Apply Ohad's requested changes

Author: jjezra

fdb-record-layer-lucene/src/main/java/com/apple/foundationdb/record/lucene/directory/FDBDirectoryLockFactory.java

@@ -45,6 +45,7 @@
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Function;
 
 /**
@@ -92,8 +93,7 @@ protected static class FDBDirectoryLock extends Lock {
          */
         private FDBRecordContext closingContext = null;
         private final Object fileLockSetLock = new Object();
-        private boolean clearingLockNow = false;
-        private final Object clearingLockNowLock = new Object();
+        private final AtomicBoolean clearingLockNow = new AtomicBoolean();
 
         private FDBDirectoryLock(final AgilityContext agilityContext, final String lockName, byte[] fileLockKey, int timeWindowMilliseconds) {
             this.agilityContext = agilityContext;
@@ -212,12 +212,9 @@ private void fileLockCheckNewLock(byte[] val, long nowMillis) {
         }
 
         private void fileLockClearFlushAndClose(boolean isRecovery) {
-            synchronized (clearingLockNowLock) {
+            if (!clearingLockNow.compareAndExchange(false, true)) {
                 // Here: this function is being called from too many paths. Until cleanup, this guard is here to avoid recursions
-                if (clearingLockNow) {
-                    return;
-                }
-                clearingLockNow = true;
+                return;
             }
             Function<FDBRecordContext, CompletableFuture<Void>> fileLockFunc = aContext ->
                     aContext.ensureActive().get(fileLockKey)
@@ -253,10 +250,7 @@ private void fileLockClearFlushAndClose(boolean isRecovery) {
             } finally {
                 closed = flushed; // allow close retry
                 closingContext = null;
-                synchronized (clearingLockNowLock) {
-                    // clearing under lock to avoid spotbugsMain's "Inconsistent synchronization" issue.
-                    clearingLockNow = false;
-                }
+                clearingLockNow.compareAndExchange(true, false);
             }
         }