demonstrate ordering of calls to leveldb.Cache

leveldb_cache_stress

package main

import (
	"github.com/syndtr/goleveldb/leveldb/cache"

	"fmt"
	"sync"
	"time"
)

var cCache = cache.NewCache(nil)

func main() {
	var initial_val = "handle1 setter"
	getfunc := func() (int, cache.Value) {
		return 1, initial_val
	}
	wg := &sync.WaitGroup{}

	handle1 := cCache.Get(0, 0, getfunc)
	fmt.Println("cache pop")
	wg.Add(1)
	go func() {
		fmt.Println("waiting to release")
		time.Sleep(time.Second * 3)
		fmt.Println("first release start")
		handle1.Release()
		fmt.Println("first release finish")
		wg.Done()
	}()
	wg.Add(1)
	go func() {
		fmt.Println("delete call start")
		cCache.Delete(0, 0, func() {
			fmt.Println("delete func firing going to sleep")
			time.Sleep(time.Second * 1)
			/*
				cCache.Get(0, 0, func() (int, cache.Value) {
					fmt.Println("getter from delete running ")
					return 1, "delete"
				})
			*/

			fmt.Println("delete fires and blocks 3 secs")
			time.Sleep(time.Second * 3)
			fmt.Println("delete returns")
		})
		fmt.Println("delete call done")
		wg.Done()
	}()
	getfunc = func() (int, cache.Value) {
		return 1, "new value"
	}
	for {
		//<-time.After(time.Millisecond * 10)
		if handle2 := cCache.Get(0, 0, getfunc); handle2 == nil {
			break
		} else if s, ok := handle2.Value().(string); !ok {
			panic(fmt.Errorf("WTF!"))

		} else {
			//fmt.Printf("cache value is: %s\n", s)
			handle2.Release()
			if s != initial_val {
				fmt.Printf("ending loop after cache rewrite: %s\n", s)
				break
			}
		}
	}

	wg.Wait()
}