commit 9f3053de78630815d60cf48a2cf2348cc5867c45
author Dan Stoza <stoza@google.com> Thu Mar 06 15:14:33 2014 -0800
committer Dan Stoza <stoza@google.com> Mon Mar 10 16:45:38 2014 -0700
tree e87e2a86d1ca837a80fc7730daece3f28a41e800
parent 544b09523b791935ffe9aa64d1f20335f7e2dc78

BufferQueue: Allow detaching/reattaching buffers

Adds detachBuffer and attachBuffer calls to both the producer and
consumer sides of BufferQueue. Buffers may be detached while dequeued
by the producer or acquired by the consumer, and when attached, enter
the dequeued and acquired states, respectively.

Bug: 13173343
Change-Id: Ic152692b0a94d99e0135b9bfa62747dab2a54220

libs/gui/BufferQueueConsumer.cpp

diff --git a/libs/gui/BufferQueueConsumer.cpp b/libs/gui/BufferQueueConsumer.cpp
index dc7aa15..66fdab3 100644
--- a/libs/gui/BufferQueueConsumer.cpp
+++ b/libs/gui/BufferQueueConsumer.cpp
@@ -168,13 +168,96 @@
     return NO_ERROR;
 }
 
+status_t BufferQueueConsumer::detachBuffer(int slot) {
+    ATRACE_CALL();
+    ATRACE_BUFFER_INDEX(slot);
+    BQ_LOGV("detachBuffer(C): slot %d", slot);
+    Mutex::Autolock lock(mCore->mMutex);
+
+    if (mCore->mIsAbandoned) {
+        BQ_LOGE("detachBuffer(C): BufferQueue has been abandoned");
+        return NO_INIT;
+    }
+
+    if (slot < 0 || slot >= BufferQueueDefs::NUM_BUFFER_SLOTS) {
+        BQ_LOGE("detachBuffer(C): slot index %d out of range [0, %d)",
+                slot, BufferQueueDefs::NUM_BUFFER_SLOTS);
+        return BAD_VALUE;
+    } else if (mSlots[slot].mBufferState != BufferSlot::ACQUIRED) {
+        BQ_LOGE("detachBuffer(C): slot %d is not owned by the consumer "
+                "(state = %d)", slot, mSlots[slot].mBufferState);
+        return BAD_VALUE;
+    }
+
+    mCore->freeBufferLocked(slot);
+    mCore->mDequeueCondition.broadcast();
+
+    return NO_ERROR;
+}
+
+status_t BufferQueueConsumer::attachBuffer(int* outSlot,
+        const sp<android::GraphicBuffer>& buffer) {
+    ATRACE_CALL();
+
+    if (outSlot == NULL) {
+        BQ_LOGE("attachBuffer(P): outSlot must not be NULL");
+        return BAD_VALUE;
+    } else if (buffer == NULL) {
+        BQ_LOGE("attachBuffer(P): cannot attach NULL buffer");
+        return BAD_VALUE;
+    }
+
+    Mutex::Autolock lock(mCore->mMutex);
+
+    // Make sure we don't have too many acquired buffers and find a free slot
+    // to put the buffer into (the oldest if there are multiple).
+    int numAcquiredBuffers = 0;
+    int found = BufferQueueCore::INVALID_BUFFER_SLOT;
+    for (int s = 0; s < BufferQueueDefs::NUM_BUFFER_SLOTS; ++s) {
+        if (mSlots[s].mBufferState == BufferSlot::ACQUIRED) {
+            ++numAcquiredBuffers;
+        } else if (mSlots[s].mBufferState == BufferSlot::FREE) {
+            if (found == BufferQueueCore::INVALID_BUFFER_SLOT ||
+                    mSlots[s].mFrameNumber < mSlots[found].mFrameNumber) {
+                found = s;
+            }
+        }
+    }
+
+    if (numAcquiredBuffers >= mCore->mMaxAcquiredBufferCount + 1) {
+        BQ_LOGE("attachBuffer(P): max acquired buffer count reached: %d "
+                "(max %d)", numAcquiredBuffers,
+                mCore->mMaxAcquiredBufferCount);
+        return INVALID_OPERATION;
+    }
+    if (found == BufferQueueCore::INVALID_BUFFER_SLOT) {
+        BQ_LOGE("attachBuffer(P): could not find free buffer slot");
+        return NO_MEMORY;
+    }
+
+    *outSlot = found;
+    ATRACE_BUFFER_INDEX(*outSlot);
+    BQ_LOGV("attachBuffer(C): returning slot %d", *outSlot);
+
+    mSlots[*outSlot].mGraphicBuffer = buffer;
+    mSlots[*outSlot].mBufferState = BufferSlot::ACQUIRED;
+    mSlots[*outSlot].mAttachedByConsumer = true;
+    mSlots[*outSlot].mAcquireCalled = true;
+    mSlots[*outSlot].mNeedsCleanupOnRelease = false;
+    mSlots[*outSlot].mFence = Fence::NO_FENCE;
+    mSlots[*outSlot].mFrameNumber = 0;
+
+    return NO_ERROR;
+}
+
 status_t BufferQueueConsumer::releaseBuffer(int slot, uint64_t frameNumber,
         const sp<Fence>& releaseFence, EGLDisplay eglDisplay,
         EGLSyncKHR eglFence) {
     ATRACE_CALL();
     ATRACE_BUFFER_INDEX(slot);
 
-    if (slot == BufferQueueCore::INVALID_BUFFER_SLOT || releaseFence == NULL) {
+    if (slot < 0 || slot >= BufferQueueDefs::NUM_BUFFER_SLOTS ||
+            releaseFence == NULL) {
         return BAD_VALUE;
     }
 
@@ -192,7 +275,7 @@
         if (current->mSlot == slot) {
             BQ_LOGE("releaseBuffer: buffer slot %d pending release is "
                     "currently queued", slot);
-            return -EINVAL;
+            return BAD_VALUE;
         }
         ++current;
     }
@@ -210,7 +293,7 @@
     } else {
         BQ_LOGV("releaseBuffer: attempted to release buffer slot %d "
                 "but its state was %d", slot, mSlots[slot].mBufferState);
-        return -EINVAL;
+        return BAD_VALUE;
     }
 
     mCore->mDequeueCondition.broadcast();
@@ -252,7 +335,7 @@
 
     if (mCore->mConsumerListener == NULL) {
         BQ_LOGE("disconnect(C): no consumer is connected");
-        return -EINVAL;
+        return BAD_VALUE;
     }
 
     mCore->mIsAbandoned = true;