Allow custom lock tokens (#66)

CHANGELOG.md

@@ -1,3 +1,7 @@
+## v0.9.3
+
+- Feature: allow custom lock tokens [#66](https://github.com/bsm/redislock/pull/66)
+
 ## v0.9.2
 
 - Feature: better handling of nil lock.Release() [#68](https://github.com/bsm/redislock/pull/68)

go.mod

@@ -2,7 +2,7 @@ module github.com/bsm/redislock
 
 go 1.17
 
-require github.com/redis/go-redis/v9 v9.0.2
+require github.com/redis/go-redis/v9 v9.0.3
 
 require (
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect

go.sum

@@ -1,26 +1,10 @@
-github.com/bsm/ginkgo/v2 v2.5.0 h1:aOAnND1T40wEdAtkGSkvSICWeQ8L3UASX7YVCqQx+eQ=
-github.com/bsm/ginkgo/v2 v2.5.0/go.mod h1:AiKlXPm7ItEHNc/2+OkrNG4E0ITzojb9/xWzvQ9XZ9w=
-github.com/bsm/gomega v1.20.0 h1:JhAwLmtRzXFTx2AkALSLa8ijZafntmhSoU63Ok18Uq8=
-github.com/bsm/gomega v1.20.0/go.mod h1:JifAceMQ4crZIWYUKrlGcmbN3bqHogVTADMD2ATsbwk=
+github.com/bsm/ginkgo/v2 v2.7.0 h1:ItPMPH90RbmZJt5GtkcNvIRuGEdwlBItdNVoyzaNQao=
+github.com/bsm/ginkgo/v2 v2.7.0/go.mod h1:AiKlXPm7ItEHNc/2+OkrNG4E0ITzojb9/xWzvQ9XZ9w=
+github.com/bsm/gomega v1.26.0 h1:LhQm+AFcgV2M0WyKroMASzAzCAJVpAxQXv4SaI9a69Y=
+github.com/bsm/gomega v1.26.0/go.mod h1:JyEr/xRbxbtgWNi8tIEVPUYZ5Dzef52k01W3YH0H+O0=
 github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
 github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/redis/go-redis/v9 v9.0.2 h1:BA426Zqe/7r56kCcvxYLWe1mkaz71LKF77GwgFzSxfE=
-github.com/redis/go-redis/v9 v9.0.2/go.mod h1:/xDTe9EF1LM61hek62Poq2nzQSGj0xSrEtEHbBQevps=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
-github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
-github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
-github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+github.com/redis/go-redis/v9 v9.0.3 h1:+7mmR26M0IvyLxGZUHxu4GiBkJkVDid0Un+j4ScYu4k=
+github.com/redis/go-redis/v9 v9.0.3/go.mod h1:WqMKv5vnQbRuZstUwxQI195wHy+t4PuXDOjzMvcuQHk=

redislock.go

@@ -49,10 +49,14 @@ func New(client RedisClient) *Client {
 // Obtain tries to obtain a new lock using a key with the given TTL.
 // May return ErrNotObtained if not successful.
 func (c *Client) Obtain(ctx context.Context, key string, ttl time.Duration, opt *Options) (*Lock, error) {
+	token := opt.getToken()
+
 	// Create a random token
-	token, err := c.randomToken()
-	if err != nil {
-		return nil, err
+	if token == "" {
+		var err error
+		if token, err = c.randomToken(); err != nil {
+			return nil, err
+		}
 	}
 
 	value := token + opt.getMetadata()
@@ -71,7 +75,7 @@ func (c *Client) Obtain(ctx context.Context, key string, ttl time.Duration, opt
 		if err != nil {
 			return nil, err
 		} else if ok {
-			return &Lock{Client: c, key: key, value: value}, nil
+			return &Lock{Client: c, key: key, value: value, tokenLen: len(token)}, nil
 		}
 
 		backoff := retry.NextBackoff()
@@ -117,8 +121,9 @@ func (c *Client) randomToken() (string, error) {
 // Lock represents an obtained, distributed lock.
 type Lock struct {
 	*Client
-	key   string
-	value string
+	key      string
+	value    string
+	tokenLen int
 }
 
 // Obtain is a short-cut for New(...).Obtain(...).
@@ -133,12 +138,12 @@ func (l *Lock) Key() string {
 
 // Token returns the token value set by the lock.
 func (l *Lock) Token() string {
-	return l.value[:22]
+	return l.value[:l.tokenLen]
 }
 
 // Metadata returns the metadata of the lock.
 func (l *Lock) Metadata() string {
-	return l.value[22:]
+	return l.value[l.tokenLen:]
 }
 
 // TTL returns the remaining time-to-live. Returns 0 if the lock has expired.
@@ -197,8 +202,12 @@ type Options struct {
 	// Default: do not retry
 	RetryStrategy RetryStrategy
 
-	// Metadata string is appended to the lock token.
+	// Metadata string.
 	Metadata string
+
+	// Token is a unique value that is used to identify the lock. By default, a random tokens are generated. Use this
+	// option to provide a custom token instead.
+	Token string
 }
 
 func (o *Options) getMetadata() string {
@@ -208,6 +217,13 @@ func (o *Options) getMetadata() string {
 	return ""
 }
 
+func (o *Options) getToken() string {
+	if o != nil {
+		return o.Token
+	}
+	return ""
+}
+
 func (o *Options) getRetryStrategy() RetryStrategy {
 	if o != nil && o.RetryStrategy != nil {
 		return o.RetryStrategy

redislock_test.go

@@ -90,6 +90,25 @@ func TestObtain_metadata(t *testing.T) {
 	}
 }
 
+func TestObtain_custom_token(t *testing.T) {
+	ctx := context.Background()
+	rc := redis.NewClient(redisOpts)
+	defer teardown(t, rc)
+
+	lock, err := Obtain(ctx, rc, lockKey, time.Hour, &Options{Token: "foo", Metadata: "bar"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer lock.Release(ctx)
+
+	if exp, got := "foo", lock.Token(); exp != got {
+		t.Fatalf("expected %v, got %v", exp, got)
+	}
+	if exp, got := "bar", lock.Metadata(); exp != got {
+		t.Fatalf("expected %v, got %v", exp, got)
+	}
+}
+
 func TestObtain_retry_success(t *testing.T) {
 	ctx := context.Background()
 	rc := redis.NewClient(redisOpts)