/* * 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. */ #define LOG_TAG "SharedBufferStack" #include <stdint.h> #include <sys/types.h> #include <utils/Debug.h> #include <utils/Log.h> #include <utils/threads.h> #include <private/ui/SharedBufferStack.h> #include <ui/Rect.h> #include <ui/Region.h> #define DEBUG_ATOMICS 0 namespace android { // ---------------------------------------------------------------------------- SharedClient::SharedClient() : lock(Mutex::SHARED) { } SharedClient::~SharedClient() { } // these functions are used by the clients status_t SharedClient::validate(size_t i) const { if (uint32_t(i) >= uint32_t(NUM_LAYERS_MAX)) return BAD_INDEX; return surfaces[i].status; } uint32_t SharedClient::getIdentity(size_t token) const { return uint32_t(surfaces[token].identity); } // ---------------------------------------------------------------------------- SharedBufferStack::SharedBufferStack() { } void SharedBufferStack::init(int32_t i) { inUse = -1; status = NO_ERROR; identity = i; } status_t SharedBufferStack::setDirtyRegion(int buffer, const Region& dirty) { if (uint32_t(buffer) >= NUM_BUFFER_MAX) return BAD_INDEX; // in the current implementation we only send a single rectangle const Rect bounds(dirty.getBounds()); FlatRegion& reg(dirtyRegion[buffer]); reg.count = 1; reg.rects[0] = uint16_t(bounds.left); reg.rects[1] = uint16_t(bounds.top); reg.rects[2] = uint16_t(bounds.right); reg.rects[3] = uint16_t(bounds.bottom); return NO_ERROR; } Region SharedBufferStack::getDirtyRegion(int buffer) const { Region res; if (uint32_t(buffer) >= NUM_BUFFER_MAX) return res; const FlatRegion& reg(dirtyRegion[buffer]); res.set(Rect(reg.rects[0], reg.rects[1], reg.rects[2], reg.rects[3])); return res; } // ---------------------------------------------------------------------------- SharedBufferBase::SharedBufferBase(SharedClient* sharedClient, int surface, int num) : mSharedClient(sharedClient), mSharedStack(sharedClient->surfaces + surface), mNumBuffers(num) { } SharedBufferBase::~SharedBufferBase() { } uint32_t SharedBufferBase::getIdentity() { SharedBufferStack& stack( *mSharedStack ); return stack.identity; } size_t SharedBufferBase::getFrontBuffer() const { SharedBufferStack& stack( *mSharedStack ); return size_t( stack.head ); } String8 SharedBufferBase::dump(char const* prefix) const { const size_t SIZE = 1024; char buffer[SIZE]; String8 result; SharedBufferStack& stack( *mSharedStack ); snprintf(buffer, SIZE, "%s[ head=%2d, available=%2d, queued=%2d ] " "reallocMask=%08x, inUse=%2d, identity=%d, status=%d\n", prefix, stack.head, stack.available, stack.queued, stack.reallocMask, stack.inUse, stack.identity, stack.status); result.append(buffer); return result; } // ============================================================================ // conditions and updates // ============================================================================ SharedBufferClient::DequeueCondition::DequeueCondition( SharedBufferClient* sbc) : ConditionBase(sbc) { } bool SharedBufferClient::DequeueCondition::operator()() { return stack.available > 0; } SharedBufferClient::LockCondition::LockCondition( SharedBufferClient* sbc, int buf) : ConditionBase(sbc), buf(buf) { } bool SharedBufferClient::LockCondition::operator()() { return (buf != stack.head || (stack.queued > 0 && stack.inUse != buf)); } SharedBufferServer::ReallocateCondition::ReallocateCondition( SharedBufferBase* sbb, int buf) : ConditionBase(sbb), buf(buf) { } bool SharedBufferServer::ReallocateCondition::operator()() { // TODO: we should also check that buf has been dequeued return (buf != stack.head); } // ---------------------------------------------------------------------------- SharedBufferClient::QueueUpdate::QueueUpdate(SharedBufferBase* sbb) : UpdateBase(sbb) { } ssize_t SharedBufferClient::QueueUpdate::operator()() { android_atomic_inc(&stack.queued); return NO_ERROR; } SharedBufferClient::UndoDequeueUpdate::UndoDequeueUpdate(SharedBufferBase* sbb) : UpdateBase(sbb) { } ssize_t SharedBufferClient::UndoDequeueUpdate::operator()() { android_atomic_inc(&stack.available); return NO_ERROR; } SharedBufferServer::UnlockUpdate::UnlockUpdate( SharedBufferBase* sbb, int lockedBuffer) : UpdateBase(sbb), lockedBuffer(lockedBuffer) { } ssize_t SharedBufferServer::UnlockUpdate::operator()() { if (stack.inUse != lockedBuffer) { LOGE("unlocking %d, but currently locked buffer is %d", lockedBuffer, stack.inUse); return BAD_VALUE; } android_atomic_write(-1, &stack.inUse); return NO_ERROR; } SharedBufferServer::RetireUpdate::RetireUpdate( SharedBufferBase* sbb, int numBuffers) : UpdateBase(sbb), numBuffers(numBuffers) { } ssize_t SharedBufferServer::RetireUpdate::operator()() { // head is only written in this function, which is single-thread. int32_t head = stack.head; // Preventively lock the current buffer before updating queued. android_atomic_write(head, &stack.inUse); // Decrement the number of queued buffers int32_t queued; do { queued = stack.queued; if (queued == 0) { return NOT_ENOUGH_DATA; } } while (android_atomic_cmpxchg(queued, queued-1, &stack.queued)); // update the head pointer head = ((head+1 >= numBuffers) ? 0 : head+1); // lock the buffer before advancing head, which automatically unlocks // the buffer we preventively locked upon entering this function android_atomic_write(head, &stack.inUse); // advance head android_atomic_write(head, &stack.head); // now that head has moved, we can increment the number of available buffers android_atomic_inc(&stack.available); return head; } SharedBufferServer::StatusUpdate::StatusUpdate( SharedBufferBase* sbb, status_t status) : UpdateBase(sbb), status(status) { } ssize_t SharedBufferServer::StatusUpdate::operator()() { android_atomic_write(status, &stack.status); return NO_ERROR; } // ============================================================================ SharedBufferClient::SharedBufferClient(SharedClient* sharedClient, int surface, int num) : SharedBufferBase(sharedClient, surface, num), tail(0) { } ssize_t SharedBufferClient::dequeue() { //LOGD("[%d] about to dequeue a buffer", // mSharedStack->identity); DequeueCondition condition(this); status_t err = waitForCondition(condition); if (err != NO_ERROR) return ssize_t(err); SharedBufferStack& stack( *mSharedStack ); // NOTE: 'stack.available' is part of the conditions, however // decrementing it, never changes any conditions, so we don't need // to do this as part of an update. if (android_atomic_dec(&stack.available) == 0) { LOGW("dequeue probably called from multiple threads!"); } int dequeued = tail; tail = ((tail+1 >= mNumBuffers) ? 0 : tail+1); LOGD_IF(DEBUG_ATOMICS, "dequeued=%d, tail=%d, %s", dequeued, tail, dump("").string()); return dequeued; } status_t SharedBufferClient::undoDequeue(int buf) { UndoDequeueUpdate update(this); status_t err = updateCondition( update ); return err; } status_t SharedBufferClient::lock(int buf) { LockCondition condition(this, buf); status_t err = waitForCondition(condition); return err; } status_t SharedBufferClient::queue(int buf) { QueueUpdate update(this); status_t err = updateCondition( update ); LOGD_IF(DEBUG_ATOMICS, "queued=%d, %s", buf, dump("").string()); return err; } bool SharedBufferClient::needNewBuffer(int buffer) const { SharedBufferStack& stack( *mSharedStack ); const uint32_t mask = 1<<buffer; return (android_atomic_and(~mask, &stack.reallocMask) & mask) != 0; } status_t SharedBufferClient::setDirtyRegion(int buffer, const Region& reg) { SharedBufferStack& stack( *mSharedStack ); return stack.setDirtyRegion(buffer, reg); } // ---------------------------------------------------------------------------- SharedBufferServer::SharedBufferServer(SharedClient* sharedClient, int surface, int num, int32_t identity) : SharedBufferBase(sharedClient, surface, num) { mSharedStack->init(identity); mSharedStack->head = num-1; mSharedStack->available = num; mSharedStack->queued = 0; mSharedStack->reallocMask = 0; memset(mSharedStack->dirtyRegion, 0, sizeof(mSharedStack->dirtyRegion)); } ssize_t SharedBufferServer::retireAndLock() { RetireUpdate update(this, mNumBuffers); ssize_t buf = updateCondition( update ); LOGD_IF(DEBUG_ATOMICS, "retire=%d, %s", int(buf), dump("").string()); return buf; } status_t SharedBufferServer::unlock(int buffer) { UnlockUpdate update(this, buffer); status_t err = updateCondition( update ); return err; } void SharedBufferServer::setStatus(status_t status) { StatusUpdate update(this, status); updateCondition( update ); } status_t SharedBufferServer::reallocate() { SharedBufferStack& stack( *mSharedStack ); uint32_t mask = (1<<mNumBuffers)-1; android_atomic_or(mask, &stack.reallocMask); return NO_ERROR; } status_t SharedBufferServer::assertReallocate(int buffer) { ReallocateCondition condition(this, buffer); status_t err = waitForCondition(condition); return err; } Region SharedBufferServer::getDirtyRegion(int buffer) const { SharedBufferStack& stack( *mSharedStack ); return stack.getDirtyRegion(buffer); } // --------------------------------------------------------------------------- }; // namespace android