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authorJustin Clark-Casey (justincc)2013-07-16 21:54:00 +0100
committerJustin Clark-Casey (justincc)2013-07-16 22:03:49 +0100
commit21a09ad3ad42b24bce4fc04c6bcd6f7d9a80af08 (patch)
treef08f178dcc35e59eb6b4d946ca57d459c7cceff8 /OpenSim
parentIn the pursuit of using less CPU: now trying to avoid blocking queues altoget... (diff)
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Revert "MSDN documentation is unclear about whether exiting a lock() block will trigger a Monitor.Wait() to exit, so avoid some locks that don't actually affect the state of the internal queues in the BlockingQueue class."
This reverts commit 42e2a0d66eaa7e322bce817e9e2cc9a288de167b Reverting because unfortunately this introduces race conditions because Contains(), Count() and GetQueueArray() may now end up returning the wrong result if another thread performs a simultaneous update on m_queue. Code such as PollServiceRequestManager.Stop() relies on the count being correct otherwise a request may be lost. Also, though some of the internal queue methods do not affect state, they are not thread-safe and could return the wrong result generating the same problem lock() generates Monitor.Enter() and Monitor.Exit() under the covers. Monitor.Exit() does not cause Monitor.Wait() to exist, only Pulse() and PulseAll() will do this Reverted with agreement.
Diffstat (limited to 'OpenSim')
-rw-r--r--OpenSim/Framework/BlockingQueue.cs13
1 files changed, 5 insertions, 8 deletions
diff --git a/OpenSim/Framework/BlockingQueue.cs b/OpenSim/Framework/BlockingQueue.cs
index cc016b0..3658161 100644
--- a/OpenSim/Framework/BlockingQueue.cs
+++ b/OpenSim/Framework/BlockingQueue.cs
@@ -58,7 +58,7 @@ namespace OpenSim.Framework
58 { 58 {
59 lock (m_queueSync) 59 lock (m_queueSync)
60 { 60 {
61 while (m_queue.Count < 1 && m_pqueue.Count < 1) 61 if (m_queue.Count < 1 && m_pqueue.Count < 1)
62 { 62 {
63 Monitor.Wait(m_queueSync); 63 Monitor.Wait(m_queueSync);
64 } 64 }
@@ -91,9 +91,6 @@ namespace OpenSim.Framework
91 91
92 public bool Contains(T item) 92 public bool Contains(T item)
93 { 93 {
94 if (m_queue.Count < 1 && m_pqueue.Count < 1)
95 return false;
96
97 lock (m_queueSync) 94 lock (m_queueSync)
98 { 95 {
99 if (m_pqueue.Contains(item)) 96 if (m_pqueue.Contains(item))
@@ -104,14 +101,14 @@ namespace OpenSim.Framework
104 101
105 public int Count() 102 public int Count()
106 { 103 {
107 return m_queue.Count+m_pqueue.Count; 104 lock (m_queueSync)
105 {
106 return m_queue.Count+m_pqueue.Count;
107 }
108 } 108 }
109 109
110 public T[] GetQueueArray() 110 public T[] GetQueueArray()
111 { 111 {
112 if (m_queue.Count < 1 && m_pqueue.Count < 1)
113 return new T[0];
114
115 lock (m_queueSync) 112 lock (m_queueSync)
116 { 113 {
117 return m_queue.ToArray(); 114 return m_queue.ToArray();