SQOOP-79. Add scripts to start/stop metastore in background, use pidfiles.

Added start-metastore.sh and stop-metastore.sh scripts, which start and stop
the metastore silently.

From: Aaron Kimball <aaron@cloudera.com>

git-svn-id: https://svn.apache.org/repos/asf/incubator/sqoop/trunk@1149972 13f79535-47bb-0310-9956-ffa450edef68

bin/start-metastore.sh

@@ -0,0 +1,147 @@
+#!/bin/bash
+#
+# Licensed to Cloudera, Inc. under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# Cloudera, Inc. 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.
+
+# This script starts a metastore instance.
+# Usage: start-metastore.sh -p pidfilename -l logdir
+
+prgm=$0
+bin=`dirname $prgm`
+
+while [ ! -z "$1" ]; do
+  if [ "$1" == "-p" ]; then
+    shift
+    pidfilename=$1
+    shift
+  elif [ "$1" == "-l" ]; then
+    shift
+    logdir=$1
+    shift
+  else
+    echo "Unknown argument $1"
+    exit 1
+  fi
+done
+
+# Verify our arguments exist.
+
+if [ -z "${pidfilename}" ]; then
+  echo "Missing argument: -p pidfilename"
+  exit 1
+fi
+
+if [ -z "${logdir}" ]; then
+  echo "Missing argument: -l logdir"
+  exit 1
+fi
+
+if [ ! -d "${logdir}" ]; then
+  echo "Warning: Log directory ${logdir} does not exist."
+fi
+
+function pid_file_alive() {
+  local pidfile=$1 # IN
+  local programname=$2 # IN
+  local checkpid=`cat "$pidfile"`
+  ps -fp $checkpid | grep $checkpid | grep "$programname" > /dev/null 2>&1
+}
+
+function fail_if_pid_exists() {
+  local pidfile=$1 # IN
+  local programname=$2 # IN
+  if pid_file_alive "$pidfile" "$programname" ; then
+    echo "Pid file $pidfile already exists; not starting metastore."
+    exit 1
+  fi
+}
+
+# Acquire the pidfile lock.
+if [ -e "$pidfilename" ]; then
+  # If the pid file exists, check to see if the process is alive.
+  # We first write our own (bash script) pid into the pidfile.
+  # Then we write the child pid over top; the bash script then terminates.
+  # So we must be prepared to accept either case. 
+
+  # We must check for bash first. Serialization matters.
+  fail_if_pid_exists "$pidfilename" "bash"
+  fail_if_pid_exists "$pidfilename" "sqoop"
+
+  # We're good to go. Remove the existing pidfile.
+  existingpid=`cat $pidfilename`
+  [[ -e "$pidfilename" ]] && rm "$pidfilename" 
+  [[ -e "$pidfilename.$existingpid" ]] && rm "$pidfilename.$existingpid"
+fi
+
+pid=$$
+echo $pid > "$pidfilename.$pid"
+if [ ! -e "$pidfilename.$pid" ]; then
+  echo "Could not create pid file $pidfilename.$pid; not starting metastore."
+  exit 1
+fi
+
+# Hardlink the "real" pidfile to our temporary one. This is atomic.
+ln "$pidfilename.$pid" "$pidfilename"
+
+# Verify that the real pidfile exists, and contains our current pid.
+if [ ! -e "$pidfilename" ]; then
+  echo "Could not create pid file $pidfilename; not starting metastore."
+  exit 1
+fi
+
+val=`cat "$pidfilename"`
+if [ "$val" != "$pid" ]; then
+  # We lost the pid file race.
+  echo "Metastore already started; not starting metastore."
+  exit 1
+fi
+
+# Determine the log file name.
+user=`id -un`
+host=`hostname`
+
+# Log file name we would like to use.
+logfile="$logdir/sqoop-metastore-$user-$host.log"
+touch $logfile >/dev/null 2>&1
+if [ "$?" != "0" ]; then
+  # Can't open for logging.
+  echo "Warning: Cannot write to log directory. Disabling metastore log."
+  logfile=/dev/null
+fi
+
+# Actually start the metastore.
+
+if [ ! -z "$bin" ]; then
+  bin="$bin/"
+fi
+
+nohup "$bin/sqoop" metastore > "$logfile" 2>&1 </dev/null &
+ret=$?
+realpid=$!
+
+if [ "$ret" != "0" ]; then
+  echo "Error starting metastore."
+  rm "$pidfilename"
+  rm "$pidfilename.$pid"
+  exit $ret
+fi
+
+# Now replace the pid in the pidfile with the value in $realpid.
+echo $realpid > "$pidfilename"
+
+# The original pid file with the extension is no longer necessary.
+rm "$pidfilename.$pid"
+
+

bin/stop-metastore.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+#
+# Licensed to Cloudera, Inc. under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# Cloudera, Inc. 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.
+
+# This script stops a metastore instance.
+# Usage: stop-metastore.sh -p pidfilename
+
+prgm=$0
+bin=`dirname $prgm`
+
+while [ ! -z "$1" ]; do
+  if [ "$1" == "-p" ]; then
+    shift
+    pidfilename=$1
+    shift
+  else
+    echo "Unknown argument $1"
+    exit 1
+  fi
+done
+
+# Verify our arguments exist.
+
+if [ -z "${pidfilename}" ]; then
+  echo "Missing argument: -p pidfilename"
+  exit 1
+fi
+
+# Shut down any running metastore.
+
+if [ ! -z "$bin" ]; then
+  bin="$bin/"
+fi
+
+HADOOP_ROOT_LOGGER=${HADOOP_ROOT_LOGGER:-ERROR,console} \
+    "$bin/sqoop" metastore --shutdown 2>&1 >/dev/null
+ret=$?
+if [ "$ret" != "0" ]; then
+  echo "Could not shut down metastore."
+  exit $ret
+fi
+
+# Remove the pidfile lock.
+
+if [ ! -e "$pidfilename" ]; then
+  echo "No pid file $pidfilename"
+  exit 0
+fi
+
+rm "$pidfilename"
+