From 9709c3a099dcfa1d7c99bd9bcdbb6faf5a535d3d Mon Sep 17 00:00:00 2001
From: Andre Medeiros <hello@andre.cool>
Date: Sat, 1 Apr 2023 12:07:48 -0400
Subject: [PATCH] cache lock release function

---
 internal/distributedlock/distributed_lock.go  | 27 ++++++++++++++++---
 .../distributedlock/distributed_lock_test.go  | 25 ++++++++++++-----
 internal/distributedlock/lock.go              | 11 +-------
 3 files changed, 42 insertions(+), 21 deletions(-)

diff --git a/internal/distributedlock/distributed_lock.go b/internal/distributedlock/distributed_lock.go
index 2525b29..bae898a 100644
--- a/internal/distributedlock/distributed_lock.go
+++ b/internal/distributedlock/distributed_lock.go
@@ -3,23 +3,42 @@ package distributedlock
 import (
 	"context"
 	"fmt"
-	"github.com/go-redis/redis/v8"
 	"math/rand"
 	"time"
+
+	"github.com/go-redis/redis/v8"
 )
 
-const lockTopicFormat = "pubsub:locks:%s"
+const (
+	lockTopicFormat   = "pubsub:locks:%s"
+	lockReleaseScript = `
+		if redis.call("GET", KEYS[1]) == ARGV[1] then
+			redis.call("DEL", KEYS[1])
+			redis.call("PUBLISH", KEYS[2], KEYS[1])
+			return 1
+		else
+			return 0
+		end
+	`
+)
 
 type DistributedLock struct {
 	client  *redis.Client
+	sha     string
 	timeout time.Duration
 }
 
-func New(client *redis.Client, timeout time.Duration) *DistributedLock {
+func New(client *redis.Client, timeout time.Duration) (*DistributedLock, error) {
+	sha, err := client.ScriptLoad(context.Background(), lockReleaseScript).Result()
+	if err != nil {
+		return nil, err
+	}
+
 	return &DistributedLock{
 		client:  client,
+		sha:     sha,
 		timeout: timeout,
-	}
+	}, nil
 }
 
 func (d *DistributedLock) setLock(ctx context.Context, key string, uid string) error {
diff --git a/internal/distributedlock/distributed_lock_test.go b/internal/distributedlock/distributed_lock_test.go
index b0bfdfb..3d8211f 100644
--- a/internal/distributedlock/distributed_lock_test.go
+++ b/internal/distributedlock/distributed_lock_test.go
@@ -3,12 +3,15 @@ package distributedlock_test
 import (
 	"context"
 	"fmt"
-	"github.com/christianselig/apollo-backend/internal/distributedlock"
-	"github.com/go-redis/redis/v8"
-	"github.com/stretchr/testify/assert"
+	"math/rand"
 	"os"
 	"testing"
 	"time"
+
+	"github.com/christianselig/apollo-backend/internal/distributedlock"
+
+	"github.com/go-redis/redis/v8"
+	"github.com/stretchr/testify/assert"
 )
 
 func NewRedisClient(t *testing.T, ctx context.Context) (*redis.Client, func()) {
@@ -29,13 +32,17 @@ func NewRedisClient(t *testing.T, ctx context.Context) (*redis.Client, func()) {
 }
 
 func TestDistributedLock_AcquireLock(t *testing.T) {
+	t.Parallel()
+
 	ctx := context.Background()
-	key := fmt.Sprintf("%d", time.Now().UnixNano())
+	key := fmt.Sprintf("key:%d-%d", time.Now().UnixNano(), rand.Int63())
 
 	client, closer := NewRedisClient(t, ctx)
 	defer closer()
 
-	d := distributedlock.New(client, 10*time.Second)
+	d, err := distributedlock.New(client, 10*time.Second)
+	assert.NoError(t, err)
+
 	lock, err := d.AcquireLock(ctx, key)
 	assert.NoError(t, err)
 
@@ -50,13 +57,17 @@ func TestDistributedLock_AcquireLock(t *testing.T) {
 }
 
 func TestDistributedLock_WaitAcquireLock(t *testing.T) {
+	t.Parallel()
+
 	ctx := context.Background()
-	key := fmt.Sprintf("%d", time.Now().UnixNano())
+	key := fmt.Sprintf("key:%d-%d", time.Now().UnixNano(), rand.Int63())
 
 	client, closer := NewRedisClient(t, ctx)
 	defer closer()
 
-	d := distributedlock.New(client, 10*time.Second)
+	d, err := distributedlock.New(client, 10*time.Second)
+	assert.NoError(t, err)
+	
 	lock, err := d.AcquireLock(ctx, key)
 	assert.NoError(t, err)
 
diff --git a/internal/distributedlock/lock.go b/internal/distributedlock/lock.go
index 3a49f39..005730e 100644
--- a/internal/distributedlock/lock.go
+++ b/internal/distributedlock/lock.go
@@ -20,19 +20,10 @@ func NewLock(distributedLock *DistributedLock, key string, uid string) *Lock {
 }
 
 func (l *Lock) Release(ctx context.Context) error {
-	script := `
-		if redis.call("GET", KEYS[1]) == ARGV[1] then
-			redis.call("DEL", KEYS[1])
-			redis.call("PUBLISH", KEYS[2], KEYS[1])
-			return 1
-		else
-			return 0
-		end
-	`
 
 	ch := fmt.Sprintf(lockTopicFormat, l.key)
 
-	result, err := l.distributedLock.client.Eval(ctx, script, []string{l.key, ch}, l.uid).Result()
+	result, err := l.distributedLock.client.EvalSha(ctx, l.distributedLock.sha, []string{l.key, ch}, l.uid).Result()
 	if err != nil {
 		return err
 	}