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Exploit the fact the BaseService's closed Quit channel will keep emitting quit signals to close both readRoutine and writeRoutine

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This commit is contained in:
Silas Davis
2017-10-24 21:53:42 +01:00
parent f6adddb4a8
commit 4cb02d0bf2
1 changed files with 4 additions and 8 deletions
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12
rpc/lib/client/ws_client.go
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@ -51,7 +51,6 @@ type WSClient struct {
backlog chan types.RPCRequest // stores a single user request received during a conn failure backlog chan types.RPCRequest // stores a single user request received during a conn failure
reconnectAfter chan error // reconnect requests reconnectAfter chan error // reconnect requests
readRoutineQuit chan struct{} // a way for readRoutine to close writeRoutine readRoutineQuit chan struct{} // a way for readRoutine to close writeRoutine
writeRoutineQuit chan struct{} // a way for writeRoutine to close readRoutine (on <-BaseService.Quit)
wg sync.WaitGroup wg sync.WaitGroup
@ -280,7 +279,6 @@ func (c *WSClient) reconnect() error {
func (c *WSClient) startReadWriteRoutines() { func (c *WSClient) startReadWriteRoutines() {
c.wg.Add(2) c.wg.Add(2)
c.readRoutineQuit = make(chan struct{}) c.readRoutineQuit = make(chan struct{})
c.writeRoutineQuit = make(chan struct{})
go c.readRoutine() go c.readRoutine()
go c.writeRoutine() go c.writeRoutine()
} }
@ -386,9 +384,6 @@ func (c *WSClient) writeRoutine() {
case <-c.readRoutineQuit: case <-c.readRoutineQuit:
return return
case <-c.Quit: case <-c.Quit:
// We need to fan out the quit message from the single BaseService Quit Channel to the readRoutine
// Use a non-blocking close rather than a send in case readRoutine is in the process of quitting
close(c.writeRoutineQuit)
c.conn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")) c.conn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
return return
} }
@ -438,10 +433,11 @@ func (c *WSClient) readRoutine() {
continue continue
} }
c.Logger.Info("got response", "resp", response.Result) c.Logger.Info("got response", "resp", response.Result)
// Combine a non-blocking read on writeRoutineQuit with a non-blocking write on ResponsesCh to avoid blocking // Combine a non-blocking read on BaseService.Quit with a non-blocking write on ResponsesCh to avoid blocking
// c.wg.Wait() in c.Stop() // c.wg.Wait() in c.Stop(). Note we rely on Quit being closed so that it sends unlimited Quit signals to stop
// both readRoutine and writeRoutine
select { select {
case <-c.writeRoutineQuit: case <-c.Quit:
case c.ResponsesCh <- response: case c.ResponsesCh <- response:
} }
} }