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+/*
+ * Copyright (C) 2007 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_SF_SHARED_BUFFER_STACK_H
+#define ANDROID_SF_SHARED_BUFFER_STACK_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <cutils/compiler.h>
+
+#include <utils/Debug.h>
+#include <utils/threads.h>
+#include <utils/String8.h>
+
+#include <ui/Rect.h>
+
+namespace android {
+// ---------------------------------------------------------------------------
+
+/*
+ * These classes manage a stack of buffers in shared memory.
+ *
+ * SharedClient: represents a client with several stacks
+ * SharedBufferStack: represents a stack of buffers
+ * SharedBufferClient: manipulates the SharedBufferStack from the client side
+ * SharedBufferServer: manipulates the SharedBufferStack from the server side
+ *
+ * Buffers can be dequeued until there are none available, they can be locked
+ * unless they are in use by the server, which is only the case for the last
+ * dequeue-able buffer. When these various conditions are not met, the caller
+ * waits until the condition is met.
+ *
+ *
+ * CAVEATS:
+ *
+ * In the current implementation there are several limitations:
+ * - buffers must be locked in the same order they've been dequeued
+ * - buffers must be enqueued in the same order they've been locked
+ * - dequeue() is not reentrant
+ * - no error checks are done on the condition above
+ *
+ */
+
+// When changing these values, the COMPILE_TIME_ASSERT at the end of this
+// file need to be updated.
+const unsigned int NUM_LAYERS_MAX = 31;
+const unsigned int NUM_BUFFER_MAX = 4;
+const unsigned int NUM_DISPLAY_MAX = 4;
+
+// ----------------------------------------------------------------------------
+
+class Region;
+class SharedBufferStack;
+class SharedClient;
+
+// ----------------------------------------------------------------------------
+
+// should be 128 bytes (32 longs)
+class SharedBufferStack
+{
+ friend class SharedClient;
+ friend class SharedBufferBase;
+ friend class SharedBufferClient;
+ friend class SharedBufferServer;
+
+public:
+ struct FlatRegion { // 12 bytes
+ static const unsigned int NUM_RECT_MAX = 1;
+ uint32_t count;
+ uint16_t rects[4*NUM_RECT_MAX];
+ };
+
+ struct Statistics { // 4 longs
+ typedef int32_t usecs_t;
+ usecs_t totalTime;
+ usecs_t reserved[3];
+ };
+
+ SharedBufferStack();
+ void init(int32_t identity);
+ status_t setDirtyRegion(int buffer, const Region& reg);
+ Region getDirtyRegion(int buffer) const;
+
+ // these attributes are part of the conditions/updates
+ volatile int32_t head; // server's current front buffer
+ volatile int32_t available; // number of dequeue-able buffers
+ volatile int32_t queued; // number of buffers waiting for post
+ volatile int32_t inUse; // buffer currently in use by SF
+ volatile status_t status; // surface's status code
+
+ // not part of the conditions
+ volatile int32_t reallocMask;
+
+ int32_t identity; // surface's identity (const)
+ int32_t reserved32[9];
+ Statistics stats;
+ FlatRegion dirtyRegion[NUM_BUFFER_MAX]; // 12*4=48 bytes
+};
+
+// ----------------------------------------------------------------------------
+
+// 4 KB max
+class SharedClient
+{
+public:
+ SharedClient();
+ ~SharedClient();
+
+ status_t validate(size_t token) const;
+ uint32_t getIdentity(size_t token) const;
+
+private:
+ friend class SharedBufferBase;
+ friend class SharedBufferClient;
+ friend class SharedBufferServer;
+
+ // FIXME: this should be replaced by a lock-less primitive
+ Mutex lock;
+ Condition cv;
+ SharedBufferStack surfaces[ NUM_LAYERS_MAX ];
+};
+
+// ============================================================================
+
+class SharedBufferBase
+{
+public:
+ SharedBufferBase(SharedClient* sharedClient, int surface, int num,
+ int32_t identity);
+ ~SharedBufferBase();
+ uint32_t getIdentity();
+ status_t getStatus() const;
+ size_t getFrontBuffer() const;
+ String8 dump(char const* prefix) const;
+
+protected:
+ SharedClient* const mSharedClient;
+ SharedBufferStack* const mSharedStack;
+ const int mNumBuffers;
+ const int mIdentity;
+
+ friend struct Update;
+ friend struct QueueUpdate;
+
+ struct ConditionBase {
+ SharedBufferStack& stack;
+ inline ConditionBase(SharedBufferBase* sbc)
+ : stack(*sbc->mSharedStack) { }
+ };
+
+ struct UpdateBase {
+ SharedBufferStack& stack;
+ inline UpdateBase(SharedBufferBase* sbb)
+ : stack(*sbb->mSharedStack) { }
+ };
+
+ template <typename T>
+ status_t waitForCondition(T condition);
+
+ template <typename T>
+ status_t updateCondition(T update);
+};
+
+template <typename T>
+status_t SharedBufferBase::waitForCondition(T condition)
+{
+ const SharedBufferStack& stack( *mSharedStack );
+ SharedClient& client( *mSharedClient );
+ const nsecs_t TIMEOUT = s2ns(1);
+ Mutex::Autolock _l(client.lock);
+ while ((condition()==false) &&
+ (stack.identity == mIdentity) &&
+ (stack.status == NO_ERROR))
+ {
+ status_t err = client.cv.waitRelative(client.lock, TIMEOUT);
+
+ // handle errors and timeouts
+ if (CC_UNLIKELY(err != NO_ERROR)) {
+ if (err == TIMED_OUT) {
+ if (condition()) {
+ LOGE("waitForCondition(%s) timed out (identity=%d), "
+ "but condition is true! We recovered but it "
+ "shouldn't happen." , T::name(),
+ stack.identity);
+ break;
+ } else {
+ LOGW("waitForCondition(%s) timed out "
+ "(identity=%d, status=%d). "
+ "CPU may be pegged. trying again.", T::name(),
+ stack.identity, stack.status);
+ }
+ } else {
+ LOGE("waitForCondition(%s) error (%s) ",
+ T::name(), strerror(-err));
+ return err;
+ }
+ }
+ }
+ return (stack.identity != mIdentity) ? status_t(BAD_INDEX) : stack.status;
+}
+
+
+template <typename T>
+status_t SharedBufferBase::updateCondition(T update) {
+ SharedClient& client( *mSharedClient );
+ Mutex::Autolock _l(client.lock);
+ ssize_t result = update();
+ client.cv.broadcast();
+ return result;
+}
+
+// ----------------------------------------------------------------------------
+
+class SharedBufferClient : public SharedBufferBase
+{
+public:
+ SharedBufferClient(SharedClient* sharedClient, int surface, int num,
+ int32_t identity);
+
+ ssize_t dequeue();
+ status_t undoDequeue(int buf);
+
+ status_t lock(int buf);
+ status_t queue(int buf);
+ bool needNewBuffer(int buffer) const;
+ status_t setDirtyRegion(int buffer, const Region& reg);
+
+private:
+ friend struct Condition;
+ friend struct DequeueCondition;
+ friend struct LockCondition;
+
+ int32_t computeTail() const;
+
+ struct QueueUpdate : public UpdateBase {
+ inline QueueUpdate(SharedBufferBase* sbb);
+ inline ssize_t operator()();
+ };
+
+ struct UndoDequeueUpdate : public UpdateBase {
+ inline UndoDequeueUpdate(SharedBufferBase* sbb);
+ inline ssize_t operator()();
+ };
+
+ // --
+
+ struct DequeueCondition : public ConditionBase {
+ inline DequeueCondition(SharedBufferClient* sbc);
+ inline bool operator()();
+ static inline const char* name() { return "DequeueCondition"; }
+ };
+
+ struct LockCondition : public ConditionBase {
+ int buf;
+ inline LockCondition(SharedBufferClient* sbc, int buf);
+ inline bool operator()();
+ static inline const char* name() { return "LockCondition"; }
+ };
+
+ int32_t tail;
+ // statistics...
+ nsecs_t mDequeueTime[NUM_BUFFER_MAX];
+};
+
+// ----------------------------------------------------------------------------
+
+class SharedBufferServer : public SharedBufferBase
+{
+public:
+ SharedBufferServer(SharedClient* sharedClient, int surface, int num,
+ int32_t identity);
+
+ ssize_t retireAndLock();
+ status_t unlock(int buffer);
+ void setStatus(status_t status);
+ status_t reallocate();
+ status_t assertReallocate(int buffer);
+ int32_t getQueuedCount() const;
+
+ Region getDirtyRegion(int buffer) const;
+
+ SharedBufferStack::Statistics getStats() const;
+
+
+private:
+ struct UnlockUpdate : public UpdateBase {
+ const int lockedBuffer;
+ inline UnlockUpdate(SharedBufferBase* sbb, int lockedBuffer);
+ inline ssize_t operator()();
+ };
+
+ struct RetireUpdate : public UpdateBase {
+ const int numBuffers;
+ inline RetireUpdate(SharedBufferBase* sbb, int numBuffers);
+ inline ssize_t operator()();
+ };
+
+ struct StatusUpdate : public UpdateBase {
+ const status_t status;
+ inline StatusUpdate(SharedBufferBase* sbb, status_t status);
+ inline ssize_t operator()();
+ };
+
+ struct ReallocateCondition : public ConditionBase {
+ int buf;
+ inline ReallocateCondition(SharedBufferBase* sbb, int buf);
+ inline bool operator()();
+ static inline const char* name() { return "ReallocateCondition"; }
+ };
+};
+
+// ===========================================================================
+
+struct display_cblk_t
+{
+ uint16_t w;
+ uint16_t h;
+ uint8_t format;
+ uint8_t orientation;
+ uint8_t reserved[2];
+ float fps;
+ float density;
+ float xdpi;
+ float ydpi;
+ uint32_t pad[2];
+};
+
+struct surface_flinger_cblk_t // 4KB max
+{
+ uint8_t connected;
+ uint8_t reserved[3];
+ uint32_t pad[7];
+ display_cblk_t displays[NUM_DISPLAY_MAX];
+};
+
+// ---------------------------------------------------------------------------
+
+COMPILE_TIME_ASSERT(sizeof(SharedClient) <= 4096)
+COMPILE_TIME_ASSERT(sizeof(SharedBufferStack) == 128)
+COMPILE_TIME_ASSERT(sizeof(surface_flinger_cblk_t) <= 4096)
+
+// ---------------------------------------------------------------------------
+}; // namespace android
+
+#endif /* ANDROID_SF_SHARED_BUFFER_STACK_H */
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