From 17a62649faa31b474c9b48946fe5a47a440c0de3 Mon Sep 17 00:00:00 2001
From: Colin Godsey <crgodsey@gmail.com>
Date: Thu, 24 Apr 2014 22:10:51 -0500
Subject: [PATCH 1/4] Update AbstractIrpQueue.java

added synchronized blocks to thread control
---
 src/main/java/org/usb4java/javax/AbstractIrpQueue.java | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
index 39add76..9d5abfb 100644
--- a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
+++ b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
@@ -58,7 +58,7 @@ abstract class AbstractIrpQueue<T extends UsbIrp>
      * @param irp
      *            The control IRP to queue.
      */
-    public final void add(final T irp)
+    public final synchronized void add(final T irp)
     {
         this.irps.add(irp);
 
@@ -92,7 +92,7 @@ final void process()
         // if present).
         if (irp == null)
         {
-            this.processor = null;
+            synchronized { this.processor = null; }
         }
         else
         {
@@ -153,7 +153,7 @@ final void process()
      * aborted. This method returns as soon as no more IRPs are in the queue and
      * no more are processed.
      */
-    public final void abort()
+    public final synchronized void abort()
     {
         this.aborting = true;
         this.irps.clear();
@@ -180,7 +180,7 @@ public final void abort()
      * 
      * @return True if queue is busy, false if not.
      */
-    public final boolean isBusy()
+    public final synchronized boolean isBusy()
     {
         return !this.irps.isEmpty() || this.processor != null;
     }

From 626be960475fb9a4bc329b44f1c9cdfbc5653fe2 Mon Sep 17 00:00:00 2001
From: Colin Godsey <crgodsey@gmail.com>
Date: Thu, 24 Apr 2014 22:12:55 -0500
Subject: [PATCH 2/4] Update AbstractIrpQueue.java

added this
---
 src/main/java/org/usb4java/javax/AbstractIrpQueue.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
index 9d5abfb..422e555 100644
--- a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
+++ b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
@@ -92,7 +92,7 @@ final void process()
         // if present).
         if (irp == null)
         {
-            synchronized { this.processor = null; }
+            synchronized(this)  { this.processor = null; }
         }
         else
         {

From 871993771b299b547f196d8e5a1e51fbe578e248 Mon Sep 17 00:00:00 2001
From: Colin Godsey <crgodsey@gmail.com>
Date: Thu, 24 Apr 2014 23:24:58 -0500
Subject: [PATCH 3/4] Update AbstractIrpQueue.java

woops, one more sync spot
---
 src/main/java/org/usb4java/javax/AbstractIrpQueue.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
index 422e555..85f1231 100644
--- a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
+++ b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
@@ -92,7 +92,7 @@ final void process()
         // if present).
         if (irp == null)
         {
-            synchronized(this)  { this.processor = null; }
+            synchronized(this) { this.processor = null; }
         }
         else
         {
@@ -111,7 +111,7 @@ final void process()
                 // Get next IRP and mark the thread as closing before sending
                 // the events for the previous IRP
                 final T nextIrp = this.irps.poll();
-                if (nextIrp == null) this.processor = null;
+                if (nextIrp == null) synchronized(this) { this.processor = null; }
     
                 // Finish the previous IRP
                 irp.complete();

From 551e85a823a3f86e2ec190877e30ba66cc65d05d Mon Sep 17 00:00:00 2001
From: Colin Godsey <crgodsey@gmail.com>
Date: Sat, 26 Apr 2014 10:51:14 -0500
Subject: [PATCH 4/4] removed useless sync point

---
 .../org/usb4java/javax/AbstractIrpQueue.java  | 24 ++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
index 85f1231..0de6cb6 100644
--- a/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
+++ b/src/main/java/org/usb4java/javax/AbstractIrpQueue.java
@@ -58,24 +58,26 @@ abstract class AbstractIrpQueue<T extends UsbIrp>
      * @param irp
      *            The control IRP to queue.
      */
-    public final synchronized void add(final T irp)
+    public final void add(final T irp)
     {
         this.irps.add(irp);
 
         // Start the queue processor if not already running.
         if (this.processor == null)
         {
-            this.processor = new Thread(new Runnable()
-            {
-                @Override
-                public void run()
-                {
-                    process();
+            synchronized(this) {
+                if (this.processor == null) {
+                    this.processor = new Thread(new Runnable() {
+                        @Override
+                        public void run() {
+                            process();
+                        }
+                    });
+                    this.processor.setDaemon(true);
+                    this.processor.setName("usb4java IRP Queue Processor");
+                    this.processor.start();
                 }
-            });
-            this.processor.setDaemon(true);
-            this.processor.setName("usb4java IRP Queue Processor");
-            this.processor.start();
+            }
         }
     }