Debugging

Monitoring connection state

julia> using NATS
julia> nc = NATS.connect()NATS.Connection(unnamed cluster, CONNECTED, 0 subs, 0 unsubs)
julia> @async NATS.status_change(nc) do state
           @info "Connection to $(NATS.clustername(nc)) changed state to $state"
       endTask (runnable) @0x00007f352d87e8b0
julia> NATS.reconnect(nc)┌ Warning: Connection to unnamed cluster on `nats://localhost:4222` lost, trynig to reconnect.
└ @ NATS ~/work/NATS.jl/NATS.jl/src/connection/connect.jl:387
[ Info: Connection to unnamed changed state to CONNECTING
julia> NATS.drain(nc)[ Info: Reconnected to unnamed cluster on `nats://localhost:4222` after 0.01729297637939453 seconds.
[ Info: Connection to unnamed changed state to CONNECTED
[ Info: Connection to unnamed changed state to DRAINING
julia> sleep(7) # Wait a moment to get DRAINED status as well

Connection and subscription statistics

There are detailed statistics of published and received messages collected. They can be accessed for each subscription and connection. Connection statistics aggregates stats for all its subscriptions.

julia> using NATS
julia> nc = NATS.connect()NATS.Connection(unnamed cluster, CONNECTED, 0 subs, 0 unsubs)
julia> sub1 = subscribe(nc, "topic") do msg
           t = Threads.@spawn publish(nc, "other_topic", payload(msg))
           wait(t)
       endNATS.Sub("topic", nothing, 1)
julia> sub2 = subscribe(nc, "other_topic") do msg
           @show payload(msg)
       endNATS.Sub("other_topic", nothing, 2)
julia> NATS.stats(nc)published: 0
 received: 0
  pending: 0
   active: 0
  handled: 0
  errored: 0
  dropped: 0
julia> publish(nc, "topic", "Hi!")
julia> NATS.stats(nc)published: 1
 received: 1
  pending: 1
   active: 0
  handled: 0
  errored: 0
  dropped: 0
julia> NATS.stats(nc, sub1)published: 1
 received: 1
  pending: 0
   active: 0
  handled: 1
  errored: 0
  dropped: 0
julia> NATS.stats(nc, sub2)published: 0
 received: 1
  pending: 1
   active: 0
  handled: 0
  errored: 0
  dropped: 0
julia> sleep(0.1) # Wait for message to be propagatedpayload(msg) = "Hi!"
julia> NATS.stats(nc)published: 2
 received: 2
  pending: 0
   active: 0
  handled: 2
  errored: 0
  dropped: 0
julia> NATS.stats(nc, sub1)published: 1
 received: 1
  pending: 0
   active: 0
  handled: 1
  errored: 0
  dropped: 0
julia> NATS.stats(nc, sub2)published: 0
 received: 1
  pending: 0
   active: 0
  handled: 1
  errored: 0
  dropped: 0
julia> NATS.drain(nc)