cache_examples_test.go

package loadingcache_test

import (
	"context"
	"fmt"
	"time"

	"github.com/pkg/errors"

	"github.com/devzero-inc/loadingcache"
)

func ExampleCache_simpleUsage() {
	type Key string
	type Value int

	cache := loadingcache.New[Key, Value]()

	// Addign some values and reading them
	cache.Put("a", 1)
	cache.Put("b", 2)
	cache.Put("c", 3)
	val1, _ := cache.Get(context.TODO(), "a") // Don't forget to check for errors
	fmt.Printf("%v\n", val1)
	val2, _ := cache.Get(context.TODO(), "b") // Don't forget to check for errors
	fmt.Printf("%v\n", val2)

	// Getting a value that does not exist
	_, err := cache.Get(context.TODO(), "d")
	if errors.Is(err, loadingcache.ErrKeyNotFound) {
		fmt.Println("That key does not exist")
	}

	// Evicting
	cache.Invalidate("a")
	cache.Invalidate("b", "c")
	cache.InvalidateAll()

	// Output: 1
	// 2
	// That key does not exist
}

func ExampleCache_advancedUsage() {
	type Key int
	type Value string

	cache := loadingcache.New(
		loadingcache.WithMaxSize[Key, Value](2),
		loadingcache.WithExpireAfterRead[Key, Value](2*time.Minute),
		loadingcache.WithExpireAfterWrite[Key, Value](time.Minute),
		loadingcache.WithRemovalListeners(
			func(notification loadingcache.RemovalNotification[Key, Value]) {
				fmt.Printf("Entry removed due to %s\n", notification.Reason)
			},
		),
		loadingcache.WithLoadFunc(func(_ context.Context, key Key) (Value, error) {
			fmt.Printf("Loading key %v\n", key)
			return Value(fmt.Sprint(key)), nil
		}),
	)

	cache.Put(1, "1")
	val1, _ := cache.Get(context.TODO(), 1)
	fmt.Printf("%v\n", val1)

	val2, _ := cache.Get(context.TODO(), 2)
	fmt.Printf("%v\n", val2)

	val3, _ := cache.Get(context.TODO(), 3)
	fmt.Printf("%v\n", val3)

	// Output: 1
	// Loading key 2
	// 2
	// Loading key 3
	// Entry removed due to SIZE
	// 3
}