attempt to fix a race

[xgess]

i've been seeing some racey behavior in my bot. sometimes payment events don't get put into the channel if other things are happening at the same time.

a little bit of research led me to this: https://github.com/golang/go/issues/19685

@mmaxim what do you think? i was surprised it would help, but it does seem (at least locally) to have improved the situation. hard to know for sure since it's a pretty sporadic problem.

[heronhaye]

Does the race coincide with the bot trying to send messages? You could try this, don't know if it's what's causing the wallet issue in particular.

        "io"
        "os/exec"
        "strings"
+       "sync"
        "time"
 )

@@ -17,6 +18,7 @@ type API struct {
        input    io.Writer
        username string
        runOpts  RunOptions
+       sync.Mutex
 }

 func getUsername(runOpts RunOptions) (username string, err error) {
@@ -168,20 +170,32 @@ type sendMessageArg struct {
        Params sendMessageParams
 }

-func (a *API) doSend(arg sendMessageArg) error {
+func (a *API) doSend(arg sendMessageArg) (*SendMessageResponse, error) {
+       a.Lock()
+       defer a.Unlock()
+

[xgess]

@heronhaye took your suggestion (saw another race). there was already a lock, so i kinda just moved around where it was used so that it would actually lock the pipes while they're in use.