fix: checks pool maintainer is not closed on close

thiagotnunes · thiagotnunes · commit 04ffcf5ffc53 · 2021-01-15T09:52:31.000+11:00
Verifies that the pool maintainer is not closed before closing it. Also
moves the check of pendingClosures into the synchronized block to make
sure no stale reads are made.
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPool.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPool.java
@@ -1617,10 +1617,12 @@ public void run() {
 
     void close() {
       synchronized (lock) {
-        closed = true;
-        scheduledFuture.cancel(false);
-        if (!running) {
-          decrementPendingClosures(1);
+        if (!closed) {
+          closed = true;
+          scheduledFuture.cancel(false);
+          if (!running) {
+            decrementPendingClosures(1);
+          }
         }
       }
     }
@@ -2188,11 +2190,11 @@ ListenableFuture<Void> closeAsync(ClosedException closedException) {
           closeSessionAsync(session);
         }
       }
-    }
 
-    // Nothing to be closed, mark as complete
-    if (pendingClosure == 0) {
-      closureFuture.set(null);
+      // Nothing to be closed, mark as complete
+      if (pendingClosure == 0) {
+        closureFuture.set(null);
+      }
     }
 
     retFuture.addListener(

Original file line number	Diff line number	Diff line change
`@@ -1617,10 +1617,12 @@ public void run() {`
`1617`	`1617`
`1618`	`1618`	`void close() {`
`1619`	`1619`	`synchronized (lock) {`
`1620`		`- closed = true;`
`1621`		`- scheduledFuture.cancel(false);`
`1622`		`- if (!running) {`
`1623`		`- decrementPendingClosures(1);`
	`1620`	`+ if (!closed) {`
	`1621`	`+ closed = true;`
	`1622`	`+ scheduledFuture.cancel(false);`
	`1623`	`+ if (!running) {`
	`1624`	`+ decrementPendingClosures(1);`
	`1625`	`+ }`
`1624`	`1626`	`}`
`1625`	`1627`	`}`
`1626`	`1628`	`}`
`@@ -2188,11 +2190,11 @@ ListenableFuture<Void> closeAsync(ClosedException closedException) {`
`2188`	`2190`	`closeSessionAsync(session);`
`2189`	`2191`	`}`
`2190`	`2192`	`}`
`2191`		`- }`
`2192`	`2193`
`2193`		`- // Nothing to be closed, mark as complete`
`2194`		`- if (pendingClosure == 0) {`
`2195`		`- closureFuture.set(null);`
	`2194`	`+ // Nothing to be closed, mark as complete`
	`2195`	`+ if (pendingClosure == 0) {`
	`2196`	`+ closureFuture.set(null);`
	`2197`	`+ }`
`2196`	`2198`	`}`
`2197`	`2199`
`2198`	`2200`	`retFuture.addListener(`