org.apache.hadoop.io.retry.CallReturn Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.hadoop.io.retry;
import org.apache.hadoop.thirdparty.com.google.common.base.Preconditions;
/** The call return from a method invocation. */
class CallReturn {
/** The return state. */
enum State {
/** Call is returned successfully. */
RETURNED,
/** Call throws an exception. */
EXCEPTION,
/** Call should be retried according to the {@link RetryPolicy}. */
RETRY,
/** Call should wait and then retry according to the {@link RetryPolicy}. */
WAIT_RETRY,
/** Call, which is async, is still in progress. */
ASYNC_CALL_IN_PROGRESS,
/** Call, which is async, just has been invoked. */
ASYNC_INVOKED
}
static final CallReturn ASYNC_CALL_IN_PROGRESS = new CallReturn(
State.ASYNC_CALL_IN_PROGRESS);
static final CallReturn ASYNC_INVOKED = new CallReturn(State.ASYNC_INVOKED);
static final CallReturn RETRY = new CallReturn(State.RETRY);
static final CallReturn WAIT_RETRY = new CallReturn(State.WAIT_RETRY);
private final Object returnValue;
private final Throwable thrown;
private final State state;
CallReturn(Object r) {
this(r, null, State.RETURNED);
}
CallReturn(Throwable t) {
this(null, t, State.EXCEPTION);
Preconditions.checkNotNull(t);
}
private CallReturn(State s) {
this(null, null, s);
}
private CallReturn(Object r, Throwable t, State s) {
Preconditions.checkArgument(r == null || t == null);
returnValue = r;
thrown = t;
state = s;
}
State getState() {
return state;
}
Object getReturnValue() throws Throwable {
if (state == State.EXCEPTION) {
throw thrown;
}
Preconditions.checkState(state == State.RETURNED, "state == %s", state);
return returnValue;
}
}