relay: introduce ConnectContext for better control over network latency

A websocket dial may hand for an unreasonably long time and a nostr client
has no control over this when trying to connect to a relay.

Go started introducing context in networking since 2014 -
see https://go.dev/blog/context - and by now many net functions have
XxxContext equivalent, such as DialContext.

Example usage of the change introduced by this commit:

    ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
    defer cancel()
    r, err := nostr.RelayConnectContext(ctx, "ws://relay.example.org")

The code above makes RelayConnectContext last at most 3 sec, returning
an error if a connection cannot be established in the given time.
This helps whenever a tight control over connection latency is required,
such as distributed systems.

The change is backwards-compatible except the case where RelayPool.Add
sent an error over the returned channel without actually closing said
channel. I believe it was a bug.
This commit is contained in:
alex
2022-12-17 19:39:10 +01:00
committed by fiatjaf
parent ad71e083d8
commit c327f622f3
5 changed files with 138 additions and 33 deletions
+1
View File
@@ -36,6 +36,7 @@ golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9 h1:psW17arqaxU48Z5kZ0CQnk
golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
golang.org/x/exp v0.0.0-20221106115401-f9659909a136 h1:Fq7F/w7MAa1KJ5bt2aJ62ihqp9HDcRuyILskkpIAurw=
golang.org/x/exp v0.0.0-20221106115401-f9659909a136/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=