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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.
*/
#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/surfaceflinger/SharedBufferStack.h>
#include <ui/Rect.h>
#include <ui/Region.h>
#define DEBUG_ATOMICS 0
namespace android {
// ----------------------------------------------------------------------------
SharedClient::SharedClient()
: lock(Mutex::SHARED), cv(Condition::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, int32_t identity)
: mSharedClient(sharedClient),
mSharedStack(sharedClient->surfaces + surface),
mNumBuffers(num), mIdentity(identity)
{
}
SharedBufferBase::~SharedBufferBase()
{
}
uint32_t SharedBufferBase::getIdentity()
{
SharedBufferStack& stack( *mSharedStack );
return stack.identity;
}
status_t SharedBufferBase::getStatus() const
{
SharedBufferStack& stack( *mSharedStack );
return stack.status;
}
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 );
int tail = (mNumBuffers + stack.head - stack.available + 1) % mNumBuffers;
snprintf(buffer, SIZE,
"%s[ head=%2d, available=%2d, queued=%2d, tail=%2d ] "
"reallocMask=%08x, inUse=%2d, identity=%d, status=%d\n",
prefix, stack.head, stack.available, stack.queued, tail,
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, int32_t identity)
: SharedBufferBase(sharedClient, surface, num, identity), tail(0)
{
tail = computeTail();
}
int32_t SharedBufferClient::computeTail() const
{
SharedBufferStack& stack( *mSharedStack );
// we need to make sure we read available and head coherently,
// w.r.t RetireUpdate.
int32_t newTail;
int32_t avail;
int32_t head;
do {
avail = stack.available;
head = stack.head;
} while (stack.available != avail);
newTail = head - avail + 1;
if (newTail < 0) {
newTail += mNumBuffers;
} else if (newTail >= mNumBuffers) {
newTail -= mNumBuffers;
}
return newTail;
}
ssize_t SharedBufferClient::dequeue()
{
SharedBufferStack& stack( *mSharedStack );
if (stack.head == tail && stack.available == 2) {
LOGW("dequeue: tail=%d, head=%d, avail=%d, queued=%d",
tail, stack.head, stack.available, stack.queued);
}
const nsecs_t dequeueTime = systemTime(SYSTEM_TIME_THREAD);
//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);
// 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());
mDequeueTime[dequeued] = dequeueTime;
return dequeued;
}
status_t SharedBufferClient::undoDequeue(int buf)
{
UndoDequeueUpdate update(this);
status_t err = updateCondition( update );
if (err == NO_ERROR) {
tail = computeTail();
}
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());
SharedBufferStack& stack( *mSharedStack );
const nsecs_t now = systemTime(SYSTEM_TIME_THREAD);
stack.stats.totalTime = ns2us(now - mDequeueTime[buf]);
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, identity)
{
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 && buf>=0, "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)
{
if (status < NO_ERROR) {
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;
}
int32_t SharedBufferServer::getQueuedCount() const
{
SharedBufferStack& stack( *mSharedStack );
return stack.queued;
}
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);
}
SharedBufferStack::Statistics SharedBufferServer::getStats() const
{
SharedBufferStack& stack( *mSharedStack );
return stack.stats;
}
// ---------------------------------------------------------------------------
}; // namespace android