Cache GrColorSpaceXforms

Even with a modest cache, we're going to get nearly 100% hit rate
for typical usage scenarios. I'm hoping to avoid the special case
caching of sRGB -> destination, and just rely on the more general
mechanism.

Yes, this is yet-another cache class. I wanted to use one of many
that are laying around, but couldn't find a good fit. On the plus
side, it's not much code.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3726

Change-Id: I943be5c99f0d691a87ffe8c5bc3067a8eb491fc2
Reviewed-on: https://skia-review.googlesource.com/3726
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/private/SkSpinlock.h b/include/private/SkSpinlock.h
index a5d378289f..669a926c7e 100644
--- a/include/private/SkSpinlock.h
+++ b/include/private/SkSpinlock.h
@@ -23,6 +23,16 @@ public:
         }
     }
 
+    // Acquire the lock or fail (quickly). Lets the caller decide to do something other than wait.
+    bool tryAcquire() {
+        // To act as a mutex, we need an acquire barrier when we acquire the lock.
+        if (fLocked.exchange(true, std::memory_order_acquire)) {
+            // Lock was contended. Let the caller decide what to do.
+            return false;
+        }
+        return true;
+    }
+
     void release() {
         // To act as a mutex, we need a release barrier when we release the lock.
         fLocked.store(false, std::memory_order_release);