/*******************************************************************************
* Copyright (c) 2014, 2015 Cisco Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*
*******************************************************************************/
package com.cisco.yangide.core.indexing;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.SubProgressMonitor;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.osgi.util.NLS;
import com.cisco.yangide.core.YangCorePlugin;
/**
* @author Konstantin Zaitsev
* @date Jul 1, 2014
*/
public abstract class JobManager implements Runnable {
/* queue of jobs to execute */
protected IJob[] awaitingJobs = new IJob[10];
protected int jobStart = 0;
protected int jobEnd = -1;
protected boolean executing = false;
/* background processing */
protected Thread processingThread;
protected Job progressJob;
/*
* counter indicating whether job execution is enabled or not, disabled if <= 0 it cannot go
* beyond 1
*/
private int enableCount = 1;
/* flag indicating that the activation has completed */
public boolean activated = false;
private int awaitingClients = 0;
/**
* Invoked exactly once, in background, before starting processing any job
*/
public void activateProcessing() {
this.activated = true;
}
/**
* Answer the amount of awaiting jobs.
*/
public synchronized int awaitingJobsCount() {
// pretend busy in case concurrent job attempts performing before activated
return this.activated ? this.jobEnd - this.jobStart + 1 : 1;
}
/**
* Answers the first job in the queue, or null if there is no job available Until the job has
* completed, the job manager will keep answering the same job.
*/
public synchronized IJob currentJob() {
if (this.enableCount > 0 && this.jobStart <= this.jobEnd) {
return this.awaitingJobs[this.jobStart];
}
return null;
}
public synchronized void disable() {
this.enableCount--;
}
/**
* Remove the index from cache for a given project. Passing null as a job family discards them
* all.
*/
public void discardJobs(String jobFamily) {
try {
IJob currentJob;
// cancel current job if it belongs to the given family
synchronized (this) {
currentJob = currentJob();
disable();
}
if (currentJob != null && (jobFamily == null || currentJob.belongsTo(jobFamily))) {
currentJob.cancel();
// wait until current active job has finished
while (this.processingThread != null && this.executing) {
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// ignore
}
}
}
// flush and compact awaiting jobs
int loc = -1;
synchronized (this) {
for (int i = this.jobStart; i <= this.jobEnd; i++) {
currentJob = this.awaitingJobs[i];
if (currentJob != null) { // sanity check
this.awaitingJobs[i] = null;
if (!(jobFamily == null || currentJob.belongsTo(jobFamily))) { // copy down,
// compacting
this.awaitingJobs[++loc] = currentJob;
} else {
currentJob.cancel();
}
}
}
this.jobStart = 0;
this.jobEnd = loc;
}
} finally {
enable();
}
}
public synchronized void enable() {
this.enableCount++;
notifyAll(); // wake up the background thread if it is waiting (context must be
// synchronized)
}
protected synchronized boolean isJobWaiting(IJob request) {
for (int i = this.jobEnd; i > this.jobStart; i--) {
// don't check job at jobStart, as it may have already started
if (request.equals(this.awaitingJobs[i])) {
return true;
}
}
return false;
}
/**
* Advance to the next available job, once the current one has been completed. Note: clients
* awaiting until the job count is zero are still waiting at this point.
*/
protected synchronized void moveToNextJob() {
// if (!enabled) return;
if (this.jobStart <= this.jobEnd) {
this.awaitingJobs[this.jobStart++] = null;
if (this.jobStart > this.jobEnd) {
this.jobStart = 0;
this.jobEnd = -1;
}
}
}
/**
* When idle, give chance to do something
*/
protected void notifyIdle(long idlingTime) {
// do nothing
}
/**
* This API is allowing to run one job in concurrence with background processing. Indeed since
* other jobs are performed in background, resource sharing might be an issue.Therefore, this
* functionality allows a given job to be run without colliding with background ones. Note:
* multiple thread might attempt to perform concurrent jobs at the same time, and should
* synchronize (it is deliberately left to clients to decide whether concurrent jobs might
* interfere or not. In general, multiple read jobs are ok). Waiting policy can be:
* IJobConstants.ForceImmediateSearch IJobConstants.CancelIfNotReadyToSearch
* IJobConstants.WaitUntilReadyToSearch
*/
public boolean performConcurrentJob(IJob searchJob, int waitingPolicy, IProgressMonitor progress) {
searchJob.ensureReadyToRun();
boolean status = IJob.FAILED;
try {
int concurrentJobWork = 100;
if (progress != null) {
progress.beginTask("", concurrentJobWork); //$NON-NLS-1$
}
if (awaitingJobsCount() > 0) {
switch (waitingPolicy) {
case IJob.ForceImmediate:
try {
disable(); // pause indexing
status = searchJob.execute(progress == null ? null : new SubProgressMonitor(progress,
concurrentJobWork));
} finally {
enable();
}
return status;
case IJob.CancelIfNotReady:
throw new OperationCanceledException();
case IJob.WaitUntilReady:
IProgressMonitor subProgress = null;
try {
int totalWork = 1000;
if (progress != null) {
subProgress = new SubProgressMonitor(progress, concurrentJobWork * 8 / 10);
subProgress.beginTask("", totalWork); //$NON-NLS-1$
concurrentJobWork = concurrentJobWork * 2 / 10;
}
// use local variable to avoid potential NPE (see bug 20435 NPE when
// searching java method
// and bug 42760 NullPointerException in JobManager when searching)
Thread t = this.processingThread;
int originalPriority = t == null ? -1 : t.getPriority();
try {
if (t != null) {
t.setPriority(Thread.currentThread().getPriority());
}
synchronized (this) {
this.awaitingClients++;
}
IJob previousJob = null;
int awaitingJobsCount;
int lastJobsCount = totalWork;
float lastWorked = 0;
float totalWorked = 0;
while ((awaitingJobsCount = awaitingJobsCount()) > 0) {
if ((subProgress != null && subProgress.isCanceled()) || this.processingThread == null) {
throw new OperationCanceledException();
}
IJob currentJob = currentJob();
// currentJob can be null when jobs have been added to the queue but
// job manager is not enabled
if (currentJob != null && currentJob != previousJob) {
if (subProgress != null) {
String indexing = NLS.bind("{1} files to index ({0})",
currentJob.getJobFamily(), Integer.toString(awaitingJobsCount));
subProgress.subTask(indexing);
// ratio of the amount of work relative to the total work
float ratio = awaitingJobsCount < totalWork ? 1 : ((float) totalWork)
/ awaitingJobsCount;
if (lastJobsCount > awaitingJobsCount) {
totalWorked += (lastJobsCount - awaitingJobsCount) * ratio;
} else {
// more jobs were added, just increment by the ratio
totalWorked += ratio;
}
if (totalWorked - lastWorked >= 1) {
subProgress.worked((int) (totalWorked - lastWorked));
lastWorked = totalWorked;
}
lastJobsCount = awaitingJobsCount;
}
previousJob = currentJob;
}
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// ignore
}
}
} finally {
synchronized (this) {
this.awaitingClients--;
}
if (t != null && originalPriority > -1 && t.isAlive()) {
t.setPriority(originalPriority);
}
}
} finally {
if (subProgress != null) {
subProgress.done();
}
}
}
}
status = searchJob.execute(progress == null ? null : new SubProgressMonitor(progress, concurrentJobWork));
} finally {
if (progress != null) {
progress.done();
}
}
return status;
}
public abstract String processName();
public synchronized void request(IJob job) {
job.ensureReadyToRun();
// skip job if it already in manager
for (int i = this.jobEnd; i > this.jobStart; i--) {
if (job.equals(this.awaitingJobs[i])) {
return;
}
}
// append the job to the list of ones to process later on
int size = this.awaitingJobs.length;
if (++this.jobEnd == size) { // when growing, relocate jobs starting at position 0
this.jobEnd -= this.jobStart; // jobEnd now equals the number of jobs
if (this.jobEnd < 50 && this.jobEnd < this.jobStart) {
// plenty of free space in the queue so shift the remaining jobs to the beginning
// instead of growing it
System.arraycopy(this.awaitingJobs, this.jobStart, this.awaitingJobs, 0, this.jobEnd);
for (int i = this.jobStart; i < size; i++) {
this.awaitingJobs[i] = null;
}
} else {
System.arraycopy(this.awaitingJobs, this.jobStart, this.awaitingJobs = new IJob[size * 2], 0,
this.jobEnd);
}
this.jobStart = 0;
}
this.awaitingJobs[this.jobEnd] = job;
notifyAll(); // wake up the background thread if it is waiting
}
/**
* Flush current state
*/
public synchronized void reset() {
if (this.processingThread != null) {
discardJobs(null); // discard all jobs
} else {
/* initiate background processing */
this.processingThread = new Thread(this, processName());
this.processingThread.setDaemon(true);
// less prioritary by default, priority is raised if clients are actively waiting on it
this.processingThread.setPriority(Thread.NORM_PRIORITY - 1);
// https://bugs.eclipse.org/bugs/show_bug.cgi?id=296343
// set the context loader to avoid leaking the current context loader
this.processingThread.setContextClassLoader(this.getClass().getClassLoader());
this.processingThread.start();
}
}
/**
* Infinite loop performing resource indexing
*/
@Override
public void run() {
long idlingStart = -1;
activateProcessing();
try {
class ProgressJob extends Job {
ProgressJob(String name) {
super(name);
}
@Override
protected IStatus run(IProgressMonitor monitor) {
IJob job = currentJob();
while (!monitor.isCanceled() && job != null) {
String taskName = new StringBuffer("YANG indexing...").append(
NLS.bind("{1} files to index ({0})", job.getJobFamily(),
Integer.toString(awaitingJobsCount()))).toString();
monitor.subTask(taskName);
setName(taskName);
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// ignore
}
job = currentJob();
}
return Status.OK_STATUS;
}
}
this.progressJob = null;
while (this.processingThread != null) {
try {
IJob job;
synchronized (this) {
// handle shutdown case when notifyAll came before the wait but after the
// while loop was entered
if (this.processingThread == null) {
continue;
}
// must check for new job inside this sync block to avoid timing hole
if ((job = currentJob()) == null) {
if (this.progressJob != null) {
this.progressJob.cancel();
this.progressJob = null;
}
if (idlingStart < 0) {
idlingStart = System.currentTimeMillis();
} else {
notifyIdle(System.currentTimeMillis() - idlingStart);
}
this.wait(); // wait until a new job is posted (or reenabled:38901)
} else {
idlingStart = -1;
}
}
if (job == null) {
notifyIdle(System.currentTimeMillis() - idlingStart);
// just woke up, delay before processing any new jobs, allow some time for
// the active thread to finish
Thread.sleep(500);
continue;
}
try {
this.executing = true;
if (this.progressJob == null) {
this.progressJob = new ProgressJob("YANG indexing...");
this.progressJob.setPriority(Job.LONG);
this.progressJob.setSystem(true);
this.progressJob.schedule();
}
/* boolean status = */job.execute(null);
// if (status == FAILED) request(job);
} finally {
this.executing = false;
moveToNextJob();
if (this.awaitingClients == 0) {
Thread.sleep(50);
}
}
} catch (InterruptedException e) { // background indexing was interrupted
}
}
} catch (RuntimeException e) {
if (this.processingThread != null) { // if not shutting down
// log exception
YangCorePlugin.log(e, "Background Indexer Crash Recovery"); //$NON-NLS-1$
// keep job manager alive
discardJobs(null);
this.processingThread = null;
reset(); // this will fork a new thread with no waiting jobs, some indexes will be
// inconsistent
}
throw e;
} catch (Error e) {
if (this.processingThread != null && !(e instanceof ThreadDeath)) {
// log exception
YangCorePlugin.log(e, "Background Indexer Crash Recovery"); //$NON-NLS-1$
// keep job manager alive
discardJobs(null);
this.processingThread = null;
reset(); // this will fork a new thread with no waiting jobs, some indexes will be
// inconsistent
}
throw e;
}
}
/**
* Stop background processing, and wait until the current job is completed before returning
*/
public void shutdown() {
disable();
discardJobs(null); // will wait until current executing job has completed
Thread thread = this.processingThread;
try {
if (thread != null) { // see http://bugs.eclipse.org/bugs/show_bug.cgi?id=31858
synchronized (this) {
this.processingThread = null; // mark the job manager as shutting down so that
// the thread will stop by itself
notifyAll(); // ensure its awake so it can be shutdown
}
// in case processing thread is handling a job
thread.join();
}
Job job = this.progressJob;
if (job != null) {
job.cancel();
job.join();
}
} catch (InterruptedException e) {
// ignore
}
}
@Override
public String toString() {
StringBuffer buffer = new StringBuffer(10);
buffer.append("Enable count:").append(this.enableCount).append('\n'); //$NON-NLS-1$
int numJobs = this.jobEnd - this.jobStart + 1;
buffer.append("Jobs in queue:").append(numJobs).append('\n'); //$NON-NLS-1$
for (int i = 0; i < numJobs && i < 15; i++) {
buffer.append(i).append(" - job[" + i + "]: ").append(this.awaitingJobs[this.jobStart + i]).append('\n'); //$NON-NLS-1$ //$NON-NLS-2$
}
return buffer.toString();
}
}