BufferQueue: Add allocateBuffers method

This adds an allocateBuffers method to BufferQueue, which instructs
it to allocate up to the maximum number of buffers allowed by the
current configuration. The goal is that this method can be called
ahead of render time, which will prevent dequeueBuffers from blocking
in allocation and inducing jank.

This interface is also plumbed up to the native Surface (and, in
another change, up to the Java Surface and ThreadedRenderer).

Bug: 11792166
Change-Id: I4aa96b4351ea1c95ed5db228ca3ef98303229c74

3 files changed, 27 insertions, 0 deletions

diff --git a/include/gui/BufferQueueProducer.h b/include/gui/BufferQueueProducer.h
index 9df3633..fe8a308 100644
--- a/include/gui/BufferQueueProducer.h
+++ b/include/gui/BufferQueueProducer.h
@@ -169,6 +169,10 @@ public:
     // handle if any.
     virtual status_t setSidebandStream(const sp<NativeHandle>& stream);
 
+    // See IGraphicBufferProducer::allocateBuffers
+    virtual void allocateBuffers(bool async, uint32_t width, uint32_t height,
+            uint32_t format, uint32_t usage);
+
 private:
     // This is required by the IBinder::DeathRecipient interface
     virtual void binderDied(const wp<IBinder>& who);
diff --git a/include/gui/IGraphicBufferProducer.h b/include/gui/IGraphicBufferProducer.h
index d9e116b..9b96b2b 100644
--- a/include/gui/IGraphicBufferProducer.h
+++ b/include/gui/IGraphicBufferProducer.h
@@ -429,6 +429,19 @@ public:
     // Passing NULL or a different stream handle will detach the previous
     // handle if any.
     virtual status_t setSidebandStream(const sp<NativeHandle>& stream) = 0;
+
+    // Allocates buffers based on the given dimensions/format.
+    //
+    // This function will allocate up to the maximum number of buffers
+    // permitted by the current BufferQueue configuration. It will use the
+    // given format, dimensions, and usage bits, which are interpreted in the
+    // same way as for dequeueBuffer, and the async flag must be set the same
+    // way as for dequeueBuffer to ensure that the correct number of buffers are
+    // allocated. This is most useful to avoid an allocation delay during
+    // dequeueBuffer. If there are already the maximum number of buffers
+    // allocated, this function has no effect.
+    virtual void allocateBuffers(bool async, uint32_t width, uint32_t height,
+            uint32_t format, uint32_t usage) = 0;
 };
 
 // ----------------------------------------------------------------------------
diff --git a/include/gui/Surface.h b/include/gui/Surface.h
index d8e9756..dcfe74f 100644
--- a/include/gui/Surface.h
+++ b/include/gui/Surface.h
@@ -91,6 +91,16 @@ public:
      */
     void setSidebandStream(const sp<NativeHandle>& stream);
 
+    /* Allocates buffers based on the current dimensions/format.
+     *
+     * This function will allocate up to the maximum number of buffers
+     * permitted by the current BufferQueue configuration. It will use the
+     * default format and dimensions. This is most useful to avoid an allocation
+     * delay during dequeueBuffer. If there are already the maximum number of
+     * buffers allocated, this function has no effect.
+     */
+    void allocateBuffers();
+
 protected:
     virtual ~Surface();