Added missing state rollback for failed attempt-based write locking of spin locks (#12172)

jsteemann · KVS85 · web-flow · commit 10e6357b0900 · 2020-07-08T23:55:33.000+03:00
* Disable non-relevant testsuites

* Added missing state rollback for failed attempt-based write locking of spin locks.

Co-authored-by: KVS85 &lt;vadim@arangodb.com&gt;
diff --git a/lib/Basics/ReadWriteSpinLock.h b/lib/Basics/ReadWriteSpinLock.h
@@ -84,12 +84,17 @@ class ReadWriteSpinLock {
           return true;
         }
         if (++attempts > maxAttempts) {
+          // Undo the counting of us as queued writer:
+          _state.fetch_sub(QUEUED_WRITER_INC, std::memory_order_release);
           return false;
         }
       }
       cpu_relax();
       state = _state.load(std::memory_order_relaxed);
     }
+        
+    // Undo the counting of us as queued writer:
+    _state.fetch_sub(QUEUED_WRITER_INC, std::memory_order_release);
     return false;
   }
 

Original file line number	Diff line number	Diff line change
`@@ -84,12 +84,17 @@ class ReadWriteSpinLock {`
`84`	`84`	`return true;`
`85`	`85`	`}`
`86`	`86`	`if (++attempts > maxAttempts) {`
	`87`	`+ // Undo the counting of us as queued writer:`
	`88`	`+ _state.fetch_sub(QUEUED_WRITER_INC, std::memory_order_release);`
`87`	`89`	`return false;`
`88`	`90`	`}`
`89`	`91`	`}`
`90`	`92`	`cpu_relax();`
`91`	`93`	`state = _state.load(std::memory_order_relaxed);`
`92`	`94`	`}`
	`95`	`+`
	`96`	`+ // Undo the counting of us as queued writer:`
	`97`	`+ _state.fetch_sub(QUEUED_WRITER_INC, std::memory_order_release);`
`93`	`98`	`return false;`
`94`	`99`	`}`
`95`	`100`