com.google.cloud.bigtable.grpc.ResultQueueEntry.java Source code

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Here is the source code for com.google.cloud.bigtable.grpc.ResultQueueEntry.java

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/*
 * Copyright 2014 Google Inc. All Rights Reserved.
 *
 * 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.google.cloud.bigtable.grpc;

import com.google.common.base.Preconditions;

import io.grpc.Status.OperationRuntimeException;

import java.io.IOException;

/**
 * An entry in the result queue which may be one of: A data message,
 * a Throwable or a marker indicating end-of-stream.
 * @param <T> The type of messages representing data.
 */
class ResultQueueEntry<T> {

    private static final String EXCEPTION_MESSAGE = "Error in response stream";
    protected final Throwable throwable;
    protected final T response;
    protected final boolean isComplete;

    public static <T> ResultQueueEntry<T> newResult(T response) {
        Preconditions.checkArgument(response != null, "Response may not be null");
        return new ResultQueueEntry<>(null, response, false);
    }

    public static <T> ResultQueueEntry<T> newThrowable(Throwable throwable) {
        Preconditions.checkArgument(throwable != null, "Throwable may not be null");
        return new ResultQueueEntry<>(throwable, null, false);
    }

    public static <T> ResultQueueEntry<T> newCompletionMarker() {
        return new ResultQueueEntry<>(null, null, true);
    }

    protected ResultQueueEntry(Throwable throwable, T response, boolean isCompletionMarker) {
        this.throwable = throwable;
        this.response = response;
        this.isComplete = isCompletionMarker;
    }

    public boolean isCompletionMarker() {
        return isComplete;
    }

    public T getResponseOrThrow() throws IOException {
        if (throwable != null) {
            if (throwable instanceof OperationRuntimeException) {
                throw new IOExceptionWithStatus(EXCEPTION_MESSAGE, (OperationRuntimeException) throwable);
            }
            throw new IOException(EXCEPTION_MESSAGE, throwable);
        }
        if (isCompletionMarker()) {
            throw new IOException("Attempt to interpret a result stream completion marker as a result");
        }
        return response;
    }
}