Implement reducing the buffer count of a Surface.
Change-Id: I7f979c60c06d654aa8265002836277434bc1a64f
Bug: 3095167
diff --git a/libs/surfaceflinger_client/SharedBufferStack.cpp b/libs/surfaceflinger_client/SharedBufferStack.cpp
index 8f583f0..3b2ef84 100644
--- a/libs/surfaceflinger_client/SharedBufferStack.cpp
+++ b/libs/surfaceflinger_client/SharedBufferStack.cpp
@@ -265,6 +265,14 @@
(stack.queued > 0 && stack.inUse != buf));
}
+SharedBufferServer::BuffersAvailableCondition::BuffersAvailableCondition(
+ SharedBufferServer* sbs, int numBuffers) : ConditionBase(sbs),
+ mNumBuffers(numBuffers) {
+}
+bool SharedBufferServer::BuffersAvailableCondition::operator()() const {
+ return stack.available == mNumBuffers;
+}
+
// ----------------------------------------------------------------------------
SharedBufferClient::QueueUpdate::QueueUpdate(SharedBufferBase* sbb)
@@ -448,6 +456,7 @@
const nsecs_t now = systemTime(SYSTEM_TIME_THREAD);
stack.stats.totalTime = ns2us(now - mDequeueTime[buf]);
+
return err;
}
@@ -492,6 +501,7 @@
if (err == NO_ERROR) {
mNumBuffers = bufferCount;
queued_head = (stack.head + stack.queued) % mNumBuffers;
+ tail = computeTail();
}
return err;
}
@@ -606,17 +616,24 @@
*/
status_t SharedBufferServer::resize(int newNumBuffers)
{
- if (uint32_t(newNumBuffers) >= SharedBufferStack::NUM_BUFFER_MAX)
+ if ((unsigned int)(newNumBuffers) < SharedBufferStack::NUM_BUFFER_MIN ||
+ (unsigned int)(newNumBuffers) > SharedBufferStack::NUM_BUFFER_MAX) {
return BAD_VALUE;
+ }
RWLock::AutoWLock _l(mLock);
- // for now we're not supporting shrinking
- const int numBuffers = mNumBuffers;
- if (newNumBuffers < numBuffers)
- return BAD_VALUE;
+ if (newNumBuffers < mNumBuffers) {
+ return shrink(newNumBuffers);
+ } else {
+ return grow(newNumBuffers);
+ }
+}
+status_t SharedBufferServer::grow(int newNumBuffers)
+{
SharedBufferStack& stack( *mSharedStack );
+ const int numBuffers = mNumBuffers;
const int extra = newNumBuffers - numBuffers;
// read the head, make sure it's valid
@@ -650,6 +667,54 @@
return NO_ERROR;
}
+status_t SharedBufferServer::shrink(int newNumBuffers)
+{
+ SharedBufferStack& stack( *mSharedStack );
+
+ // Shrinking is only supported if there are no buffers currently dequeued.
+ int32_t avail = stack.available;
+ int32_t queued = stack.queued;
+ if (avail + queued != mNumBuffers) {
+ return INVALID_OPERATION;
+ }
+
+ // Wait for any queued buffers to be displayed.
+ BuffersAvailableCondition condition(this, mNumBuffers);
+ status_t err = waitForCondition(condition);
+ if (err < 0) {
+ return err;
+ }
+
+ // Reset head to index 0 and make it refer to buffer 0. The same renaming
+ // (head -> 0) is done in the BufferManager.
+ int32_t head = stack.head;
+ int8_t* index = const_cast<int8_t*>(stack.index);
+ for (int8_t i = 0; i < newNumBuffers; i++) {
+ index[i] = i;
+ }
+ stack.head = 0;
+ stack.headBuf = 0;
+
+ // If one of the buffers is in use it must be the head buffer, which we are
+ // renaming to buffer 0.
+ if (stack.inUse > 0) {
+ stack.inUse = 0;
+ }
+
+ // Free the buffers from the end of the list that are no longer needed.
+ for (int i = newNumBuffers; i < mNumBuffers; i++) {
+ mBufferList.remove(i);
+ }
+
+ // Tell the client to reallocate all the buffers.
+ reallocateAll();
+
+ mNumBuffers = newNumBuffers;
+ stack.available = newNumBuffers;
+
+ return NO_ERROR;
+}
+
SharedBufferStack::Statistics SharedBufferServer::getStats() const
{
SharedBufferStack& stack( *mSharedStack );