finailized #3

Author: hastmu

apt-proxy-detect.sh

@@ -5,6 +5,22 @@
 # v1 ... pure detect
 # v2 ... cache value with check
 # v3 ... add persistant caching for found proxies.
+# v4 ... extend caching to also cache no-found proxy state 
+#        and proxy checking based on testurl
+#        + debug reveals ms execution time
+#        + timeout for check_proxy
+#        + cache age per entry not per whole file.
+#        + cache leading url not full, as i get called for all packages also.
+
+
+# defaults
+service_name="_apt_proxy._tcp"
+cache_file_name=".apt-proxy-detect.$(id -un)"
+cache_file_none_retry_timeout=60 
+declare -i cache_age=0
+
+declare -A CACHED_PROXIES
+declare -A CACHED_PROXIES_AGE
 
 declare -i debug
 [ -z "${DEBUG_APT_PROXY_DETECT}" ] && debug=0 || debug=1
@@ -15,20 +31,38 @@ then
       :
    }
 else 
+   declare -i start_time=0
+   start_time=$(date +%s%N)
    function debug() {
-      printf "[%10s]: %s\n" "$1" "$2" >&2
+      printf "[%12s][%4s]: %s\n" "$1" "$(( ($(date +%s%N) - start_time) / 1000000 ))" "$2" >&2
    }
 fi
-debug "INFO" "apt-proxy-detect"
+debug "INFO" "===--- apt-proxy-detect ---==="
 
 function check_proxy() {
-   wget -e "http_proxy=$1" -e "https_proxy=$1" -qO - "$2" >> /dev/null
-   return $?
+   if [ "$1" == "NONE" ]
+   then
+      if [ ${cache_age} -gt ${cache_file_none_retry_timeout} ]
+      then
+         debug "CHECK-PROXY" "NONE-cached expired" 
+         return 1
+      else
+         debug "CHECK-PROXY" "NONE-cached" 
+         return 0
+      fi
+   else
+      debug "CHECK-PROXY" "Checking proxy (${1}) with testurl (${2})"
+      if [ $debug -gt 1 ]
+      then
+         wget -v --tries=1 -T 1 -e "http_proxy=$1" -e "https_proxy=$1" -O - "$2" >&2
+      else
+         wget -q --tries=1 -T 1 -e "http_proxy=$1" -e "https_proxy=$1" -O - "$2" >> /dev/null 2>&1
+      fi
+      return $?
+   fi
 }
 
-# cache file name
-cache_file_name=".apt-proxy-detect.$(id -un)"
-
+# --- cache location ---
 # persistant cache file location
 # $HOME or special for system accounts
 declare -A CACHE_FILE_LOC
@@ -46,33 +80,57 @@ else
    fi
 fi
 
-# check cache_file
-touch "${cache_file}" >> /dev/null 2>&1
+# check cache_file if not there create it.
+[ ! -e "${cache_file}" ] && touch "${cache_file}" >> /dev/null 2>&1
 
+# check ownership of cache file and fetch age.
 skip_cache=0
 if [ "$(stat -c %u "${cache_file}")" != "$(id -u)" ]
 then
    skip_cache=1
    echo "E: wrong owner of cache file ${cache_file}, remove or reown to $(id -un)" >&2
 fi
-service_name="_apt_proxy._tcp"
+
+# eval testurl
 [ -z "$1" ] && testurl="http://deb.debian.org/debian" || testurl="$1"
-debug "TEST-URL" "URL: ${testurl}"
+debug "TEST-URL" "URL:  ${testurl}"
+testurl_hash_url="$(echo "${testurl}" | cut -d/ -f1-3)"
+testurl_hash="$(echo "${testurl_hash_url}" | md5sum)" ; testurl_hash="${testurl_hash%% *}"
+debug "HASH" "HASH: ${testurl_hash} of (${testurl_hash_url})"
 
+# check out cached value
+now=$(date +%s)
 if [ -s "${cache_file}" ] && [ ${skip_cache} -eq 0 ]
 then
-   debug "CACHE" "using stored under: ${cache_file}"
-   proxy="$(cat "${cache_file}")"
-   debug "CHECK" "Checking cached proxy (${proxy}) with testurl (${testurl})"
-   if check_proxy "${proxy}" "${testurl}"
+   # shellcheck disable=SC1090
+   source "${cache_file}"
+   # shellcheck disable=SC2181
+   if [ $? -ne 0 ]
    then
-      debug "WORKS" "give back cached proxy"
-      debug "PROXY" "return ${proxy}"
-      echo "${proxy}"
-      exit 0
-   else
-      debug "FAILED" "remove cache file."
+      # something is wrong with the cache file remove it.
+      debug "CACHE" "invalid cachefile (cleanup): ${cache_file}"
       rm -f "${cache_file}"
+   else
+      debug "CACHE" "using stored under: ${cache_file}"
+   fi 
+   cache_age=$(( now - ${CACHED_PROXIES_AGE[${testurl_hash}]:=0} ))
+   debug "CACHE-AGE" "age: ${cache_age} sec"
+   proxy="${CACHED_PROXIES[${testurl_hash}]}"
+   if [ -n "${proxy}" ]
+   then
+      if check_proxy "${proxy}" "${testurl}"
+      then
+         debug "WORKS" "give back cached proxy"
+         debug "PROXY" "return ${proxy}"
+         [ "${proxy}" != "NONE" ] && echo "${proxy}"
+         exit 0
+      else
+         debug "FAILED" "remove from cache file."
+   #      declare -p CACHED_PROXIES >&2
+         unset 'CACHED_PROXIES["${testurl_hash}"]'
+         unset 'CACHED_PROXIES_AGE["${testurl_hash}"]'
+   #      declare -p CACHED_PROXIES >&2
+      fi
    fi
 fi
 
@@ -100,11 +158,6 @@ do
       if [ -z "${ret}" ]
       then
          ret="${proxy}"
-         if [ ${skip_cache} -eq 0 ] 
-         then
-            debug "CACHE" "Store (${proxy}) in cache file (${cache_file})"
-            echo "${proxy}" > "${cache_file}"
-         fi
       fi
       stat="OK"
    else
@@ -113,9 +166,24 @@ do
    printf "Service[%s][%s]@%s \n" "${stat}" "${name}" "${proxy}" >&2
 done
 
-debug "PROXY" "return ${ret}"
+debug "PROXY" "return :${ret}:"
+
 if [ -n "${ret}" ]
 then
    echo "${ret}"
+else
+   ret="NONE"
 fi
+
+# write back cachefile finally.
+if [ ${skip_cache} -eq 0 ] 
+then
+   debug "CACHE" "Store (${ret}) in cache file (${cache_file})"
+   CACHED_PROXIES[${testurl_hash}]="${ret}"
+   CACHED_PROXIES_AGE[${testurl_hash}]="${now}"
+   debug "CACHE" "Update cachefile."
+   declare -p CACHED_PROXIES > "${cache_file}"
+   declare -p CACHED_PROXIES_AGE >> "${cache_file}"
+fi
+
 exit 0