// concurrentIncrements starts two Goroutines in parallel, both of which
// read the integers stored at the other's key and add it onto their own.
// It is checked that the outcome is serializable, i.e. exactly one of the
// two Goroutines (the later write) sees the previous write by the other.
// The isMultiphase option runs the transaction in multiple phases recreating
// the transaction from the transaction protobuf returned from the server.
func concurrentIncrements(db *client.DB, t *testing.T, isMultiphase bool) {
// wgStart waits for all transactions to line up, wgEnd has the main
// function wait for them to finish.
var wgStart, wgEnd sync.WaitGroup
wgStart.Add(2 + 1)
wgEnd.Add(2)
for i := 0; i < 2; i++ {
go func(i int) {
// Read the other key, write key i.
readKey := []byte(fmt.Sprintf(testUser+"/value-%d", (i+1)%2))
writeKey := []byte(fmt.Sprintf(testUser+"/value-%d", i))
defer wgEnd.Done()
wgStart.Done()
// Wait until the other goroutines are running.
wgStart.Wait()
if isMultiphase {
applyInc := func(txn *client.Txn) (error, proto.Transaction) {
txn.SetDebugName(fmt.Sprintf("test-%d", i))
b := client.Batch{}
// Retrieve the other key.
b.Get(readKey)
if err := txn.Run(&b); err != nil {
return err, txn.GetState()
}
otherValue := int64(0)
gr := b.Results[0].Rows[0]
if gr.Value != nil {
otherValue = gr.ValueInt()
}
// New txn.
txn = db.ReconstructTxn(txn.GetState())
// Write our key.
b = client.Batch{}
b.Inc(writeKey, 1+otherValue)
if err := txn.Run(&b); err != nil {
return err, txn.GetState()
}
// New txn.
txn = db.ReconstructTxn(txn.GetState())
err := txn.Commit(&client.Batch{})
return err, txn.GetState()
}
for r := retry.Start(client.DefaultTxnRetryOptions); r.Next(); {
txn := db.ReconstructTxn(proto.Transaction{})
if err, txnProto := applyInc(txn); err != nil {
// New txn.
txn = db.ReconstructTxn(txnProto)
if err := txn.Rollback(); err != nil {
t.Error(err)
} else {
// retry
continue
}
}
// exit retry
break
}
} else {
if err := db.Txn(func(txn *client.Txn) error {
txn.SetDebugName(fmt.Sprintf("test-%d", i))
// Retrieve the other key.
gr, err := txn.Get(readKey)
if err != nil {
return err
}
otherValue := int64(0)
if gr.Value != nil {
otherValue = gr.ValueInt()
}
_, err = txn.Inc(writeKey, 1+otherValue)
return err
}); err != nil {
t.Error(err)
}
}
}(i)
}
// Kick the goroutines loose.
wgStart.Done()
// Wait for the goroutines to finish.
wgEnd.Wait()
// Verify that both keys contain something and, more importantly, that
// one key actually contains the value of the first writer and not only
// its own.
total := int64(0)
results := []int64(nil)
for i := 0; i < 2; i++ {
readKey := []byte(fmt.Sprintf(testUser+"/value-%d", i))
gr, err := db.Get(readKey)
if err != nil {
log.Fatal(err)
}
if gr.Value == nil {
t.Fatalf("unexpected empty key: %s=%v", readKey, gr.Value)
}
total += gr.ValueInt()
results = append(results, gr.ValueInt())
}
// First writer should have 1, second one 2
if total != 3 {
t.Fatalf("got unserializable values %v", results)
}
}