Mercurial > hg > release > thermostat-1.2
view web/server/src/main/java/com/redhat/thermostat/web/server/CursorManager.java @ 1660:c6ae78b6f3ac
[Thermostat 1.2] Update copyright year to 2015
Reviewed-by: omajid
Review-thread: http://icedtea.classpath.org/pipermail/thermostat/2015-March/013127.html
PR2273
author | Severin Gehwolf <sgehwolf@redhat.com> |
---|---|
date | Wed, 11 Mar 2015 15:07:27 +0100 |
parents | 7163ecc4e8ed |
children |
line wrap: on
line source
/* * Copyright 2012-2015 Red Hat, Inc. * * This file is part of Thermostat. * * Thermostat is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published * by the Free Software Foundation; either version 2, or (at your * option) any later version. * * Thermostat is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with Thermostat; see the file COPYING. If not see * <http://www.gnu.org/licenses/>. * * Linking this code with other modules is making a combined work * based on this code. Thus, the terms and conditions of the GNU * General Public License cover the whole combination. * * As a special exception, the copyright holders of this code give * you permission to link this code with independent modules to * produce an executable, regardless of the license terms of these * independent modules, and to copy and distribute the resulting * executable under terms of your choice, provided that you also * meet, for each linked independent module, the terms and conditions * of the license of that module. An independent module is a module * which is not derived from or based on this code. If you modify * this code, you may extend this exception to your version of the * library, but you are not obligated to do so. If you do not wish * to do so, delete this exception statement from your version. */ package com.redhat.thermostat.web.server; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Timer; import java.util.TimerTask; import com.redhat.thermostat.storage.core.experimental.BatchCursor; /** * Manages (query) cursors for a single user. * */ final class CursorManager { public static final int CURSOR_NOT_STORED = -1; private final Map<Integer, CursorHolder> cursors; private final TimerRegistry registry; private int cursorIdCounter; // test-only CursorManager(TimerRegistry registry, Map<Integer, CursorHolder> cursors) { this.registry = registry; this.cursors = cursors; } CursorManager(TimerRegistry registry) { this.cursors = new HashMap<>(); this.registry = registry; } // test-only CursorManager(int cursorIdCounter) { this(null); this.cursorIdCounter = cursorIdCounter; } /** * Add a cursor to the map we know of if it has more results. * * @param cursor The potential candidate to add to the state we keep track * of. * @return The cursor ID or {@link CursorManager#CURSOR_NOT_STORED} if the * passed in cursor has no more elements. */ synchronized int put(final BatchCursor<?> cursor) { int cursorId = CURSOR_NOT_STORED; if (cursor.hasNext()) { // Be sure we don't overflow. For a long running web storage we // could potentially run out of id's for a single user. However, // the time between 0 and Integer.MAX_VALUE should be sufficiently // large so that any given cursor expires before the id will get // reused. if (cursorIdCounter == Integer.MAX_VALUE) { cursorIdCounter = 0; // start again from 0 } cursorId = cursorIdCounter; cursors.put(cursorId, new CursorHolder(cursor, System.currentTimeMillis())); cursorIdCounter++; } return cursorId; } synchronized BatchCursor<?> get(int cursorId) { CursorHolder holder = cursors.get(cursorId); if (holder == null) { return null; } return holder.getCursor(); } synchronized void updateCursorTimeStamp(int cursorId) { CursorHolder holder = cursors.get(cursorId); if (holder == null) { return; } holder.updateTimestamp(); } synchronized void removeCursor(int cursorId) { cursors.remove(cursorId); } synchronized void expireCursors() { final long currentTime = System.currentTimeMillis(); List<Integer> expiredCursors = new ArrayList<>(); for (Entry<Integer, CursorHolder> entry: cursors.entrySet()) { CursorHolder holder = entry.getValue(); if (holder.isCursorExpired(currentTime)) { expiredCursors.add(entry.getKey()); } } for (Integer expiredKey: expiredCursors) { cursors.remove(expiredKey); } } void startSweeperTimer() { CursorTimer sweeperTimer = new CursorTimer(new CursorSweeper(this)); sweeperTimer.scheduleTask(); registry.registerTimer(sweeperTimer); } /** * * A container in order save and track cursors. This holder enables * expiring cursors, as well as extending the liveness of a cursor. * */ static class CursorHolder { private static final int MINUTES = 1000 * 60; // The time out in minutes static final int TIMEOUT = 3 * MINUTES; private final BatchCursor<?> cursor; private long lastUpdated; CursorHolder(BatchCursor<?> cursor, long lastUpdated) { this.cursor = cursor; this.lastUpdated = lastUpdated; } void updateTimestamp() { this.lastUpdated = System.currentTimeMillis(); } boolean isCursorExpired(long currentTime) { return checkIsCursorExpired(currentTime, TIMEOUT); } BatchCursor<?> getCursor() { return cursor; } // here in order to facilitate testing boolean checkIsCursorExpired(long currentTime, final int timeoutInMillis) { return lastUpdated < (currentTime - timeoutInMillis); } // test-only long getLastUpdated() { return lastUpdated; } } /** * {@link TimerTask} which times out cursors. */ static class CursorSweeper extends TimerTask { private final CursorManager manager; CursorSweeper(CursorManager manager) { this.manager = manager; } @Override public void run() { manager.expireCursors(); } } static class CursorTimer implements StoppableTimer { private static final String NAME = NAME_PREFIX + "cursor-manager"; private final Timer timer; private final TimerTask task; boolean taskScheduled = false; CursorTimer(TimerTask task) { this(task, new Timer(NAME)); } // for testing CursorTimer(TimerTask task, Timer timer) { this.timer = timer; this.task = task; } void scheduleTask() { timer.scheduleAtFixedRate(task, 0, CursorHolder.TIMEOUT); taskScheduled = true; } @Override public void stop() { timer.cancel(); } } }