Migrating daemon_conn to msg_queue and msg_queue takes over messages

We have some duplication in handling queues, so this is an attempt at
deduplicating some of that work. `daemon_conn` now uses the
`msg_queue` and `channeld` was also migrated to `msg_queue`. At the
same time I made `msg_queue` create a copy of the messages or takes
over messages marked with `take()`. This should make cleaning up
messages easier.

lightningd/channel/channel.c

@@ -17,6 +17,7 @@
 #include <lightningd/debug.h>
 #include <lightningd/derive_basepoints.h>
 #include <lightningd/key_derive.h>
+#include <lightningd/msg_queue.h>
 #include <lightningd/peer_failed.h>
 #include <secp256k1.h>
 #include <signal.h>
@@ -52,32 +53,13 @@ struct peer {
 	struct channel *channel;
 
 	u8 *req_in;
-	const u8 **peer_out;
+
+	struct msg_queue peer_out;
 
 	int gossip_client_fd;
 	struct daemon_conn gossip_client;
 };
 
-static void msg_enqueue(const u8 ***q, const u8 *add)
-{
-	size_t n = tal_count(*q);
-	tal_resize(q, n+1);
-	(*q)[n] = add;
-}
-
-static const u8 *msg_dequeue(const u8 ***q)
-{
-	size_t n = tal_count(*q);
-	const u8 *msg;
-
-	if (!n)
-		return NULL;
-	msg = (*q)[0];
-	memmove(*q, *q + 1, sizeof(**q) * (n-1));
-	tal_resize(q, n-1);
-	return msg;
-}
-
 static void queue_pkt(struct peer *peer, const u8 *msg)
 {
 	msg_enqueue(&peer->peer_out, msg);
@@ -199,7 +181,7 @@ int main(int argc, char *argv[])
 	secp256k1_ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY
 						 | SECP256K1_CONTEXT_SIGN);
 	status_setup(REQ_FD);
-	peer->peer_out = tal_arr(peer, const u8 *, 0);
+	msg_queue_init(&peer->peer_out, peer);
 	init_peer_crypto_state(peer, &peer->pcs);
 	peer->funding_locked[LOCAL] = peer->funding_locked[REMOTE] = false;
 

lightningd/connection.c

@@ -2,26 +2,6 @@
 #include <ccan/take/take.h>
 #include <wire/wire_io.h>
 
-static void daemon_conn_enqueue(struct daemon_conn *dc, u8 *msg)
-{
-	size_t n = tal_count(dc->msg_out);
-	tal_resize(&dc->msg_out, n + 1);
-	dc->msg_out[n] = tal_dup_arr(dc->ctx, u8, msg, tal_count(msg), 0);
-}
-
-static const u8 *daemon_conn_dequeue(struct daemon_conn *dc)
-{
-	const u8 *msg;
-	size_t n = tal_count(dc->msg_out);
-
-	if (n == 0)
-		return NULL;
-	msg = dc->msg_out[0];
-	memmove(dc->msg_out, dc->msg_out + 1, sizeof(dc->msg_in[0]) * (n - 1));
-	tal_resize(&dc->msg_out, n - 1);
-	return msg;
-}
-
 struct io_plan *daemon_conn_read_next(struct io_conn *conn,
 				      struct daemon_conn *dc)
 {
@@ -33,7 +13,7 @@ struct io_plan *daemon_conn_read_next(struct io_conn *conn,
 struct io_plan *daemon_conn_write_next(struct io_conn *conn,
 				       struct daemon_conn *dc)
 {
-	const u8 *msg = daemon_conn_dequeue(dc);
+	const u8 *msg = msg_dequeue(&dc->out);
 	if (msg) {
 		return io_write_wire(conn, take(msg), daemon_conn_write_next,
 				     dc);
@@ -60,7 +40,7 @@ void daemon_conn_init(tal_t *ctx, struct daemon_conn *dc, int fd,
 
 	dc->ctx = ctx;
 	dc->msg_in = NULL;
-	dc->msg_out = tal_arr(ctx, u8 *, 0);
+	msg_queue_init(&dc->out, dc->ctx);
 	dc->conn_fd = fd;
 	dc->msg_queue_cleared_cb = NULL;
 	io_new_conn(ctx, fd, daemon_conn_start, dc);
@@ -68,6 +48,6 @@ void daemon_conn_init(tal_t *ctx, struct daemon_conn *dc, int fd,
 
 void daemon_conn_send(struct daemon_conn *dc, u8 *msg)
 {
-	daemon_conn_enqueue(dc, msg);
+	msg_enqueue(&dc->out, msg);
 	io_wake(dc);
 }

lightningd/connection.h

@@ -4,6 +4,7 @@
 #include "config.h"
 #include <ccan/io/io.h>
 #include <ccan/short_types/short_types.h>
+#include <lightningd/msg_queue.h>
 
 struct daemon_conn {
 	/* Context to tallocate all things from, possibly the
@@ -13,8 +14,8 @@ struct daemon_conn {
 	/* Last message we received */
 	u8 *msg_in;
 
-	/* Array of queued outgoing messages */
-	u8 **msg_out;
+	/* Queue of outgoing messages */
+	struct msg_queue out;
 
 	int conn_fd;
 	struct io_conn *conn;

lightningd/msg_queue.c

@@ -3,13 +3,14 @@
 void msg_queue_init(struct msg_queue *q, const tal_t *ctx)
 {
 	q->q = tal_arr(ctx, const u8 *, 0);
+	q->ctx = ctx;
 }
 
 void msg_enqueue(struct msg_queue *q, const u8 *add)
 {
 	size_t n = tal_count(q->q);
 	tal_resize(&q->q, n+1);
-	q->q[n] = add;
+	q->q[n] = tal_dup_arr(q->ctx, u8, add, tal_len(add), 0);
 
 	/* In case someone is waiting */
 	io_wake(q);

lightningd/msg_queue.h

@@ -7,6 +7,7 @@
 
 struct msg_queue {
 	const u8 **q;
+	const tal_t *ctx;
 };
 
 void msg_queue_init(struct msg_queue *q, const tal_t *ctx);

lightningd/subd.c

@@ -373,7 +373,7 @@ void subd_send_msg(struct subd *sd, const u8 *msg_out)
 	assert(fromwire_peektype(msg_out) != STATUS_TRACE);
 	if (!taken(msg_out))
 		msg_out = tal_dup_arr(sd, u8, msg_out, tal_len(msg_out), 0);
-	msg_enqueue(&sd->outq, msg_out);
+	msg_enqueue(&sd->outq, take(msg_out));
 }
 
 void subd_send_fd(struct subd *sd, int fd)
@@ -382,7 +382,7 @@ void subd_send_fd(struct subd *sd, int fd)
 	u8 *fdmsg = tal_arr(sd, u8, 0);
 	towire_u16(&fdmsg, STATUS_TRACE);
 	towire_u32(&fdmsg, fd);
-	msg_enqueue(&sd->outq, fdmsg);
+	msg_enqueue(&sd->outq, take(fdmsg));
 }
 
 void subd_req_(struct subd *sd,