SkExecutor

Refactoring to refamiliarize myself with SkTaskGroup and SkThreadPool.

This adds an SkExecutor interface to describe how we use SkThreadPool,
with a global setter and getter for a default instance.  Then I rewrote
SkTaskGroup to work with any executor, the global default by default.

I also think I've made the SkTaskGroup::wait() borrow logic clearer
with the addition of SkSemaphore::try_wait().  This lets me keep the
semaphore count and actual count of work in perfect sync.

Change-Id: I6bbdfaeb0e2c3a43daff6192d34bc4a3f7210178
Reviewed-on: https://skia-review.googlesource.com/8836
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/private/SkSemaphore.h b/include/private/SkSemaphore.h
index 3da2b99ab4..dbc16b64ce 100644
--- a/include/private/SkSemaphore.h
+++ b/include/private/SkSemaphore.h
@@ -25,6 +25,9 @@ public:
     // then if the counter is <= 0, sleep this thread until the counter is > 0.
     void wait();
 
+    // If the counter is positive, decrement it by 1 and return true, otherwise return false.
+    bool try_wait();
+
     // SkBaseSemaphore has no destructor.  Call this to clean it up.
     void cleanup();