com.vmware.operations.OperationAsyncBase Maven / Gradle / Ivy
/*
* Copyright (c) 2015-2018 VMware, Inc. All Rights Reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* 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 com.vmware.operations;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Abstract base class for implementing operations that are naturally asynchronous,
* based on futures.
*
* This base class implements the synchronous versions of execute, revert, and cleanup
* in a standard way. In particular, it attempts to unwrap any thrown ExecutionExceptions
* for readability.
*/
public abstract class OperationAsyncBase extends OperationBase {
private static final Logger logger = LoggerFactory.getLogger(OperationAsyncBase.class.getPackage().getName());
private final ExecutorService executorService;
/**
* Constructor.
*/
protected OperationAsyncBase() {
super();
this.executorService = Operations.getExecutorService();
}
/**
* Constructor.
* @param executorService the executor service to use when performing asynchronous
* calls for this operation.
*/
protected OperationAsyncBase(ExecutorService executorService) {
super();
this.executorService = executorService;
}
/**
* @see com.vmware.operations.Operation#execute()
*/
@Override
public final void execute() throws Throwable {
try {
logger.debug("Executing {} [async]", toString());
executeAsync().get();
} catch (ExecutionException ex) {
// Unwrap the exception if possible
Throwable cause = ex.getCause();
if (cause != null) {
throw cause;
} else {
throw ex;
}
}
}
@Override
public final CompletableFuture executeAsync() {
// Compose the validators onto the execution result
return executeImpl()
.thenComposeAsync((unused) -> validateExecution(executorService), executorService);
}
/**
* @see com.vmware.operations.Operation#revert()
*/
@Override
public final void revert() throws Throwable {
try {
logger.debug("Reverting {} [async]", toString());
revertAsync().get();
} catch (ExecutionException ex) {
// Unwrap the exception if possible
Throwable cause = ex.getCause();
if (cause != null) {
throw cause;
} else {
throw ex;
}
}
}
@Override
public final CompletableFuture revertAsync() {
// If revert fails, then call cleanup
return revertImpl()
.thenCompose(unused -> validateRevert(executorService));
}
/**
* @see com.vmware.operations.Operation#cleanup()
*/
@Override
public final void cleanup() {
try {
cleanupAsync().get();
} catch (Exception ex) {
// This should never happen
}
}
/**
* @see com.vmware.operations.Operation#cleanupAsync()
*/
@Override
public CompletableFuture cleanupAsync() {
CompletableFuture start = isExecuted() ? revertAsync() : CompletableFuture.completedFuture(null);
return start.exceptionally(throwable -> validateCleanup(executorService).join())
.exceptionally(throwable -> {
// Catch all failures, and suppress them during cleanup
logger.info("Cleanup validator error {}", throwable.getMessage());
return null;
});
}
/**
* @see com.vmware.operations.Operation#close()
*/
@Override
public void close() {
try {
cleanup();
} catch (Throwable th) {
// Catch all failures, and suppress them during cleanup
}
}
/**
* Asynchronous implementation of the operation.
* @return A future that completes when the command is complete
*/
public abstract CompletableFuture executeImpl();
/**
* Asynchronous revert implementation of the operation.
* @return A future that completes when the command is reverted
*/
public abstract CompletableFuture revertImpl();
@Override
public abstract String toString();
}