// New initializes and returns a transaction for passed storage engine. The options
// are used to change the behavior of the transaction itself.
func New(engine storage.Engine, options Options) (*Transaction, error) {
var (
id uint64
err error
)
// Start time of the transaction.
startTime := time.Now().UTC()
// Increment the transaction ID.
if id, err = txid(engine); err != nil {
logrus.Errorf("transactor: could not create transaction: %s", err)
return nil, ErrNoID
}
if options.ReceiveWait == 0 {
options.ReceiveWait = DefaultOptions.ReceiveWait
}
if options.BufferSize == 0 {
options.BufferSize = DefaultOptions.BufferSize
}
tx := Transaction{
ID: id,
StartTime: startTime,
Engine: engine,
options: options,
pipes: make(map[string]*Pipeline),
stream: make(chan *origins.Fact, options.BufferSize),
done: make(chan struct{}),
errch: make(chan error),
pipewg: &sync.WaitGroup{},
mainwg: &sync.WaitGroup{},
entity: &origins.Ident{
Name: fmt.Sprint(id),
},
}
tx.mainwg.Add(1)
// Run transaction in the background.
go tx.run()
// Write facts about the transaction including the identity
// and start time.
tx.Write(&origins.Fact{
Domain: origins.TransactionsDomain,
Entity: tx.entity,
Attribute: &origins.Ident{
Domain: origins.AttrsDomain,
Name: "ident",
},
Value: &origins.Ident{
Name: tx.entity.Name,
},
})
tx.Write(&origins.Fact{
Domain: origins.TransactionsDomain,
Entity: tx.entity,
Attribute: &origins.Ident{
Name: "startTime",
},
Value: &origins.Ident{
Name: chrono.FormatNano(tx.StartTime),
},
})
return &tx, nil
}
func (tx *Transaction) run() {
// Start the receiver. This blocks until the stream ends or is interrupted.
err := tx.receive()
if err == nil {
// Collect the domains affected across transacted facts and generates
// facts about them.
var (
domain string
fact *origins.Fact
)
identAttr := &origins.Ident{
Domain: origins.AttrsDomain,
Name: "ident",
}
for _, domain = range tx.domains {
// Transact the identity attribute.
fact = &origins.Fact{
Domain: origins.DomainsDomain,
Entity: &origins.Ident{
Name: domain,
},
Attribute: identAttr,
Value: &origins.Ident{
Name: domain,
},
}
if err = tx.route(fact, false); err != nil {
break
}
// Transact a fact that declares the domain has been seen by this
// transaction.
fact = &origins.Fact{
Domain: origins.DomainsDomain,
Entity: &origins.Ident{
Name: domain,
},
Attribute: &origins.Ident{
Name: "ping",
},
Value: tx.entity,
}
if err = tx.route(fact, false); err != nil {
break
}
}
}
// Set the error.
tx.Error = err
// Mark the end time of processing.
tx.EndTime = time.Now().UTC()
// Transact the end time.
tx.route(&origins.Fact{
Domain: origins.TransactionsDomain,
Entity: tx.entity,
Attribute: &origins.Ident{
Name: "endTime",
},
Value: &origins.Ident{
Name: chrono.FormatNano(tx.EndTime),
},
}, false)
// Error during the transaction that caused the abort.
if tx.Error != nil {
tx.route(&origins.Fact{
Domain: origins.TransactionsDomain,
Entity: tx.entity,
Attribute: &origins.Ident{
Name: "error",
},
Value: &origins.Ident{
Name: fmt.Sprint(tx.Error),
},
}, false)
}
// Signal the transaction is closed so no more external facts are received.
close(tx.done)
// Wait for the pipelines to finish there work.
tx.pipewg.Wait()
// Complete the transaction by committing or aborting.
tx.complete()
// Signal the main goroutine is done.
tx.mainwg.Done()
}