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