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/*******************************************************************************
* Copyright (c) 2003, 2012 IBM Corporation 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
*
* Contributors:
* IBM - Initial API and implementation
*******************************************************************************/
package org.eclipse.core.runtime.jobs;
/**
* Scheduling rules are used by jobs to indicate when they need exclusive access
* to a resource. Scheduling rules can also be applied synchronously to a thread
* using <tt>IJobManager.beginRule(ISchedulingRule)</tt> and
* <tt>IJobManager.endRule(ISchedulingRule)</tt>. The job manager guarantees that
* no two jobs with conflicting scheduling rules will run concurrently.
* Multiple rules can be applied to a given thread only if the outer rule explicitly
* allows the nesting as specified by the <code>contains</code> method.
* <p>
* Clients may implement this interface.
*
* @see Job#getRule()
* @see Job#setRule(ISchedulingRule)
* @see Job#schedule(long)
* @see IJobManager#beginRule(ISchedulingRule, org.eclipse.core.runtime.IProgressMonitor)
* @see IJobManager#endRule(ISchedulingRule)
* @since 3.0
*/
public interface ISchedulingRule {
/**
* Returns whether this scheduling rule completely contains another scheduling
* rule. Rules can only be nested within a thread if the inner rule is completely
* contained within the outer rule.
* <p>
* Implementations of this method must obey the rules of a partial order relation
* on the set of all scheduling rules. In particular, implementations must be reflexive
* (a.contains(a) is always true), antisymmetric (a.contains(b) and b.contains(a) iff a.equals(b),
* and transitive (if a.contains(b) and b.contains(c), then a.contains(c)). Implementations
* of this method must return <code>false</code> when compared to a rule they
* know nothing about.
*
* @param rule the rule to check for containment
* @return <code>true</code> if this rule contains the given rule, and
* <code>false</code> otherwise.
*/
boolean contains(ISchedulingRule rule);
/**
* Returns whether this scheduling rule is compatible with another scheduling rule.
* If <code>true</code> is returned, then no job with this rule will be run at the
* same time as a job with the conflicting rule. If <code>false</code> is returned,
* then the job manager is free to run jobs with these rules at the same time.
* <p>
* Implementations of this method must be reflexive, symmetric, and consistent,
* and must return <code>false</code> when compared to a rule they know
* nothing about.
* <p>
* This method must return true if calling {@link #contains(ISchedulingRule)} on
* the same rule also returns true. This is required because it would otherwise
* allow two threads to be running concurrently with the same rule.
*
* @param rule the rule to check for conflicts
* @return <code>true</code> if the rule is conflicting, and <code>false</code>
* otherwise.
*/
boolean isConflicting(ISchedulingRule rule);
}
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