Add Fence helpers: Time, Timeline, Snapshot
FenceTime will be used to:
1) Cache and share the result of a Fence's getSignalTime with
all clients that care about it, instead of requiring a
syscall for each client.
2) Allow tests to override the valid state and signalTimes of
the underlying fence by acting as a shim.
FenceTimeline will be used to efficiently get the signal
times of Fences without having query for Fences that
likely haven't signaled.
FenceTime::Snapshot is a stable copy of a FenceTime that
can be used for serialization since it doesn't change
while flattening.
Test: adb shell /data/nativetest/libgui_test/libgui_test
--gtest_filter=*GetFrameTimestamps*
Change-Id: I9a28df7ce797311dc4d56b1147edf590e9de1517
diff --git a/libs/ui/Android.bp b/libs/ui/Android.bp
index 087e877..661d1c8 100644
--- a/libs/ui/Android.bp
+++ b/libs/ui/Android.bp
@@ -43,6 +43,7 @@
srcs: [
"ColorSpace.cpp",
"Fence.cpp",
+ "FenceTime.cpp",
"FrameStats.cpp",
"Gralloc1.cpp",
"Gralloc1On0Adapter.cpp",
diff --git a/libs/ui/Fence.cpp b/libs/ui/Fence.cpp
index 7cf8233..a1dda3a 100644
--- a/libs/ui/Fence.cpp
+++ b/libs/ui/Fence.cpp
@@ -109,17 +109,17 @@
nsecs_t Fence::getSignalTime() const {
if (mFenceFd == -1) {
- return -1;
+ return SIGNAL_TIME_INVALID;
}
struct sync_fence_info_data* finfo = sync_fence_info(mFenceFd);
if (finfo == NULL) {
ALOGE("sync_fence_info returned NULL for fd %d", mFenceFd);
- return -1;
+ return SIGNAL_TIME_INVALID;
}
if (finfo->status != 1) {
sync_fence_info_free(finfo);
- return INT64_MAX;
+ return SIGNAL_TIME_PENDING;
}
struct sync_pt_info* pinfo = NULL;
diff --git a/libs/ui/FenceTime.cpp b/libs/ui/FenceTime.cpp
new file mode 100644
index 0000000..c0245eb
--- /dev/null
+++ b/libs/ui/FenceTime.cpp
@@ -0,0 +1,282 @@
+/*
+* 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.
+*/
+
+#include <ui/FenceTime.h>
+
+#include <cutils/compiler.h> // For CC_[UN]LIKELY
+#include <inttypes.h>
+#include <stdlib.h>
+
+#include <memory>
+
+namespace android {
+
+// ============================================================================
+// FenceTime
+// ============================================================================
+
+const auto FenceTime::NO_FENCE = std::make_shared<FenceTime>(Fence::NO_FENCE);
+
+void* FenceTime::operator new(size_t byteCount) noexcept {
+ void *p = nullptr;
+ if (posix_memalign(&p, alignof(FenceTime), byteCount)) {
+ return nullptr;
+ }
+ return p;
+}
+
+void FenceTime::operator delete(void *p) {
+ free(p);
+}
+
+FenceTime::FenceTime(const sp<Fence>& fence)
+ : mState(((fence.get() != nullptr) && fence->isValid()) ?
+ State::VALID : State::INVALID),
+ mFence(fence),
+ mSignalTime(mState == State::INVALID ?
+ Fence::SIGNAL_TIME_INVALID : Fence::SIGNAL_TIME_PENDING) {
+}
+
+FenceTime::FenceTime(sp<Fence>&& fence)
+ : mState(((fence.get() != nullptr) && fence->isValid()) ?
+ State::VALID : State::INVALID),
+ mFence(std::move(fence)),
+ mSignalTime(mState == State::INVALID ?
+ Fence::SIGNAL_TIME_INVALID : Fence::SIGNAL_TIME_PENDING) {
+}
+
+FenceTime::FenceTime(nsecs_t signalTime)
+ : mState(Fence::isValidTimestamp(signalTime) ? State::VALID : State::INVALID),
+ mFence(nullptr),
+ mSignalTime(signalTime == Fence::SIGNAL_TIME_PENDING ?
+ Fence::SIGNAL_TIME_INVALID : signalTime) {
+}
+
+void FenceTime::applyTrustedSnapshot(const Snapshot& src) {
+ if (CC_UNLIKELY(src.state != Snapshot::State::SIGNAL_TIME)) {
+ // Applying Snapshot::State::FENCE, could change the valid state of the
+ // FenceTime, which is not allowed. Callers should create a new
+ // FenceTime from the snapshot instead.
+ ALOGE("FenceTime::applyTrustedSnapshot: Unexpected fence.");
+ return;
+ }
+
+ if (src.state == Snapshot::State::EMPTY) {
+ return;
+ }
+
+ nsecs_t signalTime = mSignalTime.load(std::memory_order_relaxed);
+ if (signalTime != Fence::SIGNAL_TIME_PENDING) {
+ // We should always get the same signalTime here that we did in
+ // getSignalTime(). This check races with getSignalTime(), but it is
+ // only a sanity check so that's okay.
+ if (CC_UNLIKELY(signalTime != src.signalTime)) {
+ ALOGE("FenceTime::applyTrustedSnapshot: signalTime mismatch. "
+ "(%" PRId64 " (old) != %" PRId64 " (new))",
+ signalTime, src.signalTime);
+ }
+ return;
+ }
+
+ std::lock_guard<std::mutex> lock(mMutex);
+ mFence.clear();
+ mSignalTime.store(src.signalTime, std::memory_order_relaxed);
+}
+
+bool FenceTime::isValid() const {
+ // We store the valid state in the constructors and return it here.
+ // This lets release code remember the valid state even after the
+ // underlying fence is destroyed.
+ return mState != State::INVALID;
+}
+
+nsecs_t FenceTime::getSignalTime() {
+ // See if we already have a cached value we can return.
+ nsecs_t signalTime = mSignalTime.load(std::memory_order_relaxed);
+ if (signalTime != Fence::SIGNAL_TIME_PENDING) {
+ return signalTime;
+ }
+
+ // Hold a reference to the fence on the stack in case the class'
+ // reference is removed by another thread. This prevents the
+ // fence from being destroyed until the end of this method, where
+ // we conveniently do not have the lock held.
+ sp<Fence> fence;
+ {
+ // With the lock acquired this time, see if we have the cached
+ // value or if we need to poll the fence.
+ std::lock_guard<std::mutex> lock(mMutex);
+ if (!mFence.get()) {
+ // Another thread set the signal time just before we added the
+ // reference to mFence.
+ return mSignalTime.load(std::memory_order_relaxed);
+ }
+ fence = mFence;
+ }
+
+ // Make the system call without the lock held.
+ signalTime = fence->getSignalTime();
+
+ // Make the signal time visible to everyone if it is no longer pending
+ // and remove the class' reference to the fence.
+ if (signalTime != Fence::SIGNAL_TIME_PENDING) {
+ std::lock_guard<std::mutex> lock(mMutex);
+ mFence.clear();
+ mSignalTime.store(signalTime, std::memory_order_relaxed);
+ }
+
+ return signalTime;
+}
+
+nsecs_t FenceTime::getCachedSignalTime() const {
+ // memory_order_acquire since we don't have a lock fallback path
+ // that will do an acquire.
+ return mSignalTime.load(std::memory_order_acquire);
+}
+
+FenceTime::Snapshot FenceTime::getSnapshot() const {
+ // Quick check without the lock.
+ nsecs_t signalTime = mSignalTime.load(std::memory_order_relaxed);
+ if (signalTime != Fence::SIGNAL_TIME_PENDING) {
+ return Snapshot(signalTime);
+ }
+
+ // Do the full check with the lock.
+ std::lock_guard<std::mutex> lock(mMutex);
+ signalTime = mSignalTime.load(std::memory_order_relaxed);
+ if (signalTime != Fence::SIGNAL_TIME_PENDING) {
+ return Snapshot(signalTime);
+ }
+ return Snapshot(mFence);
+}
+
+// ============================================================================
+// FenceTime::Snapshot
+// ============================================================================
+
+FenceTime::Snapshot::Snapshot(const sp<Fence>& srcFence)
+ : state(State::FENCE), fence(srcFence) {
+}
+
+FenceTime::Snapshot::Snapshot(nsecs_t srcSignalTime)
+ : state(State::SIGNAL_TIME), signalTime(srcSignalTime) {
+}
+
+size_t FenceTime::Snapshot::getFlattenedSize() const {
+ constexpr size_t min = sizeof(state);
+ switch (state) {
+ case State::EMPTY:
+ return min;
+ case State::FENCE:
+ return min + fence->getFlattenedSize();
+ case State::SIGNAL_TIME:
+ return min + sizeof(signalTime);
+ }
+ return 0;
+}
+
+size_t FenceTime::Snapshot::getFdCount() const {
+ return state == State::FENCE ? fence->getFdCount() : 0u;
+}
+
+status_t FenceTime::Snapshot::flatten(
+ void*& buffer, size_t& size, int*& fds, size_t& count) const {
+ if (size < getFlattenedSize()) {
+ return NO_MEMORY;
+ }
+
+ FlattenableUtils::write(buffer, size, state);
+ switch (state) {
+ case State::EMPTY:
+ return NO_ERROR;
+ case State::FENCE:
+ return fence->flatten(buffer, size, fds, count);
+ case State::SIGNAL_TIME:
+ FlattenableUtils::write(buffer, size, signalTime);
+ return NO_ERROR;
+ }
+
+ return NO_ERROR;
+}
+
+status_t FenceTime::Snapshot::unflatten(
+ void const*& buffer, size_t& size, int const*& fds, size_t& count) {
+ if (size < sizeof(state)) {
+ return NO_MEMORY;
+ }
+
+ FlattenableUtils::read(buffer, size, state);
+ switch (state) {
+ case State::EMPTY:
+ return NO_ERROR;
+ case State::FENCE:
+ fence = new Fence;
+ return fence->unflatten(buffer, size, fds, count);
+ case State::SIGNAL_TIME:
+ if (size < sizeof(signalTime)) {
+ return NO_MEMORY;
+ }
+ FlattenableUtils::read(buffer, size, signalTime);
+ return NO_ERROR;
+ }
+
+ return NO_ERROR;
+}
+
+// ============================================================================
+// FenceTimeline
+// ============================================================================
+void FenceTimeline::push(const std::shared_ptr<FenceTime>& fence) {
+ std::lock_guard<std::mutex> lock(mMutex);
+ while (mQueue.size() >= MAX_ENTRIES) {
+ // This is a sanity check to make sure the queue doesn't grow unbounded.
+ // MAX_ENTRIES should be big enough not to trigger this path.
+ // In case this path is taken though, users of FenceTime must make sure
+ // not to rely solely on FenceTimeline to get the final timestamp and
+ // should eventually call Fence::getSignalTime on their own.
+ std::shared_ptr<FenceTime> front = mQueue.front().lock();
+ if (front) {
+ // Make a last ditch effort to get the signalTime here since
+ // we are removing it from the timeline.
+ front->getSignalTime();
+ }
+ mQueue.pop();
+ }
+ mQueue.push(fence);
+}
+
+void FenceTimeline::updateSignalTimes() {
+ while (!mQueue.empty()) {
+ std::lock_guard<std::mutex> lock(mMutex);
+ std::shared_ptr<FenceTime> fence = mQueue.front().lock();
+ if (!fence) {
+ // The shared_ptr no longer exists and no one cares about the
+ // timestamp anymore.
+ mQueue.pop();
+ continue;
+ } else if (fence->getSignalTime() != Fence::SIGNAL_TIME_PENDING) {
+ // The fence has signaled and we've removed the sp<Fence> ref.
+ mQueue.pop();
+ continue;
+ } else {
+ // The fence didn't signal yet. Break since the later ones
+ // shouldn't have signaled either.
+ break;
+ }
+ }
+}
+
+} // namespace android