Introduce globallock as distributed locks

go.mod

@@ -49,6 +49,7 @@ require (
 	github.com/go-git/go-billy/v5 v5.5.0
 	github.com/go-git/go-git/v5 v5.12.0
 	github.com/go-ldap/ldap/v3 v3.4.6
+	github.com/go-redsync/redsync/v4 v4.13.0
 	github.com/go-sql-driver/mysql v1.8.1
 	github.com/go-swagger/go-swagger v0.31.0
 	github.com/go-testfixtures/testfixtures/v3 v3.11.0
@@ -218,7 +219,9 @@ require (
 	github.com/gorilla/mux v1.8.1 // indirect
 	github.com/gorilla/securecookie v1.1.2 // indirect
 	github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542 // indirect
+	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/hashicorp/go-retryablehttp v0.7.7 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/imdario/mergo v0.3.16 // indirect

go.sum

@@ -342,6 +342,14 @@ github.com/go-openapi/swag v0.23.0/go.mod h1:esZ8ITTYEsH1V2trKHjAN8Ai7xHb8RV+YSZ
 github.com/go-openapi/validate v0.24.0 h1:LdfDKwNbpB6Vn40xhTdNZAnfLECL81w+VX3BumrGD58=
 github.com/go-openapi/validate v0.24.0/go.mod h1:iyeX1sEufmv3nPbBdX3ieNviWnOZaJ1+zquzJEf2BAQ=
 github.com/go-redis/redis v6.15.2+incompatible/go.mod h1:NAIEuMOZ/fxfXJIrKDQDz8wamY7mA7PouImQ2Jvg6kA=
+github.com/go-redis/redis v6.15.9+incompatible h1:K0pv1D7EQUjfyoMql+r/jZqCLizCGKFlFgcHWWmHQjg=
+github.com/go-redis/redis v6.15.9+incompatible/go.mod h1:NAIEuMOZ/fxfXJIrKDQDz8wamY7mA7PouImQ2Jvg6kA=
+github.com/go-redis/redis/v7 v7.4.1 h1:PASvf36gyUpr2zdOUS/9Zqc80GbM+9BDyiJSJDDOrTI=
+github.com/go-redis/redis/v7 v7.4.1/go.mod h1:JDNMw23GTyLNC4GZu9njt15ctBQVn7xjRfnwdHj/Dcg=
+github.com/go-redis/redis/v8 v8.11.5 h1:AcZZR7igkdvfVmQTPnu9WE37LRrO/YrBH5zWyjDC0oI=
+github.com/go-redis/redis/v8 v8.11.5/go.mod h1:gREzHqY1hg6oD9ngVRbLStwAWKhA0FEgq8Jd4h5lpwo=
+github.com/go-redsync/redsync/v4 v4.13.0 h1:49X6GJfnbLGaIpBBREM/zA4uIMDXKAh1NDkvQ1EkZKA=
+github.com/go-redsync/redsync/v4 v4.13.0/go.mod h1:HMW4Q224GZQz6x1Xc7040Yfgacukdzu7ifTDAKiyErQ=
 github.com/go-sql-driver/mysql v1.4.1/go.mod h1:zAC/RDZ24gD3HViQzih4MyKcchzm+sOG5ZlKdlhCg5w=
 github.com/go-sql-driver/mysql v1.8.1 h1:LedoTUt/eveggdHS9qUFC1EFSa8bU2+1pZjSRpvNJ1Y=
 github.com/go-sql-driver/mysql v1.8.1/go.mod h1:wEBSXgmK//2ZFJyE+qWnIsVGmvmEKlqwuVSjsCm7DZg=
@@ -397,6 +405,8 @@ github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEW
 github.com/golang/snappy v0.0.2/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/golang/snappy v0.0.4 h1:yAGX7huGHXlcLOEtBnF4w7FQwA26wojNCwOYAEhLjQM=
 github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
+github.com/gomodule/redigo v1.8.9 h1:Sl3u+2BI/kk+VEatbj0scLdrFhjPmbxOc1myhDP41ws=
+github.com/gomodule/redigo v1.8.9/go.mod h1:7ArFNvsTjH8GMMzB4uy1snslv2BwmginuMs06a1uzZE=
 github.com/google/btree v1.1.2 h1:xf4v41cLI2Z6FxbKm+8Bu+m8ifhj15JuZ9sa0jZCMUU=
 github.com/google/btree v1.1.2/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
@@ -449,10 +459,15 @@ github.com/h2non/gock v1.2.0 h1:K6ol8rfrRkUOefooBC8elXoaNGYkpp7y2qcxGG6BzUE=
 github.com/h2non/gock v1.2.0/go.mod h1:tNhoxHYW2W42cYkYb1WqzdbYIieALC99kpYr7rH/BQk=
 github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542 h1:2VTzZjLZBgl62/EtslCrtky5vbi9dd7HrQPQIx6wqiw=
 github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542/go.mod h1:Ow0tF8D4Kplbc8s8sSb3V2oUCygFHVp8gC3Dn6U4MNI=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/errwrap v1.1.0 h1:OxrOeh75EUXMY8TBjag2fzXGZ40LB6IKw45YeGUDY2I=
+github.com/hashicorp/errwrap v1.1.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/go-cleanhttp v0.5.2 h1:035FKYIWjmULyFRBKPs8TBQoi0x6d9G4xc9neXJWAZQ=
 github.com/hashicorp/go-cleanhttp v0.5.2/go.mod h1:kO/YDlP8L1346E6Sodw+PrpBSV4/SoxCXGY6BqNFT48=
 github.com/hashicorp/go-hclog v1.6.3 h1:Qr2kF+eVWjTiYmU7Y31tYlP1h0q/X3Nl3tPGdaB11/k=
 github.com/hashicorp/go-hclog v1.6.3/go.mod h1:W4Qnvbt70Wk/zYJryRzDRU/4r0kIg0PVHBcfoyhpF5M=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/hashicorp/go-retryablehttp v0.7.7 h1:C8hUCYzor8PIfXHa4UrZkU4VvK8o9ISHxT2Q8+VepXU=
 github.com/hashicorp/go-retryablehttp v0.7.7/go.mod h1:pkQpWZeYWskR+D1tR2O5OcBFOxfA7DoAO6xtkuQnHTk=
 github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
@@ -674,6 +689,8 @@ github.com/quasoft/websspi v1.1.2/go.mod h1:HmVdl939dQ0WIXZhyik+ARdI03M6bQzaSEKc
 github.com/rcrowley/go-metrics v0.0.0-20190826022208-cac0b30c2563/go.mod h1:bCqnVzQkZxMG4s8nGwiZ5l3QUCyqpo9Y+/ZMZ9VjZe4=
 github.com/redis/go-redis/v9 v9.6.0 h1:NLck+Rab3AOTHw21CGRpvQpgTrAU4sgdCswqGtlhGRA=
 github.com/redis/go-redis/v9 v9.6.0/go.mod h1:hdY0cQFCN4fnSYT6TkisLufl/4W5UIXyv0b/CLO2V2M=
+github.com/redis/rueidis v1.0.19 h1:s65oWtotzlIFN8eMPhyYwxlwLR1lUdhza2KtWprKYSo=
+github.com/redis/rueidis v1.0.19/go.mod h1:8B+r5wdnjwK3lTFml5VtxjzGOQAC+5UmujoD12pDrEo=
 github.com/remyoudompheng/bigfft v0.0.0-20200410134404-eec4a21b6bb0 h1:OdAsTTz6OkFY5QxjkYwrChwuRruF69c169dPK26NUlk=
 github.com/remyoudompheng/bigfft v0.0.0-20200410134404-eec4a21b6bb0/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
 github.com/rhysd/actionlint v1.7.1 h1:WJaDzyT1StBWVKGSsZPYnbV0HF9Y9/vD6KFdZQL42qE=
@@ -765,6 +782,8 @@ github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stvp/tempredis v0.0.0-20181119212430-b82af8480203 h1:QVqDTf3h2WHt08YuiTGPZLls0Wq99X9bWd0Q5ZSBesM=
+github.com/stvp/tempredis v0.0.0-20181119212430-b82af8480203/go.mod h1:oqN97ltKNihBbwlX8dLpwxCl3+HnXKV/R0e+sRLd9C8=
 github.com/subosito/gotenv v1.6.0 h1:9NlTDc1FTs4qu0DDq7AEtTPNw6SVm7uBMsUCUjABIf8=
 github.com/subosito/gotenv v1.6.0/go.mod h1:Dk4QP5c2W3ibzajGcXpNraDfq2IrhjMIvMSWPKKo0FU=
 github.com/syndtr/goleveldb v1.0.0 h1:fBdIW9lB4Iz0n9khmH8w27SJ3QEJ7+IgjPEwGSZiFdE=

modules/globallock/globallock.go

@@ -0,0 +1,66 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package globallock
+
+import (
+	"context"
+	"sync"
+)
+
+var (
+	defaultLocker Locker
+	initOnce      sync.Once
+	initFunc      = func() {
+		// TODO: read the setting and initialize the default locker.
+		//       Before implementing this, don't use it.
+	} // define initFunc as a variable to make it possible to change it in tests
+)
+
+// DefaultLocker returns the default locker.
+func DefaultLocker() Locker {
+	initOnce.Do(func() {
+		initFunc()
+	})
+	return defaultLocker
+}
+
+// Lock tries to acquire a lock for the given key, it uses the default locker.
+// Read the documentation of Locker.Lock for more information about the behavior.
+func Lock(ctx context.Context, key string) (context.Context, ReleaseFunc, error) {
+	return DefaultLocker().Lock(ctx, key)
+}
+
+// TryLock tries to acquire a lock for the given key, it uses the default locker.
+// Read the documentation of Locker.TryLock for more information about the behavior.
+func TryLock(ctx context.Context, key string) (bool, context.Context, ReleaseFunc, error) {
+	return DefaultLocker().TryLock(ctx, key)
+}
+
+// LockAndDo tries to acquire a lock for the given key and then calls the given function.
+// It uses the default locker, and it will return an error if failed to acquire the lock.
+func LockAndDo(ctx context.Context, key string, f func(context.Context) error) error {
+	ctx, release, err := Lock(ctx, key)
+	if err != nil {
+		return err
+	}
+	defer release()
+
+	return f(ctx)
+}
+
+// TryLockAndDo tries to acquire a lock for the given key and then calls the given function.
+// It uses the default locker, and it will return false if failed to acquire the lock.
+func TryLockAndDo(ctx context.Context, key string, f func(context.Context) error) (bool, error) {
+	ok, ctx, release, err := TryLock(ctx, key)
+	if err != nil {
+		return false, err
+	}
+	defer release()
+
+	if !ok {
+		return false, nil
+	}
+
+	return true, f(ctx)
+}

modules/globallock/globallock_test.go

@@ -0,0 +1,96 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package globallock
+
+import (
+	"context"
+	"os"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLockAndDo(t *testing.T) {
+	t.Run("redis", func(t *testing.T) {
+		url := "redis://127.0.0.1:6379/0"
+		if os.Getenv("CI") == "" {
+			// Make it possible to run tests against a local redis instance
+			url = os.Getenv("TEST_REDIS_URL")
+			if url == "" {
+				t.Skip("TEST_REDIS_URL not set and not running in CI")
+				return
+			}
+		}
+
+		oldDefaultLocker := defaultLocker
+		oldInitFunc := initFunc
+		defer func() {
+			defaultLocker = oldDefaultLocker
+			initFunc = oldInitFunc
+			if defaultLocker == nil {
+				initOnce = sync.Once{}
+			}
+		}()
+
+		initOnce = sync.Once{}
+		initFunc = func() {
+			defaultLocker = NewRedisLocker(url)
+		}
+
+		testLockAndDo(t)
+		require.NoError(t, defaultLocker.(*redisLocker).Close())
+	})
+	t.Run("memory", func(t *testing.T) {
+		oldDefaultLocker := defaultLocker
+		oldInitFunc := initFunc
+		defer func() {
+			defaultLocker = oldDefaultLocker
+			initFunc = oldInitFunc
+			if defaultLocker == nil {
+				initOnce = sync.Once{}
+			}
+		}()
+
+		initOnce = sync.Once{}
+		initFunc = func() {
+			defaultLocker = NewMemoryLocker()
+		}
+
+		testLockAndDo(t)
+	})
+}
+
+func testLockAndDo(t *testing.T) {
+	const concurrency = 1000
+
+	ctx := context.Background()
+	count := 0
+	wg := sync.WaitGroup{}
+	wg.Add(concurrency)
+	for i := 0; i < concurrency; i++ {
+		go func() {
+			defer wg.Done()
+			err := LockAndDo(ctx, "test", func(ctx context.Context) error {
+				count++
+
+				// It's impossible to acquire the lock inner the function
+				ok, err := TryLockAndDo(ctx, "test", func(ctx context.Context) error {
+					assert.Fail(t, "should not acquire the lock")
+					return nil
+				})
+				assert.False(t, ok)
+				assert.NoError(t, err)
+
+				return nil
+			})
+			require.NoError(t, err)
+		}()
+	}
+
+	wg.Wait()
+
+	assert.Equal(t, concurrency, count)
+}

modules/globallock/locker.go

@@ -0,0 +1,60 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package globallock
+
+import (
+	"context"
+	"fmt"
+)
+
+type Locker interface {
+	// Lock tries to acquire a lock for the given key, it blocks until the lock is acquired or the context is canceled.
+	//
+	// Lock returns a new context which should be used in the following code.
+	// The new context will be canceled when the lock is released or lost - yes, it's possible to lose a lock.
+	// For example, it lost the connection to the redis server while holding the lock.
+	// If it fails to acquire the lock, the returned context will be the same as the input context.
+	//
+	// Lock returns a ReleaseFunc to release the lock, it cannot be nil.
+	// It's always safe to call this function even if it fails to acquire the lock, and it will do nothing in that case.
+	// And it's also safe to call it multiple times, but it will only release the lock once.
+	// That's why it's called ReleaseFunc, not UnlockFunc.
+	// But be aware that it's not safe to not call it at all; it could lead to a memory leak.
+	// So a recommended pattern is to use defer to call it:
+	//   ctx, release, err := locker.Lock(ctx, "key")
+	//   if err != nil {
+	//     return err
+	//   }
+	//   defer release()
+	// The ReleaseFunc will return the original context which was used to acquire the lock.
+	// It's useful when you want to continue to do something after releasing the lock.
+	// At that time, the ctx will be canceled, and you can use the returned context by the ReleaseFunc to continue:
+	//   ctx, release, err := locker.Lock(ctx, "key")
+	//   if err != nil {
+	//     return err
+	//   }
+	//   defer release()
+	//   doSomething(ctx)
+	//   ctx = release()
+	//   doSomethingElse(ctx)
+	// Please ignore it and use `defer release()` instead if you don't need this, to avoid forgetting to release the lock.
+	//
+	// Lock returns an error if failed to acquire the lock.
+	// Be aware that even the context is not canceled, it's still possible to fail to acquire the lock.
+	// For example, redis is down, or it reached the maximum number of tries.
+	Lock(ctx context.Context, key string) (context.Context, ReleaseFunc, error)
+
+	// TryLock tries to acquire a lock for the given key, it returns immediately.
+	// It follows the same pattern as Lock, but it doesn't block.
+	// And if it fails to acquire the lock because it's already locked, not other reasons like redis is down,
+	// it will return false without any error.
+	TryLock(ctx context.Context, key string) (bool, context.Context, ReleaseFunc, error)
+}
+
+// ReleaseFunc is a function that releases a lock.
+// It returns the original context which was used to acquire the lock.
+type ReleaseFunc func() context.Context
+
+// ErrLockReleased is used as context cause when a lock is released
+var ErrLockReleased = fmt.Errorf("lock released")