codescalersinternships/ahmed-salah-ucf-bitcask

A Go implementation of the Bitcask model.

Bitcask Description

The origin of Bitcask is tied to the history of the Riak distributed database. In a Riak key/value cluster, each node uses pluggable local storage; nearly anything k/v-shaped can be used as the per-host storage engine. This pluggability allowed progress on Riak to be parallelized such that storage engines could be improved and tested without impact on the rest of the codebase. NOTE: All project specifications and usage are mentioned in this Official Bitcask Design Paper

Bitcask API

Function	Description
func Open(directoryPath string, config ...Config) (*Bitcask, error)	Open a new or an existing bitcask datastore
func (bc *Bitcask) Put(key []byte, value []byte) error	Stores a key and a value in the bitcask datastore
func (bc *Bitcask) Get(key []byte) ([]byte, error)	Reads a value by key from a datastore
func (bc *Bitcask) Delete(key []byte) error	Removes a key from the datastore
func (bc *Bitcask) Close()	Close a bitcask data store and flushes all pending writes to disk
func (bc *Bitcask) ListKeys() [][]byte	Returns list of all keys
func (bc *Bitcask) Sync() error	Force any writes to sync to disk
func (bc *Bitcask) Merge() error	Merge several data files within a Bitcask datastore into a more compact form. Also, produce hintfiles for faster startup.
func (bc *Bitcask) Fold(fun func([]byte, []byte, any) any, acc any) any	Fold over all K/V pairs in a Bitcask datastore.→ Acc Fun is expected to be of the form: F(K,V,Acc0) → Acc

---

Basic demo_infinite_writer

package main

import (
	"bitcask"
	"fmt"
	"path"
)

func main() {
	bc, err := bitcask.Open(path.Join("bitcask"), bitcask.RWsyncConfig)
	if err != nil {
		fmt.Println(err.Error())
		return
	}

	for { }

	bc.Close()
}

NOTE: there is no output for this infinite writer, it is used to lock the bitcask.

---

Basic demo_writer

package main

import (
	"bitcask"
	"fmt"
	"path"
)

func main() {
	bc, err := bitcask.Open(path.Join("bitcask"), bitcask.RWsyncConfig)
	if err != nil {
		fmt.Println(err.Error())
		return
	}

	fmt.Println("***** append 100 item *****")
	for i := 0; i < 100; i++ {
		key := "key" + fmt.Sprintf("%d", i)
		value := "value" + fmt.Sprintf("%d", i)
		bc.Put([]byte(key), []byte(value))
	}

	fmt.Println("****** merge old files *******")
	bc.Merge()

	fmt.Println("****** Get some items ********")

	val2, err := bc.Get([]byte("key2"))
	fmt.Printf("value of key2 is: %s\n", string(val2))
	if err != nil {
		fmt.Println(err)
	}

	val15, err := bc.Get([]byte("key15"))
	fmt.Printf("value of key15 is: %s\n", string(val15))
	if err != nil {
		fmt.Println(err)
	}

	val77, err := bc.Get([]byte("key77"))
	if err != nil {
		fmt.Println(err)
	}
	fmt.Printf("value of key77 is: %s\n", string(val77))

	fmt.Println("****** close bitcask *******")
	bc.Close()
}

output with this only writer

$ go run demos/demo_writer/writer.go 
***** append 100 item *****
****** merge old files *******
****** Get some items ********
value of key2 is: value2
value of key15 is: value15
value of key77 is: value77
****** close bitcask *******

output if there another writer

$ go run demos/demo_writer/writer.go
there is another process that locked this bitcask

---

Basic demo_infinite_reader

package main

import (
	"bitcask"
	"fmt"
	"path"
)

func main() {
	bc, err := bitcask.Open(path.Join("bitcask"))
	if err != nil {
		fmt.Println(err.Error())
		return
	}

	for { }

	bc.Close()
}

---

Basic demo_reader

package main

import (
	"bitcask"
	"fmt"
	"path"
)

func main() {
	bc, err := bitcask.Open(path.Join("bitcask"))
	if err != nil {
		fmt.Println(err.Error())
		return
	}

	fmt.Println("****** Get some items ********")
	val2, _ := bc.Get([]byte("key2"))
	fmt.Printf("value of key2 is: %s\n", string(val2))

	val15, _ := bc.Get([]byte("key15"))
	fmt.Printf("value of key15 is: %s\n", string(val15))

	val77, _ := bc.Get([]byte("key77"))
	fmt.Printf("value of key77 is: %s\n", string(val77))

	fmt.Println("****** close bitcask *******")
	bc.Close()
}

output if exist bitcask

$ go run demos/demo_reader/reader.go
****** Get some items ********
value of key2 is: 
value of key15 is: 
value of key77 is: 
****** close bitcask *******

output if there is writer exist

$ go run demos/demo_reader/reader.go
there is another process that locked this bitcask

output if there is reader exist

$ go run demos/demo_reader/reader.go
****** Get some items ********
value of key2 is: 
value of key15 is: 
value of key77 is: 
****** close bitcask *******