bundles/org.eclipse.team.core/src/org/eclipse/team/internal/core/subscribers/BatchingLock.java - platform/eclipse.platform.team - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2017 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
  * which accompanies this distribution, and is available at
  * https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.team.internal.core.subscribers;

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.OperationCanceledException;
 import org.eclipse.core.runtime.jobs.ISchedulingRule;
 import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.core.runtime.jobs.MultiRule;
 import org.eclipse.team.core.TeamException;
 import org.eclipse.team.internal.core.Messages;
 import org.eclipse.team.internal.core.Policy;
 import org.eclipse.team.internal.core.TeamPlugin;

 /**
  * Provides a per-thread nested locking mechanism. A thread can acquire a
  * lock on a specific resource by calling acquire(). Subsequently, acquire() can be called
  * multiple times on the resource or any of its children from within the same thread
  * without blocking. Other threads that try
  * and acquire the lock on those same resources will be blocked until the first
  * thread releases all it's nested locks.
  * <p>
  * The locking is managed by the platform via scheduling rules. This class simply
  * provides the nesting mechanism in order to allow the client to determine when
  * the lock for the thread has been released. Therefore, this lock will block if
  * another thread already locks the same resource.</p>
  */
 public class BatchingLock {
 	// This is a placeholder rule used to indicate that no scheduling rule is needed
 	/* internal use only */ static final ISchedulingRule NULL_SCHEDULING_RULE= new ISchedulingRule() {
 		@Override
 		public boolean contains(ISchedulingRule rule) {
 			return false;
 		}
 		@Override
 		public boolean isConflicting(ISchedulingRule rule) {
 			return false;
 		}
 	};

 	public class ThreadInfo {
 		private Set<IResource> changedResources = new HashSet<>();
 		private IFlushOperation operation;
 		private List<ISchedulingRule> rules = new ArrayList<>();
 		public ThreadInfo(IFlushOperation operation) {
 			this.operation = operation;
 		}
 		/**
 		 * Push a scheduling rule onto the stack for this thread and
 		 * acquire the rule if it is not the workspace root.
 		 * @param resource
 		 * @param monitor
 		 * @return the scheduling rule that was obtained
 		 */
 		public ISchedulingRule pushRule(ISchedulingRule resource, IProgressMonitor monitor) {
 			// The scheduling rule is either the project or the resource's parent
 			final ISchedulingRule rule = getRuleForResoure(resource);
 			if (rule != NULL_SCHEDULING_RULE) {
 				boolean success = false;
 				try {
 					Job.getJobManager().beginRule(rule, monitor);
 					addRule(rule);
 					success = true;
 				} finally {
 					if (!success) {
 						try {
 							// The begin was canceled (or some other problem occurred).
 							// Free the scheduling rule
 							// so the clients of ReentrantLock don't need to
 							// do an endRule when the operation is canceled.
 							Job.getJobManager().endRule(rule);
 						} catch (RuntimeException e) {
 							// Log and ignore so the original exception is not lost
 							TeamPlugin.log(IStatus.ERROR, "Failed to end scheduling rule", e); //$NON-NLS-1$
 						}
 					}
 				}
 			} else {
 				// Record the fact that we didn't push a rule so we
 				// can match it when we pop
 				addRule(rule);
 			}
 			return rule;
 		}
 		/**
 		 * Pop the scheduling rule from the stack and release it if it
 		 * is not the workspace root. Flush any changed sync info to
 		 * disk if necessary. A flush is necessary if the stack is empty
 		 * or if the top-most non-null scheduling rule was popped as a result
 		 * of this operation.
 		 * @param rule
 		 * @param monitor
 		 * @throws TeamException
 		 */
 		public void popRule(ISchedulingRule rule, IProgressMonitor monitor) throws TeamException {
 			try {
 				if (isFlushRequired()) {
 					flush(monitor);
 				}
 			} finally {
 				ISchedulingRule stackedRule = removeRule();
 				if (rule == null) {
 					rule = NULL_SCHEDULING_RULE;
 				}
 				Assert.isTrue(stackedRule.equals(rule), "end for resource '" + rule + "' does not match stacked rule '" + stackedRule + "'"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 				if (rule != NULL_SCHEDULING_RULE) {
 					Job.getJobManager().endRule(rule);
 				}
 			}
 		}
 		private ISchedulingRule getRuleForResoure(ISchedulingRule resourceRule) {
 			ISchedulingRule rule;
 			if (resourceRule instanceof IResource) {
 				IResource resource = (IResource)resourceRule;
 				if (resource.getType() == IResource.ROOT) {
 					// Never lock the whole workspace
 					rule = NULL_SCHEDULING_RULE;
 				} else  if (resource.getType() == IResource.PROJECT) {
 					rule = resource;
 				} else {
 					rule = resource.getParent();
 				}
 			} else if (resourceRule instanceof MultiRule) {
 				// Create a MultiRule for all projects from the given rule
 				ISchedulingRule[] rules = ((MultiRule)resourceRule).getChildren();
 				Set<ISchedulingRule> projects = new HashSet<>();
 				for (int i = 0; i < rules.length; i++) {
 					ISchedulingRule childRule = rules[i];
 					if (childRule instanceof IResource) {
 						projects.add(((IResource)childRule).getProject());
 					}
 				}
 				if (projects.isEmpty()) {
 					rule = NULL_SCHEDULING_RULE;
 				} else if (projects.size() == 1) {
 					rule = projects.iterator().next();
 				} else {
 					rule = new MultiRule(projects.toArray(new ISchedulingRule[projects.size()]));
 				}
 			} else {
 				// Rule is not associated with resources so ignore it
 				rule = NULL_SCHEDULING_RULE;
 			}
 			return rule;
 		}
 		/**
 		 * Return <code>true</code> if we are still nested in
 		 * an acquire for this thread.
 		 *
 		 * @return whether there are still rules on the stack
 		 */
 		public boolean isNested() {
 			return !rules.isEmpty();
 		}
 		public void addChangedResource(IResource resource) {
 			changedResources.add(resource);
 		}
 		public boolean isEmpty() {
 			return changedResources.isEmpty();
 		}
 		public IResource[] getChangedResources() {
 			return changedResources.toArray(new IResource[changedResources.size()]);
 		}
 		public void flush(IProgressMonitor monitor) throws TeamException {
 			try {
 				operation.flush(this, monitor);
 			} catch (OutOfMemoryError e) {
 				throw e;
 			} catch (Error e) {
 				handleAbortedFlush(e);
 				throw e;
 			} catch (RuntimeException e) {
 				handleAbortedFlush(e);
 				throw e;
 			} finally {
 				// We have to clear the resources no matter what since the next attempt
 				// to flush may not have an appropriate scheduling rule
 				changedResources.clear();
 			}
 		}
 		private boolean isFlushRequired() {
 			return rules.size() == 1 || remainingRulesAreNull();
 		}
 		/*
 		 * Return true if all but the last rule in the stack is null
 		 */
 		private boolean remainingRulesAreNull() {
 			for (int i = 0; i < rules.size() - 1; i++) {
 				ISchedulingRule rule = rules.get(i);
 				if (rule != NULL_SCHEDULING_RULE) {
 					return false;
 				}
 			}
 			return true;
 		}
 		private void handleAbortedFlush(Throwable t) {
 			TeamPlugin.log(IStatus.ERROR, Messages.BatchingLock_11, t);
 		}
 		private void addRule(ISchedulingRule rule) {
 			rules.add(rule);
 		}
 		private ISchedulingRule removeRule() {
 			return rules.remove(rules.size() - 1);
 		}
 		public boolean ruleContains(IResource resource) {
 			for (Iterator iter = rules.iterator(); iter.hasNext();) {
 				ISchedulingRule rule = (ISchedulingRule) iter.next();
 				if (rule != NULL_SCHEDULING_RULE && rule.contains(resource)) {
 					return true;
 				}
 			}
 			return false;
 		}
 	}

 	public interface IFlushOperation {
 		public void flush(ThreadInfo info, IProgressMonitor monitor) throws TeamException;
 	}

 	private Map<Thread, ThreadInfo> infos = new HashMap<>();

 	/**
 	 * Return the thread info for the current thread
 	 * @return the thread info for the current thread
 	 */
 	protected ThreadInfo getThreadInfo() {
 		Thread thisThread = Thread.currentThread();
 		synchronized (infos) {
 			ThreadInfo info = infos.get(thisThread);
 			return info;
 		}
 	}

 	private ThreadInfo getThreadInfo(IResource resource) {
 		synchronized (infos) {
 			for (Iterator iter = infos.values().iterator(); iter.hasNext();) {
 				ThreadInfo info = (ThreadInfo) iter.next();
 				if (info.ruleContains(resource)) {
 					return info;
 				}
 			}
 			return null;
 		}
 	}

 	public ISchedulingRule acquire(ISchedulingRule resourceRule, IFlushOperation operation, IProgressMonitor monitor) {
 		ThreadInfo info = getThreadInfo();
 		boolean added = false;
 		synchronized (infos) {
 			if (info == null) {
 				info = createThreadInfo(operation);
 				Thread thisThread = Thread.currentThread();
 				infos.put(thisThread, info);
 				added = true;
 				if(Policy.DEBUG_THREADING) System.out.println("[" + thisThread.getName() + "] acquired batching lock on " + resourceRule); //$NON-NLS-1$ //$NON-NLS-2$
 			}
 		}
 		try {
 			return info.pushRule(resourceRule, monitor);
 		} catch (OperationCanceledException e) {
 			// The operation was canceled.
 			// If this is the outermost acquire then remove the info that was just added
 			if (added) {
 				synchronized (infos) {
 					infos.remove(Thread.currentThread());
 				}
 			}
 			throw e;
 		}
 	}

 	/**
 	 * Create the ThreadInfo instance used to cache the lock state for the
 	 * current thread. Subclass can override to provide a subclass of
 	 * ThreadInfo.
 	 * @param operation the flush operation
 	 * @return a ThreadInfo instance
 	 */
 	protected ThreadInfo createThreadInfo(IFlushOperation operation) {
 		return new ThreadInfo(operation);
 	}

 	/**
 	 * Release the lock held on any resources by this thread. The provided rule must
 	 * be identical to the rule returned by the corresponding acquire(). If the rule
 	 * for the release is non-null and all remaining rules held by the lock are null,
 	 * the the flush operation provided in the acquire method will be executed.
 	 * @param rule the scheduling rule
 	 * @param monitor a progress monitor
 	 * @throws TeamException
 	 */
 	public void release(ISchedulingRule rule, IProgressMonitor monitor) throws TeamException {
 		ThreadInfo info = getThreadInfo();
 		Assert.isNotNull(info, "Unmatched acquire/release."); //$NON-NLS-1$
 		Assert.isTrue(info.isNested(), "Unmatched acquire/release."); //$NON-NLS-1$
 		info.popRule(rule, monitor);
 		synchronized (infos) {
 			if (!info.isNested()) {
 				Thread thisThread = Thread.currentThread();
 				if(Policy.DEBUG_THREADING) System.out.println("[" + thisThread.getName() + "] released batching lock"); //$NON-NLS-1$ //$NON-NLS-2$
 				infos.remove(thisThread);
 			}
 		}
 	}

 	public void resourceChanged(IResource resource) {
 		ThreadInfo info = getThreadInfo();
 		Assert.isNotNull(info, "Folder changed outside of resource lock"); //$NON-NLS-1$
 		info.addChangedResource(resource);
 	}

 	/**
 	 * Flush any changes accumulated by the lock so far.
 	 * @param monitor a progress monitor
 	 * @throws TeamException
 	 */
 	public void flush(IProgressMonitor monitor) throws TeamException {
 		ThreadInfo info = getThreadInfo();
 		Assert.isNotNull(info, "Flush requested outside of resource lock"); //$NON-NLS-1$
 		info.flush(monitor);
 	}

 	public boolean isWithinActiveOperationScope(IResource resource) {
 		synchronized (infos) {
 			return getThreadInfo(resource) != null;
 		}
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2017 IBM Corporation and others.
	*
	* This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License 2.0
	* which accompanies this distribution, and is available at
	* https://www.eclipse.org/legal/epl-2.0/
	*
	* SPDX-License-Identifier: EPL-2.0
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.team.internal.core.subscribers;

	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	import org.eclipse.core.resources.IResource;
	import org.eclipse.core.runtime.Assert;
	import org.eclipse.core.runtime.IProgressMonitor;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.OperationCanceledException;
	import org.eclipse.core.runtime.jobs.ISchedulingRule;
	import org.eclipse.core.runtime.jobs.Job;
	import org.eclipse.core.runtime.jobs.MultiRule;
	import org.eclipse.team.core.TeamException;
	import org.eclipse.team.internal.core.Messages;
	import org.eclipse.team.internal.core.Policy;
	import org.eclipse.team.internal.core.TeamPlugin;

	/**
	* Provides a per-thread nested locking mechanism. A thread can acquire a
	* lock on a specific resource by calling acquire(). Subsequently, acquire() can be called
	* multiple times on the resource or any of its children from within the same thread
	* without blocking. Other threads that try
	* and acquire the lock on those same resources will be blocked until the first
	* thread releases all it's nested locks.
	* <p>
	* The locking is managed by the platform via scheduling rules. This class simply
	* provides the nesting mechanism in order to allow the client to determine when
	* the lock for the thread has been released. Therefore, this lock will block if
	* another thread already locks the same resource.</p>
	*/
	public class BatchingLock {
	// This is a placeholder rule used to indicate that no scheduling rule is needed
	/* internal use only */ static final ISchedulingRule NULL_SCHEDULING_RULE= new ISchedulingRule() {
	@Override
	public boolean contains(ISchedulingRule rule) {
	return false;
	}
	@Override
	public boolean isConflicting(ISchedulingRule rule) {
	return false;
	}
	};

	public class ThreadInfo {
	private Set<IResource> changedResources = new HashSet<>();
	private IFlushOperation operation;
	private List<ISchedulingRule> rules = new ArrayList<>();
	public ThreadInfo(IFlushOperation operation) {
	this.operation = operation;
	}
	/**
	* Push a scheduling rule onto the stack for this thread and
	* acquire the rule if it is not the workspace root.
	* @param resource
	* @param monitor
	* @return the scheduling rule that was obtained
	*/
	public ISchedulingRule pushRule(ISchedulingRule resource, IProgressMonitor monitor) {
	// The scheduling rule is either the project or the resource's parent
	final ISchedulingRule rule = getRuleForResoure(resource);
	if (rule != NULL_SCHEDULING_RULE) {
	boolean success = false;
	try {
	Job.getJobManager().beginRule(rule, monitor);
	addRule(rule);
	success = true;
	} finally {
	if (!success) {
	try {
	// The begin was canceled (or some other problem occurred).
	// Free the scheduling rule
	// so the clients of ReentrantLock don't need to
	// do an endRule when the operation is canceled.
	Job.getJobManager().endRule(rule);
	} catch (RuntimeException e) {
	// Log and ignore so the original exception is not lost
	TeamPlugin.log(IStatus.ERROR, "Failed to end scheduling rule", e); //$NON-NLS-1$
	}
	}
	}
	} else {
	// Record the fact that we didn't push a rule so we
	// can match it when we pop
	addRule(rule);
	}
	return rule;
	}
	/**
	* Pop the scheduling rule from the stack and release it if it
	* is not the workspace root. Flush any changed sync info to
	* disk if necessary. A flush is necessary if the stack is empty
	* or if the top-most non-null scheduling rule was popped as a result
	* of this operation.
	* @param rule
	* @param monitor
	* @throws TeamException
	*/
	public void popRule(ISchedulingRule rule, IProgressMonitor monitor) throws TeamException {
	try {
	if (isFlushRequired()) {
	flush(monitor);
	}
	} finally {
	ISchedulingRule stackedRule = removeRule();
	if (rule == null) {
	rule = NULL_SCHEDULING_RULE;
	}
	Assert.isTrue(stackedRule.equals(rule), "end for resource '" + rule + "' does not match stacked rule '" + stackedRule + "'"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	if (rule != NULL_SCHEDULING_RULE) {
	Job.getJobManager().endRule(rule);
	}
	}
	}
	private ISchedulingRule getRuleForResoure(ISchedulingRule resourceRule) {
	ISchedulingRule rule;
	if (resourceRule instanceof IResource) {
	IResource resource = (IResource)resourceRule;
	if (resource.getType() == IResource.ROOT) {
	// Never lock the whole workspace
	rule = NULL_SCHEDULING_RULE;
	} else if (resource.getType() == IResource.PROJECT) {
	rule = resource;
	} else {
	rule = resource.getParent();
	}
	} else if (resourceRule instanceof MultiRule) {
	// Create a MultiRule for all projects from the given rule
	ISchedulingRule[] rules = ((MultiRule)resourceRule).getChildren();
	Set<ISchedulingRule> projects = new HashSet<>();
	for (int i = 0; i < rules.length; i++) {
	ISchedulingRule childRule = rules[i];
	if (childRule instanceof IResource) {
	projects.add(((IResource)childRule).getProject());
	}
	}
	if (projects.isEmpty()) {
	rule = NULL_SCHEDULING_RULE;
	} else if (projects.size() == 1) {
	rule = projects.iterator().next();
	} else {
	rule = new MultiRule(projects.toArray(new ISchedulingRule[projects.size()]));
	}
	} else {
	// Rule is not associated with resources so ignore it
	rule = NULL_SCHEDULING_RULE;
	}
	return rule;
	}
	/**
	* Return <code>true</code> if we are still nested in
	* an acquire for this thread.
	*
	* @return whether there are still rules on the stack
	*/
	public boolean isNested() {
	return !rules.isEmpty();
	}
	public void addChangedResource(IResource resource) {
	changedResources.add(resource);
	}
	public boolean isEmpty() {
	return changedResources.isEmpty();
	}
	public IResource[] getChangedResources() {
	return changedResources.toArray(new IResource[changedResources.size()]);
	}
	public void flush(IProgressMonitor monitor) throws TeamException {
	try {
	operation.flush(this, monitor);
	} catch (OutOfMemoryError e) {
	throw e;
	} catch (Error e) {
	handleAbortedFlush(e);
	throw e;
	} catch (RuntimeException e) {
	handleAbortedFlush(e);
	throw e;
	} finally {
	// We have to clear the resources no matter what since the next attempt
	// to flush may not have an appropriate scheduling rule
	changedResources.clear();
	}
	}
	private boolean isFlushRequired() {
	return rules.size() == 1 \|\| remainingRulesAreNull();
	}
	/*
	* Return true if all but the last rule in the stack is null
	*/
	private boolean remainingRulesAreNull() {
	for (int i = 0; i < rules.size() - 1; i++) {
	ISchedulingRule rule = rules.get(i);
	if (rule != NULL_SCHEDULING_RULE) {
	return false;
	}
	}
	return true;
	}
	private void handleAbortedFlush(Throwable t) {
	TeamPlugin.log(IStatus.ERROR, Messages.BatchingLock_11, t);
	}
	private void addRule(ISchedulingRule rule) {
	rules.add(rule);
	}
	private ISchedulingRule removeRule() {
	return rules.remove(rules.size() - 1);
	}
	public boolean ruleContains(IResource resource) {
	for (Iterator iter = rules.iterator(); iter.hasNext();) {
	ISchedulingRule rule = (ISchedulingRule) iter.next();
	if (rule != NULL_SCHEDULING_RULE && rule.contains(resource)) {
	return true;
	}
	}
	return false;
	}
	}

	public interface IFlushOperation {
	public void flush(ThreadInfo info, IProgressMonitor monitor) throws TeamException;
	}

	private Map<Thread, ThreadInfo> infos = new HashMap<>();

	/**
	* Return the thread info for the current thread
	* @return the thread info for the current thread
	*/
	protected ThreadInfo getThreadInfo() {
	Thread thisThread = Thread.currentThread();
	synchronized (infos) {
	ThreadInfo info = infos.get(thisThread);
	return info;
	}
	}

	private ThreadInfo getThreadInfo(IResource resource) {
	synchronized (infos) {
	for (Iterator iter = infos.values().iterator(); iter.hasNext();) {
	ThreadInfo info = (ThreadInfo) iter.next();
	if (info.ruleContains(resource)) {
	return info;
	}
	}
	return null;
	}
	}

	public ISchedulingRule acquire(ISchedulingRule resourceRule, IFlushOperation operation, IProgressMonitor monitor) {
	ThreadInfo info = getThreadInfo();
	boolean added = false;
	synchronized (infos) {
	if (info == null) {
	info = createThreadInfo(operation);
	Thread thisThread = Thread.currentThread();
	infos.put(thisThread, info);
	added = true;
	if(Policy.DEBUG_THREADING) System.out.println("[" + thisThread.getName() + "] acquired batching lock on " + resourceRule); //$NON-NLS-1$ //$NON-NLS-2$
	}
	}
	try {
	return info.pushRule(resourceRule, monitor);
	} catch (OperationCanceledException e) {
	// The operation was canceled.
	// If this is the outermost acquire then remove the info that was just added
	if (added) {
	synchronized (infos) {
	infos.remove(Thread.currentThread());
	}
	}
	throw e;
	}
	}

	/**
	* Create the ThreadInfo instance used to cache the lock state for the
	* current thread. Subclass can override to provide a subclass of
	* ThreadInfo.
	* @param operation the flush operation
	* @return a ThreadInfo instance
	*/
	protected ThreadInfo createThreadInfo(IFlushOperation operation) {
	return new ThreadInfo(operation);
	}

	/**
	* Release the lock held on any resources by this thread. The provided rule must
	* be identical to the rule returned by the corresponding acquire(). If the rule
	* for the release is non-null and all remaining rules held by the lock are null,
	* the the flush operation provided in the acquire method will be executed.
	* @param rule the scheduling rule
	* @param monitor a progress monitor
	* @throws TeamException
	*/
	public void release(ISchedulingRule rule, IProgressMonitor monitor) throws TeamException {
	ThreadInfo info = getThreadInfo();
	Assert.isNotNull(info, "Unmatched acquire/release."); //$NON-NLS-1$
	Assert.isTrue(info.isNested(), "Unmatched acquire/release."); //$NON-NLS-1$
	info.popRule(rule, monitor);
	synchronized (infos) {
	if (!info.isNested()) {
	Thread thisThread = Thread.currentThread();
	if(Policy.DEBUG_THREADING) System.out.println("[" + thisThread.getName() + "] released batching lock"); //$NON-NLS-1$ //$NON-NLS-2$
	infos.remove(thisThread);
	}
	}
	}

	public void resourceChanged(IResource resource) {
	ThreadInfo info = getThreadInfo();
	Assert.isNotNull(info, "Folder changed outside of resource lock"); //$NON-NLS-1$
	info.addChangedResource(resource);
	}

	/**
	* Flush any changes accumulated by the lock so far.
	* @param monitor a progress monitor
	* @throws TeamException
	*/
	public void flush(IProgressMonitor monitor) throws TeamException {
	ThreadInfo info = getThreadInfo();
	Assert.isNotNull(info, "Flush requested outside of resource lock"); //$NON-NLS-1$
	info.flush(monitor);
	}

	public boolean isWithinActiveOperationScope(IResource resource) {
	synchronized (infos) {
	return getThreadInfo(resource) != null;
	}
	}
	}