86 lines
3.1 KiB
Java
86 lines
3.1 KiB
Java
/*
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* Copyright (c) 2014, 2022, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package javacserver.server;
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import java.util.Timer;
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import java.util.TimerTask;
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import java.util.function.Consumer;
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import javacserver.util.RunnableTimerTask;
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/**
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* Monitors the javacserver daemon, shutting it down if it recieves no new requests
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* after a certain amount of time.
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*/
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public class IdleMonitor {
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// Accept 120 seconds of inactivity before quitting.
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private static final int KEEPALIVE = 120;
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private final Consumer<String> onShutdown;
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private final Timer idlenessTimer = new Timer();
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private int outstandingCalls = 0;
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// Class invariant: idlenessTimerTask != null <-> idlenessTimerTask is scheduled
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private TimerTask idlenessTimerTask;
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public IdleMonitor(Consumer<String> onShutdown) {
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this.onShutdown = onShutdown;
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scheduleTimeout();
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}
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public synchronized void startCall() {
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// Was there no outstanding calls before this call?
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if (++outstandingCalls == 1) {
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// Then the timer task must have been scheduled
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if (idlenessTimerTask == null)
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throw new IllegalStateException("Idle timeout already cancelled");
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// Cancel timeout task
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idlenessTimerTask.cancel();
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idlenessTimerTask = null;
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}
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}
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public synchronized void endCall() {
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if (--outstandingCalls == 0) {
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// No more outstanding calls. Schedule timeout.
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scheduleTimeout();
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}
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}
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private void scheduleTimeout() {
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if (idlenessTimerTask != null)
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throw new IllegalStateException("Idle timeout already scheduled");
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idlenessTimerTask = new RunnableTimerTask(() -> {
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Server.restoreServerErrorLog();
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onShutdown.accept("Server has been idle for " + KEEPALIVE + " seconds.");
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});
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idlenessTimer.schedule(idlenessTimerTask, KEEPALIVE * 1000);
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}
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public void shutdown() {
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idlenessTimer.cancel();
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}
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}
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