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limosek-zaf/lib/cache.lib.sh
2016-12-05 11:30:10 +01:00

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# Zaf cache related functions
zaf_cache_init(){
local files
local file
if [ "$ZAF_CACHE_DIR" = "/tmp/zafc" ] && ! [ -d "$ZAF_CACHE_DIR" ]; then
mkdir -p $ZAF_CACHE_DIR
chown $ZAF_FILES_UID $ZAF_CACHE_DIR >/dev/null 2>/dev/null
fi
if ! [ -w $ZAF_CACHE_DIR ]; then
zaf_dbg "Cache dir $ZAF_CACHE_DIR is not accessible! Disabling cache."
fi
}
zaf_cache_clean(){
local files
if [ -w "$ZAF_CACHE_DIR" ]; then
zaf_wrn "Removing cache entries"
files=$(find $ZAF_CACHE_DIR/ -type f)
[ -n "$files" ] && rm -f $files
else
zaf_dbg "Cache dir not set. Disabling cache."
fi
zaf_cache_init
}
# Get cache key from requested param
zaf_cache_key(){
echo "$1" | (md5sum - ||md5) 2>/dev/null | cut -d ' ' -f 1
}
# Wait for lock
# $1 - key
zaf_cache_lock(){
local lockfile
lockfile="${ZAF_CACHE_DIR}/${key}.lock"
[ -f "$lockfile" ] && sleep 1
[ -f "$lockfile" ] && return 1
return 0
}
# Unlock cache key
# $1 - key
zaf_cache_unlock(){
local lockfile
lockfile="${ZAF_CACHE_DIR}/${key}.lock"
rm -f $lockfile
}
# Put object into cache
# $1 key
# $2 value
# $3 lifetime in seconds
zaf_tocache(){
! [ -w $ZAF_CACHE_DIR ] && return
local key
local value
local expiry
local infofile
local datafile
key=$(zaf_cache_key "$1")
datafile=${ZAF_CACHE_DIR}/$key
infofile=${ZAF_CACHE_DIR}/${key}.info
zaf_cache_lock "$key" || { zaf_wrn "Cache: Entry $1[$key] locked!"; return 1; }
rm -f $datafile $infofile
echo "$2" >$datafile
echo "$1" >$infofile
expiry=$(zaf_date_add "$3")
zaf_trc "Cache: Saving entry $1[$key,expiry=$expiry]"
touch -m -d "$expiry" $infofile
zaf_cache_unlock $key
}
# Put object into cache from stdin and copy to stdout
# $1 key
# $2 lifetime in seconds
zaf_tocache_stdin(){
! [ -w $ZAF_CACHE_DIR ] && { cat; return; }
local key
local expiry
local infofile
local datafile
key=$(zaf_cache_key "$1")
datafile=${ZAF_CACHE_DIR}/$key
lockfile=${ZAF_CACHE_DIR}/${key}.lock
infofile=${ZAF_CACHE_DIR}/${key}.info
zaf_cache_lock "$key" || { zaf_wrn "Cache: Entry $1[$key] locked!"; return 1; }
rm -f $datafile $infofile
cat >$datafile
expiry="$(zaf_date_add $2)"
echo "$1 [key=$key,expiry=$expiry]" >$infofile
zaf_trc "Cache: Saving entry $1[key=$key,expiry=$expiry]"
touch -m -d "$expiry" $infofile
zaf_cache_unlock "$key"
cat $datafile
}
# Remove entry from cache
# $1 key
zaf_cache_delentry(){
! [ -w $ZAF_CACHE_DIR ] && return 1
local key
key=$(zaf_cache_key "$1")
zaf_trc "Cache: removing $1($key) from cache"
rm -f "${ZAF_CACHE_DIR}/$key*"
}
# List entries in cache
zaf_cache_list(){
! [ -w $ZAF_CACHE_DIR ] && return 1
local i
ls ${ZAF_CACHE_DIR}/*info >/dev/null 2>/dev/null || return 1
local key
for i in ${ZAF_CACHE_DIR}/*info; do
cat $i
done
}
# Get object from cache
# $1 key
zaf_fromcache(){
! [ -w $ZAF_CACHE_DIR ] && return 3
local key
local value
local infofile
local datafile
key=$(zaf_cache_key "$1")
datafile="${ZAF_CACHE_DIR}/${key}"
infofile="${ZAF_CACHE_DIR}/${key}.info"
if [ -f $datafile ]; then
if [ "$infofile" -nt "$datafile" ]; then
zaf_trc "Cache: serving $1($key) from cache"
cat "$datafile"
else
zaf_cache_delentry $key
return 2
fi
else
zaf_trc "Cache: missing entry $1($key)"
return 1
fi
}