Move Watchdog and MemoryWatchdog classes into OpenSim.Framework.Monitoring with other monitoring code from OpenSim.Framework

1 files changed, 334 insertions, 0 deletions

diff --git a/OpenSim/Framework/Monitoring/Watchdog.cs b/OpenSim/Framework/Monitoring/Watchdog.cs
new file mode 100644
index 0000000..d4cf02f
--- /dev/null
+++ b/OpenSim/Framework/Monitoring/Watchdog.cs
@@ -0,0 +1,334 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using log4net;
+
+namespace OpenSim.Framework.Monitoring
+{
+    /// <summary>
+    /// Manages launching threads and keeping watch over them for timeouts
+    /// </summary>
+    public static class Watchdog
+    {
+        /// <summary>Timer interval in milliseconds for the watchdog timer</summary>
+        const double WATCHDOG_INTERVAL_MS = 2500.0d;
+
+        /// <summary>Default timeout in milliseconds before a thread is considered dead</summary>
+        public const int DEFAULT_WATCHDOG_TIMEOUT_MS = 5000;
+
+        [System.Diagnostics.DebuggerDisplay("{Thread.Name}")]
+        public class ThreadWatchdogInfo
+        {
+            public Thread Thread { get; private set; }
+
+            /// <summary>
+            /// Approximate tick when this thread was started.
+            /// </summary>
+            /// <remarks>
+            /// Not terribly good since this quickly wraps around.
+            /// </remarks>
+            public int FirstTick { get; private set; }
+
+            /// <summary>
+            /// Last time this heartbeat update was invoked
+            /// </summary>
+            public int LastTick { get; set; }
+
+            /// <summary>
+            /// Number of milliseconds before we notify that the thread is having a problem.
+            /// </summary>
+            public int Timeout { get; set; }
+
+            /// <summary>
+            /// Is this thread considered timed out?
+            /// </summary>
+            public bool IsTimedOut { get; set; }
+
+            /// <summary>
+            /// Will this thread trigger the alarm function if it has timed out?
+            /// </summary>
+            public bool AlarmIfTimeout { get; set; }
+
+            /// <summary>
+            /// Method execute if alarm goes off.  If null then no alarm method is fired.
+            /// </summary>
+            public Func<string> AlarmMethod { get; set; }
+
+            public ThreadWatchdogInfo(Thread thread, int timeout)
+            {
+                Thread = thread;
+                Timeout = timeout;
+                FirstTick = Environment.TickCount & Int32.MaxValue;
+                LastTick = FirstTick;
+            }
+        }
+
+        /// <summary>
+        /// This event is called whenever a tracked thread is
+        /// stopped or has not called UpdateThread() in time<
+        /// /summary>
+        public static event Action<ThreadWatchdogInfo> OnWatchdogTimeout;
+
+        private static readonly ILog m_log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
+        private static Dictionary<int, ThreadWatchdogInfo> m_threads;
+        private static System.Timers.Timer m_watchdogTimer;
+
+        /// <summary>
+        /// Last time the watchdog thread ran.
+        /// </summary>
+        /// <remarks>
+        /// Should run every WATCHDOG_INTERVAL_MS
+        /// </remarks>
+        public static int LastWatchdogThreadTick { get; private set; }
+
+        static Watchdog()
+        {
+            m_threads = new Dictionary<int, ThreadWatchdogInfo>();
+            m_watchdogTimer = new System.Timers.Timer(WATCHDOG_INTERVAL_MS);
+            m_watchdogTimer.AutoReset = false;
+            m_watchdogTimer.Elapsed += WatchdogTimerElapsed;
+
+            // Set now so we don't get alerted on the first run
+            LastWatchdogThreadTick = Environment.TickCount & Int32.MaxValue;
+
+            m_watchdogTimer.Start();
+        }
+
+        /// <summary>
+        /// Start a new thread that is tracked by the watchdog timer.
+        /// </summary>
+        /// <param name="start">The method that will be executed in a new thread</param>
+        /// <param name="name">A name to give to the new thread</param>
+        /// <param name="priority">Priority to run the thread at</param>
+        /// <param name="isBackground">True to run this thread as a background thread, otherwise false</param>
+        /// <param name="alarmIfTimeout">Trigger an alarm function is we have timed out</param>
+        /// <returns>The newly created Thread object</returns>
+        public static Thread StartThread(
+            ThreadStart start, string name, ThreadPriority priority, bool isBackground, bool alarmIfTimeout)
+        {
+            return StartThread(start, name, priority, isBackground, alarmIfTimeout, null, DEFAULT_WATCHDOG_TIMEOUT_MS);
+        }
+
+        /// <summary>
+        /// Start a new thread that is tracked by the watchdog timer
+        /// </summary>
+        /// <param name="start">The method that will be executed in a new thread</param>
+        /// <param name="name">A name to give to the new thread</param>
+        /// <param name="priority">Priority to run the thread at</param>
+        /// <param name="isBackground">True to run this thread as a background
+        /// thread, otherwise false</param>
+        /// <param name="alarmIfTimeout">Trigger an alarm function is we have timed out</param>
+        /// <param name="alarmMethod">
+        /// Alarm method to call if alarmIfTimeout is true and there is a timeout.
+        /// Normally, this will just return some useful debugging information.
+        /// </param>
+        /// <param name="timeout">Number of milliseconds to wait until we issue a warning about timeout.</param>
+        /// <returns>The newly created Thread object</returns>
+        public static Thread StartThread(
+            ThreadStart start, string name, ThreadPriority priority, bool isBackground,
+            bool alarmIfTimeout, Func<string> alarmMethod, int timeout)
+        {
+            Thread thread = new Thread(start);
+            thread.Name = name;
+            thread.Priority = priority;
+            thread.IsBackground = isBackground;
+            
+            ThreadWatchdogInfo twi
+                = new ThreadWatchdogInfo(thread, timeout)
+                    { AlarmIfTimeout = alarmIfTimeout, AlarmMethod = alarmMethod };
+
+            m_log.DebugFormat(
+                "[WATCHDOG]: Started tracking thread {0}, ID {1}", twi.Thread.Name, twi.Thread.ManagedThreadId);
+
+            lock (m_threads)
+                m_threads.Add(twi.Thread.ManagedThreadId, twi);
+
+            thread.Start();
+
+            return thread;
+        }
+
+        /// <summary>
+        /// Marks the current thread as alive
+        /// </summary>
+        public static void UpdateThread()
+        {
+            UpdateThread(Thread.CurrentThread.ManagedThreadId);
+        }
+
+        /// <summary>
+        /// Stops watchdog tracking on the current thread
+        /// </summary>
+        /// <returns>
+        /// True if the thread was removed from the list of tracked
+        /// threads, otherwise false
+        /// </returns>
+        public static bool RemoveThread()
+        {
+            return RemoveThread(Thread.CurrentThread.ManagedThreadId);
+        }
+
+        private static bool RemoveThread(int threadID)
+        {
+            lock (m_threads)
+                return m_threads.Remove(threadID);
+        }
+
+        public static bool AbortThread(int threadID)
+        {
+            lock (m_threads)
+            {
+                if (m_threads.ContainsKey(threadID))
+                {
+                    ThreadWatchdogInfo twi = m_threads[threadID];
+                    twi.Thread.Abort();
+                    RemoveThread(threadID);
+
+                    return true;
+                }
+                else
+                {
+                    return false;
+                }
+            }
+        }
+
+        private static void UpdateThread(int threadID)
+        {
+            ThreadWatchdogInfo threadInfo;
+
+            // Although TryGetValue is not a thread safe operation, we use a try/catch here instead
+            // of a lock for speed. Adding/removing threads is a very rare operation compared to
+            // UpdateThread(), and a single UpdateThread() failure here and there won't break
+            // anything
+            try
+            {
+                if (m_threads.TryGetValue(threadID, out threadInfo))
+                {
+                    threadInfo.LastTick = Environment.TickCount & Int32.MaxValue;
+                    threadInfo.IsTimedOut = false;
+                }
+                else
+                {
+                    m_log.WarnFormat("[WATCHDOG]: Asked to update thread {0} which is not being monitored", threadID);
+                }
+            }
+            catch { }
+        }
+        
+        /// <summary>
+        /// Get currently watched threads for diagnostic purposes
+        /// </summary>
+        /// <returns></returns>
+        public static ThreadWatchdogInfo[] GetThreadsInfo()
+        {
+            lock (m_threads)
+                return m_threads.Values.ToArray();
+        }
+
+        /// <summary>
+        /// Return the current thread's watchdog info.
+        /// </summary>
+        /// <returns>The watchdog info.  null if the thread isn't being monitored.</returns>
+        public static ThreadWatchdogInfo GetCurrentThreadInfo()
+        {
+            lock (m_threads)
+            {
+                if (m_threads.ContainsKey(Thread.CurrentThread.ManagedThreadId))
+                    return m_threads[Thread.CurrentThread.ManagedThreadId];
+            }
+
+            return null;
+        }
+
+        /// <summary>
+        /// Check watched threads.  Fire alarm if appropriate.
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        private static void WatchdogTimerElapsed(object sender, System.Timers.ElapsedEventArgs e)
+        {
+            int now = Environment.TickCount & Int32.MaxValue;
+            int msElapsed = now - LastWatchdogThreadTick;
+
+            if (msElapsed > WATCHDOG_INTERVAL_MS * 2)
+                m_log.WarnFormat(
+                    "[WATCHDOG]: {0} ms since Watchdog last ran.  Interval should be approximately {1} ms",
+                    msElapsed, WATCHDOG_INTERVAL_MS);
+
+            LastWatchdogThreadTick = Environment.TickCount & Int32.MaxValue;
+
+            Action<ThreadWatchdogInfo> callback = OnWatchdogTimeout;
+
+            if (callback != null)
+            {
+                List<ThreadWatchdogInfo> callbackInfos = null;
+
+                lock (m_threads)
+                {
+                    foreach (ThreadWatchdogInfo threadInfo in m_threads.Values)
+                    {
+                        if (threadInfo.Thread.ThreadState == ThreadState.Stopped)
+                        {
+                            RemoveThread(threadInfo.Thread.ManagedThreadId);
+
+                            if (callbackInfos == null)
+                                callbackInfos = new List<ThreadWatchdogInfo>();
+
+                            callbackInfos.Add(threadInfo);
+                        }
+                        else if (!threadInfo.IsTimedOut && now - threadInfo.LastTick >= threadInfo.Timeout)
+                        {
+                            threadInfo.IsTimedOut = true;
+
+                            if (threadInfo.AlarmIfTimeout)
+                            {
+                                if (callbackInfos == null)
+                                    callbackInfos = new List<ThreadWatchdogInfo>();
+
+                                callbackInfos.Add(threadInfo);
+                            }
+                        }
+                    }
+                }
+
+                if (callbackInfos != null)
+                    foreach (ThreadWatchdogInfo callbackInfo in callbackInfos)
+                        callback(callbackInfo);
+            }
+
+            if (MemoryWatchdog.Enabled)
+                MemoryWatchdog.Update();
+
+            m_watchdogTimer.Start();
+        }
+    }
+}
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