libgui: Allow an IGBProducer to disable allocation

Adds a new method IGBP::allowAllocation, which controls whether
dequeueBuffer is permitted to allocate a new buffer. If allocation is
disallowed, dequeueBuffer will block or return an error as it
normally would (as controlled by *ControlledByApp).

If there are free buffers, but they are not of the correct dimensions,
format, or usage, they may be freed if a more suitable buffer is not
found first.

Bug: 19801715
Change-Id: I0d604958b78b2fd775c2547690301423f9a52165

1 files changed, 36 insertions, 0 deletions

diff --git a/libs/gui/tests/BufferQueue_test.cpp b/libs/gui/tests/BufferQueue_test.cpp
index c38c797..112dcb9 100644
--- a/libs/gui/tests/BufferQueue_test.cpp
+++ b/libs/gui/tests/BufferQueue_test.cpp
@@ -364,4 +364,40 @@ TEST_F(BufferQueueTest, MoveFromConsumerToProducer) {
     ASSERT_EQ(OK, item.mGraphicBuffer->unlock());
 }
 
+TEST_F(BufferQueueTest, TestDisallowingAllocation) {
+    createBufferQueue();
+    sp<DummyConsumer> dc(new DummyConsumer);
+    ASSERT_EQ(OK, mConsumer->consumerConnect(dc, true));
+    IGraphicBufferProducer::QueueBufferOutput output;
+    ASSERT_EQ(OK, mProducer->connect(new DummyProducerListener,
+            NATIVE_WINDOW_API_CPU, true, &output));
+
+    static const uint32_t WIDTH = 320;
+    static const uint32_t HEIGHT = 240;
+
+    ASSERT_EQ(OK, mConsumer->setDefaultBufferSize(WIDTH, HEIGHT));
+
+    int slot;
+    sp<Fence> fence;
+    sp<GraphicBuffer> buffer;
+    // This should return an error since it would require an allocation
+    ASSERT_EQ(OK, mProducer->allowAllocation(false));
+    ASSERT_EQ(WOULD_BLOCK, mProducer->dequeueBuffer(&slot, &fence, false, 0, 0,
+            0, GRALLOC_USAGE_SW_WRITE_OFTEN));
+
+    // This should succeed, now that we've lifted the prohibition
+    ASSERT_EQ(OK, mProducer->allowAllocation(true));
+    ASSERT_EQ(IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION,
+            mProducer->dequeueBuffer(&slot, &fence, false, 0, 0, 0,
+            GRALLOC_USAGE_SW_WRITE_OFTEN));
+
+    // Release the previous buffer back to the BufferQueue
+    mProducer->cancelBuffer(slot, fence);
+
+    // This should fail since we're requesting a different size
+    ASSERT_EQ(OK, mProducer->allowAllocation(false));
+    ASSERT_EQ(WOULD_BLOCK, mProducer->dequeueBuffer(&slot, &fence, false,
+            WIDTH * 2, HEIGHT * 2, 0, GRALLOC_USAGE_SW_WRITE_OFTEN));
+}
+
 } // namespace android