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/*
This file is part of the iText (R) project.
Copyright (c) 1998-2018 iText Group NV
Authors: Bruno Lowagie, Paulo Soares, et al.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License version 3
as published by the Free Software Foundation with the addition of the
following permission added to Section 15 as permitted in Section 7(a):
FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
OF THIRD PARTY RIGHTS
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program; if not, see http://www.gnu.org/licenses or write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA, 02110-1301 USA, or download the license from the following URL:
http://itextpdf.com/terms-of-use/
The interactive user interfaces in modified source and object code versions
of this program must display Appropriate Legal Notices, as required under
Section 5 of the GNU Affero General Public License.
In accordance with Section 7(b) of the GNU Affero General Public License,
a covered work must retain the producer line in every PDF that is created
or manipulated using iText.
You can be released from the requirements of the license by purchasing
a commercial license. Buying such a license is mandatory as soon as you
develop commercial activities involving the iText software without
disclosing the source code of your own applications.
These activities include: offering paid services to customers as an ASP,
serving PDFs on the fly in a web application, shipping iText with a closed
source product.
For more information, please contact iText Software Corp. at this
address: [email protected]
*/
package com.itextpdf.kernel.counter.data;
import com.itextpdf.io.util.SystemUtil;
import com.itextpdf.kernel.counter.event.IEvent;
import com.itextpdf.kernel.counter.event.IMetaInfo;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicLong;
/**
* This class is intended for some heavy concurrent event operations
* (like writing to database or file).
*
* On registration of new {@link IEvent} the instance of {@link EventData} is created with
* the {@link IEventDataFactory} that can add some additional information like system info
* or version.
* This data instance is immediately cached with {@link IEventDataCache} that can for example
* merge data with the same signature by summing there count.
* If the previous processing operation is finished and the wait time is passed then the next event is retrieved from cache
* (it may be for example based on some comparator like the biggest count, if {@link EventDataCacheComparatorBased}
* is used, or just queue based if the {@link EventDataCacheQueueBased} is used or any other order determined by
* custom cache) and the processing is started asynchronously
*
* This class can be considered thread-safe if the cache and factory instances aren't used anywhere else in the code.
*
* @param data signature type
* @param data type
*/
public abstract class EventDataHandler> {
private final Object processLock = new Object();
private final IEventDataCache cache;
private final IEventDataFactory factory;
private final AtomicLong lastProcessedTime = new AtomicLong();
private volatile WaitTime waitTime;
public EventDataHandler(IEventDataCache cache, IEventDataFactory factory, long initialWaitTimeMillis, long maxWaitTimeMillis) {
this.cache = cache;
this.factory = factory;
this.waitTime = new WaitTime(initialWaitTimeMillis, maxWaitTimeMillis);
}
public List clear() {
List all;
synchronized (cache) {
all = cache.clear();
}
lastProcessedTime.set(0);
resetWaitTime();
return all != null ? all : Collections.emptyList();
}
public void register(IEvent event, IMetaInfo metaInfo) {
V data;
//Synchronization is left here mostly in consistency with cache and process, but factories are usually not thread safe anyway.
synchronized (factory) {
data = factory.create(event, metaInfo);
}
if (data != null) {
synchronized (cache) {
cache.put(data);
}
tryProcessNextAsync();
}
}
public void tryProcessNext() {
long currentTime = SystemUtil.getRelativeTimeMillis();
if (currentTime - lastProcessedTime.get() > waitTime.getTime()) {
lastProcessedTime.set(SystemUtil.getRelativeTimeMillis());
V data;
synchronized (cache) {
data = cache.retrieveNext();
}
if (data != null) {
boolean successful;
synchronized (processLock) {
successful = tryProcess(data);
}
if (successful) {
onSuccess(data);
} else {
synchronized (cache) {
cache.put(data);
}
onFailure(data);
}
}
}
}
public void tryProcessNextAsync() {
tryProcessNextAsync(null);
}
public void tryProcessNextAsync(Boolean daemon) {
long currentTime = SystemUtil.getRelativeTimeMillis();
if (currentTime - lastProcessedTime.get() > waitTime.getTime()) {
Thread thread = new Thread() {
@Override
public void run() {
tryProcessNext();
}
};
if (daemon != null) {
thread.setDaemon((boolean) daemon);
}
thread.start();
}
}
/**
* Method that will try to immediately process all cashed data, ignoring the usual error fallback procedures.
*/
public void tryProcessRest() {
List unprocessedEvents = clear();
if (!unprocessedEvents.isEmpty()) {
try {
synchronized (processLock) {
for (V data : unprocessedEvents) {
process(data);
}
}
} catch (Exception ignored) {
}
}
}
public void resetWaitTime() {
WaitTime local = waitTime;
waitTime = new WaitTime(local.getInitial(), local.getMaximum());
}
public void increaseWaitTime() {
WaitTime local = waitTime;
waitTime = new WaitTime(local.getInitial(), local.getMaximum(), Math.min(local.getTime() * 2, local.getMaximum()));
}
public void setNoWaitTime() {
WaitTime local = waitTime;
waitTime = new WaitTime(local.getInitial(), local.getMaximum(), 0);
}
public WaitTime getWaitTime() {
return waitTime;
}
protected void onSuccess(V data) {
resetWaitTime();
}
protected void onFailure(V data) {
increaseWaitTime();
}
/**
* Is called when exception is thrown in process.
*
* @param exception caught exception
* @return whether processing is treated as success
*/
protected boolean onProcessException(Exception exception) {
return false;
}
protected abstract boolean process(V data);
private boolean tryProcess(V data) {
try {
return process(data);
} catch (Exception any) {
return onProcessException(any);
}
}
}
