From: Pepijn Van Eeckhoudt <pepijn@vaneeckhoudt.net>
Date: Mon, 20 Aug 2018 12:22:37 +0000 (+0200)
Subject: Release queueMutex using finally blocks
X-Git-Tag: v1.9.90~93^2
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=991c857e0efcc2e8676b2fc033247be806292053;p=tigervnc.git

Release queueMutex using finally blocks

Ensure queueMutex is always correctly released by using finally blocks. This is the closest approximation of AutoMutex style automatic release you can get in Java.
---

diff --git a/java/com/tigervnc/rfb/DecodeManager.java b/java/com/tigervnc/rfb/DecodeManager.java
index 9c7cacbb..d8494446 100644
--- a/java/com/tigervnc/rfb/DecodeManager.java
+++ b/java/com/tigervnc/rfb/DecodeManager.java
@@ -116,16 +116,18 @@ public class DecodeManager {
     // Wait for an available memory buffer
     queueMutex.lock();
 
-    while (freeBuffers.isEmpty())
-      try {
-      producerCond.await();
-      } catch (InterruptedException e) { }
-
-    // Don't pop the buffer in case we throw an exception
-    // whilst reading
-    bufferStream = freeBuffers.getFirst();
+    try {
+      while (freeBuffers.isEmpty())
+        try {
+        producerCond.await();
+        } catch (InterruptedException e) { }
 
-    queueMutex.unlock();
+      // Don't pop the buffer in case we throw an exception
+      // whilst reading
+      bufferStream = freeBuffers.getFirst();
+    } finally {
+      queueMutex.unlock();
+    }
 
     // First check if any thread has encountered a problem
     throwThreadException();
@@ -151,29 +153,33 @@ public class DecodeManager {
 
     queueMutex.lock();
 
-    // The workers add buffers to the end so it's safe to assume
-    // the front is still the same buffer
-    freeBuffers.removeFirst();
-
-    workQueue.addLast(entry);
+    try {
+      // The workers add buffers to the end so it's safe to assume
+      // the front is still the same buffer
+      freeBuffers.removeFirst();
 
-    // We only put a single entry on the queue so waking a single
-    // thread is sufficient
-    consumerCond.signal();
+      workQueue.addLast(entry);
 
-    queueMutex.unlock();
+      // We only put a single entry on the queue so waking a single
+      // thread is sufficient
+      consumerCond.signal();
+    } finally {
+      queueMutex.unlock();
+    }
   }
 
   public void flush()
   {
     queueMutex.lock();
 
-    while (!workQueue.isEmpty())
-      try {
-      producerCond.await();
-      } catch (InterruptedException e) { }
-
-    queueMutex.unlock();
+    try {
+      while (!workQueue.isEmpty())
+        try {
+        producerCond.await();
+        } catch (InterruptedException e) { }
+    } finally {
+      queueMutex.unlock();
+    }
 
     throwThreadException();
   }
@@ -183,11 +189,15 @@ public class DecodeManager {
     //os::AutoMutex a(queueMutex);
     queueMutex.lock();
 
-    if (threadException != null)
-      return;
+    try {
+      if (threadException != null)
+        return;
 
-    threadException =
-      new Exception("Exception on worker thread: "+e.getMessage());
+      threadException =
+        new Exception("Exception on worker thread: "+e.getMessage());
+    } finally {
+      queueMutex.unlock();
+    }
   }
 
   private void throwThreadException()
@@ -195,14 +205,18 @@ public class DecodeManager {
     //os::AutoMutex a(queueMutex);
     queueMutex.lock();
 
-    if (threadException == null)
-      return;
+    try {
+      if (threadException == null)
+        return;
 
-    Exception e = new Exception(threadException.getMessage());
+      Exception e = new Exception(threadException.getMessage());
 
-    threadException = null;
+      threadException = null;
 
-    throw e;
+      throw e;
+    } finally {
+      queueMutex.unlock();
+    }
   }
 
   private class QueueEntry {
@@ -236,13 +250,17 @@ public class DecodeManager {
       //os::AutoMutex a(manager.queueMutex);
       manager.queueMutex.lock();
 
-      if (!thread.isAlive())
-        return;
+      try {
+        if (!thread.isAlive())
+          return;
 
-      stopRequested = true;
+        stopRequested = true;
 
-      // We can't wake just this thread, so wake everyone
-      manager.consumerCond.signalAll();
+        // We can't wake just this thread, so wake everyone
+        manager.consumerCond.signalAll();
+      } finally {
+        manager.queueMutex.unlock();
+      }
     }
 
     public void run()