rpcserver: Convert ws client lifecycle to context. #3025
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This is a minor change to only cast the request method once when parsing a JSON-RPC command.
dnldd
reviewed
Nov 27, 2022
| @@ -124,8 +125,7 @@ func (s *Server) WebsocketHandler(conn *websocket.Conn, remoteAddr string, authe | |||
| return | |||
| } | |||
| s.ntfnMgr.AddClient(client) | |||
| client.Start() | |||
| client.WaitForShutdown() | |||
| client.Run(context.TODO()) | |||
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A todo here to pass down the dcrd parent context to synchronize lifecycles would be good.
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Disregard, just noticed this is being done in #3026.
dnldd
approved these changes
Nov 27, 2022
matheusd
reviewed
Nov 28, 2022
This updates the websocket notification manager block connected handler to skip creation of the associated notification when no clients have requested it inside of the handler instead of prior to it so it is consistent with the rest of the handlers. It was previously done outside of the handler in order to skip a bunch of work that is no longer relevant due to the change to the filters some time ago.
This modifies the lifecycle of websocket clients to use the expected pattern for running subsystems based on contexts. In particular, this replaces the Start and WaitForShutdown methods with a single method named Run and arranges for it to block until the provided context is cancelled. This is more flexible for the caller since it can easily turn blocking code into async code while the reverse is not true. The new Run method waits for all goroutines that it starts to shutdown before returning to help ensure an orderly shutdown. Since there are exported methods that send messages to the output and notification handler goroutines via channels and those goroutines are stopped during the shutdown process, all sends select across both the channels in question as well as a quit channel which is closed when the context it cancelled. This ensures callers can't end up blocking on send to a goroutine that is no longer running without needing additional mutexes.
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This requires #3024.This modifies the lifecycle of websocket clients to use the expected pattern for running subsystems based on contexts.
In particular, this replaces the
StartandWaitForShutdownmethods with a single method namedRunand arranges for it to block until the provided context is cancelled. This is more flexible for the caller since it can easily turn blocking code into async code while the reverse is not true.The new
Runmethod waits for all goroutines that it starts to shutdown before returning to help ensure an orderly shutdown.Since there are exported methods that send messages to the output and notification handler goroutines via channels and those goroutines are stopped during the shutdown process, all sends select across both the channels in question as well as a quit channel which is closed when the context it cancelled. This ensures callers can't end up blocking on send to a goroutine that is no longer running without needing additional mutexes.
It also contains a couple of other minor consistency cleanup commits.