/juju

rpc: introduce ClientConn and ServerConn interfaces #4905

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merged 8 commits into from Apr 4, 2016

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@davecheney @howbazaar @jujubot
@davecheney
Contributor

davecheney commented Mar 29, 2016

This PR is in preparation for adding tests for retrying temporary RPC errors.

It introduces two new interface types, rpc.ClientConn and rpc.ServerConn whose purposes are self explanatory. Also provide constructor functions for these new interface types as NewConn has been unexported.

Remove the ability to provide a RequestNotifier when requesting a ClientConn, this was never used by any non test caller and is only part of the bidirectional code for the rpc package, which is also unused by juju.

Adjust the callers in the api and apiserver packages to these new interfaces, very few changes were needed apart from adjusting the types in various wrapper types.

The bidirection nature of the rpc package remains, but if needed the caller must assert their ServerConn value to a ClientConn, or vice versa. No code in Juju does this, but the rpc tests assert this behaviour

Finally, unexport rpc.Conn.

davecheney added some commits Mar 24, 2016

@davecheney
rpc: refactor NewConn into Client and Server methods 
The underlying rpc.Conn is bidirectional, but in our use case we always
send requests from the client to the server which responds.

Hide rpc.NewConn and replace it with a pair of NewClientConn and
NewServerConn methods to deliniate the method sets of both types so they
can be mocked.
9ef92fd
@davecheney
rpc: introduce interim rpc.ClientConn interface
764849d
@davecheney
rpc: remove ClientConn.Start method 
ClientConn.Start is always called on return from rpc.NewClientConn, so
just make NewClientConn call Start before returning. This simplifies the
rpc client API.
54200f5
@davecheney
rpc: use atomic operation to increment conn.reqId
83a0405
@davecheney
api: remove unused RPCClient testing turd
90a2aa6
@davecheney
rpc: introduce rpc.ServerConn interface
6e745c2
@davecheney
rpc: unexport rpc.Conn
c1c59e5
rpc/rpc_test.go
@@ -234,7 +235,7 @@ func (a *CallbackMethods) Factorial(x int64val) (int64val, error) {
return int64val{1}, nil
}
var r int64val
- err := a.root.conn.Call(rpc.Request{"CallbackMethods", 0, "", "Factorial"}, int64val{x.I - 1}, &r)
+ err := a.root.conn.(rpc.ClientConn).Call(rpc.Request{"CallbackMethods", 0, "", "Factorial"}, int64val{x.I - 1}, &r)
@howbazaar

howbazaar Apr 3, 2016

Owner

Can we please make this two lines?

client := a.root.conn.(rpc.ClientConn)
err := client.Call(...)
@howbazaar
Owner

howbazaar commented Apr 3, 2016

The diff was much larger than necessary due to the renaming the receiver of 'conn' -> 'c'.

However, LGTM with one suggestion.
@davecheney
Contributor

davecheney commented Apr 3, 2016

The diff was much larger than necessary due to the renaming the receiver of 'conn' -> 'c'.

That's because conn became a type, so it couldn't also be the name of the receiver.
@davecheney
Contributor

davecheney commented Apr 3, 2016

$$merge$$
@jujubot
Contributor

jujubot commented Apr 3, 2016

Status: merge request accepted. Url: http://juju-ci.vapour.ws:8080/job/github-merge-juju

@jujubot jujubot merged commit da28cfa into juju:api-call-retry Apr 4, 2016

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