From 855f77aec2c9ca6a91be51361673fda4b58b3adf Mon Sep 17 00:00:00 2001
From: neil_a_wilson <neil_a_wilson@localhost>
Date: Thu, 02 Aug 2007 21:47:09 +0000
Subject: [PATCH] Fix a potential deadlock in the task code that could occur if a client tried to retrieve the task entry at the same time that it was being updated.

---
 opendj-sdk/opends/src/server/org/opends/server/backends/task/Task.java          |   56 ++++++++++++++++++++++++----
 opendj-sdk/opends/src/server/org/opends/server/backends/task/TaskScheduler.java |   13 ++++++
 2 files changed, 61 insertions(+), 8 deletions(-)

diff --git a/opendj-sdk/opends/src/server/org/opends/server/backends/task/Task.java b/opendj-sdk/opends/src/server/org/opends/server/backends/task/Task.java
index 39ae64d..8879aba 100644
--- a/opendj-sdk/opends/src/server/org/opends/server/backends/task/Task.java
+++ b/opendj-sdk/opends/src/server/org/opends/server/backends/task/Task.java
@@ -555,7 +555,14 @@
    */
   void setTaskState(TaskState taskState)
   {
-    Lock lock = taskScheduler.writeLockEntry(taskEntryDN);
+    // We only need to grab the entry-level lock if we don't already hold the
+    // broader scheduler lock.
+    boolean needLock = (! taskScheduler.holdsSchedulerLock());
+    Lock lock = null;
+    if (needLock)
+    {
+      lock = taskScheduler.writeLockEntry(taskEntryDN);
+    }
 
     try
     {
@@ -579,7 +586,10 @@
     }
     finally
     {
-      taskScheduler.unlockEntry(taskEntryDN, lock);
+      if (needLock)
+      {
+        taskScheduler.unlockEntry(taskEntryDN, lock);
+      }
     }
   }
 
@@ -625,7 +635,14 @@
    */
   private void setActualStartTime(long actualStartTime)
   {
-    Lock lock = taskScheduler.writeLockEntry(taskEntryDN);
+    // We only need to grab the entry-level lock if we don't already hold the
+    // broader scheduler lock.
+    boolean needLock = (! taskScheduler.holdsSchedulerLock());
+    Lock lock = null;
+    if (needLock)
+    {
+      lock = taskScheduler.writeLockEntry(taskEntryDN);
+    }
 
     try
     {
@@ -654,7 +671,10 @@
     }
     finally
     {
-      taskScheduler.unlockEntry(taskEntryDN, lock);
+      if (needLock)
+      {
+        taskScheduler.unlockEntry(taskEntryDN, lock);
+      }
     }
   }
 
@@ -685,7 +705,14 @@
    */
   private void setCompletionTime(long completionTime)
   {
-    Lock lock = taskScheduler.writeLockEntry(taskEntryDN);
+    // We only need to grab the entry-level lock if we don't already hold the
+    // broader scheduler lock.
+    boolean needLock = (! taskScheduler.holdsSchedulerLock());
+    Lock lock = null;
+    if (needLock)
+    {
+      lock = taskScheduler.writeLockEntry(taskEntryDN);
+    }
 
     try
     {
@@ -714,7 +741,10 @@
     }
     finally
     {
-      taskScheduler.unlockEntry(taskEntryDN, lock);
+      if (needLock)
+      {
+        taskScheduler.unlockEntry(taskEntryDN, lock);
+      }
     }
   }
 
@@ -879,7 +909,14 @@
   public void addLogMessage(ErrorLogSeverity severity, int messageID,
                             String messageString)
   {
-    Lock lock = taskScheduler.writeLockEntry(taskEntryDN);
+    // We only need to grab the entry-level lock if we don't already hold the
+    // broader scheduler lock.
+    boolean needLock = (! taskScheduler.holdsSchedulerLock());
+    Lock lock = null;
+    if (needLock)
+    {
+      lock = taskScheduler.writeLockEntry(taskEntryDN);
+    }
 
     try
     {
@@ -935,7 +972,10 @@
     }
     finally
     {
-      taskScheduler.unlockEntry(taskEntryDN, lock);
+      if (needLock)
+      {
+        taskScheduler.unlockEntry(taskEntryDN, lock);
+      }
     }
   }
 
diff --git a/opendj-sdk/opends/src/server/org/opends/server/backends/task/TaskScheduler.java b/opendj-sdk/opends/src/server/org/opends/server/backends/task/TaskScheduler.java
index 6bdebcf..9160631 100644
--- a/opendj-sdk/opends/src/server/org/opends/server/backends/task/TaskScheduler.java
+++ b/opendj-sdk/opends/src/server/org/opends/server/backends/task/TaskScheduler.java
@@ -1468,6 +1468,19 @@
 
 
   /**
+   * Indicates whether the current thread already holds a lock on the scheduler.
+   *
+   * @return  {@code true} if the current thread holds the scheduler lock, or
+   *          {@code false} if not.
+   */
+  boolean holdsSchedulerLock()
+  {
+    return schedulerLock.isHeldByCurrentThread();
+  }
+
+
+
+  /**
    * Attempts to acquire a write lock on the specified entry, trying as many
    * times as necessary until the lock has been acquired.
    *

--
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