org.eclipse.xtext.util.concurrent.IReadAccess Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2008 itemis AG (http://www.itemis.eu) and others.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* SPDX-License-Identifier: EPL-2.0
*
*******************************************************************************/
package org.eclipse.xtext.util.concurrent;
import java.util.function.Function;
import java.util.function.Supplier;
/**
* @author Sven Efftinge - Initial contribution and API
* @author Jan Koehnlein - Separated read and write access
*/
public interface IReadAccess {
/**
* Gets a read-only copy of the State and executes {@code work} on it.
*
* WARNING: the State passed to {@code work} can be null.
* e.g. when reading from a read-only zip/jar entry
*
* @param work Work to execute on the State
*
* @return The result of executing {@code work}
* @since 2.7
*/
Result readOnly(IUnitOfWork work);
/**
* Tries to get a read-only copy of the State and execute {@code work} on it.
*
* @param work Work to execute on the State
* @param defaultResult Supplies a result in case the State is null
*
* @return The result of executing {@code work}, or
* the result of querying {@code defaultResult} if the State is null
* @since 2.14
*/
default Result tryReadOnly(
IUnitOfWork work,
Supplier defaultResult
) {
// Some implementations rely on the type of {@code work}
if (work instanceof CancelableUnitOfWork) {
return readOnly(new WrappingCancelableUnitOfWork<>(defaultResult, work));
}
return readOnly((state) -> {
if (state == null) {
return defaultResult.get();
}
return work.exec(state);
});
}
/**
* Tries to get a read-only copy of the State and execute {@code work} on it.
*
* @param work Work to execute on the State
*
* @return The result of executing {@code work}, or
* null if the State is null
* @since 2.15
*/
default Result tryReadOnly(IUnitOfWork work) {
return tryReadOnly(work, () -> null);
}
/**
* Tries to get a read-only copy of the State and execute {@code work} on it.
*
* @param work Work to execute on the State
* @param defaultResult Supplies a result in case the State is null
* @param exceptionHandler Supplies a result in case an exception is raised during execution
*
* @return The result of executing {@code work},
* the result of querying {@code defaultResult} if the State is null, or
* the result of executing {@code exceptionHandler} in case an exception is raised
* @since 2.14
*/
default Result tryReadOnly(
IUnitOfWork work,
Supplier defaultResult,
Function exceptionHandler
) {
try {
return tryReadOnly(work, defaultResult);
} catch (Exception e) {
return exceptionHandler.apply(e);
}
}
/**
* @since 2.7
*/
interface Priority {
/**
* Gets a read-only copy of the State and executes {@code work} on it.
* Cancels all cancelable readers before executing the {@link IUnitOfWork}.
* For interactive jobs that need fastest possible execution.
*
* WARNING: the State passed to {@code work} can be null.
*
* @since 2.7
* @see CancelableUnitOfWork
*/
Result priorityReadOnly(IUnitOfWork work);
/**
* Tries to get a read-only copy of the State and execute {@code work} on it.
* Cancels all cancelable readers before executing the {@link IUnitOfWork}.
* For interactive jobs that need fastest possible execution.
*
* @param work Work to execute on the State
* @param defaultResult Supplies a result in case the State is null
*
* @return The result of executing {@code work}, or
* the result of querying {@code defaultResult} if the State is null
* @since 2.14
* @see CancelableUnitOfWork
*/
default Result tryPriorityReadOnly(
IUnitOfWork work,
Supplier defaultResult
) {
// Some implementations rely on the type of {@code work}
if (work instanceof CancelableUnitOfWork) {
return priorityReadOnly(new WrappingCancelableUnitOfWork<>(defaultResult, work));
}
return priorityReadOnly((state) -> {
if (state == null) {
return defaultResult.get();
}
return work.exec(state);
});
}
/**
* Tries to get a read-only copy of the State and execute {@code work} on it.
* Cancels all cancelable readers before executing the {@link IUnitOfWork}.
* For interactive jobs that need fastest possible execution.
*
* @param work Work to execute on the State
*
* @return The result of executing {@code work}, or
* null if the State is null
* @since 2.15
* @see CancelableUnitOfWork
*/
default Result tryPriorityReadOnly(IUnitOfWork work) {
return tryPriorityReadOnly(work, () -> null);
}
/**
* Tries to get a read-only copy of the State and execute {@code work} on it.
* Cancels all cancelable readers before executing the {@link IUnitOfWork}.
* For interactive jobs that need fastest possible execution.
*
* @param work Work to execute on the State
* @param defaultResult Supplies a result in case the State is null
* @param exceptionHandler Supplies a result in case an exception is raised during execution
*
* @return The result of executing {@code work},
* the result of querying {@code defaultResult} if the State is null, or
* the result of executing {@code exceptionHandler} in case an exception is raised
* @since 2.14
* @see CancelableUnitOfWork
*/
default Result tryPriorityReadOnly(
IUnitOfWork work,
Supplier defaultResult,
Function exceptionHandler
) {
try {
return tryPriorityReadOnly(work, defaultResult);
} catch (Exception e) {
return exceptionHandler.apply(e);
}
}
}
}