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
diff --git a/include/ui/Fence.h b/include/ui/Fence.h
index 2fbc9ef..1df15f8 100644
--- a/include/ui/Fence.h
+++ b/include/ui/Fence.h
@@ -27,6 +27,8 @@
#include <utils/String8.h>
#include <utils/Timers.h>
+#include <experimental/optional>
+
struct ANativeWindowBuffer;
namespace android {
@@ -96,16 +98,26 @@
// 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;