Added cache, funcspec and implemented total cache

pkg/cache/example_usage.go

@@ -0,0 +1,252 @@
+package cache
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+)
+
+// ExampleInMemoryCache demonstrates using the in-memory cache provider.
+func ExampleInMemoryCache() {
+	// Initialize with in-memory provider
+	err := UseMemory(&Options{
+		DefaultTTL: 5 * time.Minute,
+		MaxSize:    1000,
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer Close()
+
+	ctx := context.Background()
+
+	// Get the cache instance
+	cache := GetDefaultCache()
+
+	// Store a value
+	type User struct {
+		ID   int
+		Name string
+	}
+
+	user := User{ID: 1, Name: "John Doe"}
+	err = cache.Set(ctx, "user:1", user, 10*time.Minute)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Retrieve a value
+	var retrieved User
+	err = cache.Get(ctx, "user:1", &retrieved)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Retrieved user: %+v\n", retrieved)
+
+	// Check if key exists
+	exists := cache.Exists(ctx, "user:1")
+	fmt.Printf("Key exists: %v\n", exists)
+
+	// Delete a key
+	err = cache.Delete(ctx, "user:1")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Get statistics
+	stats, err := cache.Stats(ctx)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Cache stats: %+v\n", stats)
+}
+
+// ExampleRedisCache demonstrates using the Redis cache provider.
+func ExampleRedisCache() {
+	// Initialize with Redis provider
+	err := UseRedis(&RedisConfig{
+		Host:     "localhost",
+		Port:     6379,
+		Password: "", // Set if Redis requires authentication
+		DB:       0,
+		Options: &Options{
+			DefaultTTL: 5 * time.Minute,
+		},
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer Close()
+
+	ctx := context.Background()
+
+	// Get the cache instance
+	cache := GetDefaultCache()
+
+	// Store raw bytes
+	data := []byte("Hello, Redis!")
+	err = cache.SetBytes(ctx, "greeting", data, 1*time.Hour)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Retrieve raw bytes
+	retrieved, err := cache.GetBytes(ctx, "greeting")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Retrieved data: %s\n", string(retrieved))
+
+	// Clear all cache
+	err = cache.Clear(ctx)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+// ExampleMemcacheCache demonstrates using the Memcache cache provider.
+func ExampleMemcacheCache() {
+	// Initialize with Memcache provider
+	err := UseMemcache(&MemcacheConfig{
+		Servers: []string{"localhost:11211"},
+		Options: &Options{
+			DefaultTTL: 5 * time.Minute,
+		},
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer Close()
+
+	ctx := context.Background()
+
+	// Get the cache instance
+	cache := GetDefaultCache()
+
+	// Store a value
+	type Product struct {
+		ID    int
+		Name  string
+		Price float64
+	}
+
+	product := Product{ID: 100, Name: "Widget", Price: 29.99}
+	err = cache.Set(ctx, "product:100", product, 30*time.Minute)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Retrieve a value
+	var retrieved Product
+	err = cache.Get(ctx, "product:100", &retrieved)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Retrieved product: %+v\n", retrieved)
+}
+
+// ExampleGetOrSet demonstrates the GetOrSet pattern for lazy loading.
+func ExampleGetOrSet() {
+	err := UseMemory(&Options{
+		DefaultTTL: 5 * time.Minute,
+		MaxSize:    1000,
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer Close()
+
+	ctx := context.Background()
+	cache := GetDefaultCache()
+
+	type ExpensiveData struct {
+		Result string
+	}
+
+	var data ExpensiveData
+	err = cache.GetOrSet(ctx, "expensive:computation", &data, 10*time.Minute, func() (interface{}, error) {
+		// This expensive operation only runs if the key is not in cache
+		fmt.Println("Computing expensive result...")
+		time.Sleep(1 * time.Second)
+		return ExpensiveData{Result: "computed value"}, nil
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Data: %+v\n", data)
+
+	// Second call will use cached value
+	err = cache.GetOrSet(ctx, "expensive:computation", &data, 10*time.Minute, func() (interface{}, error) {
+		fmt.Println("This won't be called!")
+		return ExpensiveData{Result: "new value"}, nil
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Cached data: %+v\n", data)
+}
+
+// ExampleCustomProvider demonstrates using a custom provider.
+func ExampleCustomProvider() {
+	// Create a custom provider
+	memProvider := NewMemoryProvider(&Options{
+		DefaultTTL: 10 * time.Minute,
+		MaxSize:    500,
+	})
+
+	// Initialize with custom provider
+	Initialize(memProvider)
+	defer Close()
+
+	ctx := context.Background()
+	cache := GetDefaultCache()
+
+	// Use the cache
+	err := cache.SetBytes(ctx, "key", []byte("value"), 5*time.Minute)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Clean expired items (memory provider specific)
+	if mp, ok := cache.provider.(*MemoryProvider); ok {
+		count := mp.CleanExpired(ctx)
+		fmt.Printf("Cleaned %d expired items\n", count)
+	}
+}
+
+// ExampleDeleteByPattern demonstrates pattern-based deletion (Redis only).
+func ExampleDeleteByPattern() {
+	err := UseRedis(&RedisConfig{
+		Host: "localhost",
+		Port: 6379,
+		Options: &Options{
+			DefaultTTL: 5 * time.Minute,
+		},
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer Close()
+
+	ctx := context.Background()
+	cache := GetDefaultCache()
+
+	// Store multiple keys with a pattern
+	cache.SetBytes(ctx, "user:1:profile", []byte("profile1"), 10*time.Minute)
+	cache.SetBytes(ctx, "user:2:profile", []byte("profile2"), 10*time.Minute)
+	cache.SetBytes(ctx, "user:1:settings", []byte("settings1"), 10*time.Minute)
+
+	// Delete all keys matching pattern (Redis glob pattern)
+	err = cache.DeleteByPattern(ctx, "user:*:profile")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println("Deleted all user profile keys")
+}