19b42c3c9b
The BlockChain struct emits notifications for various events, but it is only possible to register one listener. This changes the interface and implementations to allow multiple listeners.
82 lines
2.7 KiB
Go
82 lines
2.7 KiB
Go
// Copyright (c) 2013-2016 The btcsuite developers
|
|
// Use of this source code is governed by an ISC
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package blockchain
|
|
|
|
import (
|
|
"fmt"
|
|
)
|
|
|
|
// NotificationType represents the type of a notification message.
|
|
type NotificationType int
|
|
|
|
// NotificationCallback is used for a caller to provide a callback for
|
|
// notifications about various chain events.
|
|
type NotificationCallback func(*Notification)
|
|
|
|
// Constants for the type of a notification message.
|
|
const (
|
|
// NTBlockAccepted indicates the associated block was accepted into
|
|
// the block chain. Note that this does not necessarily mean it was
|
|
// added to the main chain. For that, use NTBlockConnected.
|
|
NTBlockAccepted NotificationType = iota
|
|
|
|
// NTBlockConnected indicates the associated block was connected to the
|
|
// main chain.
|
|
NTBlockConnected
|
|
|
|
// NTBlockDisconnected indicates the associated block was disconnected
|
|
// from the main chain.
|
|
NTBlockDisconnected
|
|
)
|
|
|
|
// notificationTypeStrings is a map of notification types back to their constant
|
|
// names for pretty printing.
|
|
var notificationTypeStrings = map[NotificationType]string{
|
|
NTBlockAccepted: "NTBlockAccepted",
|
|
NTBlockConnected: "NTBlockConnected",
|
|
NTBlockDisconnected: "NTBlockDisconnected",
|
|
}
|
|
|
|
// String returns the NotificationType in human-readable form.
|
|
func (n NotificationType) String() string {
|
|
if s, ok := notificationTypeStrings[n]; ok {
|
|
return s
|
|
}
|
|
return fmt.Sprintf("Unknown Notification Type (%d)", int(n))
|
|
}
|
|
|
|
// Notification defines notification that is sent to the caller via the callback
|
|
// function provided during the call to New and consists of a notification type
|
|
// as well as associated data that depends on the type as follows:
|
|
// - NTBlockAccepted: *btcutil.Block
|
|
// - NTBlockConnected: *btcutil.Block
|
|
// - NTBlockDisconnected: *btcutil.Block
|
|
type Notification struct {
|
|
Type NotificationType
|
|
Data interface{}
|
|
}
|
|
|
|
// Subscribe to block chain notifications. Registers a callback to be executed
|
|
// when various events take place. See the documentation on Notification and
|
|
// NotificationType for details on the types and contents of notifications.
|
|
func (b *BlockChain) Subscribe(callback NotificationCallback) {
|
|
b.notificationsLock.Lock()
|
|
b.notifications = append(b.notifications, callback)
|
|
b.notificationsLock.Unlock()
|
|
}
|
|
|
|
// sendNotification sends a notification with the passed type and data if the
|
|
// caller requested notifications by providing a callback function in the call
|
|
// to New.
|
|
func (b *BlockChain) sendNotification(typ NotificationType, data interface{}) {
|
|
b.notificationsLock.RLock()
|
|
defer b.notificationsLock.RUnlock()
|
|
|
|
// Generate and send the notification.
|
|
n := Notification{Type: typ, Data: data}
|
|
for _, callback := range b.notifications {
|
|
callback(&n)
|
|
}
|
|
}
|