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Java idiomatic client for Cloud Logging
There is a newer version: 3.21.1
/*
 * Copyright 2021 Google LLC
 *
 * 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
 *
 * https://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.logging;

import com.google.api.gax.rpc.BidiStream;
import com.google.common.collect.Lists;
import com.google.logging.v2.TailLogEntriesRequest;
import com.google.logging.v2.TailLogEntriesResponse;
import java.util.Iterator;
import java.util.List;

/**
 * The class implements {@link Iterable} interface over {@see LogEntry}. It wraps around {@link
 * BidiStream} bi-directional gRPC stream to support iterating through ingested responses. The class
 * uses {@see LogEntryIterator} to iterate through the processed responses. The stream should be
 * explicitly canceled by calling {@see LogEntryServerStream#cancel()} method. The class does not
 * provide recovery or resuming functionality over the stream.
 *
 * To iterate run:
 *
 * 
{@code
 * LogEntryServerStream stream;
 * // code to initialize stream
 * for (LogEntry log : stream) {
 *   // do something with logs
 * }
 * stream.cancel();
 * }
 *
 * The iteration can be blocked on waiting for another response sent in the stream.
 */
public class LogEntryServerStream implements Iterable {
  private final BidiStream serverStream;

  LogEntryServerStream(BidiStream serverStream) {
    this.serverStream = serverStream;
  }

  /** {@inheritDoc} */
  @Override
  public Iterator iterator() {
    return new LogEntryIterator(serverStream.iterator());
  }

  public BidiStream getInternalStream() {
    return serverStream;
  }

  public List convert(TailLogEntriesResponse resp) {
    return Lists.transform(resp.getEntriesList(), LogEntry.FROM_PB_FUNCTION);
  }

  /**
   * Returns true if the next call to the iterator's hasNext() or next() is guaranteed to be
   * nonblocking.
   *
   * @return If the call on any of the iterator's methods is guaranteed to be nonblocking.
   */
  public boolean isReceiveReady() {
    return serverStream.isReceiveReady();
  }

  /**
   * Cleanly cancels a partially consumed stream. The associated iterator will return false for the
   * hasNext() in the next iteration. This maintains the contract that an observed true from
   * hasNext() will yield an item in next(), but afterwards will return false.
   */
  public void cancel() {
    serverStream.cancel();
  }
}