diff options
| -rw-r--r-- | libs/gui/ConsumerBase.cpp | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/libs/gui/ConsumerBase.cpp b/libs/gui/ConsumerBase.cpp index 5c6158c771..292f13de2d 100644 --- a/libs/gui/ConsumerBase.cpp +++ b/libs/gui/ConsumerBase.cpp @@ -324,16 +324,25 @@ status_t ConsumerBase::addReleaseFenceLocked(int slot, return OK; } - auto status = mSlots[slot].mFence->getStatus(); - - if (status == Fence::Status::Invalid) { - CB_LOGE("fence has invalid state"); + // Check status of fences first because merging is expensive. + // Merging an invalid fence with any other fence results in an + // invalid fence. + auto currentStatus = mSlots[slot].mFence->getStatus(); + if (currentStatus == Fence::Status::Invalid) { + CB_LOGE("Existing fence has invalid state"); return BAD_VALUE; } - if (status == Fence::Status::Signaled) { + auto incomingStatus = fence->getStatus(); + if (incomingStatus == Fence::Status::Invalid) { + CB_LOGE("New fence has invalid state"); mSlots[slot].mFence = fence; - } else { // status == Fence::Status::Unsignaled + return BAD_VALUE; + } + + // If both fences are signaled or both are unsignaled, we need to merge + // them to get an accurate timestamp. + if (currentStatus == incomingStatus) { char fenceName[32] = {}; snprintf(fenceName, 32, "%.28s:%d", mName.string(), slot); sp<Fence> mergedFence = Fence::merge( @@ -346,7 +355,17 @@ status_t ConsumerBase::addReleaseFenceLocked(int slot, return BAD_VALUE; } mSlots[slot].mFence = mergedFence; + } else if (incomingStatus == 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. + mSlots[slot].mFence = fence; } + // else if (currentStatus == Fence::Status::Unsignaled) is a no-op. return OK; } |