README.md

sniper

A simple and efficient thread-safe key/value store for Go.

Getting Started

Features

• Store hundreds of millions of entries
• Fast. High concurrent. Thread-safe. Scales on multi-core CPUs
• Extremly low memory usage
• Zero GC overhead
• Simple, pure Go implementation

Installing

To start using sniper, install Go and run go get:

$ go get -u github.com/recoilme/sniper

This will retrieve the library.

Usage

The Sniper includes this methods: Set, Get, Incr, Decr, Delete, Count, Walk, WalkPll, Open, Close, FileSize, Backup.

s, _ := sniper.Open("1")
s.Set([]byte("hello"), []byte("go"))
res, _ = s.Get([]byte("hello"))
fmt.Println(res)
s.Close()
// Output:
// go

Walk:

s, _ := sniper.Open("1")
s.Set([]byte("hello"), []byte("go"))
s.Set([]byte("hello1"), []byte("go1"))
s.Set([]byte("hello2"), []byte("go2"))

walk := func(key []byte, val []byte) bool {
	fmt.Printf("Key: %s ; Value: %s\n", string(key), string(val))
	return false
}

err = s.Walk(walk)
if err != nil {
	fmt.Println(err)
}
s.Close()

Walk with stop logic:

var mu sync.Mutex
var stop bool

s, _ := sniper.Open("1")
s.Set([]byte("hello"), []byte("go"))
s.Set([]byte("hello1"), []byte("go1"))
s.Set([]byte("hello2"), []byte("go2"))

walk := func(key []byte, val []byte) bool {
	mu.Lock()
	defer mu.Unlock()
	if stop {
		return stop
	}
	if string(key) == "hello1" {
		fmt.Printf("Key: %s ; Value: %s\n", string(key), string(val))
		stop = true
		return stop
	}
	return false
}

err = s.Walk(walk)
if err != nil {
	fmt.Println(err)
}
s.Close()

Walk parallel with limit at 8 threads and stop logic:

var mu sync.Mutex

s, _ := sniper.Open("1")
s.Set([]byte("hello"), []byte("go"))
s.Set([]byte("hello1"), []byte("go1"))
s.Set([]byte("hello2"), []byte("go2"))

walkpll := func(key []byte, val []byte) bool {
	mu.Lock()
	fmt.Printf("Key: %s ; Value: %s\n", string(key), string(val))
	mu.Unlock()
	return false
}

err = s.WalkPll(walkpll, 8)
if err != nil {
	fmt.Println(err)
}
s.Close()

Performance

MacBook Pro 2019 (Quad-Core Intel Core i7 2,8 GHz, 16 ГБ, APPLE SSD AP0512M)

go version go1.14 darwin/amd64

     number of cpus: 8
     number of keys: 10000000
            keysize: 10
        random seed: 1570109110136449000

-- sniper --
set: 10,000,000 ops over 8 threads in 63159ms, 158,331/sec, 6315 ns/op, 644.3 MB, 67 bytes/op
get: 10,000,000 ops over 8 threads in 4455ms, 2,244,629/sec, 445 ns/op, 305.5 MB, 32 bytes/op
del: 10,000,000 ops over 8 threads in 37568ms, 266,182/sec, 3756 ns/op, 122.8 MB, 12 bytes/op

How it is done

• Sniper database is sharded on 250+ chunks. Each chunk has its own lock (RW), so it supports high concurrent access on multi-core CPUs.
• Each chunk store hash(key) -> (value addr, value size), map.
• Hash is very short, and has collisions. Sniper has collisions resolver.
• Efficient space reuse alghorithm. Every packet has power of 2 size, for inplace rewrite on value update and map of deleted entrys, for reusing space.

Limitations

• 512 Kb - maximum entry size len(key) + len(value)
• 1 Tb - maximum database size

Contact

Vadim Kulibaba @recoilme

License

sniper source code is available under the MIT License.