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authorAlexander Sulfrian <alexander@sulfrian.net>2010-10-15 11:26:47 +0200
committerAlexander Sulfrian <alexander@sulfrian.net>2010-10-15 11:26:47 +0200
commit3c11d5040d2d38616a51aa562ac94e251aa69f6a (patch)
tree9f70e660d6ae6cba2259ea5175e5aedb9e3a925b /common
parent32abe1a28b74263e12afd4475fd7896d9c4e6a9d (diff)
downloaderlang-3c11d5040d2d38616a51aa562ac94e251aa69f6a.tar.gz
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added comments
Diffstat (limited to 'common')
-rw-r--r--common/server.erl31
1 files changed, 26 insertions, 5 deletions
diff --git a/common/server.erl b/common/server.erl
index 67fb000..713a443 100644
--- a/common/server.erl
+++ b/common/server.erl
@@ -8,56 +8,78 @@
-export([start/2, start/3, start_on_node/3, rpc/2]).
start(Name, Mod) ->
- register(Name, spawn(fun() -> loop(Mod, Mod:init()) end)).
+ %% like start/3 but call Mod:init() for getting the initial state
+ start(Name, Mod, Mod:init()).
start(Name, Mod, State) ->
+ %% start a server with the given initial State and register it as
+ %% Name
register(Name, spawn(fun() -> loop(Mod, State) end)).
start_on_node(Node, Mod, State) ->
+ %% link start/3 but start the process on the given Node and not
+ %% register it (only local processes could be registered)
spawn(Node, fun() -> loop(Mod, State) end).
wait_response(_, Ref) ->
+ %% wait for a specific reponse form the server
receive
{Ref, crash} -> exit(rpc);
{Ref, ok, Response} -> Response
end.
rpc(Client, Request) ->
+ %% make a call to the given client (make a reference to find the
+ %% corresponding response)
Ref = make_ref(),
Client ! {Ref, self(), Request},
wait_response(Client, Ref).
loop(Mod, OldState) ->
+ %% main lopp
receive
+ %% pattern, that is matched if a message is directly sended to
+ %% a server (like register and login called form the client
+ %% over the dispatcher)
{From, Request} ->
try Mod:handle(Request, OldState) of
{Response, NewState} ->
From ! {ok, Response},
loop(Mod, NewState)
catch
- _: Why ->
+ %% log error if handle function is not working
+ %% correctly and report the crash to the sender
+ _: Why ->
log_the_error(Request, Why),
From ! {crash},
loop(Mod, OldState)
end;
+ %% pattern is matched if rpc/2 is used, response is send with
+ %% the received reference to match the correct response
{Ref, From, Request} when is_reference(Ref) ->
try Mod:handle(Request, OldState) of
{Response, NewState} ->
From ! {Ref, ok, Response},
loop(Mod, NewState)
catch
+ %% log error if handle function is not working
+ %% correctly and report the crash to the sender
_: Why ->
log_the_error(Request, Why),
From ! {Ref, crash},
loop(Mod, OldState)
end;
+ %% handle messages if a linked process emits an error (no
+ %% response to sender nessessary, sender is dead)
{'EXIT', From, Why} ->
try Mod:handle({'EXIT', From, Why}, OldState) of
NewState ->
loop(Mod, NewState)
catch
+ %% log error if handle function is not working
+ %% correctly and report the crash to the sender
_: Why ->
log_the_error('EXIT', Why),
loop(Mod, OldState)
@@ -65,6 +87,5 @@ loop(Mod, OldState) ->
end.
log_the_error(Request, Why) ->
- io:format("Server request ~p ~n"
- "caused exception ~p~n",
- [Request, Why]).
+ %% helper function to log an error
+ io:format("Server request ~p caused exception ~p~n", [Request, Why]).