steem-block-db/main.go

package main

//import "github.com/spf13/viper"
//import "encoding/json"
//import "fmt"
import "sync"
import "time"
import "encoding/json"
import log "github.com/sirupsen/logrus"

const steemAPIURL = "https://api.steemit.com"

func main() {
	processinit()
	app := NewApp(&appconfig{})
	app.main()
}

func processinit() {
	//FIXME(sneak) use viper to set loglevel
	//log.SetLevel(log.DebugLevel)
	log.SetLevel(log.InfoLevel)
}

type BlockNumber uint64

type App struct {
	datastore                 SteemDataStorer
	api                       *SteemAPI
	currentNetworkBlockHeight BlockNumber
	currentLocalBlockHeight   BlockNumber
	currentFetchingThreads    uint
	desiredFetchingThreads    uint
	lock                      *sync.Mutex
}

type appconfig map[string]string

func NewApp(config *appconfig) *App {
	self := new(App)
	self.init(config)
	return self
}

func (self *App) init(config *appconfig) {
	self.api = NewSteemAPI(steemAPIURL)
	self.datastore = NewSteemDataStore("./d")
	self.desiredFetchingThreads = 20
	self.currentFetchingThreads = 0
	self.lock = &sync.Mutex{}
}

func (self *App) updateCurrentBlockHeight() {
	h := self.fetchCurrentBlockHeight()
	if h > self.currentNetworkBlockHeight {
		self.lock.Lock()
		defer self.lock.Unlock()
		self.currentNetworkBlockHeight = h
		log.Infof("current block height is now %d", self.currentNetworkBlockHeight)
	}
}

func (self *App) main() {
	log.Infof("steem block data fetcher starting up...")
	self.mainloop()
}

func (self *App) numFetchers() uint {
	self.lock.Lock()
	defer self.lock.Unlock()
	return self.currentFetchingThreads
}

func (self *App) incrFetchers() {
	self.lock.Lock()
	defer self.lock.Unlock()
	self.currentFetchingThreads += 1
}

func (self *App) decrFetchers() {
	self.lock.Lock()
	defer self.lock.Unlock()
	self.currentFetchingThreads -= 1
}

func (self *App) spawnNewFetcher(blockNum BlockNumber) {
	log.Infof("spawning fetcher for block %d", blockNum)
	go func() {
		self.incrFetchers()
		self.storeBlockOps(blockNum, self.fetchBlockOps(blockNum))
		self.datastore.SetCurrentBlockHeight()
		time.Sleep(250 * time.Millisecond)
		self.decrFetchers()

	}()
}

func (self *App) storeBlockOps(blockNum BlockNumber, blockOps *[]byte) {
	self.datastore.StoreBlockOps(blockNum, blockOps)
}

// note that parallelFetchAndStoreBlocks does not respect the
// limitation on number of desired fetchers, that is for the caller
func (self *App) parallelFetchAndStoreBlocks(start BlockNumber, end BlockNumber) {
	var diff = uint64(end) - uint64(start)
	var i uint64
	for i = 0; i < diff; i++ {
		self.spawnNewFetcher(BlockNumber(uint64(start) + i))
	}
}

func (self *App) mainloop() {
	log.Infof("using %d fetching threads", self.desiredFetchingThreads)
	for {
		self.updateCurrentBlockHeight()
		localHeight := self.datastore.CurrentBlockHeight()
		log.Infof("our highest fetched block height is %d", localHeight)
		log.Infof("current number of active fetchers: %d", self.numFetchers())
		time.Sleep(1 * time.Second)
		if localHeight < self.currentNetworkBlockHeight {
			// we need to fetch some blocks from the network
			avail := self.desiredFetchingThreads - self.numFetchers()
			diff := uint64(self.currentNetworkBlockHeight) - uint64(localHeight)
			log.Infof("we need to fetch %d blocks", diff)
			if uint64(diff) > uint64(avail) {
				self.parallelFetchAndStoreBlocks(BlockNumber(uint64(localHeight)+1), BlockNumber(uint64(localHeight)+1+uint64(avail)))
			} else {
				// just spawn fetchers for the blocks we don't have
				// spawning will update the number of running fetchers
				self.parallelFetchAndStoreBlocks(localHeight+1, self.currentNetworkBlockHeight)
			}
		}
		//needFetchers := self.desiredFetchingThreads - self.numFetchers()
	}
}

func (self *App) fetchCurrentBlockHeight() BlockNumber {
	r, err := self.api.GetDynamicGlobalProperties()
	if err != nil {
		panic("can't fetch global properties, bailing")
	}
	if r.LastIrreversibleBlockNum < 100 {
		panic("can't fetch global properties, bailing")
	}
	return r.LastIrreversibleBlockNum
}

func (self *App) fetchBlockOps(blockNum BlockNumber) *[]byte {
	r, err := self.api.GetOpsInBlock(blockNum)
	if err != nil {
		panic(err)
	}
	bytes, err := json.Marshal(r)
	if err != nil {
		panic(err)
	}
	return &bytes
	//self.datastore.writeBlockOps(blockNum, bytes)
}