first commit

src/merle.erl

@@ -0,0 +1,235 @@
+%%%%-------------------------------------------------------------------
+%%% File    : merle.erl
+%%% Author  : Joe Williams (joe at joetify dot com)
+%%% Description : merle an Erlang memcached client
+%%% License	: Released under the MIT License.
+%%%
+%%% Created : 20090109
+%%%-------------------------------------------------------------------
+
+-module(merle).
+
+-behaviour(gen_server).
+
+-define(SERVER, ?MODULE).
+
+-define(TCP_OPTS, [binary, {packet, raw}, {nodelay, true}, 
+	{reuseaddr, true}, {active, true}]).
+
+%% API
+-export([start_link/2, memcache_stats/0, memcache_get/1,
+	memcache_delete/2,memcache_set/4,memcache_add/4,
+	memcache_replace/4,memcache_append/2,memcache_prepend/2,
+	memcache_cas/5,memcache_quit/0]).
+
+%% gen_server callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+	terminate/2, code_change/3]).
+
+-record(state, {socket}).
+
+%%====================================================================
+%% API
+%%====================================================================
+%%--------------------------------------------------------------------
+%% Function: start_link() -> {ok,Pid} | ignore | {error,Error}
+%% Description: Starts the server
+%%--------------------------------------------------------------------
+start_link(Host, Port) ->
+    gen_server:start_link({local, ?SERVER}, ?MODULE, [Host, Port], []).
+
+%%====================================================================
+%% gen_server callbacks
+%%====================================================================
+
+%%--------------------------------------------------------------------
+%% Function: init(Args) -> {ok, State} |
+%%                         {ok, State, Timeout} |
+%%                         ignore               |
+%%                         {stop, Reason}
+%% Description: Initiates the server
+%%--------------------------------------------------------------------
+init([Host, Port]) ->
+	{ok, Socket} = gen_tcp:connect(Host, Port, ?TCP_OPTS),
+  	{ok, #state{socket = Socket}}.
+
+%%--------------------------------------------------------------------
+%% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |
+%%                                      {reply, Reply, State, Timeout} |
+%%                                      {noreply, State} |
+%%                                      {noreply, State, Timeout} |
+%%                                      {stop, Reason, Reply, State} |
+%%                                      {stop, Reason, State}
+%% Description: Handling call messages
+%%--------------------------------------------------------------------
+
+handle_call({stats}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "stats"),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({getkey, {Key}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "get " ++ Key),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({delete, {Key, Time}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "delete " ++ Key ++ " " ++ Time),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({set, {Key, Flag, ExpTime, Data}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "set " ++ Key ++ " " ++ Flag ++ " " ++ ExpTime ++ " " ++ integer_to_list(length(Data)) ++ "\r\n" ++ Data),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({add, {Key, Flag, ExpTime, Data}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "add " ++ Key ++ " " ++ Flag ++ " " ++ ExpTime ++ " " ++ integer_to_list(length(Data)) ++ "\r\n" ++ Data),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({replace, {Key, Flag, ExpTime, Data}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "replace " ++ Key ++ " " ++ Flag ++ " " ++ ExpTime ++ " " ++ integer_to_list(length(Data)) ++ "\r\n" ++ Data),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({append, {Key, Data}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "append " ++ Key ++ " " ++ "0" ++ " " ++ "0" ++ " " ++ integer_to_list(length(Data)) ++ "\r\n" ++ Data),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({prepend, {Key, Data}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "prepend " ++ Key ++ " " ++ "0" ++ " " ++ "0" ++ " " ++ integer_to_list(length(Data)) ++ "\r\n" ++ Data),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({cas, {Key, Flag, ExpTime, CasUniq, Data}}, _From, #state{socket = Socket} = S) ->
+    Reply = send_cmd(Socket, "set " ++ Key ++ " " ++ Flag ++ " " ++ ExpTime ++ " " ++ integer_to_list(length(Data)) ++ CasUniq ++ "\r\n" ++ Data),
+    {reply, Reply, S#state{socket = Socket}};
+
+handle_call({quit}, _From, #state{socket = Socket} = _) ->
+	gen_tcp:close(Socket),
+	{reply, ok, {}}.
+
+%%--------------------------------------------------------------------
+%% Function: handle_cast(Msg, State) -> {noreply, State} |
+%%                                      {noreply, State, Timeout} |
+%%                                      {stop, Reason, State}
+%% Description: Handling cast messages
+%%--------------------------------------------------------------------
+handle_cast(_Msg, State) ->
+    {noreply, State}.
+
+%%--------------------------------------------------------------------
+%% Function: handle_info(Info, State) -> {noreply, State} |
+%%                                       {noreply, State, Timeout} |
+%%                                       {stop, Reason, State}
+%% Description: Handling all non call/cast messages
+%%--------------------------------------------------------------------
+handle_info(_Info, State) ->
+    {noreply, State}.
+
+%%--------------------------------------------------------------------
+%% Function: terminate(Reason, State) -> void()
+%% Description: This function is called by a gen_server when it is about to
+%% terminate. It should be the opposite of Module:init/1 and do any necessary
+%% cleaning up. When it returns, the gen_server terminates with Reason.
+%% The return value is ignored.
+%%--------------------------------------------------------------------
+terminate(_Reason, _State) ->
+    ok.
+
+%%--------------------------------------------------------------------
+%% Func: code_change(OldVsn, State, Extra) -> {ok, NewState}
+%% Description: Convert process state when code is changed
+%%--------------------------------------------------------------------
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+%%--------------------------------------------------------------------
+%%% API functions
+%%--------------------------------------------------------------------
+
+%% Command descriptions savagely ripped from:
+%% http://code.sixapart.com/svn/memcached/trunk/server/doc/protocol.txt
+
+%%    
+%% Retrieval Commands
+%%	
+
+%% Retrieve memcached stats
+memcache_stats() ->
+	gen_server:call(?SERVER, {stats}).
+
+%% Retrieve value based off of key
+memcache_get(Key) ->
+	gen_server:call(?SERVER, {getkey,{Key}}).
+
+%%
+%% Deletion Commands
+%%	
+
+%% Delete a key and specify time. 
+%%
+%% Time is the amount of time in seconds
+%% the client wishes the server to refuse 
+%% "add" and "replace" commands with this key.
+memcache_delete(Key, Time) ->
+	gen_server:call(?SERVER, {delete, {Key, Time}}).
+
+%%	
+%% Storage Commands
+%%
+
+%% *Flag* is an arbitrary 16-bit unsigned integer (written out in
+%% decimal) that the server stores along with the data and sends back
+%% when the item is retrieved.
+
+%% *ExpTime* is expiration time. If it's 0, the item never expires
+%% (although it may be deleted from the cache to make place for other
+%%  items).
+
+%% *CasUniq* is a unique 64-bit value of an existing entry.
+%% Clients should use the value returned from the "gets" command
+%% when issuing "cas" updates.
+
+%% *Data* is the data you want to store. 
+
+%% set - "store this data"
+memcache_set(Key, Flag, ExpTime, Data) ->
+	gen_server:call(?SERVER, {set, {Key, Flag, ExpTime, Data}}).
+
+%% add - "store this data, but only if the server *doesn't* already hold data for this key"
+memcache_add(Key, Flag, ExpTime, Data) ->
+	gen_server:call(?SERVER, {add, {Key, Flag, ExpTime, Data}}).
+
+%% replace - "store this data, but only if the server *does* already hold data for this key"
+memcache_replace(Key, Flag, ExpTime, Data) ->
+	gen_server:call(?SERVER, {replace, {Key, Flag, ExpTime, Data}}).
+
+%% append - "add this data to an existing key after existing data"
+memcache_append(Key, Data) ->
+	gen_server:call(?SERVER, {append, {Key, Data}}).	
+
+%% prepend - "add this data to an existing key before existing data"
+memcache_prepend(Key, Data) ->
+	gen_server:call(?SERVER, {prepend, {Key, Data}}).
+
+%% cas - "store this data but only if no one else has updated since I last fetched it"
+memcache_cas(Key, Flag, ExpTime, CasUniq, Data) ->
+	gen_server:call(?SERVER, {cas, {Key, Flag, ExpTime, CasUniq, Data}}).
+
+%% Close the socket
+memcache_quit() ->
+	gen_server:call(?SERVER, {quit}).			
+
+%%--------------------------------------------------------------------
+%%% Internal functions
+%%--------------------------------------------------------------------
+
+send_cmd(Socket, Cmd) ->
+    gen_tcp:send(Socket, Cmd ++ "\r\n"),
+    Reply = recv_reply(),
+    io:format("~p~n", [Reply]).
+
+recv_reply() ->
+    receive
+	{tcp,_,Reply} ->
+	    Reply
+    after 5000 ->
+	    timeout
+    end.
+
+