The invoker is a useful tool for services that need to block and - * therefore cannot be run on the distributed object thread. For example, - * a user of the Presents system might provide an invoker on which to run - * database queries. - * - *
Bear in mind that each invoker instance runs units on its own
- * thread and care must be taken to ensure that code running on separate
- * invokers properly synchronizes access to shared information. Where
- * possible, complete isolation of the services provided by a particular
- * invoker is desirable.
- */
-public class Invoker extends LoopingThread
- implements Reporter
-{
- /**
- * The unit encapsulates a unit of executable code that will be run on
- * the invoker thread. It also provides facilities for additional code
- * to be run on the dobjmgr thread once the primary code has completed
- * on the invoker thread.
- */
- public static abstract class Unit implements Runnable
- {
- /** The default constructor. */
- public Unit () {}
-
- /** Creates an invoker unit which will report the supplied name in
- * {@link #toString}. */
- public Unit (String name)
- {
- _name = name;
- }
-
- /**
- * This method is called on the invoker thread and should be used
- * to perform the primary function of the unit. It can return true
- * to cause the handleResult method to be
- * subsequently invoked on the dobjmgr thread (generally to allow
- * the results of the invocation to be acted upon back in the
- * context of the distributed object world) or false to indicate
- * that no further processing should be performed.
- *
- *
Note that an invocation unit can do things like post events
- * from the invoker thread (which includes modification of
- * distributed object fields) and need not jump over to the
- * dobjmgr thread to do so. However, it cannot read
- * distributed object fields from the invoker thread. Any field
- * values needed during the course of the invocation should be
- * provided from the dobjmgr thread at the time that the
- * invocation unit is created and posted.
- *
- * @return true if the handleResult method should be
- * invoked on the dobjmgr thread, false if not.
- */
- public abstract boolean invoke ();
-
- /**
- * Invocation unit implementations can implement this function to
- * perform any post-unit-invocation processing back on the dobjmgr
- * thread. It will be invoked if invoke returns true.
- */
- public void handleResult ()
- {
- // do nothing by default
- }
-
- // we want to be a runnable to make the dobjmgr happy, but we'd
- // like for invocation unit implementations to be able to put
- // their result handling code into an aptly named method
- public void run ()
- {
- handleResult();
- }
-
- /** Returns the name of this invoker. */
- public String toString ()
- {
- return _name;
- }
-
- protected String _name = "Unknown";
- }
-
- /**
- * Creates an invoker that will post results to the supplied
- * distributed object manager.
- */
- public Invoker (PresentsDObjectMgr omgr)
- {
- super("presents.Invoker");
- _omgr = omgr;
- if (PERF_TRACK) {
- PresentsServer.registerReporter(this);
- }
- }
-
- /**
- * Posts a unit to this invoker for subsequent invocation on the
- * invoker's thread.
- */
- public void postUnit (Unit unit)
- {
- // simply append it to the queue
- _queue.append(unit);
- }
-
- // documentation inherited
- public void iterate ()
- {
- // pop the next item off of the queue
- Unit unit = (Unit) _queue.get();
-
- long start;
- if (PERF_TRACK) {
- start = System.currentTimeMillis();
- _unitsRun++;
- }
-
- try {
- if (unit.invoke()) {
- // if it returned true, we post it to the dobjmgr
- // thread to invoke the result processing
- _omgr.postUnit(unit);
- }
-
- // track some performance metrics
- if (PERF_TRACK) {
- long duration = System.currentTimeMillis() - start;
- Object key = unit.getClass();
- Histogram histo = (Histogram)_tracker.get(key);
- if (histo == null) {
- // track in buckets of 50ms up to 500ms
- _tracker.put(key, histo = new Histogram(0, 50, 10));
- }
- histo.addValue((int)duration);
-
- // report long runners
- if (duration > 500L) {
- Log.warning("Invoker unit ran for '" + duration + "ms: " +
- unit + "' (" + key + ").");
- }
- }
-
- } catch (Exception e) {
- Log.warning("Invocation unit failed [unit=" + unit + "].");
- Log.logStackTrace(e);
- }
- }
-
- /**
- * Will do a sophisticated shutdown of both itself and the DObjectManager
- * thread.
- */
- public void shutdown ()
- {
- _queue.append(new ShutdownUnit());
- }
-
- // documentation inherited from interface
- public void appendReport (StringBuffer buffer, long now, long sinceLast)
- {
- buffer.append("* presents.util.Invoker:\n");
- buffer.append("- Units executed: ").append(_unitsRun).append("\n");
- _unitsRun = 0;
- for (Iterator iter = _tracker.keySet().iterator(); iter.hasNext(); ) {
- Class key = (Class)iter.next();
- Histogram histo = (Histogram)_tracker.get(key);
- buffer.append(" ");
- buffer.append(StringUtil.shortClassName(key)).append(": ");
- buffer.append(histo.summarize()).append("\n");
- histo.clear();
- }
- }
-
- /**
- * This unit gets posted back and forth between the invoker and DObjectMgr
- * until both of their queues are empty and they can both be safely
- * shutdown.
- */
- protected class ShutdownUnit extends Unit
- {
- // run on the invoker thread
- public boolean invoke ()
- {
- if (checkLoops()) {
- return false;
-
- // if the invoker queue is not empty, we put ourselves back on it
- } else if (_queue.hasElements()) {
- _loopCount++;
- postUnit(this);
- return false;
-
- } else {
- // the invoker is empty, let's go over to the omgr
- _loopCount = 0;
- _passCount++;
- return true;
- }
- }
-
- // run on the dobj thread
- public void handleResult ()
- {
- if (checkLoops()) {
- return;
-
- // if the queue isn't empty, re-post
- } else if (!_omgr.queueIsEmpty()) {
- _loopCount++;
- _omgr.postUnit(this);
-
- // if the invoker still has stuff and we're still under the pass
- // limit, go ahead and pass it back to the invoker
- } else if (_queue.hasElements() && (_passCount < MAX_PASSES)) {
- // pass the buck back to the invoker
- _loopCount = 0;
- postUnit(this);
-
- } else {
- // otherwise end it, and complain if we're ending it
- // because of passes
- if (_passCount >= MAX_PASSES) {
- Log.warning("Shutdown Unit passed 50 times without " +
- "finishing, shutting down harshly.");
- }
- doShutdown();
- }
- }
-
- /**
- * Check to make sure we haven't looped too many times.
- */
- protected boolean checkLoops ()
- {
- if (_loopCount > MAX_LOOPS) {
- Log.warning("Shutdown Unit looped on one thread 10000 times " +
- "without finishing, shutting down harshly.");
- doShutdown();
- return true;
- }
-
- return false;
- }
-
- /**
- * Do the actual shutdown.
- */
- protected void doShutdown ()
- {
- _omgr.harshShutdown(); // end the dobj thread
-
- // end the invoker thread
- postUnit(new Unit() {
- public boolean invoke () {
- _running = false;
- return false;
- }
- });
- }
-
- /** The number of times we've been passed to the object manager. */
- protected int _passCount = 0;
-
- /** How many times we've looped on the thread we're currently on. */
- protected int _loopCount = 0;
-
- /** The maximum number of passes we allow before just ending things. */
- protected static final int MAX_PASSES = 50;
-
- /** The maximum number of loops we allow before just ending things. */
- protected static final int MAX_LOOPS = 10000;
- }
-
- /** The invoker's queue of units to be executed. */
- protected Queue _queue = new Queue();
-
- /** The object manager with which we're working. */
- protected PresentsDObjectMgr _omgr;
-
- /** Tracks the counts of invocations by unit's class. */
- protected HashMap _tracker = new HashMap();
-
- /** The total number of invoker units run since the last report. */
- protected int _unitsRun;
-
- /** Whether or not to track invoker unit performance. */
- protected static final boolean PERF_TRACK = true;
-}
diff --git a/src/java/com/threerings/whirled/server/SceneManager.java b/src/java/com/threerings/whirled/server/SceneManager.java
index fbdb0ff44..867017627 100644
--- a/src/java/com/threerings/whirled/server/SceneManager.java
+++ b/src/java/com/threerings/whirled/server/SceneManager.java
@@ -1,13 +1,13 @@
//
-// $Id: SceneManager.java,v 1.17 2004/05/19 22:09:04 ray Exp $
+// $Id: SceneManager.java,v 1.18 2004/06/29 03:22:22 mdb Exp $
package com.threerings.whirled.server;
import com.samskivert.io.PersistenceException;
+import com.samskivert.util.Invoker;
import com.threerings.crowd.server.PlaceManager;
import com.threerings.presents.server.PresentsServer;
-import com.threerings.presents.util.Invoker;
import com.threerings.whirled.Log;
import com.threerings.whirled.data.Scene;
diff --git a/src/java/com/threerings/whirled/server/SceneRegistry.java b/src/java/com/threerings/whirled/server/SceneRegistry.java
index 73d37d855..c5e5c94d3 100644
--- a/src/java/com/threerings/whirled/server/SceneRegistry.java
+++ b/src/java/com/threerings/whirled/server/SceneRegistry.java
@@ -1,12 +1,12 @@
//
-// $Id: SceneRegistry.java,v 1.22 2004/02/25 14:50:28 mdb Exp $
+// $Id: SceneRegistry.java,v 1.23 2004/06/29 03:22:22 mdb Exp $
package com.threerings.whirled.server;
import java.util.ArrayList;
import com.samskivert.util.HashIntMap;
-import com.threerings.presents.util.Invoker;
+import com.samskivert.util.Invoker;
import com.threerings.presents.server.InvocationManager;