path: root/dashboard/dashboard.go

// Copyright 2017 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 dashboard

//go:generate go-bindata -nometadata -o assets.go -prefix assets -pkg dashboard assets/public/...

import (
    "fmt"
    "io/ioutil"
    "net"
    "net/http"
    "path/filepath"
    "sync"
    "sync/atomic"
    "time"

    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/rpc"
    "github.com/rcrowley/go-metrics"
    "golang.org/x/net/websocket"
)

const (
    memorySampleLimit  = 200 // Maximum number of memory data samples
    trafficSampleLimit = 200 // Maximum number of traffic data samples
)

var nextId uint32 // Next connection id

// Dashboard contains the dashboard internals.
type Dashboard struct {
    config *Config

    listener net.Listener
    conns    map[uint32]*client // Currently live websocket connections
    charts   charts             // The collected data samples to plot
    lock     sync.RWMutex       // Lock protecting the dashboard's internals

    quit chan chan error // Channel used for graceful exit
    wg   sync.WaitGroup
}

// message embraces the data samples of a client message.
type message struct {
    History *charts     `json:"history,omitempty"` // Past data samples
    Memory  *chartEntry `json:"memory,omitempty"`  // One memory sample
    Traffic *chartEntry `json:"traffic,omitempty"` // One traffic sample
    Log     string      `json:"log,omitempty"`     // One log
}

// client represents active websocket connection with a remote browser.
type client struct {
    conn   *websocket.Conn // Particular live websocket connection
    msg    chan message    // Message queue for the update messages
    logger log.Logger      // Logger for the particular live websocket connection
}

// charts contains the collected data samples.
type charts struct {
    Memory  []*chartEntry `json:"memorySamples,omitempty"`
    Traffic []*chartEntry `json:"trafficSamples,omitempty"`
}

// chartEntry represents one data sample
type chartEntry struct {
    Time  time.Time `json:"time,omitempty"`
    Value float64   `json:"value,omitempty"`
}

// New creates a new dashboard instance with the given configuration.
func New(config *Config) (*Dashboard, error) {
    return &Dashboard{
        conns:  make(map[uint32]*client),
        config: config,
        quit:   make(chan chan error),
    }, nil
}

// Protocols is a meaningless implementation of node.Service.
func (db *Dashboard) Protocols() []p2p.Protocol { return nil }

// APIs is a meaningless implementation of node.Service.
func (db *Dashboard) APIs() []rpc.API { return nil }

// Start implements node.Service, starting the data collection thread and the listening server of the dashboard.
func (db *Dashboard) Start(server *p2p.Server) error {
    db.wg.Add(2)
    go db.collectData()
    go db.collectLogs() // In case of removing this line change 2 back to 1 in wg.Add.

    http.HandleFunc("/", db.webHandler)
    http.Handle("/api", websocket.Handler(db.apiHandler))

    listener, err := net.Listen("tcp", fmt.Sprintf("%s:%d", db.config.Host, db.config.Port))
    if err != nil {
        return err
    }
    db.listener = listener

    go http.Serve(listener, nil)

    return nil
}

// Stop implements node.Service, stopping the data collection thread and the connection listener of the dashboard.
func (db *Dashboard) Stop() error {
    // Close the connection listener.
    var errs []error
    if err := db.listener.Close(); err != nil {
        errs = append(errs, err)
    }
    // Close the collectors.
    errc := make(chan error, 1)
    for i := 0; i < 2; i++ {
        db.quit <- errc
        if err := <-errc; err != nil {
            errs = append(errs, err)
        }
    }
    // Close the connections.
    db.lock.Lock()
    for _, c := range db.conns {
        if err := c.conn.Close(); err != nil {
            c.logger.Warn("Failed to close connection", "err", err)
        }
    }
    db.lock.Unlock()

    // Wait until every goroutine terminates.
    db.wg.Wait()
    log.Info("Dashboard stopped")

    var err error
    if len(errs) > 0 {
        err = fmt.Errorf("%v", errs)
    }

    return err
}

// webHandler handles all non-api requests, simply flattening and returning the dashboard website.
func (db *Dashboard) webHandler(w http.ResponseWriter, r *http.Request) {
    log.Debug("Request", "URL", r.URL)

    path := r.URL.String()
    if path == "/" {
        path = "/dashboard.html"
    }
    // If the path of the assets is manually set
    if db.config.Assets != "" {
        blob, err := ioutil.ReadFile(filepath.Join(db.config.Assets, path))
        if err != nil {
            log.Warn("Failed to read file", "path", path, "err", err)
            http.Error(w, "not found", http.StatusNotFound)
            return
        }
        w.Write(blob)
        return
    }
    blob, err := Asset(filepath.Join("public", path))
    if err != nil {
        log.Warn("Failed to load the asset", "path", path, "err", err)
        http.Error(w, "not found", http.StatusNotFound)
        return
    }
    w.Write(blob)
}

// apiHandler handles requests for the dashboard.
func (db *Dashboard) apiHandler(conn *websocket.Conn) {
    id := atomic.AddUint32(&nextId, 1)
    client := &client{
        conn:   conn,
        msg:    make(chan message, 128),
        logger: log.New("id", id),
    }
    done := make(chan struct{}) // Buffered channel as sender may exit early

    // Start listening for messages to send.
    db.wg.Add(1)
    go func() {
        defer db.wg.Done()

        for {
            select {
            case <-done:
                return
            case msg := <-client.msg:
                if err := websocket.JSON.Send(client.conn, msg); err != nil {
                    client.logger.Warn("Failed to send the message", "msg", msg, "err", err)
                    client.conn.Close()
                    return
                }
            }
        }
    }()
    // Send the past data.
    client.msg <- message{
        History: &db.charts,
    }
    // Start tracking the connection and drop at connection loss.
    db.lock.Lock()
    db.conns[id] = client
    db.lock.Unlock()
    defer func() {
        db.lock.Lock()
        delete(db.conns, id)
        db.lock.Unlock()
    }()
    for {
        fail := []byte{}
        if _, err := conn.Read(fail); err != nil {
            close(done)
            return
        }
        // Ignore all messages
    }
}

// collectData collects the required data to plot on the dashboard.
func (db *Dashboard) collectData() {
    defer db.wg.Done()

    for {
        select {
        case errc := <-db.quit:
            errc <- nil
            return
        case <-time.After(db.config.Refresh):
            inboundTraffic := metrics.DefaultRegistry.Get("p2p/InboundTraffic").(metrics.Meter).Rate1()
            memoryInUse := metrics.DefaultRegistry.Get("system/memory/inuse").(metrics.Meter).Rate1()
            now := time.Now()
            memory := &chartEntry{
                Time:  now,
                Value: memoryInUse,
            }
            traffic := &chartEntry{
                Time:  now,
                Value: inboundTraffic,
            }
            // Remove the first elements in case the samples' amount exceeds the limit.
            first := 0
            if len(db.charts.Memory) == memorySampleLimit {
                first = 1
            }
            db.charts.Memory = append(db.charts.Memory[first:], memory)
            first = 0
            if len(db.charts.Traffic) == trafficSampleLimit {
                first = 1
            }
            db.charts.Traffic = append(db.charts.Traffic[first:], traffic)

            db.sendToAll(&message{
                Memory:  memory,
                Traffic: traffic,
            })
        }
    }
}

// collectLogs collects and sends the logs to the active dashboards.
func (db *Dashboard) collectLogs() {
    defer db.wg.Done()

    // TODO (kurkomisi): log collection comes here.
    for {
        select {
        case errc := <-db.quit:
            errc <- nil
            return
        case <-time.After(db.config.Refresh / 2):
            db.sendToAll(&message{
                Log: "This is a fake log.",
            })
        }
    }
}

// sendToAll sends the given message to the active dashboards.
func (db *Dashboard) sendToAll(msg *message) {
    db.lock.Lock()
    for _, c := range db.conns {
        select {
        case c.msg <- *msg:
        default:
            c.conn.Close()
        }
    }
    db.lock.Unlock()
}