func ExampleTransaction() {
ctx := Example_auth()
const retries = 3
// Increment a counter.
// See https://cloud.google.com/appengine/articles/sharding_counters for
// a more scalable solution.
type Counter struct {
Count int
}
key := datastore.NewKey(ctx, "counter", "CounterA", 0, nil)
for i := 0; i < retries; i++ {
tx, err := datastore.NewTransaction(ctx)
if err != nil {
break
}
var c Counter
if err := tx.Get(key, &c); err != nil && err != datastore.ErrNoSuchEntity {
break
}
c.Count++
if _, err := tx.Put(key, &c); err != nil {
break
}
// Attempt to commit the transaction. If there's a conflict, try again.
if _, err := tx.Commit(); err != datastore.ErrConcurrentTransaction {
break
}
}
}
// LogRunComplete logs the end of a completed (failed of finished) run of
// a coduno testrun
func LogRunComplete(pKey *datastore.Key, build *BuildData, in,
out, extra string, exit error, prepLog string, stats syscall.Rusage) {
tx, err := datastore.NewTransaction(ctx)
if err != nil {
fmt.Fprintf(os.Stderr, "LogRunComplete: Could not get transaction!")
}
build.EndTime = time.Now()
if exit != nil {
build.Status = "failed"
} else {
build.Status = "good"
}
_, err = tx.Put(pKey, build)
if err != nil {
fmt.Fprintf(os.Stderr, "LogRunComplete: Putting build failed!")
tx.Rollback()
return
}
data := &LogData{in, out, extra, prepLog, stats}
k := datastore.NewIncompleteKey(ctx, buildKind, pKey)
_, err = tx.Put(k, data)
if err != nil {
fmt.Fprintf(os.Stderr, "LogRunComplete: Putting data failed!")
tx.Rollback()
return
}
tx.Commit()
}