refactor open call to enable the OTP-8623 receive optimization

Refactored the handling of the open call and the driver's handling of the port_control call to enable the OTP-8623 receive optimization.
vinoski · Mar 24, 2013 · c34b18a · c34b18a · okeuday · Feb 11, 2014
1 parent a67e9b6
commit c34b18a
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Showing 2 changed files with 26 additions and 33 deletions.
diff --git a/c_src/syslog_drv.c b/c_src/syslog_drv.c
@@ -51,17 +51,6 @@ struct syslogdrv {
 
 typedef struct syslogdrv syslogdrv_t;
 
-static ErlDrvSSizeT encode_error(char* buf, char* error) {
-    int index = 0;
-    if (ei_encode_version(buf, &index) ||
-        ei_encode_tuple_header(buf, &index, 2) ||
-        ei_encode_atom(buf, &index, "error") ||
-        ei_encode_atom(buf, &index, error)) {
-        return (ErlDrvSSizeT)ERL_DRV_ERROR_GENERAL;
-    }
-    return index+1;
-}
-
 static ErlDrvData syslogdrv_start(ErlDrvPort port, char *buf)
 {
     syslogdrv_t* d = (syslogdrv_t*)driver_alloc(sizeof(syslogdrv_t));
@@ -110,7 +99,7 @@ static ErlDrvSSizeT syslogdrv_control(ErlDrvData handle, unsigned int command,
     }
 
     if (ei_decode_version(buf, &index, &version)) {
-        return encode_error(*rbuf, "badver");
+        return (ErlDrvSSizeT)ERL_DRV_ERROR_BADARG;
     }
     if (ei_decode_tuple_header(buf, &index, &arity) || arity != 4) {
         return (ErlDrvSSizeT)ERL_DRV_ERROR_BADARG;
@@ -124,11 +113,13 @@ static ErlDrvSSizeT syslogdrv_control(ErlDrvData handle, unsigned int command,
 
         syslogdrv_t* nd = (syslogdrv_t*)driver_alloc(sizeof(syslogdrv_t));
         if (nd == NULL) {
-            return encode_error(*rbuf, "enomem");
+            errno = ENOMEM;
+            return (ErlDrvSSizeT)ERL_DRV_ERROR_ERRNO;
         }
         nd->ident = driver_alloc(size+1);
         if (nd->ident == NULL) {
-            return encode_error(*rbuf, "enomem");
+            errno = ENOMEM;
+            return (ErlDrvSSizeT)ERL_DRV_ERROR_ERRNO;
         }
         if (ei_decode_string(buf, &index, nd->ident)) {
             driver_free(nd->ident);
@@ -153,7 +144,10 @@ static ErlDrvSSizeT syslogdrv_control(ErlDrvData handle, unsigned int command,
         }
         ref = driver_alloc_binary(size);
         if (ref == NULL) {
-            return encode_error(*rbuf, "enomem");
+            driver_free(nd->ident);
+            driver_free(nd);
+            errno = ENOMEM;
+            return (ErlDrvSSizeT)ERL_DRV_ERROR_ERRNO;
         }
         if (ei_decode_binary(buf, &index, ref->orig_bytes, &len)) {
             driver_free_binary(ref);

diff --git a/src/syslog.erl b/src/syslog.erl
@@ -128,24 +128,23 @@ init([]) ->
     end.
 
 handle_call({open, Ident, Logopt, Facility}, {Pid,_}, #state{port = Port} = State) ->
-    Ref = make_ref(),
-    Args = term_to_binary({Ident, Logopt, Facility, term_to_binary(Ref)}),
-    Reply = try erlang:port_control(Port, ?SYSLOGDRV_OPEN, Args) of
-                <<>> ->
-                    receive
-                        {Ref, {ok, Log}=Result} ->
-                            erlang:port_connect(Log, Pid),
-                            unlink(Log),
-                            Result;
-                        {Ref, Result} ->
-                            Result
-                    end;
-                BinError ->
-                    binary_to_term(BinError)
-            catch
-                _:Reason ->
-                    {error, Reason}
-            end,
+    Reply =
+        try
+            Ref = make_ref(),
+            Args = term_to_binary({Ident, Logopt, Facility, term_to_binary(Ref)}),
+            erlang:port_control(Port, ?SYSLOGDRV_OPEN, Args),
+            receive
+                {Ref, {ok, Log}=Result} ->
+                    erlang:port_connect(Log, Pid),
+                    unlink(Log),
+                    Result;
+                {Ref, Result} ->
+                    Result
+            end
+        catch
+            _:Reason ->
+                {error, Reason}
+        end,
     {reply, Reply, State};
 handle_call(_Msg, _From, State) ->
     {reply, ok, State}.