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Diffstat (limited to 'java/src/TimerQueue.java')
| -rw-r--r-- | java/src/TimerQueue.java | 421 |
1 files changed, 0 insertions, 421 deletions
diff --git a/java/src/TimerQueue.java b/java/src/TimerQueue.java deleted file mode 100644 index eeab38f9206..00000000000 --- a/java/src/TimerQueue.java +++ /dev/null @@ -1,421 +0,0 @@ -/************************************************* - * - * = PACKAGE - * ACE.Reactor - * - * = FILENAME - * TimerQueue.java - * - *@author Prashant Jain - * - *************************************************/ -package ACE.Reactor; - -import java.util.*; -import ACE.ASX.*; - -class TimerNode -{ - public TimerNode (EventHandler handler, - Object arg, - TimeValue timerValue, - TimeValue interval, - TimerNode next, - int timerId) - { - this.handler_ = handler; - this.arg_ = arg; - this.timerValue_ = timerValue; - this.interval_ = interval; - this.next_ = next; - this.timerId_ = timerId; - } - - public EventHandler handler_; - // Handler to invoke <handleTimeout> on when a timeout occurs. - - public Object arg_; - // Argument to pass to <handleTimeout>. - - public TimeValue timerValue_; - // Time until the timer expires. - - public TimeValue interval_; - // If this is a periodic timer this holds the time until the next - // timeout. - - public TimerNode next_; - // Pointer to next timer. - - public int timerId_; - // Id of this timer (used to cancel timers before they expire). -} - -class WaitObject extends TimedWait -{ - public boolean condition () - { - return this.condition_; - } - - public void condition (boolean c) - { - this.condition_ = c; - } - - private boolean condition_ = false; -} - -/** - * <hr> - * <h2>SYNOPSIS</h2> - *<blockquote> - * Class that provides an interface to timers. - * - *</blockquote> - * - * <h2>DESCRIPTION</h2> - *<blockquote> - * This is a simple implementation that keeps a linked list of - * absolute timers. It allows multiple timers to be scheduled - * and returns a timer id for each timer scheduled. In addition, - * it allows periodic timers to be scheduled. - *</blockquote> - */ -public class TimerQueue implements Runnable -{ - /** - * Constructor. - *@param createInternalThread flag specifying whether to create an - * internal thread that runs the event loop. If it is true, a thread - * is spawned and it runs the event loop, handling all timeout - * events. If it is false, the caller is then responsible for calling - * handleEvents () to run the event loop. - */ - public TimerQueue (boolean createInternalThread) - { - this.eventLoopRunning_ = false; - if (createInternalThread) - new Thread (this).start (); - } - - /** - * The thread run method. Do *NOT* call this method! It gets called - * automatically. - */ - public void run () - { - this.handleEvents (); - } - - /** - * Handle timeout events. This forms the event loop and takes care - * of all scheduling. This method should only be called if the Timer - * Queue was constructed with the value of createInternalThread as - * false. - */ - public void handleEvents () - { - if (!this.eventLoopRunning_) - { - // Set the flag indicating that the event loop is now running - this.eventLoopRunning_ = true; - - TimeValue timeout = null; - TimeValue earliest = null; - - for (;;) - { - synchronized (this.obj_) - { - earliest = this.earliestTime (); - if (earliest != null) - timeout = TimeValue.minus (earliest, TimeValue.getTimeOfDay ()); - else - timeout = new TimeValue (); - try - { - // Extract the earliest time from the queue and do a timed wait - this.obj_.timedWait (timeout); - - // We have been notified. Check to see if we need to - // restart the wait with a different timeout - if (this.reset_) - { - this.reset_ = false; - this.obj_.condition (false); - timeout = TimeValue.minus (this.earliestTime (), TimeValue.getTimeOfDay ()); - } - } - catch (TimeoutException e) - { - // Timeout occurred. Call handleTimeout on appropriate - // Event Handlers - this.dispatchHandlers (); - } - catch (InterruptedException e) - { - } - } - } - } - } - - /** - * Check if the queue is empty. - *@return true if queue is empty, else false. - */ - boolean isEmpty () - { - return this.head_ == null; - } - - /** - * Get the node of the earliest node in the TimerQueue. - *@return the time of the earlier node in the TimerQueue. - */ - TimeValue earliestTime () - { - synchronized (this.obj_) - { - if (!this.isEmpty ()) - return this.head_.timerValue_; - else - return null; - } - } - - /** - * Schedule an <EventHandler> that will expire after <delta> amount - * of time. If it expires then <obj> is passed in as the value to - * the <EventHandler>'s <handleTimeout> callback method. This method - * returns a timer id that uniquely identifies the timer and can be - * used to cancel the timer before it expires. - *@param handler Event Handler that is to be scheduled with the timer - *@param obj Object that is passed back to the Event Handler when - * timeout occurs (Asynchronous Completion Token) - *@param delta amount of time for which to schedule the timer - *@return id of the timer scheduled - */ - public int scheduleTimer (EventHandler handler, - Object obj, - TimeValue delta) - { - return this.scheduleTimer (handler, obj, delta, TimeValue.zero); - } - - /** - * Schedule an <EventHandler> that will expire after <delta> amount - * of time. If it expires then <obj> is passed in as the value to - * the <EventHandler>'s <handleTimeout> callback method. If - * <interval> is != to <TimeValue.zero> then it is used to - * reschedule the <EventHandler> automatically. This method - * returns a timer id that uniquely identifies the timer and can be - * used to cancel the timer before it expires. - *@param handler Event Handler that is to be scheduled with the timer - *@param arg Object that is passed back to the Event Handler when - * timeout occurs (Asynchronous Completion Token) - *@param timeout amount of time for which to schedule the timer - *@param interval amount of time to use to reschedule the timer - *@return id of the timer scheduled - */ - public int scheduleTimer (EventHandler handler, - Object arg, - TimeValue timeout, - TimeValue interval) - { - // Increment the sequence number (it will wrap around). - this.timerId_++; - TimeValue futureTime = TimeValue.plus (timeout, TimeValue.getTimeOfDay ()); - TimerNode node = new TimerNode (handler, - arg, - futureTime, - interval, - null, - this.timerId_); - synchronized (this.obj_) - { - // Check if event loop is running. If it is not, then we can - // just place it at the appropriate place in the queue and - // don't need to do any notification. If event loop is - // running, then check if the node is the first node in the - // queue (either because the queue is empty or because the - // time for the node is earlier than the currently scheduled - // timer node). - if (this.eventLoopRunning_ && - (this.isEmpty () || futureTime.lessThan (this.earliestTime ()))) - { - // Insert the node into (the beginning of) the queue to be - // scheduled. - this.reschedule (node); - - // Notify the waiting thread so that it can reschedule - // using the earliest timeout - this.obj_.notify (); - } - else // Place in the appropriate position in the queue. - { - this.reschedule (node); - } - } - return this.timerId_; - } - - - /** - * Cancel the single timer associated with <timerId>. - *@param timerId id of the timer that needs to be cancelled. - *@return Object that was passed in when timer was scheduled - * (Asynchronous Completion Token). - */ - public Object cancelTimer (int timerId) - { - TimerNode prev = null; - TimerNode curr = null; - - synchronized (this.obj_) - { - // Try to locate the TimerNode that matches the timerId. - for (curr = this.head_; - curr != null && curr.timerId_ != timerId; - curr = curr.next_) - prev = curr; - - if (curr != null) - { - if (prev == null) - this.head_ = curr.next_; - else - prev.next_ = curr.next_; - - return curr.arg_; - } - } - return null; - } - - /** - * Cancel all timers associated with <Event Handler>. - *@param handler Event Handler whose associated timers need to be cancelled. - */ - public void cancelTimer (EventHandler handler) - { - TimerNode prev = null; - TimerNode curr = this.head_; - - synchronized (this.obj_) - { - while (curr != null) - { - if (curr.handler_ == handler) - { - if (prev == null) - { - this.head_ = curr.next_; - curr = this.head_; - } - else - { - prev.next_ = curr.next_; - curr = prev.next_; - } - } - else - { - prev = curr; - curr = curr.next_; - } - } - } - } - - // Call handleTimeout() on all handlers whose timers have expired. - private void dispatchHandlers () - { - TimeValue currentTime = TimeValue.getTimeOfDay (); - - for (;;) - { - if (this.isEmpty () || this.earliestTime ().greaterThan (currentTime)) - break; // There aren't any more timers eligible to expire. - - TimerNode expired = this.head_; - EventHandler handler = expired.handler_; - Object arg = expired.arg_; - int result; - - this.head_ = this.head_.next_; - - // Check whether this is an interval timer. - if (expired.interval_.greaterThan (TimeValue.zero)) - { - // Make sure that we skip past values that have already - // "expired". - do - expired.timerValue_.plusEquals (expired.interval_); - while (expired.timerValue_.lessThanEqual (currentTime)); - - // Since this is an interval timer, we need to reschedule - // it. - this.reschedule (expired); - } - - // Perform the callback. - result = handler.handleTimeout (currentTime, arg); - - if (result == -1) - this.cancelTimer (handler); - } - } - - // Reschedule a TimerNode by inserting it at the appropriate - // position in the queue. - private void reschedule (TimerNode expired) - { - if (this.isEmpty () || - expired.timerValue_.lessThan (this.earliestTime ())) - { - expired.next_ = this.head_; - this.head_ = expired; - // Set the condition to true so that the waiting thread can be - // notified and it can reschedule. - this.obj_.condition (true); - this.reset_ = true; - } - else - { - TimerNode prev = this.head_; - TimerNode after = this.head_.next_; - - // Locate the proper position in the queue. - - while (after != null - && expired.timerValue_.greaterThan (after.timerValue_)) - { - prev = after; - after = after.next_; - } - - expired.next_ = after; - prev.next_ = expired; - } - } - - private WaitObject obj_ = new WaitObject (); - // Synchronization object (as well as object to use to do wait on) - - private TimerNode head_; - // Pointer to linked list of TimerHandles. - - private int timerId_; - // Keeps track of the timer id that uniquely identifies each timer. - // This id can be used to cancel a timer via the <cancel (int)> - // method. - - private boolean reset_; - // Flag indicating whether to start the wait again - - private boolean eventLoopRunning_; - // Flag indicating whether the event loop is running or not -} - |