gradle-master/subprojects/base-services/src/main/java/org/gradle/internal/operations/BuildOperationExecutor.java
/*
 * Copyright 2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.gradle.internal.operations;

import org.gradle.api.Action;
import org.gradle.internal.Factory;
import org.gradle.internal.service.scopes.Scopes;
import org.gradle.internal.service.scopes.ServiceScope;

import javax.annotation.concurrent.ThreadSafe;

/**
 * Executes build operations synchronously, asynchronously or via a {@link BuildOperationQueue}.
 *
 * The executor provides several capabilities:
 *
 * <ul>
 *     <li>Fires events via {@link BuildOperationListener}. For example, this means that notification of build operation
 *     execution can be received by tooling API clients.</li>
 *     <li>Generates progress logging events.</li>
 * </ul>
 */
@ThreadSafe
@ServiceScope(Scopes.BuildSession.class)
public interface BuildOperationExecutor extends BuildOperationRunner {
    /**
     * Runs the given build operation synchronously. Invokes the given operation from the current thread.
     *
     * <p>Rethrows any exception thrown by the action.
     * Runtime exceptions are rethrown as is.
     * Checked exceptions are wrapped in {@link BuildOperationInvocationException}.</p>
     */
    void run(RunnableBuildOperation buildOperation);

    /**
     * Calls the given build operation synchronously. Invokes the given operation from the current thread.
     * Returns the result.
     *
     * <p>Rethrows any exception thrown by the action.
     * Runtime exceptions are rethrown as is.
     * Checked exceptions are wrapped in {@link BuildOperationInvocationException}.</p>
     */
    <T> T call(CallableBuildOperation<T> buildOperation);

    /**
     * Starts an operation that can be finished later.
     *
     * When a parent operation is finished any unfinished child operations will be failed.
     */
    BuildOperationContext start(BuildOperationDescriptor.Builder descriptor);

    /**
     * Returns the state of the build operation currently running on this thread. Can be used as parent of a new build operation
     * started in a different thread (or process). See {@link BuildOperationDescriptor.Builder#parent(BuildOperationRef)}
     *
     * @throws IllegalStateException When the current thread is not executing an operation.
     */
    BuildOperationRef getCurrentOperation();

    /**
     * Submits an arbitrary number of runnable operations, created synchronously by the scheduling action, to be executed in the global
     * build operation thread pool. Operations may execute concurrently. Blocks until all operations are complete.
     *
     * <p>Actions are not permitted to access any mutable project state. Generally, this is preferred.</p>
     */
    <O extends RunnableBuildOperation> void runAll(Action<BuildOperationQueue<O>> schedulingAction);

    /**
     * Overload allowing {@link BuildOperationConstraint} to be specified.
     *
     * @see BuildOperationExecutor#runAllWithAccessToProjectState(Action)
     */
    <O extends RunnableBuildOperation> void runAll(Action<BuildOperationQueue<O>> schedulingAction, BuildOperationConstraint buildOperationConstraint);

    /**
     * Same as {@link #runAll(Action)}. However, the actions are allowed to access mutable project state. In general, this is more likely to
     * result in deadlocks and other flaky behaviours.
     *
     * <p>See {@link org.gradle.internal.resources.ProjectLeaseRegistry#whileDisallowingProjectLockChanges(Factory)} for more details.
     */
    <O extends RunnableBuildOperation> void runAllWithAccessToProjectState(Action<BuildOperationQueue<O>> schedulingAction);

    /**
     * Overload allowing {@link BuildOperationConstraint} to be specified.
     *
     * @see BuildOperationExecutor#runAllWithAccessToProjectState(Action)
     */
    <O extends RunnableBuildOperation> void runAllWithAccessToProjectState(Action<BuildOperationQueue<O>> schedulingAction, BuildOperationConstraint buildOperationConstraint);

    /**
     * Submits an arbitrary number of operations, created synchronously by the scheduling action, to be executed by the supplied
     * worker in the global build operation thread pool. Operations may execute concurrently, so the worker should be thread-safe.
     * Blocks until all operations are complete.
     *
     * <p>Actions are not permitted to access any mutable project state. Generally, this is preferred.</p>
     */
    <O extends BuildOperation> void runAll(BuildOperationWorker<O> worker, Action<BuildOperationQueue<O>> schedulingAction);

    /**
     * Overload allowing {@link BuildOperationConstraint} to be specified.
     *
     * @see BuildOperationExecutor#runAll(BuildOperationWorker, Action)
     */
    <O extends BuildOperation> void runAll(BuildOperationWorker<O> worker, Action<BuildOperationQueue<O>> schedulingAction, BuildOperationConstraint buildOperationConstraint);
}
