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/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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 android.os;
import android.annotation.NonNull;
import android.annotation.Nullable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Extends ResultReceiver to allow the server end of the ResultReceiver to synchronously wait
* on the response from the client. This enables an RPC like system but with the ability to
* timeout and discard late results.
*
* NOTE: Can only be used for one response. Subsequent responses on the same instance are ignored.
* {@hide}
*/
public class SynchronousResultReceiver extends ResultReceiver {
public static class Result {
public int resultCode;
@Nullable public Bundle bundle;
public Result(int resultCode, @Nullable Bundle bundle) {
this.resultCode = resultCode;
this.bundle = bundle;
}
}
private final CompletableFuture<Result> mFuture = new CompletableFuture<>();
private final String mName;
public SynchronousResultReceiver() {
super((Handler) null);
mName = null;
}
/**
* @param name Name for logging purposes
*/
public SynchronousResultReceiver(String name) {
super((Handler) null);
mName = name;
}
@Override
final protected void onReceiveResult(int resultCode, Bundle resultData) {
super.onReceiveResult(resultCode, resultData);
mFuture.complete(new Result(resultCode, resultData));
}
public String getName() {
return mName;
}
/**
* Blocks waiting for the result from the remote client.
*
* @return the Result
* @throws TimeoutException if the timeout in milliseconds expired.
*/
public @NonNull Result awaitResult(long timeoutMillis) throws TimeoutException {
final long deadline = System.currentTimeMillis() + timeoutMillis;
while (timeoutMillis >= 0) {
try {
return mFuture.get(timeoutMillis, TimeUnit.MILLISECONDS);
} catch (ExecutionException e) {
// This will NEVER happen.
throw new AssertionError("Error receiving response", e);
} catch (InterruptedException e) {
// The thread was interrupted, try and get the value again, this time
// with the remaining time until the deadline.
timeoutMillis -= deadline - System.currentTimeMillis();
}
}
throw new TimeoutException();
}
}
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