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package main
import (
"log"
"reflect"
"strings"
"time"
"github.com/getwtxt/registry"
"github.com/syndtr/goleveldb/leveldb"
)
// Checks whether it's time to refresh
// the cache.
func checkCacheTime() bool {
return time.Since(confObj.lastCache) > confObj.cacheInterval
}
// Checks whether it's time to push
// the cache to the database
func checkDBtime() bool {
return time.Since(confObj.lastPush) > confObj.dbInterval
}
// Launched by init as a goroutine to constantly watch
// for the update interval to pass.
func cacheAndPush() {
for {
if checkCacheTime() {
refreshCache()
}
if checkDBtime() {
if err := pushDatabase(); err != nil {
log.Printf("Error pushing cache to database: %v\n", err)
}
}
}
}
// Refreshes the cache.
func refreshCache() {
// Iterate over the registry and
// update each individual user.
for k := range twtxtCache.Reg {
err := twtxtCache.UpdateUser(k)
if err != nil {
log.Printf("%v\n", err)
continue
}
}
// Re-scrape all the remote registries
// to see if they have any new users
// to add locally.
for _, v := range remoteRegistries.List {
err := twtxtCache.ScrapeRemoteRegistry(v)
if err != nil {
log.Printf("Error while refreshing local copy of remote registry user data: %v\n", err)
}
}
confObj.mu.Lock()
confObj.lastCache = time.Now()
confObj.mu.Unlock()
}
// Pushes the registry's cache data to a local
// database for safe keeping.
func pushDatabase() error {
// Acquire the database from the aether.
// goleveldb is concurrency-safe, so we
// can immediately push it back into the
// channel for other functions to use.
db := <-dbChan
dbChan <- db
// Create a batch write job so it can
// be done at one time rather than
// per entry.
twtxtCache.Mu.RLock()
var dbBasket = &leveldb.Batch{}
for k, v := range twtxtCache.Reg {
dbBasket.Put([]byte(k+"*Nick"), []byte(v.Nick))
dbBasket.Put([]byte(k+"*URL"), []byte(v.URL))
dbBasket.Put([]byte(k+"*IP"), []byte(v.IP.String()))
dbBasket.Put([]byte(k+"*Date"), []byte(v.Date))
for i, e := range v.Status {
rfc := i.Format(time.RFC3339)
dbBasket.Put([]byte(k+"*Status*"+rfc), []byte(e))
}
}
twtxtCache.Mu.RUnlock()
// Save our list of remote registries to scrape.
for k, v := range remoteRegistries.List {
dbBasket.Put([]byte("remote*"+string(k)), []byte(v))
}
// Execute the batch job.
if err := db.Write(dbBasket, nil); err != nil {
return err
}
// Update the last push time for
// our timer/watch function to
// reference.
confObj.mu.Lock()
confObj.lastPush = time.Now()
confObj.mu.Unlock()
return nil
}
// Pulls registry data from the DB on startup.
// Iterates over the database one entry at a time.
func pullDatabase() {
// Acquire the database from the aether.
// goleveldb is concurrency-safe, so we
// can immediately push it back into the
// channel for other functions to use.
db := <-dbChan
dbChan <- db
iter := db.NewIterator(nil, nil)
// Read the database key-by-key
for iter.Next() {
key := iter.Key()
val := iter.Value()
split := strings.Split(string(key), "*")
urls := string(split[0])
field := string(split[1])
// Start with an empty Data struct. If
// there's already one in the cache, pull
// it and use it instead.
data := registry.NewUserData()
twtxtCache.Mu.RLock()
if _, ok := twtxtCache.Reg[urls]; ok {
data = twtxtCache.Reg[urls]
}
twtxtCache.Mu.RUnlock()
ref := reflect.ValueOf(data).Elem()
// Use reflection to find the right field
// in the Data struct. Once found, assign
// the value and break so the DB iteration
// can continue.
if field != "Status" && urls != "remote" {
for i := 0; i < ref.NumField(); i++ {
f := ref.Field(i)
if strings.Contains(f.String(), field) {
f.Set(reflect.ValueOf(val))
break
}
}
} else if field == "Status" && urls != "remote" {
// If we're looking at a Status entry in the DB,
// parse the time then add it to the TimeMap under
// data.Status
thetime, err := time.Parse(time.RFC3339, split[2])
if err != nil {
log.Printf("%v\n", err)
}
data.Status[thetime] = string(val)
} else {
// The third and final possibility is
// if we've come across an entry for
// a remote twtxt registry to scrape.
// If so, add it to our list.
remoteRegistries.Mu.Lock()
remoteRegistries.List = append(remoteRegistries.List, string(val))
remoteRegistries.Mu.Unlock()
continue
}
// Push the data struct (back) into
// the cache.
twtxtCache.Mu.Lock()
twtxtCache.Reg[urls] = data
twtxtCache.Mu.Unlock()
}
iter.Release()
err := iter.Error()
if err != nil {
log.Printf("Error while pulling DB into registry cache: %v\n", err)
}
}
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