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// Copyright 2017 Tendermint. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package trust
import (
"encoding/json"
"fmt"
"sync"
"time"
"github.com/tendermint/tendermint/libs/service"
dbm "github.com/tendermint/tm-db"
)
const defaultStorePeriodicSaveInterval = 1 * time.Minute
var trustMetricKey = []byte("trustMetricStore")
// MetricStore - Manages all trust metrics for peers
type MetricStore struct {
service.BaseService
// Maps a Peer.Key to that peer's TrustMetric
peerMetrics map[string]*Metric
// Mutex that protects the map and history data file
mtx sync.Mutex
// The db where peer trust metric history data will be stored
db dbm.DB
// This configuration will be used when creating new TrustMetrics
config MetricConfig
}
// NewTrustMetricStore returns a store that saves data to the DB
// and uses the config when creating new trust metrics.
// Use Start to to initialize the trust metric store
func NewTrustMetricStore(db dbm.DB, tmc MetricConfig) *MetricStore {
tms := &MetricStore{
peerMetrics: make(map[string]*Metric),
db: db,
config: tmc,
}
tms.BaseService = *service.NewBaseService(nil, "MetricStore", tms)
return tms
}
// OnStart implements Service
func (tms *MetricStore) OnStart() error {
if err := tms.BaseService.OnStart(); err != nil {
return err
}
tms.mtx.Lock()
defer tms.mtx.Unlock()
tms.loadFromDB()
go tms.saveRoutine()
return nil
}
// OnStop implements Service
func (tms *MetricStore) OnStop() {
tms.BaseService.OnStop()
tms.mtx.Lock()
defer tms.mtx.Unlock()
// Stop all trust metric go-routines
for _, tm := range tms.peerMetrics {
tm.Stop()
}
// Make the final trust history data save
tms.saveToDB()
}
// Size returns the number of entries in the trust metric store
func (tms *MetricStore) Size() int {
tms.mtx.Lock()
defer tms.mtx.Unlock()
return tms.size()
}
// AddPeerTrustMetric takes an existing trust metric and associates it with a peer key.
// The caller is expected to call Start on the TrustMetric being added
func (tms *MetricStore) AddPeerTrustMetric(key string, tm *Metric) {
tms.mtx.Lock()
defer tms.mtx.Unlock()
if key == "" || tm == nil {
return
}
tms.peerMetrics[key] = tm
}
// GetPeerTrustMetric returns a trust metric by peer key
func (tms *MetricStore) GetPeerTrustMetric(key string) *Metric {
tms.mtx.Lock()
defer tms.mtx.Unlock()
tm, ok := tms.peerMetrics[key]
if !ok {
// If the metric is not available, we will create it
tm = NewMetricWithConfig(tms.config)
tm.Start()
// The metric needs to be in the map
tms.peerMetrics[key] = tm
}
return tm
}
// PeerDisconnected pauses the trust metric associated with the peer identified by the key
func (tms *MetricStore) PeerDisconnected(key string) {
tms.mtx.Lock()
defer tms.mtx.Unlock()
// If the Peer that disconnected has a metric, pause it
if tm, ok := tms.peerMetrics[key]; ok {
tm.Pause()
}
}
// Saves the history data for all peers to the store DB.
// This public method acquires the trust metric store lock
func (tms *MetricStore) SaveToDB() {
tms.mtx.Lock()
defer tms.mtx.Unlock()
tms.saveToDB()
}
/* Private methods */
// size returns the number of entries in the store without acquiring the mutex
func (tms *MetricStore) size() int {
return len(tms.peerMetrics)
}
/* Loading & Saving */
/* Both loadFromDB and savetoDB assume the mutex has been acquired */
// Loads the history data for all peers from the store DB
// cmn.Panics if file is corrupt
func (tms *MetricStore) loadFromDB() bool {
// Obtain the history data we have so far
bytes, err := tms.db.Get(trustMetricKey)
if err != nil {
panic(err)
}
if bytes == nil {
return false
}
peers := make(map[string]MetricHistoryJSON)
err = json.Unmarshal(bytes, &peers)
if err != nil {
panic(fmt.Sprintf("Could not unmarshal Trust Metric Store DB data: %v", err))
}
// If history data exists in the file,
// load it into trust metric
for key, p := range peers {
tm := NewMetricWithConfig(tms.config)
tm.Start()
tm.Init(p)
// Load the peer trust metric into the store
tms.peerMetrics[key] = tm
}
return true
}
// Saves the history data for all peers to the store DB
func (tms *MetricStore) saveToDB() {
tms.Logger.Debug("Saving TrustHistory to DB", "size", tms.size())
peers := make(map[string]MetricHistoryJSON)
for key, tm := range tms.peerMetrics {
// Add an entry for the peer identified by key
peers[key] = tm.HistoryJSON()
}
// Write all the data back to the DB
bytes, err := json.Marshal(peers)
if err != nil {
tms.Logger.Error("Failed to encode the TrustHistory", "err", err)
return
}
tms.db.SetSync(trustMetricKey, bytes)
}
// Periodically saves the trust history data to the DB
func (tms *MetricStore) saveRoutine() {
t := time.NewTicker(defaultStorePeriodicSaveInterval)
defer t.Stop()
loop:
for {
select {
case <-t.C:
tms.SaveToDB()
case <-tms.Quit():
break loop
}
}
}