1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
|
// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package downloader
import (
"context"
"sync"
ethereum "github.com/dexon-foundation/dexon"
"github.com/dexon-foundation/dexon/event"
"github.com/dexon-foundation/dexon/rpc"
)
// PublicDownloaderAPI provides an API which gives information about the current synchronisation status.
// It offers only methods that operates on data that can be available to anyone without security risks.
type PublicDownloaderAPI struct {
d *Downloader
mux *event.TypeMux
installSyncSubscription chan chan interface{}
uninstallSyncSubscription chan *uninstallSyncSubscriptionRequest
}
// NewPublicDownloaderAPI create a new PublicDownloaderAPI. The API has an internal event loop that
// listens for events from the downloader through the global event mux. In case it receives one of
// these events it broadcasts it to all syncing subscriptions that are installed through the
// installSyncSubscription channel.
func NewPublicDownloaderAPI(d *Downloader, m *event.TypeMux) *PublicDownloaderAPI {
api := &PublicDownloaderAPI{
d: d,
mux: m,
installSyncSubscription: make(chan chan interface{}),
uninstallSyncSubscription: make(chan *uninstallSyncSubscriptionRequest),
}
go api.eventLoop()
return api
}
// eventLoop runs a loop until the event mux closes. It will install and uninstall new
// sync subscriptions and broadcasts sync status updates to the installed sync subscriptions.
func (api *PublicDownloaderAPI) eventLoop() {
var (
sub = api.mux.Subscribe(StartEvent{}, DoneEvent{}, FailedEvent{})
syncSubscriptions = make(map[chan interface{}]struct{})
)
for {
select {
case i := <-api.installSyncSubscription:
syncSubscriptions[i] = struct{}{}
case u := <-api.uninstallSyncSubscription:
delete(syncSubscriptions, u.c)
close(u.uninstalled)
case event := <-sub.Chan():
if event == nil {
return
}
var notification interface{}
switch event.Data.(type) {
case StartEvent:
notification = &SyncingResult{
Syncing: true,
Status: api.d.Progress(),
}
case DoneEvent, FailedEvent:
notification = false
}
// broadcast
for c := range syncSubscriptions {
c <- notification
}
}
}
}
// Syncing provides information when this nodes starts synchronising with the Ethereum network and when it's finished.
func (api *PublicDownloaderAPI) Syncing(ctx context.Context) (*rpc.Subscription, error) {
notifier, supported := rpc.NotifierFromContext(ctx)
if !supported {
return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
}
rpcSub := notifier.CreateSubscription()
go func() {
statuses := make(chan interface{})
sub := api.SubscribeSyncStatus(statuses)
for {
select {
case status := <-statuses:
notifier.Notify(rpcSub.ID, status)
case <-rpcSub.Err():
sub.Unsubscribe()
return
case <-notifier.Closed():
sub.Unsubscribe()
return
}
}
}()
return rpcSub, nil
}
// SyncingResult provides information about the current synchronisation status for this node.
type SyncingResult struct {
Syncing bool `json:"syncing"`
Status ethereum.SyncProgress `json:"status"`
}
// uninstallSyncSubscriptionRequest uninstalles a syncing subscription in the API event loop.
type uninstallSyncSubscriptionRequest struct {
c chan interface{}
uninstalled chan interface{}
}
// SyncStatusSubscription represents a syncing subscription.
type SyncStatusSubscription struct {
api *PublicDownloaderAPI // register subscription in event loop of this api instance
c chan interface{} // channel where events are broadcasted to
unsubOnce sync.Once // make sure unsubscribe logic is executed once
}
// Unsubscribe uninstalls the subscription from the DownloadAPI event loop.
// The status channel that was passed to subscribeSyncStatus isn't used anymore
// after this method returns.
func (s *SyncStatusSubscription) Unsubscribe() {
s.unsubOnce.Do(func() {
req := uninstallSyncSubscriptionRequest{s.c, make(chan interface{})}
s.api.uninstallSyncSubscription <- &req
for {
select {
case <-s.c:
// drop new status events until uninstall confirmation
continue
case <-req.uninstalled:
return
}
}
})
}
// SubscribeSyncStatus creates a subscription that will broadcast new synchronisation updates.
// The given channel must receive interface values, the result can either
func (api *PublicDownloaderAPI) SubscribeSyncStatus(status chan interface{}) *SyncStatusSubscription {
api.installSyncSubscription <- status
return &SyncStatusSubscription{api: api, c: status}
}
|
