code layouts and comments

conf/defaults.ini

@@ -108,11 +108,10 @@ cache_mode = private
 
 #################################### Cache server #############################
 [cache_server]
-# Either "memory", "redis", "memcached" or "database" default is "database"
+# Either "redis", "memcached" or "database" default is "database"
 type = database
 
 # cache connectionstring options
-# memory: no config required. Should only be used on single install grafana.
 # database: will use Grafana primary database.
 # redis: config like redis server e.g. `addr=127.0.0.1:6379,pool_size=100,db=grafana`
 # memcache: 127.0.0.1:11211

pkg/cmd/grafana-server/server.go

@@ -28,6 +28,7 @@ import (
 
 	// self registering services
 	_ "github.com/grafana/grafana/pkg/extensions"
+	_ "github.com/grafana/grafana/pkg/infra/distcache"
 	_ "github.com/grafana/grafana/pkg/infra/metrics"
 	_ "github.com/grafana/grafana/pkg/infra/serverlock"
 	_ "github.com/grafana/grafana/pkg/infra/tracing"

pkg/infra/distcache/database_storage.go

@@ -1,6 +1,7 @@
 package distcache
 
 import (
+	"context"
 	"time"
 
 	"github.com/grafana/grafana/pkg/log"
@@ -18,32 +19,33 @@ func newDatabaseCache(sqlstore *sqlstore.SqlStore) *databaseCache {
 		log:      log.New("distcache.database"),
 	}
 
-	//go dc.StartGC() //TODO: start the GC somehow
 	return dc
 }
 
+func (dc *databaseCache) Run(ctx context.Context) error {
+	ticker := time.NewTicker(time.Minute * 10)
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-ticker.C:
+			dc.internalRunGC()
+		}
+	}
+}
+
 var getTime = time.Now
 
 func (dc *databaseCache) internalRunGC() {
 	now := getTime().Unix()
-	sql := `DELETE FROM cache_data WHERE (? - created) >= expire`
+	sql := `DELETE FROM cache_data WHERE (? - created_at) >= expires AND expires <> 0`
 
-	//EXTRACT(EPOCH FROM NOW()) - created >= expire
-	//UNIX_TIMESTAMP(NOW()) - created >= expire
 	_, err := dc.SQLStore.NewSession().Exec(sql, now)
 	if err != nil {
 		dc.log.Error("failed to run garbage collect", "error", err)
 	}
 }
 
-func (dc *databaseCache) StartGC() {
-	dc.internalRunGC()
-
-	time.AfterFunc(time.Second*10, func() {
-		dc.StartGC()
-	})
-}
-
 func (dc *databaseCache) Get(key string) (interface{}, error) {
 	cacheHits := []cacheData{}
 	err := dc.SQLStore.NewSession().Where(`key = ?`, key).Find(&cacheHits)
@@ -57,8 +59,10 @@ func (dc *databaseCache) Get(key string) (interface{}, error) {
 	}
 
 	cacheHit = cacheHits[0]
+	// if Expires is set. Make sure its still valid.
 	if cacheHit.Expires > 0 {
-		if getTime().Unix()-cacheHit.CreatedAt >= cacheHit.Expires {
+		existedButExpired := getTime().Unix()-cacheHit.CreatedAt >= cacheHit.Expires
+		if existedButExpired {
 			dc.Delete(key)
 			return nil, ErrCacheItemNotFound
 		}
@@ -72,13 +76,6 @@ func (dc *databaseCache) Get(key string) (interface{}, error) {
 	return item.Val, nil
 }
 
-type cacheData struct {
-	Key       string
-	Data      []byte
-	Expires   int64
-	CreatedAt int64
-}
-
 func (dc *databaseCache) Set(key string, value interface{}, expire time.Duration) error {
 	item := &cachedItem{Val: value}
 	data, err := encodeGob(item)
@@ -87,22 +84,23 @@ func (dc *databaseCache) Set(key string, value interface{}, expire time.Duration
 	}
 
 	now := getTime().Unix()
-
 	cacheHits := []cacheData{}
 	err = dc.SQLStore.NewSession().Where(`key = ?`, key).Find(&cacheHits)
 	if err != nil {
 		return err
 	}
 
-	var expiresInEpoch int64
+	var expiresAtEpoch int64
 	if expire != 0 {
-		expiresInEpoch = int64(expire) / int64(time.Second)
+		expiresAtEpoch = int64(expire) / int64(time.Second)
 	}
 
+	session := dc.SQLStore.NewSession()
+	// insert or update depending on if item already exist
 	if len(cacheHits) > 0 {
-		_, err = dc.SQLStore.NewSession().Exec("UPDATE cache_data SET data=?, created=?, expire=? WHERE key=?", data, now, expiresInEpoch, key)
+		_, err = session.Exec("UPDATE cache_data SET data=?, created=?, expire=? WHERE key=?", data, now, expiresAtEpoch, key)
 	} else {
-		_, err = dc.SQLStore.NewSession().Exec("INSERT INTO cache_data(key,data,created_at,expires) VALUES(?,?,?,?)", key, data, now, expiresInEpoch)
+		_, err = session.Exec("INSERT INTO cache_data(key,data,created_at,expires) VALUES(?,?,?,?)", key, data, now, expiresAtEpoch)
 	}
 
 	return err
@@ -110,8 +108,14 @@ func (dc *databaseCache) Set(key string, value interface{}, expire time.Duration
 
 func (dc *databaseCache) Delete(key string) error {
 	sql := `DELETE FROM cache_data WHERE key = ?`
-
 	_, err := dc.SQLStore.NewSession().Exec(sql, key)
 
 	return err
 }
+
+type cacheData struct {
+	Key       string
+	Data      []byte
+	Expires   int64
+	CreatedAt int64
+}

pkg/infra/distcache/distcache.go

@@ -2,6 +2,7 @@ package distcache
 
 import (
 	"bytes"
+	"context"
 	"encoding/gob"
 	"errors"
 	"time"
@@ -22,6 +23,29 @@ func init() {
 	registry.RegisterService(&DistributedCache{})
 }
 
+// CacheStorage allows the caller to set, get and delete items in the cache.
+// Cached items are stored as byte arrays and marshalled using "encoding/gob"
+// so any struct added to the cache needs to be registred with `distcache.Register`
+// ex `distcache.Register(CacheableStruct{})``
+type CacheStorage interface {
+	// Get reads object from Cache
+	Get(key string) (interface{}, error)
+
+	// Set sets an object into the cache
+	Set(key string, value interface{}, expire time.Duration) error
+
+	// Delete object from cache
+	Delete(key string) error
+}
+
+// DistributedCache allows Grafana to cache data outside its own process
+type DistributedCache struct {
+	log      log.Logger
+	Client   CacheStorage
+	SQLStore *sqlstore.SqlStore `inject:""`
+	Cfg      *setting.Cfg       `inject:""`
+}
+
 // Init initializes the service
 func (ds *DistributedCache) Init() error {
 	ds.log = log.New("distributed.cache")
@@ -31,6 +55,16 @@ func (ds *DistributedCache) Init() error {
 	return nil
 }
 
+func (ds *DistributedCache) Run(ctx context.Context) error {
+	backgroundjob, ok := ds.Client.(registry.BackgroundService)
+	if ok {
+		return backgroundjob.Run(ctx)
+	}
+
+	<-ctx.Done()
+	return ctx.Err()
+}
+
 func createClient(opts *setting.CacheOpts, sqlstore *sqlstore.SqlStore) CacheStorage {
 	if opts.Name == "redis" {
 		return newRedisStorage(opts)
@@ -43,12 +77,14 @@ func createClient(opts *setting.CacheOpts, sqlstore *sqlstore.SqlStore) CacheSto
 	return newDatabaseCache(sqlstore)
 }
 
-// DistributedCache allows Grafana to cache data outside its own process
-type DistributedCache struct {
-	log      log.Logger
-	Client   CacheStorage
-	SQLStore *sqlstore.SqlStore `inject:""`
-	Cfg      *setting.Cfg       `inject:""`
+// Register records a type, identified by a value for that type, under its
+// internal type name. That name will identify the concrete type of a value
+// sent or received as an interface variable. Only types that will be
+// transferred as implementations of interface values need to be registered.
+// Expecting to be used only during initialization, it panics if the mapping
+// between types and names is not a bijection.
+func Register(value interface{}) {
+	gob.Register(value)
 }
 
 type cachedItem struct {
@@ -65,18 +101,3 @@ func decodeGob(data []byte, out *cachedItem) error {
 	buf := bytes.NewBuffer(data)
 	return gob.NewDecoder(buf).Decode(&out)
 }
-
-// CacheStorage allows the caller to set, get and delete items in the cache.
-// Cached items are stored as byte arrays and marshalled using "encoding/gob"
-// so any struct added to the cache needs to be registred with `gob.Register`
-// ex `gob.Register(CacheableStruct{})``
-type CacheStorage interface {
-	// Get reads object from Cache
-	Get(key string) (interface{}, error)
-
-	// Set sets an object into the cache
-	Set(key string, value interface{}, expire time.Duration) error
-
-	// Delete object from cache
-	Delete(key string) error
-}

pkg/infra/distcache/distcache_test.go

@@ -1,7 +1,6 @@
 package distcache
 
 import (
-	"encoding/gob"
 	"testing"
 	"time"
 
@@ -17,7 +16,7 @@ type CacheableStruct struct {
 }
 
 func init() {
-	gob.Register(CacheableStruct{})
+	Register(CacheableStruct{})
 }
 
 func createTestClient(t *testing.T, opts *setting.CacheOpts, sqlstore *sqlstore.SqlStore) CacheStorage {

pkg/infra/distcache/memcached_storage.go

@@ -28,21 +28,18 @@ func newItem(sid string, data []byte, expire int32) *memcache.Item {
 // Set sets value to given key in the cache.
 func (s *memcachedStorage) Set(key string, val interface{}, expires time.Duration) error {
 	item := &cachedItem{Val: val}
-
 	bytes, err := encodeGob(item)
 	if err != nil {
 		return err
 	}
 
-	memcacheItem := newItem(key, bytes, int32(expires))
-
-	return s.c.Set(memcacheItem)
+	memcachedItem := newItem(key, bytes, int32(expires))
+	return s.c.Set(memcachedItem)
 }
 
 // Get gets value by given key in the cache.
 func (s *memcachedStorage) Get(key string) (interface{}, error) {
-	i, err := s.c.Get(key)
-
+	memcachedItem, err := s.c.Get(key)
 	if err != nil && err.Error() == "memcache: cache miss" {
 		return nil, ErrCacheItemNotFound
 	}
@@ -53,7 +50,7 @@ func (s *memcachedStorage) Get(key string) (interface{}, error) {
 
 	item := &cachedItem{}
 
-	err = decodeGob(i.Value, item)
+	err = decodeGob(memcachedItem.Value, item)
 	if err != nil {
 		return nil, err
 	}

pkg/setting/setting.go

@@ -783,8 +783,6 @@ func (cfg *Cfg) Load(args *CommandLineArgs) error {
 	cfg.EnterpriseLicensePath = enterprise.Key("license_path").MustString(filepath.Join(cfg.DataPath, "license.jwt"))
 
 	cacheServer := iniFile.Section("cache_server")
-	//cfg.DistCacheType = cacheServer.Key("type").MustString("database")
-	//cfg.DistCacheConnStr = cacheServer.Key("connstr").MustString("")
 	cfg.CacheOptions = &CacheOpts{
 		Name:    cacheServer.Key("type").MustString("database"),
 		ConnStr: cacheServer.Key("connstr").MustString(""),