#!/usr/bin/env bash

#
# 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.
#

# Starts a slave on the machine this script is executed on.
#
# Environment Variables
#
#   SPARK_WORKER_INSTANCES  The number of worker instances to run on this 
#                           slave.  Default is 1.
#   SPARK_WORKER_PORT       The base port number for the first worker. If set, 
#                           subsequent workers will increment this number.  If
#                           unset, Spark will find a valid port number, but
#                           with no guarantee of a predictable pattern.
#   SPARK_WORKER_WEBUI_PORT The base port for the web interface of the first
#                           worker.  Subsequent workers will increment this 
#                           number.  Default is 8081.

usage="Usage: start-slave.sh <spark-master-URL> where <spark-master-URL> is like spark://localhost:7077"

if [ $# -lt 1 ]; then
  echo $usage
  echo Called as start-slave.sh $*
  exit 1
fi

sbin="`dirname "$0"`"
sbin="`cd "$sbin"; pwd`"

. "$sbin/spark-config.sh"

. "$SPARK_PREFIX/bin/load-spark-env.sh"

# First argument should be the master; we need to store it aside because we may
# need to insert arguments between it and the other arguments
MASTER=$1
shift

# Determine desired worker port
if [ "$SPARK_WORKER_WEBUI_PORT" = "" ]; then
  SPARK_WORKER_WEBUI_PORT=8081
fi

# Start up the appropriate number of workers on this machine.
# quick local function to start a worker
function start_instance {
  WORKER_NUM=$1
  shift

  if [ "$SPARK_WORKER_PORT" = "" ]; then
    PORT_FLAG=
    PORT_NUM=
  else
    PORT_FLAG="--port"
    PORT_NUM=$(( $SPARK_WORKER_PORT + $WORKER_NUM - 1 ))
  fi
  WEBUI_PORT=$(( $SPARK_WORKER_WEBUI_PORT + $WORKER_NUM - 1 ))

  "$sbin"/spark-daemon.sh start org.apache.spark.deploy.worker.Worker $WORKER_NUM \
     --webui-port "$WEBUI_PORT" $PORT_FLAG $PORT_NUM $MASTER "$@"
}

if [ "$SPARK_WORKER_INSTANCES" = "" ]; then
  start_instance 1 "$@"
else
  for ((i=0; i<$SPARK_WORKER_INSTANCES; i++)); do
    start_instance $(( 1 + $i )) "$@"
  done
fi