Add. Basic cache class

Fix. When memcache stopped and mod_memcache loaded dialplan did not build from DB.

resources/install/scripts/app/xml_handler/resources/scripts/dialplan/dialplan.lua

@@ -24,15 +24,21 @@
 --	ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 --	POSSIBILITY OF SUCH DAMAGE.
 
+	local cache = require"resources.functions.cache"
+
 --get the cache
-	if (trim(api:execute("module_exists", "mod_memcache")) == "true") then
-		XML_STRING = trim(api:execute("memcache", "get dialplan:" .. call_context));
-	else
-		XML_STRING = "-ERR NOT FOUND";
+	XML_STRING, err = cache.get("dialplan:" .. call_context)
+
+	if debug['cache'] then
+		if XML_STRING then
+			freeswitch.consoleLog("notice", "[xml_handler] dialplan:"..call_context.." source: memcache\n");
+		elseif err ~= 'NOT FOUND' then
+			freeswitch.consoleLog("notice", "[xml_handler] error get element form cache: " .. err .. "\n");
+		end
 	end
 
 --set the cache
-	if (XML_STRING == "-ERR NOT FOUND") then
+	if not XML_STRING then
 
 		--connect to the database
 			require "resources.functions.database_handle";
@@ -287,8 +293,9 @@
 			XML_STRING = table.concat(xml, "\n");
 
 		--set the cache
-			tmp = XML_STRING:gsub("\\", "\\\\");
-			result = trim(api:execute("memcache", "set dialplan:" .. call_context .. " '"..tmp:gsub("'", "'").."' "..expire["dialplan"]));
+			if cache.support() then
+				cache.set("dialplan:" .. call_context, XML_STRING, expire["dialplan"])
+			end
 
 		--send the xml to the console
 			if (debug["xml_string"]) then
@@ -304,12 +311,5 @@
 
 		--close the database connection
 			dbh:release();
-	else
-		--replace the &#39 back to a single quote
-			XML_STRING = XML_STRING:gsub("'", "'");
-
-		--send to the console
-			if (debug["cache"]) then
-				freeswitch.consoleLog("notice", "[xml_handler] dialplan:"..call_context.." source: memcache\n");
-			end
 	end
+

resources/install/scripts/resources/functions/cache.lua

@@ -0,0 +1,63 @@
+-- @usage cache = require "resources.functions.cache"
+-- value = cache.get(key)
+-- if not value then
+--   ...
+--   cache.set(key, value, expire)
+-- end
+--
+
+require "resources.functions.trim";
+
+local api = api or freeswitch.API();
+
+local Cache = {}
+
+local function check_error(result)
+  result = trim(result or '')
+
+  if result and result:sub(1, 4) == '-ERR' then
+    return nil, trim(result:sub(5))
+  end
+
+  if result == 'INVALID COMMAND!' and not Cache.support() then
+      return nil, 'INVALID COMMAND'
+  end
+
+  return result
+end
+
+function Cache.support()
+  -- assume it is not unloadable
+  if Cache._support then
+    return true
+  end
+  Cache._support = (trim(api:execute('module_exists', 'mod_memcache')) == 'true')
+  return Cache._support
+end
+
+--- Get element from cache
+--
+-- @tparam key string
+-- @return[1] string value
+-- @return[2] nil
+-- @return[2] error string `e.g. 'NOT FOUND'
+-- @note error string does not contain `-ERR` prefix
+function Cache.get(key)
+  local result, err = check_error(api:execute('memcache', 'get ' .. key))
+  if not result then return nil, err end
+  return (result:gsub("'", "'"))
+end
+
+function Cache.set(key, value, expire)
+  value = value:gsub("'", "'"):gsub("\\", "\\\\")
+  expire = expire and tostring(expire) or ""
+  return check_error(api:execute("memcache", "set " .. key .. " '" .. value .. "' " .. expire))
+end
+
+function Cache.del(key)
+  local result, err = check_error(api:execute("memcache", "set " .. key .. " '" .. value .. "' " .. expire))
+  if not result then return nil, err end
+  return result == '+OK'
+end
+
+return Cache