Release v0.1.0

vendor/github.com/btcsuite/btcd/blockchain/notifications.go

@@ -0,0 +1,81 @@
+// 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{}) {
+	// Generate and send the notification.
+	n := Notification{Type: typ, Data: data}
+	b.notificationsLock.RLock()
+	for _, callback := range b.notifications {
+		callback(&n)
+	}
+	b.notificationsLock.RUnlock()
+}