.available; - head = stack.head; - } while (stack.available != avail); - newTail = head - avail + 1; - if (newTail < 0) { - newTail += mNumBuffers; - } else if (newTail >= mNumBuffers) { - newTail -= mNumBuffers; - } - return newTail; -} - ssize_t SharedBufferClient::dequeue() { SharedBufferStack& stack( *mSharedStack ); @@ -350,6 +336,7 @@ ssize_t SharedBufferClient::dequeue() int dequeued = tail; tail = ((tail+1 >= mNumBuffers) ? 0 : tail+1); + undoDequeueTail = dequeued; LOGD_IF(DEBUG_ATOMICS, "dequeued=%d, tail=%d, %s", dequeued, tail, dump("").string()); @@ -363,7 +350,7 @@ status_t SharedBufferClient::undoDequeue(int buf) UndoDequeueUpdate update(this); status_t err = updateCondition( update ); if (err == NO_ERROR) { - tail = computeTail(); + tail = undoDequeueTail; } return err; } |