bb641244d7
this change introduces R/W locks in the right places. on the server-side, it guarantees that setBufferCount() is synchronized with "retire" and "resize". on the client-side, it guarantees that setBufferCount() is synchronized with "dequeue", "lockbuffer" and "queue"
403 lines
12 KiB
C++
403 lines
12 KiB
C++
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_SF_SHARED_BUFFER_STACK_H
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#define ANDROID_SF_SHARED_BUFFER_STACK_H
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#include <stdint.h>
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#include <sys/types.h>
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#include <cutils/compiler.h>
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#include <utils/Debug.h>
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#include <utils/threads.h>
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#include <utils/String8.h>
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#include <ui/Rect.h>
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namespace android {
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// ---------------------------------------------------------------------------
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/*
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* These classes manage a stack of buffers in shared memory.
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*
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* SharedClient: represents a client with several stacks
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* SharedBufferStack: represents a stack of buffers
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* SharedBufferClient: manipulates the SharedBufferStack from the client side
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* SharedBufferServer: manipulates the SharedBufferStack from the server side
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*
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* Buffers can be dequeued until there are none available, they can be locked
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* unless they are in use by the server, which is only the case for the last
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* dequeue-able buffer. When these various conditions are not met, the caller
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* waits until the condition is met.
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*
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*
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* CAVEATS:
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*
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* In the current implementation there are several limitations:
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* - buffers must be locked in the same order they've been dequeued
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* - buffers must be enqueued in the same order they've been locked
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* - dequeue() is not reentrant
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* - no error checks are done on the condition above
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*
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*/
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// ----------------------------------------------------------------------------
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class Region;
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class SharedBufferStack;
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class SharedClient;
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// ----------------------------------------------------------------------------
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// 4 * (11 + 7 + (1 + 2*NUM_RECT_MAX) * NUM_BUFFER_MAX) * NUM_LAYERS_MAX
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// 4 * (11 + 7 + (1 + 2*7)*16) * 31
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// 1032 * 31
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// = ~27 KiB (31992)
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class SharedBufferStack
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{
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friend class SharedClient;
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friend class SharedBufferBase;
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friend class SharedBufferClient;
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friend class SharedBufferServer;
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public:
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// When changing these values, the COMPILE_TIME_ASSERT at the end of this
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// file need to be updated.
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static const unsigned int NUM_LAYERS_MAX = 31;
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static const unsigned int NUM_BUFFER_MAX = 16;
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static const unsigned int NUM_DISPLAY_MAX = 4;
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struct Statistics { // 4 longs
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typedef int32_t usecs_t;
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usecs_t totalTime;
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usecs_t reserved[3];
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};
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struct SmallRect {
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uint16_t l, t, r, b;
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};
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struct FlatRegion { // 52 bytes = 4 * (1 + 2*N)
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static const unsigned int NUM_RECT_MAX = 6;
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uint32_t count;
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SmallRect rects[NUM_RECT_MAX];
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};
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struct BufferData {
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FlatRegion dirtyRegion;
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SmallRect crop;
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};
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SharedBufferStack();
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void init(int32_t identity);
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status_t setDirtyRegion(int buffer, const Region& reg);
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status_t setCrop(int buffer, const Rect& reg);
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Region getDirtyRegion(int buffer) const;
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// these attributes are part of the conditions/updates
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volatile int32_t head; // server's current front buffer
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volatile int32_t available; // number of dequeue-able buffers
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volatile int32_t queued; // number of buffers waiting for post
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volatile int32_t inUse; // buffer currently in use by SF
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volatile status_t status; // surface's status code
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// not part of the conditions
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volatile int32_t reallocMask;
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volatile int8_t index[NUM_BUFFER_MAX];
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int32_t identity; // surface's identity (const)
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int32_t reserved32[2];
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Statistics stats;
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int32_t reserved;
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BufferData buffers[NUM_BUFFER_MAX]; // 960 bytes
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};
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// ----------------------------------------------------------------------------
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// 32 KB max
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class SharedClient
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{
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public:
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SharedClient();
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~SharedClient();
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status_t validate(size_t token) const;
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uint32_t getIdentity(size_t token) const;
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private:
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friend class SharedBufferBase;
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friend class SharedBufferClient;
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friend class SharedBufferServer;
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// FIXME: this should be replaced by a lock-less primitive
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Mutex lock;
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Condition cv;
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SharedBufferStack surfaces[ SharedBufferStack::NUM_LAYERS_MAX ];
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};
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// ============================================================================
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class SharedBufferBase
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{
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public:
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SharedBufferBase(SharedClient* sharedClient, int surface,
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int32_t identity);
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~SharedBufferBase();
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uint32_t getIdentity();
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status_t getStatus() const;
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size_t getFrontBuffer() const;
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String8 dump(char const* prefix) const;
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protected:
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SharedClient* const mSharedClient;
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SharedBufferStack* const mSharedStack;
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const int mIdentity;
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friend struct Update;
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friend struct QueueUpdate;
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struct ConditionBase {
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SharedBufferStack& stack;
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inline ConditionBase(SharedBufferBase* sbc)
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: stack(*sbc->mSharedStack) { }
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virtual ~ConditionBase() { };
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virtual bool operator()() const = 0;
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virtual const char* name() const = 0;
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};
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status_t waitForCondition(const ConditionBase& condition);
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struct UpdateBase {
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SharedBufferStack& stack;
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inline UpdateBase(SharedBufferBase* sbb)
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: stack(*sbb->mSharedStack) { }
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};
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template <typename T>
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status_t updateCondition(T update);
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};
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template <typename T>
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status_t SharedBufferBase::updateCondition(T update) {
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SharedClient& client( *mSharedClient );
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Mutex::Autolock _l(client.lock);
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ssize_t result = update();
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client.cv.broadcast();
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return result;
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}
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// ----------------------------------------------------------------------------
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class SharedBufferClient : public SharedBufferBase
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{
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public:
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SharedBufferClient(SharedClient* sharedClient, int surface, int num,
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int32_t identity);
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ssize_t dequeue();
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status_t undoDequeue(int buf);
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status_t lock(int buf);
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status_t queue(int buf);
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bool needNewBuffer(int buffer) const;
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status_t setDirtyRegion(int buffer, const Region& reg);
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status_t setCrop(int buffer, const Rect& reg);
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class SetBufferCountCallback {
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friend class SharedBufferClient;
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virtual status_t operator()(int bufferCount) const = 0;
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protected:
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virtual ~SetBufferCountCallback() { }
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};
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status_t setBufferCount(int bufferCount, const SetBufferCountCallback& ipc);
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private:
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friend struct Condition;
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friend struct DequeueCondition;
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friend struct LockCondition;
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struct QueueUpdate : public UpdateBase {
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inline QueueUpdate(SharedBufferBase* sbb);
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inline ssize_t operator()();
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};
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struct UndoDequeueUpdate : public UpdateBase {
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inline UndoDequeueUpdate(SharedBufferBase* sbb);
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inline ssize_t operator()();
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};
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// --
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struct DequeueCondition : public ConditionBase {
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inline DequeueCondition(SharedBufferClient* sbc);
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inline bool operator()() const;
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inline const char* name() const { return "DequeueCondition"; }
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};
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struct LockCondition : public ConditionBase {
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int buf;
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inline LockCondition(SharedBufferClient* sbc, int buf);
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inline bool operator()() const;
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inline const char* name() const { return "LockCondition"; }
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};
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int32_t computeTail() const;
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mutable RWLock mLock;
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int mNumBuffers;
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int32_t tail;
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int32_t undoDequeueTail;
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int32_t queued_head;
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// statistics...
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nsecs_t mDequeueTime[SharedBufferStack::NUM_BUFFER_MAX];
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};
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// ----------------------------------------------------------------------------
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class SharedBufferServer : public SharedBufferBase
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{
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public:
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SharedBufferServer(SharedClient* sharedClient, int surface, int num,
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int32_t identity);
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ssize_t retireAndLock();
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status_t unlock(int buffer);
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void setStatus(status_t status);
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status_t reallocate();
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status_t assertReallocate(int buffer);
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int32_t getQueuedCount() const;
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Region getDirtyRegion(int buffer) const;
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status_t resize(int newNumBuffers);
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SharedBufferStack::Statistics getStats() const;
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private:
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/*
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* BufferList is basically a fixed-capacity sorted-vector of
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* unsigned 5-bits ints using a 32-bits int as storage.
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* it has efficient iterators to find items in the list and not in the list.
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*/
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class BufferList {
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size_t mCapacity;
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uint32_t mList;
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public:
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BufferList(size_t c = SharedBufferStack::NUM_BUFFER_MAX)
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: mCapacity(c), mList(0) { }
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status_t add(int value);
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status_t remove(int value);
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class const_iterator {
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friend class BufferList;
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uint32_t mask, curr;
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const_iterator(uint32_t mask) :
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mask(mask), curr(__builtin_clz(mask)) {
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}
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public:
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inline bool operator == (const const_iterator& rhs) const {
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return mask == rhs.mask;
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}
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inline bool operator != (const const_iterator& rhs) const {
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return mask != rhs.mask;
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}
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inline int operator *() const { return curr; }
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inline const const_iterator& operator ++() {
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mask &= ~(1<<(31-curr));
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curr = __builtin_clz(mask);
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return *this;
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}
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};
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inline const_iterator begin() const {
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return const_iterator(mList);
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}
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inline const_iterator end() const {
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return const_iterator(0);
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}
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inline const_iterator free_begin() const {
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uint32_t mask = (1 << (32-mCapacity)) - 1;
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return const_iterator( ~(mList | mask) );
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}
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};
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// this protects mNumBuffers and mBufferList
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mutable RWLock mLock;
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int mNumBuffers;
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BufferList mBufferList;
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struct UnlockUpdate : public UpdateBase {
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const int lockedBuffer;
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inline UnlockUpdate(SharedBufferBase* sbb, int lockedBuffer);
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inline ssize_t operator()();
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};
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struct RetireUpdate : public UpdateBase {
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const int numBuffers;
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inline RetireUpdate(SharedBufferBase* sbb, int numBuffers);
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inline ssize_t operator()();
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};
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struct StatusUpdate : public UpdateBase {
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const status_t status;
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inline StatusUpdate(SharedBufferBase* sbb, status_t status);
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inline ssize_t operator()();
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};
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struct ReallocateCondition : public ConditionBase {
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int buf;
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inline ReallocateCondition(SharedBufferBase* sbb, int buf);
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inline bool operator()() const;
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inline const char* name() const { return "ReallocateCondition"; }
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};
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};
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// ===========================================================================
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struct display_cblk_t
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{
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uint16_t w;
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uint16_t h;
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uint8_t format;
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uint8_t orientation;
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uint8_t reserved[2];
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float fps;
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float density;
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float xdpi;
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float ydpi;
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uint32_t pad[2];
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};
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struct surface_flinger_cblk_t // 4KB max
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{
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uint8_t connected;
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uint8_t reserved[3];
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uint32_t pad[7];
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display_cblk_t displays[SharedBufferStack::NUM_DISPLAY_MAX];
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};
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// ---------------------------------------------------------------------------
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COMPILE_TIME_ASSERT(sizeof(SharedClient) <= 32768)
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COMPILE_TIME_ASSERT(sizeof(surface_flinger_cblk_t) <= 4096)
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// ---------------------------------------------------------------------------
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}; // namespace android
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#endif /* ANDROID_SF_SHARED_BUFFER_STACK_H */
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