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//! `sled` is a high-performance embedded database with //! an API that is similar to a `BTreeMap<[u8], [u8]>`, //! but with several additional capabilities for //! assisting creators of stateful systems. //! //! It is fully thread-safe, and all operations are //! atomic. Multiple `Tree`s are supported with the //! [`Db::open_tree`](struct.Db.html#method.open_tree) method. //! //! ACID transactions involving reads and writes to //! multiple items are supported with the //! [`Tree::transaction`](struct.Tree.html#method.transaction) //! method. Transactions may also operate over //! multiple `Tree`s (see //! [`Tree::transaction`](struct.Tree.html#method.transaction) //! docs for more info). //! //! Users may also subscribe to updates on individual //! `Tree`s by using the //! [`Tree::watch_prefix`](struct.Tree.html#method.watch_prefix) //! method, which returns a blocking `Iterator` over //! updates to keys that begin with the provided //! prefix. You may supply an empty prefix to subscribe //! to everything. //! //! [Merge operators](https://github.com/spacejam/sled/wiki/merge-operators) //! (aka read-modify-write operators) are supported. A //! merge operator is a function that specifies //! how new data can be merged into an existing value //! without requiring both a read and a write. //! Using the //! [`Tree::merge`](struct.Tree.html#method.merge) //! method, you may "push" data to a `Tree` value //! and have the provided merge operator combine //! it with the existing value, if there was one. //! They are set on a per-`Tree` basis, and essentially //! allow any sort of data structure to be built //! using merges as an atomic high-level operation. //! //! `sled` is built by experienced database engineers //! who think users should spend less time tuning and //! working against high-friction APIs. Expect //! significant ergonomic and performance improvements //! over time. Most surprises are bugs, so please //! [let us know](mailto:t@jujit.su?subject=sled%20sucks!!!) if something //! is high friction. //! //! # Examples //! //! ``` //! use sled::Db; //! //! let t = Db::open("my_db").unwrap(); //! //! // insert and get //! t.insert(b"yo!", b"v1"); //! assert_eq!(&t.get(b"yo!").unwrap().unwrap(), b"v1"); //! //! // Atomic compare-and-swap. //! t.cas( //! b"yo!", // key //! Some(b"v1"), // old value, None for not present //! Some(b"v2"), // new value, None for delete //! ) //! .unwrap(); //! //! // Iterates over key-value pairs, starting at the given key. //! let scan_key: &[u8] = b"a non-present key before yo!"; //! let mut iter = t.range(scan_key..); //! assert_eq!(&iter.next().unwrap().unwrap().0, b"yo!"); //! assert_eq!(iter.next(), None); //! //! t.remove(b"yo!"); //! assert_eq!(t.get(b"yo!"), Ok(None)); //! ``` #![cfg_attr(test, deny(warnings))] #![deny(missing_docs)] #![deny(future_incompatible)] #![deny(nonstandard_style)] #![deny(rust_2018_compatibility)] #![deny(rust_2018_idioms)] mod batch; mod binary_search; mod context; mod data; mod db; mod frag; mod iter; mod ivec; mod materializer; mod meta; mod node; mod prefix; mod subscription; mod tree; mod tx; #[cfg(any(windows, target_os = "linux", target_os = "macos"))] mod flusher; const DEFAULT_TREE_ID: &[u8] = b"__sled__default"; pub use { self::{ batch::Batch, db::Db, iter::Iter, ivec::IVec, subscription::{Event, Subscriber}, tree::Tree, tx::{ TransactionError, TransactionResult, Transactional, TransactionalTree, }, }, pagecache::{Config, ConfigBuilder, Error, OneShot, Result}, }; use { self::{ binary_search::binary_search_lub, context::Context, data::Data, frag::Frag, node::Node, prefix::{ prefix_cmp, prefix_cmp_encoded, prefix_decode, prefix_encode, prefix_reencode, }, subscription::Subscriptions, }, log::{debug, error, trace}, pagecache::{ debug::debug_delay, pin, threadpool, Materializer, Measure, PageCache, PageId, RecoveryGuard, M, }, serde::{Deserialize, Serialize}, }; type TreePtr<'g> = pagecache::PagePtr<'g, Frag>; /// Allows arbitrary logic to be injected into mere operations of the /// `PageCache`. pub type MergeOperator = fn( key: &[u8], last_value: Option<&[u8]>, new_merge: &[u8], ) -> Option<Vec<u8>>;