[FSSDK-11151] Add remove method to lru cache (#400)

* add remove method to lru cache

* place remove mthod into separate cache CacheWithRemove that extends Cache interface

* exclude from linting

* lint

* move cache dir to pkg root

* cache file moved to pkg root

Author: Mat001

pkg/odp/cache/lru_cache.go renamed to pkg/cache/lru_cache.go

@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2022, Optimizely, Inc. and contributors                        *
+ * Copyright 2022-2025, Optimizely, Inc. and contributors                        *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -30,6 +30,13 @@ type Cache interface {
 	Reset()
 }
 
+// CacheWithRemove extends the Cache interface with removal capability
+// nolint:golint // Keeping name consistent with other language SDKs
+type CacheWithRemove interface {
+	Cache
+	Remove(key string)
+}
+
 type cacheElement struct {
 	data   interface{}
 	time   time.Time
@@ -102,6 +109,19 @@ func (l *LRUCache) Reset() {
 	l.items = make(map[string]*cacheElement)
 }
 
+// Remove deletes an element from the cache by key
+func (l *LRUCache) Remove(key string) {
+	if l.maxSize <= 0 {
+		return
+	}
+	l.lock.Lock()
+	defer l.lock.Unlock()
+	if item, ok := l.items[key]; ok {
+		l.queue.Remove(item.keyPtr)
+		delete(l.items, key)
+	}
+}
+
 func (l *LRUCache) isValid(e *cacheElement) bool {
 	if l.timeout <= 0 {
 		return true

pkg/odp/cache/lru_cache_test.go renamed to pkg/cache/lru_cache_test.go

@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2022, Optimizely, Inc. and contributors                        *
+ * Copyright 2022-2025, Optimizely, Inc. and contributors                        *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -204,3 +204,122 @@ func TestTimeout(t *testing.T) {
 	assert.Equal(t, 200, cache2.Lookup("2"))
 	assert.Equal(t, 300, cache2.Lookup("3"))
 }
+
+func TestRemove(t *testing.T) {
+	// Test removing an existing key
+	t.Run("Remove existing key", func(t *testing.T) {
+		cache := NewLRUCache(3, 1000*time.Second)
+
+		// Add items to cache
+		cache.Save("1", 100)
+		cache.Save("2", 200)
+		cache.Save("3", 300)
+
+		// Verify items exist
+		assert.Equal(t, 100, cache.Lookup("1"))
+		assert.Equal(t, 200, cache.Lookup("2"))
+		assert.Equal(t, 300, cache.Lookup("3"))
+		assert.Equal(t, 3, cache.queue.Len())
+		assert.Equal(t, 3, len(cache.items))
+
+		// Remove an item
+		cache.Remove("2")
+
+		// Verify item was removed
+		assert.Equal(t, 100, cache.Lookup("1"))
+		assert.Nil(t, cache.Lookup("2"))
+		assert.Equal(t, 300, cache.Lookup("3"))
+		assert.Equal(t, 2, cache.queue.Len())
+		assert.Equal(t, 2, len(cache.items))
+	})
+
+	// Test removing a non-existent key
+	t.Run("Remove non-existent key", func(t *testing.T) {
+		cache := NewLRUCache(3, 1000*time.Second)
+
+		// Add items to cache
+		cache.Save("1", 100)
+		cache.Save("2", 200)
+
+		// Remove a non-existent key
+		cache.Remove("3")
+
+		// Verify state remains unchanged
+		assert.Equal(t, 100, cache.Lookup("1"))
+		assert.Equal(t, 200, cache.Lookup("2"))
+		assert.Equal(t, 2, cache.queue.Len())
+		assert.Equal(t, 2, len(cache.items))
+	})
+
+	// Test removing from a zero-sized cache
+	t.Run("Remove from zero-sized cache", func(t *testing.T) {
+		cache := NewLRUCache(0, 1000*time.Second)
+
+		// Try to add and remove items
+		cache.Save("1", 100)
+		cache.Remove("1")
+
+		// Verify nothing happened
+		assert.Nil(t, cache.Lookup("1"))
+		assert.Equal(t, 0, cache.queue.Len())
+		assert.Equal(t, 0, len(cache.items))
+	})
+
+	// Test removing and then adding back
+	t.Run("Remove and add back", func(t *testing.T) {
+		cache := NewLRUCache(3, 1000*time.Second)
+
+		// Add items to cache
+		cache.Save("1", 100)
+		cache.Save("2", 200)
+		cache.Save("3", 300)
+
+		// Remove an item
+		cache.Remove("2")
+
+		// Add it back with a different value
+		cache.Save("2", 201)
+
+		// Verify item was added back
+		assert.Equal(t, 100, cache.Lookup("1"))
+		assert.Equal(t, 201, cache.Lookup("2"))
+		assert.Equal(t, 300, cache.Lookup("3"))
+		assert.Equal(t, 3, cache.queue.Len())
+		assert.Equal(t, 3, len(cache.items))
+	})
+
+	// Test thread safety of Remove
+	t.Run("Thread safety", func(t *testing.T) {
+		maxSize := 100
+		cache := NewLRUCache(maxSize, 1000*time.Second)
+		wg := sync.WaitGroup{}
+
+		// Add entries
+		for i := 1; i <= maxSize; i++ {
+			cache.Save(fmt.Sprintf("%d", i), i*100)
+		}
+
+		// Concurrently remove half the entries
+		wg.Add(maxSize / 2)
+		for i := 1; i <= maxSize/2; i++ {
+			go func(k int) {
+				defer wg.Done()
+				cache.Remove(fmt.Sprintf("%d", k))
+			}(i)
+		}
+		wg.Wait()
+
+		// Verify first half is removed, second half remains
+		for i := 1; i <= maxSize; i++ {
+			if i <= maxSize/2 {
+				assert.Nil(t, cache.Lookup(fmt.Sprintf("%d", i)))
+			} else {
+				assert.Equal(t, i*100, cache.Lookup(fmt.Sprintf("%d", i)))
+			}
+		}
+
+		// Verify cache size
+		assert.Equal(t, maxSize/2, cache.queue.Len())
+		assert.Equal(t, maxSize/2, len(cache.items))
+	})
+}

pkg/client/factory_test.go

@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2019-2020,2022,2024 Optimizely, Inc. and contributors          *
+ * Copyright 2019-2020,2022,2025 Optimizely, Inc. and contributors          *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -27,14 +27,14 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 
+	"github.com/optimizely/go-sdk/v2/pkg/cache"
 	"github.com/optimizely/go-sdk/v2/pkg/config"
 	"github.com/optimizely/go-sdk/v2/pkg/decide"
 	"github.com/optimizely/go-sdk/v2/pkg/decision"
 	"github.com/optimizely/go-sdk/v2/pkg/event"
 	"github.com/optimizely/go-sdk/v2/pkg/metrics"
 	"github.com/optimizely/go-sdk/v2/pkg/notification"
 	"github.com/optimizely/go-sdk/v2/pkg/odp"
-	"github.com/optimizely/go-sdk/v2/pkg/odp/cache"
 	pkgOdpEvent "github.com/optimizely/go-sdk/v2/pkg/odp/event"
 	pkgOdpSegment "github.com/optimizely/go-sdk/v2/pkg/odp/segment"
 	pkgOdpUtils "github.com/optimizely/go-sdk/v2/pkg/odp/utils"

pkg/odp/odp_manager.go

@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2022, Optimizely, Inc. and contributors                        *
+ * Copyright 2022-2025, Optimizely, Inc. and contributors                        *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -21,8 +21,8 @@ import (
 	"errors"
 	"time"
 
+	"github.com/optimizely/go-sdk/v2/pkg/cache"
 	"github.com/optimizely/go-sdk/v2/pkg/logging"
-	"github.com/optimizely/go-sdk/v2/pkg/odp/cache"
 	"github.com/optimizely/go-sdk/v2/pkg/odp/config"
 	"github.com/optimizely/go-sdk/v2/pkg/odp/event"
 	"github.com/optimizely/go-sdk/v2/pkg/odp/segment"

pkg/odp/odp_manager_test.go

@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2022-2023, Optimizely, Inc. and contributors                   *
+ * Copyright 2022-2025, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -23,7 +23,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/optimizely/go-sdk/v2/pkg/odp/cache"
+	"github.com/optimizely/go-sdk/v2/pkg/cache"
 	"github.com/optimizely/go-sdk/v2/pkg/odp/config"
 	"github.com/optimizely/go-sdk/v2/pkg/odp/event"
 	"github.com/optimizely/go-sdk/v2/pkg/odp/segment"

pkg/odp/segment/segment_manager.go

@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2022, Optimizely, Inc. and contributors                        *
+ * Copyright 2022-2025, Optimizely, Inc. and contributors                        *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -21,7 +21,7 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/optimizely/go-sdk/v2/pkg/odp/cache"
+	"github.com/optimizely/go-sdk/v2/pkg/cache"
 	"github.com/optimizely/go-sdk/v2/pkg/odp/utils"
 )
 

pkg/odp/segment/segment_manager_test.go

@@ -150,3 +150,5 @@ func (l *TestCache) Lookup(key string) interface{} {
 }
 func (l *TestCache) Reset() {
 }
+func (l *TestCache) Remove(key string) {
+}