cache: initial version of db cache

pkg/infra/distcache/database_storage.go

@@ -0,0 +1,82 @@
+package distcache
+
+import (
+	"time"
+
+	"github.com/grafana/grafana/pkg/services/sqlstore"
+)
+
+type databaseCache struct {
+	SQLStore *sqlstore.SqlStore
+}
+
+var getTime = time.Now
+
+func (dc *databaseCache) Get(key string) (interface{}, error) {
+	//now := getTime().Unix()
+
+	cacheHits := []CacheData{}
+	err := dc.SQLStore.NewSession().Where(`key = ?`, key).Find(&cacheHits)
+	if err != nil {
+		return nil, err
+	}
+
+	var cacheHit CacheData
+	if len(cacheHits) == 0 {
+		return nil, ErrCacheItemNotFound
+	}
+
+	cacheHit = cacheHits[0]
+	if cacheHit.Expires > 0 {
+		if getTime().Unix()-cacheHit.CreatedAt >= cacheHit.Expires {
+			dc.Delete(key)
+			return nil, ErrCacheItemNotFound
+		}
+	}
+
+	item := &Item{}
+	if err = DecodeGob(cacheHit.Data, item); err != nil {
+		return nil, err
+	}
+
+	return item.Val, nil
+}
+
+type CacheData struct {
+	Key       string
+	Data      []byte
+	Expires   int64
+	CreatedAt int64
+}
+
+func (dc *databaseCache) Put(key string, value interface{}, expire int64) error {
+	item := &Item{Val: value}
+	data, err := EncodeGob(item)
+	if err != nil {
+		return err
+	}
+
+	now := getTime().Unix()
+
+	cacheHits := []CacheData{}
+	err = dc.SQLStore.NewSession().Where(`key = ?`, key).Find(&cacheHits)
+	if err != nil {
+		return err
+	}
+
+	if len(cacheHits) > 0 {
+		_, err = dc.SQLStore.NewSession().Exec("UPDATE cached_data SET data=?, created=?, expire=? WHERE key=?", data, now, expire, key)
+	} else {
+		_, err = dc.SQLStore.NewSession().Exec("INSERT INTO cache_data(key,data,created_at,expires) VALUES(?,?,?,?)", key, data, now, expire)
+	}
+
+	return err
+}
+
+func (dc *databaseCache) Delete(key string) error {
+	sql := `DELETE FROM cache_data WHERE key = ?`
+
+	_, err := dc.SQLStore.NewSession().Exec(sql, key)
+
+	return err
+}

pkg/infra/distcache/distcache.go

@@ -0,0 +1,68 @@
+package distcache
+
+import (
+	"bytes"
+	"encoding/gob"
+	"errors"
+
+	"github.com/grafana/grafana/pkg/log"
+	"github.com/grafana/grafana/pkg/services/sqlstore"
+
+	"github.com/grafana/grafana/pkg/registry"
+)
+
+var (
+	ErrCacheItemNotFound = errors.New("cache item not found")
+)
+
+func init() {
+	registry.RegisterService(&DistributedCache{})
+}
+
+// Init initializes the service
+func (ds *DistributedCache) Init() error {
+	ds.log = log.New("distributed.cache")
+
+	// memory
+	// redis
+	// memcache
+	// database. using SQLSTORE
+	ds.Client = &databaseCache{SQLStore: ds.SQLStore}
+
+	return nil
+}
+
+// DistributedCache allows Grafana to cache data outside its own process
+type DistributedCache struct {
+	log      log.Logger
+	Client   cacheStorage
+	SQLStore *sqlstore.SqlStore `inject:""`
+}
+
+type Item struct {
+	Val     interface{}
+	Created int64
+	Expire  int64
+}
+
+func EncodeGob(item *Item) ([]byte, error) {
+	buf := bytes.NewBuffer(nil)
+	err := gob.NewEncoder(buf).Encode(item)
+	return buf.Bytes(), err
+}
+
+func DecodeGob(data []byte, out *Item) error {
+	buf := bytes.NewBuffer(data)
+	return gob.NewDecoder(buf).Decode(&out)
+}
+
+type cacheStorage interface {
+	// Get reads object from Cache
+	Get(key string) (interface{}, error)
+
+	// Puts an object into the cache
+	Put(key string, value interface{}, expire int64) error
+
+	// Delete object from cache
+	Delete(key string) error
+}

pkg/infra/distcache/distcache_test.go

@@ -0,0 +1,87 @@
+package distcache
+
+import (
+	"encoding/gob"
+	"testing"
+	"time"
+
+	"github.com/bmizerany/assert"
+
+	"github.com/grafana/grafana/pkg/log"
+	"github.com/grafana/grafana/pkg/services/sqlstore"
+)
+
+type CacheableStruct struct {
+	String string
+	Int64  int64
+}
+
+func init() {
+	gob.Register(CacheableStruct{})
+}
+
+func createClient(t *testing.T) cacheStorage {
+	t.Helper()
+
+	sqlstore := sqlstore.InitTestDB(t)
+	dc := DistributedCache{log: log.New("test.logger"), SQLStore: sqlstore}
+	dc.Init()
+	return dc.Client
+}
+
+func TestCanPutIntoDatabaseStorage(t *testing.T) {
+	client := createClient(t)
+	cacheableStruct := CacheableStruct{String: "hej", Int64: 2000}
+
+	err := client.Put("key", cacheableStruct, 1000)
+	assert.Equal(t, err, nil)
+
+	data, err := client.Get("key")
+	s, ok := data.(CacheableStruct)
+
+	assert.Equal(t, ok, true)
+	assert.Equal(t, s.String, "hej")
+	assert.Equal(t, s.Int64, int64(2000))
+
+	err = client.Delete("key")
+	assert.Equal(t, err, nil)
+
+	_, err = client.Get("key")
+	assert.Equal(t, err, ErrCacheItemNotFound)
+}
+
+func TestCanNotFetchExpiredItems(t *testing.T) {
+	client := createClient(t)
+
+	cacheableStruct := CacheableStruct{String: "hej", Int64: 2000}
+
+	// insert cache item one day back
+	getTime = func() time.Time { return time.Now().AddDate(0, 0, -2) }
+	err := client.Put("key", cacheableStruct, 10000)
+	assert.Equal(t, err, nil)
+
+	// should not be able to read that value since its expired
+	getTime = time.Now
+	_, err = client.Get("key")
+	assert.Equal(t, err, ErrCacheItemNotFound)
+}
+
+func TestCanSetInfiniteCacheExpiration(t *testing.T) {
+	client := createClient(t)
+
+	cacheableStruct := CacheableStruct{String: "hej", Int64: 2000}
+
+	// insert cache item one day back
+	getTime = func() time.Time { return time.Now().AddDate(0, 0, -2) }
+	err := client.Put("key", cacheableStruct, 0)
+	assert.Equal(t, err, nil)
+
+	// should not be able to read that value since its expired
+	getTime = time.Now
+	data, err := client.Get("key")
+	s, ok := data.(CacheableStruct)
+
+	assert.Equal(t, ok, true)
+	assert.Equal(t, s.String, "hej")
+	assert.Equal(t, s.Int64, int64(2000))
+}

pkg/services/sqlstore/migrations/cache_data_mig.go

@@ -0,0 +1,17 @@
+package migrations
+
+import . "github.com/grafana/grafana/pkg/services/sqlstore/migrator"
+
+func addCacheMigration(mg *Migrator) {
+	var cacheDataV1 = Table{
+		Name: "cache_data",
+		Columns: []*Column{
+			{Name: "key", Type: DB_Char, IsPrimaryKey: true, Length: 16},
+			{Name: "data", Type: DB_Blob},
+			{Name: "expires", Type: DB_Integer, Length: 255, Nullable: false},
+			{Name: "created_at", Type: DB_Integer, Length: 255, Nullable: false},
+		},
+	}
+
+	mg.AddMigration("create cache_data table", NewAddTableMigration(cacheDataV1))
+}

pkg/services/sqlstore/migrations/migrations.go

@@ -33,6 +33,7 @@ func AddMigrations(mg *Migrator) {
 	addUserAuthMigrations(mg)
 	addServerlockMigrations(mg)
 	addUserAuthTokenMigrations(mg)
+	addCacheMigration(mg)
 }
 
 func addMigrationLogMigrations(mg *Migrator) {