OpenNebula

#!/bin/sh

# version : 2012-06-07

# author : CMRI zhangzhihong

# 

# if CACHE_ANY is set, image donwloaded will be cached locally

CACHE_ANY="true"

SCRIPT_NAME=`basename $0`

SED="sed -r"

# Log function that knows how to deal with severities and adds the

# script name

function log_function

{

    echo "$1: $SCRIPT_NAME: $2" 1>&2

}

# Logs an info message

function log_info

{

    log_function "INFO" "$1"

}

# Logs a message, alias to log_info

function log

{

    log_info "$1"

}

# Logs an error message

function log_error

{

    log_function "ERROR" "$1"

}

# This function is used to pass error message to the mad

function error_message

{

    (

        echo "ERROR MESSAGE --8<------"

        echo "$1"

        echo "ERROR MESSAGE ------>8--"

    ) 1>&2

}

# Executes a command, if it fails returns error message and exits

# If a second parameter is present it is used as the error message when

# the command fails

function exec_and_log

{

    message=$2

    output=`$1 2>&1 1>/dev/null`

    code=$?

    if [ "x$code" != "x0" ]; then

        log_error "Command \"$1\" failed."

        log_error "$output"

        if [ -z "$message" ]; then

            error_message "$output"

        else

            error_message "$message"

        fi

        exit $code

    fi

    log "Executed \"$1\"."

}

# Gets the host from an argument

function arg_host

{

    echo $1 | $SED 's/^([^:]*):.*$/\1/'

}

# Gets the path from an argument

function arg_path

{

    echo $1 | $SED 's/^[^:]*:(.*)$/\1/'

}

function arg_first_dir

{

   temp="/`echo $1 | cut -d/ -f2`"  	

   echo $temp	

}

#try to lock image file

#return 0 if success lock file

#return 1 if file is locked by others

function lock_file

{

	lockfile -r 0 ${1}.lock >/dev/null 2>&1

	return $?	

}

function release_lock

{

	exec_and_log "rm -f ${1}.lock" "the lock is released by others!!!"

}

function mv_image

{

	exec_and_log "mv $1 $2"

}

function download_image

{

	exec_and_log "wget $1 $2 $3"

}

function prefetch_cache_image

{

	LOCAL_CACHE_IMAGE=$1

	CACHE_IMAGE=$2

	if [ -f $LOCAL_CACHE_IMAGE ] && lock_file $CACHE_IMAGE

	then

		exec_and_log "cp $LOCAL_CACHE_IMAGE $CACHE_IMAGE"

		release_lock $CACHE_IMAGE

	fi

}

function prefetch_local_cache 

{

	OPT=$1

	LOCAL_CACHE_IMAGE=$2

	SOURCE=$3

	CACHE_IMAGE=$4

	if lock_file $LOCAL_CACHE_IMAGE

	then

		exec_and_log "wget $OPT $LOCAL_CACHE_IMAGE $SOURCE "

		release_lock $LOCAL_CACHE_IMAGE

		prefetch_cache_image $LOCAL_CACHE_IMAGE $CACHE_IMAGE

	fi	

}

if [ $# -lt 3 ]

then 

	echo "usage $0 -O TARGET SOURCE_URL"

	exit 1

fi

#main

OPT=$1

TARGET=$2

SOURCE=$3

SOURCE_IMAGE=`basename $SOURCE`

CACHE_DIR="`arg_first_dir $TARGET`/.cache"

CACHE_IMAGE="${CACHE_DIR}/${SOURCE_IMAGE}"

LOCAL_CACHE_DIR="`arg_first_dir $TARGET`/.local_cache"

LOCAL_CACHE_IMAGE="${LOCAL_CACHE_DIR}/${SOURCE_IMAGE}"

if [ ! -d $CACHE_DIR ] || [ ! -d $LOCAL_CACHE_DIR ]

then

	mkdir -p $CACHE_DIR

	mkdir -p $LOCAL_CACHE_DIR

fi

if [ -f $CACHE_IMAGE ] && lock_file $CACHE_IMAGE

then

	mv_image $CACHE_IMAGE $TARGET

	release_lock $CACHE_IMAGE

	prefetch_cache_image $LOCAL_CACHE_IMAGE $CACHE_IMAGE  >/dev/null 2>&1 &

else

	if [ -f $LOCAL_CACHE_IMAGE ] && lock_file $LOCAL_CACHE_IMAGE

	then

		release_lock $LOCAL_CACHE_IMAGE

		exec_and_log "cp $LOCAL_CACHE_IMAGE $TARGET"

		prefetch_cache_image $LOCAL_CACHE_IMAGE $CACHE_IMAGE >/dev/null 2>&1 &

	else

		download_image $OPT $TARGET $SOURCE 

		if [ "$CACHE_ANY"=="true" ]

		then

			prefetch_local_cache $OPT $LOCAL_CACHE_IMAGE $SOURCE $CACHE_IMAGE >/dev/null 2>&1 & 

		fi

	fi		

fi