client/core: safe swap and comms tweaks #663
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chappjc
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chappjc
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Sep 9, 2020
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| // reconnect begins reconnection immediately. | ||
| func (conn *wsConn) reconnect() { | ||
| conn.setConnected(false) | ||
| conn.reconnectCh <- struct{}{} | ||
| } | ||
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| // queueReconnect queues a reconnection attempt. | ||
| func (conn *wsConn) queueReconnect(wait time.Duration) { | ||
| conn.setConnected(false) | ||
| log.Infof("Attempting reconnect to %s in %d seconds.", conn.cfg.URL, wait/time.Second) | ||
| time.AfterFunc(wait, func() { conn.reconnectCh <- struct{}{} }) | ||
| } |
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Using these from outside read() would be all kinds of problematic, so they are moved into read.
| err = conn.ws.WriteMessage(websocket.TextMessage, b) | ||
| if err != nil { | ||
| log.Errorf("write error: %v", err) | ||
| log.Errorf("Send: WriteMessage error: %v", err) |
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I had briefly added a conn.close() here to cause the read loop to error and trigger reconnect, but the write error itself seems to be enough to cause reads (e.g. ws.ReadJSON) to return with an error immediately.
buck54321
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Sep 9, 2020
client/core: prevent swap bcast with stale dex conn more careful reconnect, remove max reconnects
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Swap contracts are no longer permitted to be broadcast if the DEX connection is known to be down. This can happen when a computer or client process comes out of suspend and immediately tries to take their action, particularly the taker trying to bcast their swap. The net connection's read timeout must still put the link into a failed state quickly for this to work during a resume, but this connectivity check is also valuable with normal connectivity trouble, not just machine/process suspend.
Triggering of ticks with the tick timer is also modified to skip tick execution if a long delay since the previous timer fire is detected (computer resume) to allow time for DEX re-connection. This together with the swap check described above prevents needlessly broadcasting a swap contract for a match that is revoked unbeknownst to the client. The swap check is still necessary however since asset tip changes also trigger a tick.
client/comms.WsConn reconnect logic is tweaked to prevent back-to-back or duplicate queued reconnect attempts. This is especially necessary now since send errors in Send and the ping handler now also trigger reconnect. Previously read errors would only trigger reconnect. The (*wsConn).read loop now detects and logs timeouts immediately before all other error checks to hasten flagging the connection as down and to log the timeout as the cause in plain language.