Decouple ..attach_circuit() from most of its callers.

Long ago we used to call connection_ap_handshake_attach_circuit()
only in a few places, since connection_ap_attach_pending() attaches
all the pending connections, and does so regularly.  But this turned
out to have a performance problem: it would introduce a delay to
launching or connecting a stream.

We couldn't just call connection_ap_attach_pending() every time we
make a new connection, since it walks the whole connection list.  So
we started calling connection_ap_attach_pending all over, instead!
But that's kind of ugly and messes up our callgraph.

So instead, we now have connection_ap_attach_pending() use a list
only of the pending connections, so we can call it much more
frequently.  We have a separate function to scan the whole
connection array to see if we missed adding anything, and log a
warning if so.

Closes ticket #17590

1 files changed, 2 insertions, 0 deletions

diff --git a/src/or/connection_edge.h b/src/or/connection_edge.h
index 7c0b9c0767..203099976f 100644
--- a/src/or/connection_edge.h
+++ b/src/or/connection_edge.h
@@ -64,7 +64,9 @@ int connection_edge_is_rendezvous_stream(edge_connection_t *conn);
 int connection_ap_can_use_exit(const entry_connection_t *conn,
                                const node_t *exit);
 void connection_ap_expire_beginning(void);
+void connection_ap_rescan_and_attach_pending(void);
 void connection_ap_attach_pending(void);
+void connection_ap_mark_as_pending_circuit(entry_connection_t *entry_conn);
 void connection_ap_fail_onehop(const char *failed_digest,
                                cpath_build_state_t *build_state);
 void circuit_discard_optional_exit_enclaves(extend_info_t *info);