// Serve starts the horizon system, binding it to a socket, setting up
// the shutdown signals and starting the appropriate db-streaming pumps.
func (a *App) Serve() {
a.web.router.Compile()
http.Handle("/", a.web.router)
listenStr := fmt.Sprintf(":%d", a.config.Port)
listener := bind.Socket(listenStr)
log.Infof(a.ctx, "Starting horizon on %s", listener.Addr())
graceful.HandleSignals()
bind.Ready()
graceful.PreHook(func() {
log.Info(a.ctx, "received signal, gracefully stopping")
a.Cancel()
})
graceful.PostHook(func() {
log.Info(a.ctx, "stopped")
})
if a.config.Autopump {
sse.SetPump(a.ctx, sse.AutoPump)
} else {
sse.SetPump(a.ctx, db.NewLedgerClosePump(a.ctx, a.historyDb))
}
err := graceful.Serve(listener, http.DefaultServeMux)
if err != nil {
log.Panic(a.ctx, err)
}
graceful.Wait()
}
// NewLedgerClosePump starts a background proc that continually watches the
// history database provided. The watch is stopped after the provided context
// is cancelled.
//
// Every second, the proc spawned by calling this func will check to see
// if a new ledger has been imported (by ruby-horizon as of 2015-04-30, but
// should eventually end up being in this project). If a new ledger is seen
// the the channel returned by this function emits
func NewLedgerClosePump(ctx context.Context, db *sql.DB) <-chan time.Time {
result := make(chan time.Time)
go func() {
var lastSeenLedger int32
for {
select {
case <-time.After(1 * time.Second):
var latestLedger int32
row := db.QueryRow("SELECT MAX(sequence) FROM history_ledgers")
err := row.Scan(&latestLedger)
if err != nil {
log.Warn(ctx, "Failed to check latest ledger", err)
break
}
if latestLedger > lastSeenLedger {
log.Debugf(ctx, "saw new ledger: %d, prev: %d", latestLedger, lastSeenLedger)
lastSeenLedger = latestLedger
result <- time.Now()
}
case <-ctx.Done():
log.Info(ctx, "canceling ledger pump")
return
}
}
}()
return result
}