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Commit 6db42ac3 authored by Dan Stoza's avatar Dan Stoza Committed by Matthew Bouyack
Browse files

libui: Change hasSignaled to return optional<bool> 

Since the android::Fence::wait() call can possibly return an error,
we need some way of indicating to the caller of hasSignaled that a
fence that has not yet signaled (because it is in an error state) will
never signal. To do this, we return an optional<bool>, where true and
false indicate both that the fence is valid and that it has or hasn't
signaled. If an error is returned from wait(), we return a default
optional value (that is neither true nor false).

Test: m

Change-Id: Ibce48cd2e71ddb8ccf6cabe3284afe0efca8c132
parent 5736f7dc

include/ui/Fence.h

+15 −3
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ 
#include <utils/String8.h>

#include <utils/Timers.h>



#include <experimental/optional>



struct ANativeWindowBuffer;



namespace android {
@@ -96,16 +98,26 @@ public: 
    // occurs then -1 is returned.

    nsecs_t getSignalTime() const;



#if __cplusplus > 201103L

    // hasSignaled returns whether the fence has signaled yet. Prefer this to

    // getSignalTime() or wait() if all you care about is whether the fence has

    // signaled.

    inline bool hasSignaled() {

    // signaled. Returns an optional bool, which will have a value if there was

    // no error.

    inline std::experimental::optional<bool> hasSignaled() {

        // The sync_wait call underlying wait() has been measured to be

        // significantly faster than the sync_fence_info call underlying

        // getSignalTime(), which might otherwise appear to be the more obvious

        // way to check whether a fence has signaled.

        return wait(0) == NO_ERROR;

        switch (wait(0)) {

            case NO_ERROR:

                return true;

            case -ETIME:

                return false;

            default:

                return {};

        }

    }

#endif



    // Flattenable interface

    size_t getFlattenedSize() const;