// 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
}
// Run initializes the provided application, but running every Initializer
func (is *initializerSet) Run(app *App) {
init := *is
alreadyRun := make(map[string]bool)
for {
ranInitializer := false
for _, i := range init {
runnable := true
// if we've already been run, skip
if _, ok := alreadyRun[i.Name]; ok {
runnable = false
}
// if any of our dependencies haven't been run, skip
for _, d := range i.Deps {
if _, ok := alreadyRun[d]; !ok {
runnable = false
break
}
}
if !runnable {
continue
}
log.Debugf(context.Background(), "running init:%s", i.Name)
i.Fn(app)
alreadyRun[i.Name] = true
ranInitializer = true
log.Debugf(context.Background(), "ran init:%s", i.Name)
}
// If, after a full loop through the initializers we ran nothing
// we are done
if !ranInitializer {
break
}
}
// if we didn't get to run all initializers, we have a cycle
if len(alreadyRun) != len(init) {
log.Panicln(context.Background(), "initializer cycle detected")
}
}