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This article mainly introduces the relevant knowledge of how to use sled, the content is detailed and easy to understand, the operation is simple and fast, and has a certain reference value. I believe you will gain something after reading this article on how to use sled. Let's take a look at it.

Brief introduction

Sled is an embedded KV database based on Bw tree, and its API is close to a thread-safe BTreeMap. The data structure of its Bw tree, coupled with the "GC" technology including crossbeam-epoch, makes Sled a lock-free database and stands out in the concurrent environment. Forget the slow locks, but officials claim that on a 16-core machine, you can do up to 1 billion operations per minute on a small data set (95% read core 5% write) to use sled, just add sled = "0.32" to the Cargo.toml example basic usage to open the database let tree = sled::open ("/ tmp/welcome-to-sled"). Expect ("open")

/ / insert KV and read the corresponding value of Key tree.insert ("KEY1", "VAL1"); assert_eq! (tree.get (& "KEY1"), Ok (Some (sled::IVec::from ("VAL1")

/ / scope query for kv in tree.range ("KEY1".. "KEY9") {.}

/ / Delete tree.remove (& "KEY1")

/ / atomic compare and swap, which can be used in concurrent programming with tree.compare_and_swap ("KEY1", Some ("VAL1"), Some ("VAL2"))

/ / Block until all modifications are written to the hard disk tree.flush (); process structure use {byteorder:: {BigEndian, LittleEndian}, zerocopy:: {byteorder::U64, AsBytes, FromBytes, LayoutVerified, Unaligned,},}

/ / key structure / / zerocopy::byteorder::U64 ensures data alignment # [derive (FromBytes, AsBytes, Unaligned)] # [repr (C)] struct Key {a: U64, b: U64,}

/ / value structure # [derive (FromBytes, AsBytes, Unaligned)] # [repr (C)] struct Value {count: U64, whatever: [U8; 16],}

Let key = Key {a: U64::new (21), b: U64::new (21)}

/ / get the value corresponding to the key and apply the given function to do db.update_and_fetch (key.as_bytes (), | value_opt | {if let Some (existing) = value_opt {let mut backing_bytes = sled::IVec::from (existing))

/ / verify data alignment (this is not really necessary because we used U64) let layout: LayoutVerified = LayoutVerified::new_unaligned (& mut * backing_bytes) .alignment ("bytes do not fit schema")

/ / get a variable reference to the underlying data let value: & mut Value = layout.into_mut ()

Let new_count = value.count.get () + 1

Println! ("incrementing count to {}", new_count)

Value.count.set (new_count)

Some (backing_bytes)} else {println! ("setting count to 0")

/ / initialize a Value Some (sled::IVec::from (Value {count: U64::new (0), whatever: [0; 16]}. As_bytes (),)})?; that's all for the article "how to use sled". Thank you for reading! I believe you all have a certain understanding of the knowledge of "how to use sled". If you want to learn more, you are welcome to follow the industry information channel.

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