feat: support default locker

Author: wolfogre

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.
+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 +1,87 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package globallock
+
+import (
+	"context"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	"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
+			}
+		}
+
+		initOnce = sync.Once{}
+		initFunc = func() {
+			defaultLocker = NewRedisLocker(url)
+		}
+
+		testLockAndDo(t)
+	})
+	t.Run("memory", func(t *testing.T) {
+		initOnce = sync.Once{}
+		initFunc = func() {
+			defaultLocker = NewMemoryLocker()
+		}
+
+		testLockAndDo(t)
+	})
+}
+
+func testLockAndDo(t *testing.T) {
+	const (
+		duration    = 2 * time.Second
+		concurrency = 100
+	)
+
+	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 {
+				select {
+				case <-ctx.Done():
+					return ctx.Err()
+				case <-time.After(duration / concurrency):
+					count++
+				}
+				return nil
+			})
+			require.NoError(t, err)
+		}()
+	}
+
+	ok, err := TryLockAndDo(ctx, "test", func(ctx context.Context) error {
+		return nil
+	})
+	assert.False(t, ok)
+	assert.NoError(t, err)
+
+	wg.Wait()
+
+	ok, err = TryLockAndDo(ctx, "test", func(ctx context.Context) error {
+		return nil
+	})
+	assert.True(t, ok)
+	assert.NoError(t, err)
+
+	assert.Equal(t, concurrency, count)
+}