Use resources on stream handler

Author: MegaRedHand

libp2p/libp2p.c

@@ -114,6 +114,22 @@ static ERL_NIF_TERM get_handle_result(ErlNifEnv *env, ErlNifResourceType *type,
     return make_ok_tuple2(env, term);
 }
 
+void send_message(erl_pid_t _pid, uintptr_t stream_handle)
+{
+    // Passed as void* to avoid including erl_nif.h in the header.
+    ErlNifPid *pid = (ErlNifPid *)_pid;
+    ErlNifEnv *env = enif_alloc_env();
+
+    ERL_NIF_TERM message = get_handle_result(env, Stream, stream_handle);
+
+    int result = enif_send(NULL, pid, env, message);
+    // On error, the env isn't freed by the function.
+    if (!result)
+    {
+        enif_free_env(env);
+    }
+}
+
 /*********/
 /* Utils */
 /*********/
@@ -171,7 +187,7 @@ ERL_FUNCTION(host_set_stream_handler)
 
     IF_ERROR(!enif_self(env, pid), "failed to get pid");
 
-    SetStreamHandler(host, proto_id, (void *)pid);
+    SetStreamHandler(host, proto_id, (void *)pid, send_message);
 
     return enif_make_atom(env, "ok");
 }

libp2p/main.go

@@ -82,14 +82,13 @@ func (h C.uintptr_t) HostClose() {
 }
 
 //export SetStreamHandler
-func (h C.uintptr_t) SetStreamHandler(protoId string, procId C.erl_pid_t) {
+func (h C.uintptr_t) SetStreamHandler(protoId string, procId C.erl_pid_t, callback C.send_message_t) {
 	handle := cgo.Handle(h)
 	host := handle.Value().(host.Host)
 	// WARN: we clone the string because the underlying buffer is owned by Elixir
 	goProtoId := protocol.ID(strings.Clone(protoId))
 	handler := func(stream network.Stream) {
-		// NOTE: the stream handle should be deleted by calling Stream.Close()
-		C.send_message(procId, C.uintptr_t(cgo.NewHandle(stream)))
+		C.run_callback(callback, procId, C.uintptr_t(cgo.NewHandle(stream)))
 	}
 	host.SetStreamHandler(protocol.ID(goProtoId), handler)
 }

libp2p/utils.c

@@ -1,23 +1,6 @@
 #include "utils.h"
-#include <erl_nif.h>
 
-ErlNifPid *get_pid(erl_pid_t _pid)
+void run_callback(send_message_t send_message, erl_pid_t pid, uintptr_t stream)
 {
-    return (ErlNifPid *)_pid;
-}
-
-void send_message(erl_pid_t _pid, uintptr_t stream_handle)
-{
-    // Passed as void* to avoid including erl_nif.h in the header.
-    ErlNifPid *pid = get_pid(_pid);
-    ErlNifEnv *env = enif_alloc_env();
-
-    ERL_NIF_TERM message = enif_make_tuple2(env, enif_make_atom(env, "ok"), enif_make_uint64(env, stream_handle));
-
-    int result = enif_send(NULL, pid, env, message);
-    // On error, the env isn't freed by the function.
-    if (!result)
-    {
-        enif_free_env(env);
-    }
+    send_message(pid, stream);
 }

libp2p/utils.h

@@ -2,6 +2,11 @@
 
 #include <stdint.h> // for uintptr_t
 
+// For better readability. Pointer is casted to opaque,
+// to avoid having to include erl_nif.h in Go.
 typedef void *erl_pid_t;
 
-void send_message(erl_pid_t pid, uintptr_t stream);
+// send_message function signature.
+typedef void (*send_message_t)(erl_pid_t pid, uintptr_t stream);
+
+void run_callback(send_message_t send_message, erl_pid_t pid, uintptr_t stream);