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/**
* Copyright (C) 2024 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.
*/
#pragma once
#include <ui/Fence.h>
namespace android {
// TODO: measure if Fence::merge is cheaper
inline void mergeFence(const char* debugName, sp<Fence>&& incomingFence, sp<Fence>& prevFence) {
if (prevFence == nullptr && incomingFence->getStatus() != Fence::Status::Invalid) {
prevFence = std::move(incomingFence);
} else if (prevFence != nullptr) {
// If both fences are signaled or both are unsignaled, we need to merge
// them to get an accurate timestamp.
if (prevFence->getStatus() != Fence::Status::Invalid &&
prevFence->getStatus() == incomingFence->getStatus()) {
char fenceName[32] = {};
snprintf(fenceName, 32, "%.28s", debugName);
sp<Fence> mergedFence = Fence::merge(fenceName, prevFence, incomingFence);
if (mergedFence->isValid()) {
prevFence = std::move(mergedFence);
}
} else if (incomingFence->getStatus() == Fence::Status::Unsignaled) {
// If one fence has signaled and the other hasn't, the unsignaled
// fence will approximately correspond with the correct timestamp.
// There's a small race if both fences signal at about the same time
// and their statuses are retrieved with unfortunate timing. However,
// by this point, they will have both signaled and only the timestamp
// will be slightly off; any dependencies after this point will
// already have been met.
prevFence = std::move(incomingFence);
}
}
}
} // namespace android
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