/*
 * 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.htrace.impl;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.htrace.HBaseHTraceConfiguration;
import org.apache.htrace.core.HTraceConfiguration;
import org.apache.htrace.core.Sampler;
import org.apache.htrace.core.Span;
import org.apache.htrace.core.SpanReceiver;
import org.apache.htrace.core.TimelineAnnotation;
import org.apache.htrace.core.TraceScope;
import org.apache.htrace.core.Tracer;
import org.apache.htrace.protobuf.generated.SpanProtos;

/**
 * HBase is an open source distributed datastore.
 * This span receiver store spans into HBase.
 * HTrace spans are queued into a blocking queue.
 * From there background worker threads will send them
 * to a HBase database.
 */
public class HBaseSpanReceiver extends SpanReceiver {
  private static final Log LOG = LogFactory.getLog(HBaseSpanReceiver.class);

  public static final String COLLECTOR_QUORUM_KEY = "htrace.hbase.collector-quorum";
  public static final String DEFAULT_COLLECTOR_QUORUM = "127.0.0.1";
  public static final String ZOOKEEPER_CLIENT_PORT_KEY = "htrace.hbase.zookeeper.property.clientPort";
  public static final int DEFAULT_ZOOKEEPER_CLIENT_PORT = 2181;
  public static final String ZOOKEEPER_ZNODE_PARENT_KEY = "htrace.hbase.zookeeper.znode.parent";
  public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
  public static final String NUM_THREADS_KEY = "htrace.hbase.num-threads";
  public static final int DEFAULT_NUM_THREADS = 1;
  public static final String MAX_SPAN_BATCH_SIZE_KEY = "htrace.hbase.batch.size";
  public static final int DEFAULT_MAX_SPAN_BATCH_SIZE = 100;
  public static final String TABLE_KEY = "htrace.hbase.table";
  public static final String DEFAULT_TABLE = "htrace";
  public static final String COLUMNFAMILY_KEY = "htrace.hbase.columnfamily";
  public static final String DEFAULT_COLUMNFAMILY = "s";
  public static final String INDEXFAMILY_KEY = "htrace.hbase.indexfamily";
  public static final String DEFAULT_INDEXFAMILY = "i";
  public static final byte[] INDEX_SPAN_QUAL = Bytes.toBytes("s");
  public static final byte[] INDEX_TIME_QUAL = Bytes.toBytes("t");

  /**
   * How long this receiver will try and wait for all threads to shutdown.
   */
  private static final int SHUTDOWN_TIMEOUT = 30;

  /**
   * How many errors in a row before we start dropping traces on the floor.
   */
  private static final int MAX_ERRORS = 10;

  /**
   * The queue that will get all HTrace spans that are to be sent.
   */
  private final BlockingQueue<Span> queue;

  /**
   * Boolean used to signal that the threads should end.
   */
  private final AtomicBoolean running = new AtomicBoolean(true);

  /**
   * The thread factory used to create new ExecutorService.
   * <p/>
   * This will be the same factory for the lifetime of this object so that
   * no thread names will ever be duplicated.
   */
  private final ThreadFactory tf = new ThreadFactory() {
    private final AtomicLong receiverIdx = new AtomicLong(0);

    @Override
    public Thread newThread(Runnable r) {
      Thread t = new Thread(r);
      t.setDaemon(true);
      t.setName(String.format("hbaseSpanReceiver-%d",
            receiverIdx.getAndIncrement()));
      return t;
    }
  };

  private ExecutorService service;
  private final HTraceConfiguration conf;
  private final Configuration hconf;
  private final byte[] table;
  private final byte[] cf;
  private final byte[] icf;
  private final int maxSpanBatchSize;

  public HBaseSpanReceiver(HTraceConfiguration conf) {
    this.queue = new ArrayBlockingQueue<Span>(1000);
    this.conf = conf;
    this.hconf = HBaseConfiguration.create();
    this.table = Bytes.toBytes(conf.get(TABLE_KEY, DEFAULT_TABLE));
    this.cf = Bytes.toBytes(conf.get(COLUMNFAMILY_KEY, DEFAULT_COLUMNFAMILY));
    this.icf = Bytes.toBytes(conf.get(INDEXFAMILY_KEY, DEFAULT_INDEXFAMILY));
    this.maxSpanBatchSize = conf.getInt(MAX_SPAN_BATCH_SIZE_KEY,
                                        DEFAULT_MAX_SPAN_BATCH_SIZE);
    String quorum = conf.get(COLLECTOR_QUORUM_KEY, DEFAULT_COLLECTOR_QUORUM);
    hconf.set(HConstants.ZOOKEEPER_QUORUM, quorum);
    String znodeParent = conf.get(ZOOKEEPER_ZNODE_PARENT_KEY, DEFAULT_ZOOKEEPER_ZNODE_PARENT);
    hconf.set(HConstants.ZOOKEEPER_ZNODE_PARENT, znodeParent);
    int clientPort = conf.getInt(ZOOKEEPER_CLIENT_PORT_KEY, DEFAULT_ZOOKEEPER_CLIENT_PORT);
    hconf.setInt(HConstants.ZOOKEEPER_CLIENT_PORT, clientPort);

    // If there are already threads runnnig tear them down.
    if (this.service != null) {
      this.service.shutdownNow();
      this.service = null;
    }
    int numThreads = conf.getInt(NUM_THREADS_KEY, DEFAULT_NUM_THREADS);
    this.service = Executors.newFixedThreadPool(numThreads, tf);
    for (int i = 0; i < numThreads; i++) {
      this.service.submit(new WriteSpanRunnable());
    }
  }

  private class WriteSpanRunnable implements Runnable {
    private Connection hconnection;
    private Table htable;

    public WriteSpanRunnable() {
    }

    /**
     * This runnable sends a HTrace span to the HBase.
     */
    @Override
    public void run() {
      SpanProtos.Span.Builder sbuilder = SpanProtos.Span.newBuilder();
      SpanProtos.TimelineAnnotation.Builder tlbuilder =
          SpanProtos.TimelineAnnotation.newBuilder();
      List<Span> dequeuedSpans = new ArrayList<Span>(maxSpanBatchSize);
      long errorCount = 0;

      while (running.get() || queue.size() > 0) {
        Span firstSpan = null;
        try {
          // Block for up to a second. to try and get a span.
          // We only block for a little bit in order to notice
          // if the running value has changed
          firstSpan = queue.poll(1, TimeUnit.SECONDS);

          // If the poll was successful then it's possible that there
          // will be other spans to get. Try and get them.
          if (firstSpan != null) {
            // Add the first one that we got
            dequeuedSpans.add(firstSpan);
            // Try and get up to 100 queues
            queue.drainTo(dequeuedSpans, maxSpanBatchSize - 1);
          }
        } catch (InterruptedException ie) {
          // Ignored.
        }
        startClient();
        if (dequeuedSpans.isEmpty()) {
          try {
            this.htable.flushCommits();
          } catch (IOException e) {
            LOG.error("failed to flush writes to HBase.");
            closeClient();
          }
          continue;
        }

        try {
          for (Span span : dequeuedSpans) {
            sbuilder.clear()
                    .setTraceId(span.getSpanId().getHigh())
                    .setStart(span.getStartTimeMillis())
                    .setStop(span.getStopTimeMillis())
                    .setSpanId(span.getSpanId().getLow())
                    .setProcessId(span.getTracerId())
                    .setDescription(span.getDescription());

            if (span.getParents().length == 0) {
              sbuilder.setParentId(0);
            } else if (span.getParents().length > 0) {
              sbuilder.setParentId(span.getParents()[0].getLow());
              if (span.getParents().length > 1) {
                LOG.error("error: HBaseSpanReceiver does not support spans " +
                    "with multiple parents.  Ignoring multiple parents for " +
                    span);
              }
            }
            for (TimelineAnnotation ta : span.getTimelineAnnotations()) {
              sbuilder.addTimeline(tlbuilder.clear()
                                            .setTime(ta.getTime())
                                            .setMessage(ta.getMessage())
                                            .build());
            }
            Put put = new Put(Bytes.toBytes(span.getSpanId().getHigh()));
            put.add(HBaseSpanReceiver.this.cf,
                    sbuilder.build().toByteArray(),
                    null);
            if (span.getParents().length == 0) {
              put.add(HBaseSpanReceiver.this.icf,
                      INDEX_TIME_QUAL,
                      Bytes.toBytes(span.getStartTimeMillis()));
              put.add(HBaseSpanReceiver.this.icf,
                      INDEX_SPAN_QUAL,
                      sbuilder.build().toByteArray());
            }
            this.htable.put(put);
          }
          // clear the list for the next time through.
          dequeuedSpans.clear();
          // reset the error counter.
          errorCount = 0;
        } catch (Exception e) {
          errorCount += 1;
          // If there have been ten errors in a row start dropping things.
          if (errorCount < MAX_ERRORS) {
            try {
              queue.addAll(dequeuedSpans);
            } catch (IllegalStateException ex) {
              LOG.error("Drop " + dequeuedSpans.size() +
                        " span(s) because writing to HBase failed.");
            }
          }
          closeClient();
          try {
            // Since there was an error sleep just a little bit to try and allow the
            // HBase some time to recover.
            Thread.sleep(500);
          } catch (InterruptedException e1) {
            // Ignored
          }
        }
      }
      closeClient();
    }

    /**
     * Close out the connection.
     */
    private void closeClient() {
      // close out the transport.
      try {
        if (this.htable != null) {
          this.htable.close();
          this.htable = null;
        }
        if (this.hconnection != null) {
          this.hconnection.close();
          this.hconnection = null;
        }
      } catch (IOException e) {
        LOG.warn("Failed to close HBase connection. " + e.getMessage());
      }
    }

    /**
     * Re-connect to HBase
     */
    private void startClient() {
      if (this.htable == null) {
        try {
          hconnection = ConnectionFactory.createConnection(hconf);
          htable = hconnection.getTable(TableName.valueOf(table));
        } catch (IOException e) {
          LOG.warn("Failed to create HBase connection. " + e.getMessage());
        }
      }
    }
  }

  /**
   * Close the receiver.
   * <p/>
   * This tries to shutdown thread pool.
   *
   * @throws IOException
   */
  @Override
  public void close() throws IOException {
    running.set(false);
    service.shutdown();
    try {
      if (!service.awaitTermination(SHUTDOWN_TIMEOUT, TimeUnit.SECONDS)) {
        LOG.error("Was not able to process all remaining spans upon closing in: " +
            SHUTDOWN_TIMEOUT + " " + TimeUnit.SECONDS +
            ". Left Spans could be dropped.");
       }
    } catch (InterruptedException e1) {
      LOG.warn("Thread interrupted when terminating executor.", e1);
    }
  }

  @Override
  public void receiveSpan(Span span) {
    if (running.get()) {
      try {
        this.queue.add(span);
      } catch (IllegalStateException e) {
        // todo: supress repeating error logs.
        LOG.error("Error trying to append span (" +
            span.getDescription() +
            ") to the queue. Blocking Queue was full.");
      }
    }
  }

  /**
   * Run basic test. Adds span to an existing htrace table in an existing hbase setup.
   * Requires a running hbase to send the traces too with an already created trace
   * table (Default table name is 'htrace' with column families 's' and 'i').
   * @throws IOException
   */
  public static void main(String[] args) throws Exception {
    Tracer tracer = new Tracer.Builder().
        conf(new HBaseHTraceConfiguration(HBaseConfiguration.create())).
        build();
    tracer.addSampler(Sampler.ALWAYS);
    TraceScope parent = tracer.newScope("HBaseSpanReceiver.main.parent");
    Thread.sleep(10);
    long traceid = parent.getSpan().getSpanId().getHigh();
    TraceScope child1 = tracer.newScope("HBaseSpanReceiver.main.child.1");
    Thread.sleep(10);
    child1.close();
    TraceScope child2 = tracer.newScope("HBaseSpanReceiver.main.child.2");
    Thread.sleep(10);
    TraceScope gchild = tracer.newScope("HBaseSpanReceiver.main.grandchild");
    gchild.addTimelineAnnotation("annotation 1.");
    Thread.sleep(10);
    gchild.addTimelineAnnotation("annotation 2.");
    gchild.close();
    Thread.sleep(10);
    child2.close();
    Thread.sleep(10);
    parent.close();
    tracer.close();
    System.out.println("trace id: " + traceid);
  }
}