Change cache to thread safe lru

blockchain/cache.go

@@ -19,26 +19,14 @@
 package blockchain
 
 import (
-	"fmt"
-	"github.com/golang/groupcache/lru"
+	"github.com/getsentry/sentry-go"
 	"github.com/google/uuid"
+	lru "github.com/hashicorp/golang-lru"
 )
 
-// newEmulatorCache returns a new instance of cache with provided capacity.
-func newEmulatorCache(capacity int) *emulatorCache {
-	c := lru.New(capacity)
-	c.OnEvicted = func(key lru.Key, value interface{}) {
-		fmt.Printf("Cache evicted emulator for project: %s - (%v)\n", key.(uuid.UUID).String(), key)
-	}
-
-	return &emulatorCache{
-		cache: c,
-	}
-}
-
 // emulatorCache caches the emulator state.
 //
-// In the environment where multiple replicas maintain it's own cache copy it can get into multiple states:
+// In the environment where multiple replicas maintain its own cache copy it can get into multiple states:
 // - it can get stale because replica A receives transaction execution 1, and replica B receives transaction execution 2,
 //   then replica A needs to apply missed transaction execution 2 before continuing
 // - it can be outdated because replica A receives project reset, which clears all executions and the cache, but replica B
@@ -48,13 +36,32 @@ type emulatorCache struct {
 	cache *lru.Cache
 }
 
-// reset the cache for the ID.
+// newEmulatorCache returns a new instance of emulatorCache with provided capacity.
+func newEmulatorCache(capacity int) *emulatorCache {
+	cache, err := lru.New(capacity)
+	if err != nil {
+		sentry.CaptureMessage("Continuing without emulator caching: " + err.Error())
+	}
+
+	return &emulatorCache{
+		cache: cache,
+	}
+}
+
+// reset the cached emulator for the ID.
 func (c *emulatorCache) reset(ID uuid.UUID) {
+	if c.cache == nil {
+		return
+	}
 	c.cache.Remove(ID)
 }
 
-// get returns a cached emulator if exists, but also checks if it's stale.
+// get returns a cached emulator for specified ID if it exists
 func (c *emulatorCache) get(ID uuid.UUID) *emulator {
+	if c.cache == nil {
+		return nil
+	}
+
 	val, ok := c.cache.Get(ID)
 	if !ok {
 		return nil
@@ -63,7 +70,10 @@ func (c *emulatorCache) get(ID uuid.UUID) *emulator {
 	return val.(*emulator)
 }
 
-// add new entry in the cache.
+// add new emulator to the cache.
 func (c *emulatorCache) add(ID uuid.UUID, emulator *emulator) {
+	if c.cache == nil {
+		return
+	}
 	c.cache.Add(ID, emulator)
 }

blockchain/cache_test.go

@@ -19,13 +19,14 @@
 package blockchain
 
 import (
+	"fmt"
+	"github.com/dapperlabs/flow-playground-api/model"
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"testing"
 )
 
-/*
 func createExecutions(count int) []*model.TransactionExecution {
 	executions := make([]*model.TransactionExecution, count)
 	for i := 0; i < count; i++ {
@@ -38,7 +39,6 @@ func createExecutions(count int) []*model.TransactionExecution {
 	}
 	return executions
 }
-*/
 
 func Test_Cache(t *testing.T) {
 
@@ -63,4 +63,63 @@ func Test_Cache(t *testing.T) {
 		assert.Equal(t, height, cacheHeight)
 	})
 
+	t.Run("returns cached emulator with executions", func(t *testing.T) {
+		const numExecutions = 5
+
+		testID := uuid.New()
+		c := newEmulatorCache(2)
+
+		em, err := newEmulator()
+		require.NoError(t, err)
+
+		// Add executions to emulator
+		exes := createExecutions(numExecutions)
+		for _, ex := range exes {
+			_, _, err := em.executeTransaction(ex.Script, nil, nil)
+			require.NoError(t, err)
+		}
+
+		latestBlock, err := em.blockchain.GetLatestBlock()
+		require.NoError(t, err)
+
+		assert.Equal(t, latestBlock.Header.Height, uint64(numExecutions))
+
+		c.add(testID, em)
+
+		cacheEm := c.get(testID)
+
+		latestCacheBlock, err := cacheEm.blockchain.GetLatestBlock()
+		require.NoError(t, err)
+
+		// Verify cached emulator block height
+		assert.Equal(t, latestCacheBlock.Header.Height, uint64(numExecutions))
+
+		// Verify all cached emulator executions
+		for i := 0; i <= numExecutions; i++ {
+			block, err := em.blockchain.GetBlockByHeight(uint64(i))
+			require.NoError(t, err)
+
+			cacheBlock, err := em.blockchain.GetBlockByHeight(uint64(i))
+			require.NoError(t, err)
+
+			assert.Equal(t, block.ID(), cacheBlock.ID())
+			assert.Equal(t, block.Checksum(), cacheBlock.Checksum())
+		}
+	})
+
+	t.Run("disabled emulator cache", func(t *testing.T) {
+		// Invalid capacity will disable caching
+		c := newEmulatorCache(-2)
+
+		em, err := newEmulator()
+		require.NoError(t, err)
+
+		testID := uuid.New()
+		c.add(testID, em)
+
+		cacheEm := c.get(testID)
+		assert.Nil(t, cacheEm)
+
+		c.reset(testID)
+	})
 }

controller/projects_test.go

@@ -20,13 +20,14 @@ package controller
 
 import (
 	"fmt"
-	"github.com/kelseyhightower/envconfig"
-	"github.com/onflow/flow-go-sdk"
-	"github.com/stretchr/testify/assert"
 	"os"
 	"strings"
 	"testing"
 
+	"github.com/kelseyhightower/envconfig"
+	"github.com/onflow/flow-go-sdk"
+	"github.com/stretchr/testify/assert"
+
 	"github.com/dapperlabs/flow-playground-api/blockchain"
 	"github.com/dapperlabs/flow-playground-api/model"
 	"github.com/dapperlabs/flow-playground-api/storage"

go.mod

@@ -12,11 +12,11 @@ require (
 	github.com/go-chi/chi v3.3.2+incompatible
 	github.com/go-chi/httplog v0.2.5
 	github.com/go-chi/render v1.0.1
-	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da
 	github.com/google/uuid v1.3.0
 	github.com/gorilla/mux v1.8.0
 	github.com/gorilla/sessions v1.2.0
 	github.com/gorilla/websocket v1.5.0
+	github.com/hashicorp/golang-lru v0.5.4
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/mitchellh/mapstructure v1.5.0
 	github.com/onflow/cadence v0.27.0
@@ -63,7 +63,6 @@ require (
 	github.com/google/go-cmp v0.5.8 // indirect
 	github.com/gorilla/securecookie v1.1.1 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
-	github.com/hashicorp/golang-lru v0.5.4 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/ipfs/go-cid v0.2.0 // indirect

go.sum

@@ -269,8 +269,6 @@ github.com/golang/groupcache v0.0.0-20190129154638-5b532d6fd5ef/go.mod h1:cIg4er
 github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20191227052852-215e87163ea7/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
-github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da h1:oI5xCqsCo564l8iNU+DwB5epxmsaqB+rhGL0m5jtYqE=
-github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.2.0/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.3.1/go.mod h1:sBzyDLLjw3U8JLTeZvSv8jJB+tU5PVekmnlKIyFUx0Y=