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cache.go
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cache.go
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package main
import (
"encoding/json"
"fmt"
"github.com/fzzy/radix/redis"
"github.com/samalba/dockerclient"
"net/url"
"reflect"
"strconv"
"strings"
"time"
)
const CACHE_PREFIX = "docker"
const EVENTS_CHANNEL = "docker_events"
type Cache struct {
redisConn *redis.Client
id string
ttl time.Duration
}
func NewCache(cacheUrl string, id string, ttl time.Duration) (*Cache, error) {
u, err := url.Parse(cacheUrl)
if err != nil {
return nil, err
}
redisConn, err := redis.DialTimeout("tcp", u.Host,
time.Duration(30)*time.Second)
if err != nil {
return nil, err
}
if len(u.Path) > 2 {
db, err := strconv.Atoi(u.Path[1:])
if err == nil {
return nil, fmt.Errorf("Wrong Redis db: %s", err)
}
r := redisConn.Cmd("select", db)
if r.Err != nil {
return nil, r.Err
}
}
if u.User != nil {
if pwd, ok := u.User.Password(); ok {
r := redisConn.Cmd("auth", pwd)
if r.Err != nil {
return nil, r.Err
}
}
}
cache := &Cache{redisConn, id, ttl}
cache.publishEvent("new_host", id)
return cache, nil
}
func (cache *Cache) publishEvent(args ...string) error {
event := strings.Join(args, ":")
r := cache.redisConn.Cmd("publish", EVENTS_CHANNEL, event)
if r.Err != nil {
return r.Err
}
return nil
}
func (cache *Cache) getHostTimestamp() int64 {
localts := time.Now().UTC().Unix()
r := cache.redisConn.Cmd("time")
if r.Err != nil {
// Redis is too old to support the "time" command
return localts
}
ts, err := r.List()
if err == nil {
return localts
}
// Return time from Redis (all hosts will be synchronized)
timestamp, err := strconv.ParseInt(ts[0], 10, 64)
if err != nil {
return localts
}
return timestamp
}
func (cache *Cache) refreshHostLastUpdate() error {
lastUpdate := strconv.FormatInt(cache.getHostTimestamp(), 10)
return cache.SetHostParam("last_update", lastUpdate)
}
func (cache *Cache) deleteHost(id string) {
c := cache.redisConn
c.Append("multi")
key := CACHE_PREFIX + ":hosts"
c.Append("srem", key, id)
key += ":" + id
c.Append("del", key)
key += ":containers"
c.Append("del", key)
c.Append("exec")
for i := 0; i < 5; i++ {
c.GetReply()
}
}
func (cache *Cache) ClearExpiredHosts() error {
hosts, err := cache.ListHosts()
if err != nil {
return err
}
for _, host := range hosts {
if host == cache.id {
// ignore myself
continue
}
key := fmt.Sprintf("%s:hosts:%s", CACHE_PREFIX, host)
r := cache.redisConn.Cmd("hget", key, "last_update")
if r.Err != nil {
continue
}
lastUpdate, err := r.Int64()
if err != nil {
continue
}
r = cache.redisConn.Cmd("hget", key, "update_interval")
if r.Err != nil {
continue
}
updateInterval, err := r.Int64()
if err != nil {
continue
}
timestamp := cache.getHostTimestamp()
// If the host missed 2 updates, we consider it expired
if (timestamp - lastUpdate) < (2 * updateInterval) {
continue
}
cache.deleteHost(host)
cache.publishEvent("expired_host", host)
}
return nil
}
// Converts a struct to a map of strings
func structToMap(st interface{}, out *map[string]string, prefix string) {
val := reflect.ValueOf(st)
if reflect.TypeOf(st).Kind() == reflect.Ptr {
val = val.Elem()
}
for i := 0; i < val.NumField(); i++ {
valueField := val.Field(i)
typeField := val.Type().Field(i)
f := valueField.Interface()
val := reflect.ValueOf(f)
if val.Kind() == reflect.Ptr {
val = val.Elem()
}
name := prefix + strings.ToLower(typeField.Name)
if val.Kind() == reflect.Struct {
structToMap(f, out, name+"_")
continue
}
switch val.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
(*out)[name] = strconv.FormatInt(val.Int(), 10)
case reflect.Bool:
(*out)[name] = strconv.FormatBool(val.Bool())
case reflect.String:
(*out)[name] = val.String()
case reflect.Array, reflect.Slice, reflect.Map:
b, err := json.Marshal(val.Interface())
if err != nil {
continue
}
(*out)[name] = string(b)
}
}
}
func (cache *Cache) SetContainerInfo(container *dockerclient.ContainerInfo) error {
m := make(map[string]string)
structToMap(container, &m, "")
key := fmt.Sprintf("%s:containers:%s", CACHE_PREFIX, container.Id)
c := cache.redisConn
c.Append("multi")
c.Append("del", key)
for k, v := range m {
c.Append("hset", key, k, v)
}
c.Append("hset", key, "host", cache.id)
c.Append("expire", key, int(cache.ttl.Seconds()))
c.Append("exec")
for i := 0; i < len(m)+4; i++ {
r := c.GetReply()
if r.Err != nil {
return r.Err
}
}
// Set the container's json
key += ":json"
b, err := json.Marshal(container)
if err != nil {
return err
}
c.Append("multi")
c.Append("del", key)
c.Append("set", key, string(b))
c.Append("expire", key, int(cache.ttl.Seconds()))
c.Append("exec")
for i := 0; i < 5; i++ {
r := c.GetReply()
if r.Err != nil {
return r.Err
}
}
// Save container info to extra keys for easier identification
c.Append("multi")
key = fmt.Sprintf("%s:containers", CACHE_PREFIX)
c.Append("sadd", key, container.Id)
key = fmt.Sprintf("%s:images", CACHE_PREFIX)
c.Append("sadd", key, container.Image)
key = fmt.Sprintf("%s:images:%s:hosts", CACHE_PREFIX, container.Image)
c.Append("sadd", key, cache.id)
key = fmt.Sprintf("%s:images:%s:containers", CACHE_PREFIX, container.Image)
c.Append("sadd", key, container.Id)
c.Append("exec")
for i := 0; i < 6; i++ {
r := c.GetReply()
if r.Err != nil {
return r.Err
}
}
key = fmt.Sprintf("%s:images:%s", CACHE_PREFIX, container.Image)
r := cache.redisConn.Cmd("hincrby", key, "containers_running", 1)
if r.Err != nil {
return r.Err
}
return nil
}
func (cache *Cache) AddContainer(container *dockerclient.ContainerInfo) error {
err := cache.SetContainerInfo(container)
if err != nil {
return err
}
key := fmt.Sprintf("%s:hosts:%s", CACHE_PREFIX, cache.id)
r := cache.redisConn.Cmd("hincrby", key, "containers_running", 1)
if r.Err != nil {
return r.Err
}
err = cache.refreshHostLastUpdate()
if err != nil {
return err
}
cache.publishEvent("new_container", cache.id, container.Id)
return nil
}
func (cache *Cache) DeleteContainer(container *dockerclient.ContainerInfo) error {
key := fmt.Sprintf("%s:containers:%s", CACHE_PREFIX, container.Id)
c := cache.redisConn
c.Append("multi")
c.Append("del", key)
key = fmt.Sprintf("%s:hosts:%s:containers", CACHE_PREFIX, cache.id)
c.Append("srem", key, container.Id)
key = fmt.Sprintf("%s:images:%s:hosts", CACHE_PREFIX, container.Image)
c.Append("srem", key, cache.id)
key = fmt.Sprintf("%s:images:%s:containers", CACHE_PREFIX, container.Image)
c.Append("srem", key, container.Id)
key = fmt.Sprintf("%s:hosts:%s", CACHE_PREFIX, cache.id)
c.Append("hincrby", key, "containers_running", -1)
key = fmt.Sprintf("%s:images:%s", CACHE_PREFIX, container.Image)
c.Append("hincrby", key, "containers_running", -1)
c.Append("exec")
for i := 0; i < 9; i++ {
r := c.GetReply()
if r.Err != nil {
return r.Err
}
}
err := cache.refreshHostLastUpdate()
if err != nil {
return err
}
cache.publishEvent("delete_container", cache.id, container.Id)
return nil
}
func (cache *Cache) SetContainersList(containers []dockerclient.Container) error {
// Store containers list and set containers info
key := fmt.Sprintf("%s:hosts:%s:containers", CACHE_PREFIX, cache.id)
c := cache.redisConn
c.Append("multi")
c.Append("del", key)
for _, container := range containers {
c.Append("sadd", key, container.Id)
}
c.Append("expire", key, int(cache.ttl.Seconds()))
c.Append("exec")
for i := 0; i < len(containers)+4; i++ {
r := c.GetReply()
if r.Err != nil {
return r.Err
}
}
// Store some host stats
err := cache.SetHostParam("containers_running", strconv.Itoa(len(containers)))
if err != nil {
return err
}
err = cache.SetHostParam("update_interval", strconv.Itoa(int(cache.ttl.Seconds())))
if err != nil {
return err
}
err = cache.refreshHostLastUpdate()
if err != nil {
return err
}
key = fmt.Sprintf("%s:hosts:%s", CACHE_PREFIX, cache.id)
r := cache.redisConn.Cmd("expire", key, int(cache.ttl.Seconds()))
if err != nil {
return err
}
// Register the host in the host list
key = CACHE_PREFIX + ":hosts"
r = cache.redisConn.Cmd("sadd", key, cache.id)
if r.Err != nil {
return r.Err
}
r = cache.redisConn.Cmd("expire", key, int(cache.ttl.Seconds()))
if r.Err != nil {
return r.Err
}
cache.publishEvent("refresh_containers", cache.id)
return nil
}
func (cache *Cache) SetHostParam(key string, value string) error {
hKey := fmt.Sprintf("%s:hosts:%s", CACHE_PREFIX, cache.id)
r := cache.redisConn.Cmd("hset", hKey, key, value)
if r.Err != nil {
return r.Err
}
return nil
}
/*
* All Methods below are used to read data from the Cache
*/
func (cache *Cache) ListHosts() ([]string, error) {
r := cache.redisConn.Cmd("smembers", CACHE_PREFIX+":hosts")
if r.Err != nil {
return nil, r.Err
}
hosts, err := r.List()
if err != nil {
return nil, err
}
return hosts, nil
}
func (cache *Cache) ListContainers(host string) ([]string, error) {
}