src/com/android/phone/vvm/omtp/sync/VvmNetworkRequest.java

/*
 * 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 com.android.phone.vvm.omtp.sync;

import android.net.Network;
import android.support.annotation.NonNull;
import android.telecom.PhoneAccountHandle;
import com.android.phone.VoicemailStatus;
import com.android.phone.vvm.omtp.OmtpVvmCarrierConfigHelper;
import com.android.phone.vvm.omtp.VvmLog;
import java.io.Closeable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

/**
 * Class to retrieve a {@link Network} synchronously. {@link #getNetwork(OmtpVvmCarrierConfigHelper,
 * PhoneAccountHandle)} will block until a suitable network is retrieved or it has failed.
 */
public class VvmNetworkRequest {

    private static final String TAG = "VvmNetworkRequest";

    /**
     * A wrapper around a Network returned by a {@link VvmNetworkRequestCallback}, which should be
     * closed once not needed anymore.
     */
    public static class NetworkWrapper implements Closeable {

        private final Network mNetwork;
        private final VvmNetworkRequestCallback mCallback;

        private NetworkWrapper(Network network, VvmNetworkRequestCallback callback) {
            mNetwork = network;
            mCallback = callback;
        }

        public Network get() {
            return mNetwork;
        }

        @Override
        public void close() {
            mCallback.releaseNetwork();
        }
    }

    public static class RequestFailedException extends Exception {

        private RequestFailedException(Throwable cause) {
            super(cause);
        }
    }

    @NonNull
    public static NetworkWrapper getNetwork(OmtpVvmCarrierConfigHelper config,
        PhoneAccountHandle handle, VoicemailStatus.Editor status) throws RequestFailedException {
        FutureNetworkRequestCallback callback = new FutureNetworkRequestCallback(config, handle,
            status);
        callback.requestNetwork();
        try {
            return callback.getFuture().get();
        } catch (InterruptedException | ExecutionException e) {
            callback.releaseNetwork();
            VvmLog.e(TAG, "can't get future network", e);
            throw new RequestFailedException(e);
        }
    }

    private static class FutureNetworkRequestCallback extends VvmNetworkRequestCallback {

        /**
         * {@link CompletableFuture#get()} will block until {@link CompletableFuture#
         * complete(Object) } has been called on the other thread.
         */
        private final CompletableFuture<NetworkWrapper> mFuture = new CompletableFuture<>();

        public FutureNetworkRequestCallback(OmtpVvmCarrierConfigHelper config,
            PhoneAccountHandle phoneAccount, VoicemailStatus.Editor status) {
            super(config, phoneAccount, status);
        }

        public Future<NetworkWrapper> getFuture() {
            return mFuture;
        }

        @Override
        public void onAvailable(Network network) {
            super.onAvailable(network);
            mFuture.complete(new NetworkWrapper(network, this));
        }

        @Override
        public void onFailed(String reason) {
            super.onFailed(reason);
            mFuture.complete(null);
        }

    }
}