/*
* Copyright 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_SERVERS_CAMERA3_BUFFER_MANAGER_H
#define ANDROID_SERVERS_CAMERA3_BUFFER_MANAGER_H
#include <list>
#include <algorithm>
#include <ui/GraphicBuffer.h>
#include <utils/RefBase.h>
#include <utils/KeyedVector.h>
#include "Camera3OutputStream.h"
namespace android {
namespace camera3 {
struct StreamInfo;
class Camera3OutputStream;
/**
* A class managing the graphic buffers that is used by camera output streams. It allocates and
* hands out Gralloc buffers to the clients (e.g., Camera3OutputStream) based on the requests.
* When clients request a buffer, buffer manager will pick a buffer if there are some already
* allocated buffer available, will allocate a buffer otherwise. When there are too many allocated
* buffer maintained by the buffer manager, it will dynamically deallocate some buffers that are
* solely owned by this buffer manager.
* In doing so, it reduces the memory footprint unless it is already minimal without impacting
* performance.
*
*/
class Camera3BufferManager: public virtual RefBase {
public:
explicit Camera3BufferManager();
virtual ~Camera3BufferManager();
/**
* This method registers an output stream to this buffer manager by using the provided stream
* information.
*
* The stream info includes the necessary information such as stream size, format, buffer count,
* usage flags, etc. for the buffer manager to allocate and hand out buffers for this stream.
*
* It's illegal to call this method if the stream is not CONFIGURED yet, as some critical
* stream properties (e.g., combined usage flags) are only available in this state. It is also
* illegal to call this method with an invalid stream set ID (CAMERA3_STREAM_SET_ID_INVALID),
* as the invalid stream set ID indicates that this stream doesn't intend to use buffer manager.
*
*
* Once a stream is successfully registered to this buffer manager, the buffer manager takes
* over the buffer allocation role and provides buffers to this stream via getBufferForStream().
* The returned buffer can be sent to the camera HAL for image output, and then queued to the
* ANativeWindow (Surface) for downstream consumer to acquire. Once the image buffer is released
* by the consumer end point, the BufferQueueProducer callback onBufferReleased will call
* returnBufferForStream() to return the free buffer to this buffer manager. If the stream
* uses buffer manager to manage the stream buffers, it should disable the BufferQueue
* allocation via IGraphicBufferProducer::allowAllocation(false).
*
* Registering an already registered stream has no effect.
*
* Return values:
*
* OK: Registration of the new stream was successful.
* BAD_VALUE: This stream is not at CONFIGURED state, or the stream ID or stream set
* ID are invalid, or attempting to register the same stream to multiple
* stream sets, or other stream properties are invalid.
* INVALID_OPERATION: This buffer manager doesn't support buffer sharing across this stream
* and other streams that were already registered with the same stream set
* ID.
*/
status_t registerStream(wp<Camera3OutputStream>& stream, const StreamInfo &streamInfo);
/**
* This method unregisters a stream from this buffer manager.
*
* After a stream is unregistered, further getBufferForStream() calls will fail for this stream.
* After all streams for a given stream set are unregistered, all the buffers solely owned (for
* this stream set) by this buffer manager will be freed; all buffers subsequently returned to
* this buffer manager for this stream set will be freed immediately.
*
* Return values:
*
* OK: Removal of the a stream from this buffer manager was successful.
* BAD_VALUE: stream ID or stream set ID are invalid, or stream ID and stream set ID
* combination doesn't match what was registered, or this stream wasn't registered
* to this buffer manager before.
*/
status_t unregisterStream(int streamId, int streamSetId);
/**
* This method obtains a buffer for a stream from this buffer manager.
*
* This method returns the first free buffer from the free buffer list (associated with this
* stream set) if there is any. Otherwise, it will allocate a buffer for this stream, return
* it and increment its count of handed-out buffers. When the total number of allocated buffers
* is too high, it may deallocate the unused buffers to save memory footprint of this stream
* set.
*
* After this call, the client takes over the ownership of this buffer if it is not freed.
*
* Return values:
*
* OK: Getting buffer for this stream was successful.
* ALREADY_EXISTS: Enough free buffers are already attached to this output buffer queue,
* user should just dequeue from the buffer queue.
* BAD_VALUE: stream ID or streamSetId are invalid, or stream ID and stream set ID
* combination doesn't match what was registered, or this stream wasn't registered
* to this buffer manager before.
* NO_MEMORY: Unable to allocate a buffer for this stream at this time.
*/
status_t getBufferForStream(int streamId, int streamSetId, sp<GraphicBuffer>* gb, int* fenceFd);
/**
* This method notifies the manager that a buffer has been released by the consumer.
*
* The buffer is not returned to the buffer manager, but is available for the stream the buffer
* is attached to for dequeuing.
*
* The notification lets the manager know how many buffers are directly available to the stream.
*
* If onBufferReleased is called for a given released buffer,
* returnBufferForStream may not be called for the same buffer, until the
* buffer has been reused. The manager will call detachBuffer on the stream
* if it needs the released buffer otherwise.
*
* When shouldFreeBuffer is set to true, caller must detach and free one buffer from the
* buffer queue, and then call notifyBufferRemoved to update the manager.
*
* Return values:
*
* OK: Buffer release was processed succesfully
* BAD_VALUE: stream ID or streamSetId are invalid, or stream ID and stream set ID
* combination doesn't match what was registered, or this stream wasn't registered
* to this buffer manager before, or shouldFreeBuffer is null/
*/
status_t onBufferReleased(int streamId, int streamSetId, /*out*/bool* shouldFreeBuffer);
/**
* This method notifies the manager that certain buffers has been removed from the
* buffer queue by detachBuffer from the consumer.
*
* The notification lets the manager update its internal handout buffer count and
* attached buffer counts accordingly. When buffers are detached from
* consumer, both handout and attached counts are decremented.
*
* Return values:
*
* OK: Buffer removal was processed succesfully
* BAD_VALUE: stream ID or streamSetId are invalid, or stream ID and stream set ID
* combination doesn't match what was registered, or this stream wasn't registered
* to this buffer manager before, or the removed buffer count is larger than
* current total handoutCount or attachedCount.
*/
status_t onBuffersRemoved(int streamId, int streamSetId, size_t count);
/**
* This method notifiers the manager that a buffer is freed from the buffer queue, usually
* because onBufferReleased signals the caller to free a buffer via the shouldFreeBuffer flag.
*/
void notifyBufferRemoved(int streamId, int streamSetId);
/**
* Dump the buffer manager statistics.
*/
void dump(int fd, const Vector<String16> &args) const;
private:
// allocatedBufferWaterMark will be decreased when:
// numAllocatedBuffersThisSet > numHandoutBuffersThisSet + BUFFER_WATERMARK_DEC_THRESHOLD
// This allows the watermark go back down after a burst of buffer requests
static const int BUFFER_WATERMARK_DEC_THRESHOLD = 3;
// onBufferReleased will set shouldFreeBuffer to true when:
// numAllocatedBuffersThisSet > allocatedBufferWaterMark AND
// numAllocatedBuffersThisStream > numHandoutBuffersThisStream + BUFFER_FREE_THRESHOLD
// So after a burst of buffer requests and back to steady state, the buffer queue should have
// (BUFFER_FREE_THRESHOLD + steady state handout buffer count) buffers.
static const int BUFFER_FREE_THRESHOLD = 3;
/**
* Lock to synchronize the access to the methods of this class.
*/
mutable Mutex mLock;
static const size_t kMaxBufferCount = BufferQueueDefs::NUM_BUFFER_SLOTS;
struct GraphicBufferEntry {
sp<GraphicBuffer> graphicBuffer;
int fenceFd;
explicit GraphicBufferEntry(const sp<GraphicBuffer>& gb = 0, int fd = -1) :
graphicBuffer(gb),
fenceFd(fd) {}
};
/**
* A buffer entry (indexed by stream ID) represents a single physically allocated buffer. For
* Gralloc V0, since each physical buffer is associated with one stream, this is
* a single entry map. For Gralloc V1, one physical buffer can be shared between different
* streams in one stream set, so this entry may include multiple entries, where the different
* graphic buffers have the same common Gralloc backing store.
*/
typedef int StreamId;
typedef KeyedVector<StreamId, GraphicBufferEntry> BufferEntry;
typedef std::list<BufferEntry> BufferList;
/**
* Stream info map (indexed by stream ID) tracks all the streams registered to a particular
* stream set.
*/
typedef KeyedVector<StreamId, StreamInfo> InfoMap;
/**
* Stream set buffer count map (indexed by stream ID) tracks all buffer counts of the streams
* registered to a particular stream set.
*/
typedef KeyedVector<StreamId, size_t> BufferCountMap;
/**
* StreamSet keeps track of the stream info, free buffer list and hand-out buffer counts for
* each stream set.
*/
struct StreamSet {
/**
* Stream set buffer count water mark representing the max number of allocated buffers
* (hand-out buffers + free buffers) count for each stream set. For a given stream set, when
* getBufferForStream() is called on this buffer manager, if the total allocated buffer
* count exceeds this water mark, the buffer manager will attempt to reduce it as follows:
*
* In getBufferForStream(), find a buffer associated with other streams (inside the same
* stream set) on the free buffer list and free it. For Gralloc V1, can just free the top
* of the free buffer list if the physical buffer sharing in this stream is supported.
*
* For a particular stream set, a larger allocatedBufferWaterMark increases the memory
* footprint of the stream set, but reduces the chance that getBufferForStream() will have
* to allocate a new buffer. We assume that the streams in one stream set are not streaming
* simultaneously, the max allocated buffer count water mark for a stream set will the max
* of all streams' total buffer counts. This will avoid new buffer allocation in steady
* streaming state.
*
* This water mark can be dynamically changed, and will grow when the hand-out buffer count
* of each stream increases, until it reaches the maxAllowedBufferCount.
*/
size_t allocatedBufferWaterMark;
/**
* The max allowed buffer count for this stream set. It is the max of total number of
* buffers for each stream. This is the upper bound of the allocatedBufferWaterMark.
*/
size_t maxAllowedBufferCount;
/**
* The stream info for all streams in this set
*/
InfoMap streamInfoMap;
/**
* The count of the buffers that were handed out to the streams of this set.
*/
BufferCountMap handoutBufferCountMap;
/**
* The count of the buffers that are attached to the streams of this set.
* An attached buffer may be free or handed out
*/
BufferCountMap attachedBufferCountMap;
StreamSet() {
allocatedBufferWaterMark = 0;
maxAllowedBufferCount = 0;
}
};
/**
* Stream set map managed by this buffer manager.
*/
typedef int StreamSetId;
KeyedVector<StreamSetId, StreamSet> mStreamSetMap;
KeyedVector<StreamId, wp<Camera3OutputStream>> mStreamMap;
// TODO: There is no easy way to query the Gralloc version in this code yet, we have different
// code paths for different Gralloc versions, hardcode something here for now.
const uint32_t mGrallocVersion = GRALLOC_DEVICE_API_VERSION_0_1;
/**
* Check if this stream was successfully registered already. This method needs to be called with
* mLock held.
*/
bool checkIfStreamRegisteredLocked(int streamId, int streamSetId) const;
/**
* Check if other streams in the stream set has extra buffer available to be freed, and
* free one if so.
*/
status_t checkAndFreeBufferOnOtherStreamsLocked(int streamId, int streamSetId);
};
} // namespace camera3
} // namespace android
#endif // ANDROID_SERVERS_CAMERA3_BUFFER_MANAGER_H