path: root/eth/downloader/api.go

// Copyright 2015 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.

package downloader

import (
    "sync"

    "golang.org/x/net/context"

    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/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
    muSyncSubscriptions sync.Mutex
    syncSubscriptions   map[string]rpc.Subscription
}

// NewPublicDownloaderAPI create a new PublicDownloaderAPI.
func NewPublicDownloaderAPI(d *Downloader, m *event.TypeMux) *PublicDownloaderAPI {
    api := &PublicDownloaderAPI{d: d, mux: m, syncSubscriptions: make(map[string]rpc.Subscription)}

    go api.run()

    return api
}

func (api *PublicDownloaderAPI) run() {
    sub := api.mux.Subscribe(StartEvent{}, DoneEvent{}, FailedEvent{})

    for event := range sub.Chan() {
        var notification interface{}

        switch event.Data.(type) {
        case StartEvent:
            result := &SyncingResult{Syncing: true}
            result.Status.Origin, result.Status.Current, result.Status.Height, result.Status.Pulled, result.Status.Known = api.d.Progress()
            notification = result
        case DoneEvent, FailedEvent:
            notification = false
        }

        api.muSyncSubscriptions.Lock()
        for id, sub := range api.syncSubscriptions {
            if sub.Notify(notification) == rpc.ErrNotificationNotFound {
                delete(api.syncSubscriptions, id)
            }
        }
        api.muSyncSubscriptions.Unlock()
    }
}

// Progress gives progress indications when the node is synchronising with the Ethereum network.
type Progress struct {
    Origin  uint64 `json:"startingBlock"`
    Current uint64 `json:"currentBlock"`
    Height  uint64 `json:"highestBlock"`
    Pulled  uint64 `json:"pulledStates"`
    Known   uint64 `json:"knownStates"`
}

// SyncingResult provides information about the current synchronisation status for this node.
type SyncingResult struct {
    Syncing bool     `json:"syncing"`
    Status  Progress `json:"status"`
}

// 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 := ctx.Value(rpc.NotifierContextKey).(rpc.Notifier)
    if !supported {
        return nil, rpc.ErrNotificationsUnsupported
    }

    subscription, err := notifier.NewSubscription(func(id string) {
        api.muSyncSubscriptions.Lock()
        delete(api.syncSubscriptions, id)
        api.muSyncSubscriptions.Unlock()
    })

    if err != nil {
        return nil, err
    }

    api.muSyncSubscriptions.Lock()
    api.syncSubscriptions[subscription.ID()] = subscription
    api.muSyncSubscriptions.Unlock()

    return subscription, nil
}