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| -rw-r--r-- | third_party/rust/rkv/src/lib.rs | 236 |
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diff --git a/third_party/rust/rkv/src/lib.rs b/third_party/rust/rkv/src/lib.rs new file mode 100644 index 0000000000..0c8951e191 --- /dev/null +++ b/third_party/rust/rkv/src/lib.rs @@ -0,0 +1,236 @@ +// Copyright 2018-2019 Mozilla +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use +// this file except in compliance with the License. You may obtain a copy of the +// License at http://www.apache.org/licenses/LICENSE-2.0 +// Unless required by applicable law or agreed to in writing, software distributed +// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR +// CONDITIONS OF ANY KIND, either express or implied. See the License for the +// specific language governing permissions and limitations under the License. +#![allow(clippy::from_over_into)] // TODO: `Into` implementations in [safe/lmdb]/flags.rs + +//! A simple, humane, typed key-value storage solution. It supports multiple backend +//! engines with varying guarantees, such as [LMDB](http://www.lmdb.tech/doc/) for +//! performance, or "SafeMode" for reliability. +//! +//! It aims to achieve the following: +//! +//! - Avoid sharp edges (e.g., obscure error codes for common situations). +//! - Correctly restrict access to one handle per process via a +//! [Manager](struct.Manager.html). +//! - Use Rust's type system to make single-typed key stores safe and ergonomic. +//! - Encode and decode values via [bincode](https://docs.rs/bincode/)/[serde](https://docs.rs/serde/) +//! and type tags, achieving platform-independent storage and input/output flexibility. +//! +//! It exposes these primary abstractions: +//! +//! - [Manager](struct.Manager.html): a singleton that controls access to environments +//! - [Rkv](struct.Rkv.html): an environment contains a set of key/value databases +//! - [SingleStore](store/single/struct.SingleStore.html): a database contains a set of +//! key/value pairs +//! +//! Keys can be anything that implements `AsRef<[u8]>` or integers +//! (when accessing an [IntegerStore](store/integer/struct.IntegerStore.html)). +//! +//! Values can be any of the types defined by the [Value](value/enum.Value.html) enum, +//! including: +//! +//! - booleans (`Value::Bool`) +//! - integers (`Value::I64`, `Value::U64`) +//! - floats (`Value::F64`) +//! - strings (`Value::Str`) +//! - blobs (`Value::Blob`) +//! +//! See [Value](value/enum.Value.html) for the complete list of supported types. +//! +//! ## Basic Usage +//! ``` +//! use rkv::{Manager, Rkv, SingleStore, Value, StoreOptions}; +//! use rkv::backend::{SafeMode, SafeModeEnvironment}; +//! use std::fs; +//! use tempfile::Builder; +//! +//! // First determine the path to the environment, which is represented on disk as a +//! // directory containing two files: +//! // +//! // * a data file containing the key/value stores +//! // * a lock file containing metadata about current transactions +//! // +//! // In this example, we use the `tempfile` crate to create the directory. +//! // +//! let root = Builder::new().prefix("simple-db").tempdir().unwrap(); +//! fs::create_dir_all(root.path()).unwrap(); +//! let path = root.path(); +//! +//! // The `Manager` enforces that each process opens the same environment at most once by +//! // caching a handle to each environment that it opens. Use it to retrieve the handle +//! // to an opened environment—or create one if it hasn't already been opened: +//! let mut manager = Manager::<SafeModeEnvironment>::singleton().write().unwrap(); +//! let created_arc = manager.get_or_create(path, Rkv::new::<SafeMode>).unwrap(); +//! let env = created_arc.read().unwrap(); +//! +//! // Then you can use the environment handle to get a handle to a datastore: +//! let store = env.open_single("mydb", StoreOptions::create()).unwrap(); +//! +//! { +//! // Use a write transaction to mutate the store via a `Writer`. There can be only +//! // one writer for a given environment, so opening a second one will block until +//! // the first completes. +//! let mut writer = env.write().unwrap(); +//! +//! // Keys are `AsRef<[u8]>`, while values are `Value` enum instances. Use the `Blob` +//! // variant to store arbitrary collections of bytes. Putting data returns a +//! // `Result<(), StoreError>`, where StoreError is an enum identifying the reason +//! // for a failure. +//! store.put(&mut writer, "int", &Value::I64(1234)).unwrap(); +//! store.put(&mut writer, "uint", &Value::U64(1234_u64)).unwrap(); +//! store.put(&mut writer, "float", &Value::F64(1234.0.into())).unwrap(); +//! store.put(&mut writer, "instant", &Value::Instant(1528318073700)).unwrap(); +//! store.put(&mut writer, "boolean", &Value::Bool(true)).unwrap(); +//! store.put(&mut writer, "string", &Value::Str("Héllo, wörld!")).unwrap(); +//! store.put(&mut writer, "json", &Value::Json(r#"{"foo":"bar", "number": 1}"#)).unwrap(); +//! store.put(&mut writer, "blob", &Value::Blob(b"blob")).unwrap(); +//! +//! // You must commit a write transaction before the writer goes out of scope, or the +//! // transaction will abort and the data won't persist. +//! writer.commit().unwrap(); +//! } +//! +//! { +//! // Use a read transaction to query the store via a `Reader`. There can be multiple +//! // concurrent readers for a store, and readers never block on a writer nor other +//! // readers. +//! let reader = env.read().expect("reader"); +//! +//! // Keys are `AsRef<u8>`, and the return value is `Result<Option<Value>, StoreError>`. +//! println!("Get int {:?}", store.get(&reader, "int").unwrap()); +//! println!("Get uint {:?}", store.get(&reader, "uint").unwrap()); +//! println!("Get float {:?}", store.get(&reader, "float").unwrap()); +//! println!("Get instant {:?}", store.get(&reader, "instant").unwrap()); +//! println!("Get boolean {:?}", store.get(&reader, "boolean").unwrap()); +//! println!("Get string {:?}", store.get(&reader, "string").unwrap()); +//! println!("Get json {:?}", store.get(&reader, "json").unwrap()); +//! println!("Get blob {:?}", store.get(&reader, "blob").unwrap()); +//! +//! // Retrieving a non-existent value returns `Ok(None)`. +//! println!("Get non-existent value {:?}", store.get(&reader, "non-existent").unwrap()); +//! +//! // A read transaction will automatically close once the reader goes out of scope, +//! // so isn't necessary to close it explicitly, although you can do so by calling +//! // `Reader.abort()`. +//! } +//! +//! { +//! // Aborting a write transaction rolls back the change(s). +//! let mut writer = env.write().unwrap(); +//! store.put(&mut writer, "foo", &Value::Str("bar")).unwrap(); +//! writer.abort(); +//! let reader = env.read().expect("reader"); +//! println!("It should be None! ({:?})", store.get(&reader, "foo").unwrap()); +//! } +//! +//! { +//! // Explicitly aborting a transaction is not required unless an early abort is +//! // desired, since both read and write transactions will implicitly be aborted once +//! // they go out of scope. +//! { +//! let mut writer = env.write().unwrap(); +//! store.put(&mut writer, "foo", &Value::Str("bar")).unwrap(); +//! } +//! let reader = env.read().expect("reader"); +//! println!("It should be None! ({:?})", store.get(&reader, "foo").unwrap()); +//! } +//! +//! { +//! // Deleting a key/value pair also requires a write transaction. +//! let mut writer = env.write().unwrap(); +//! store.put(&mut writer, "foo", &Value::Str("bar")).unwrap(); +//! store.put(&mut writer, "bar", &Value::Str("baz")).unwrap(); +//! store.delete(&mut writer, "foo").unwrap(); +//! +//! // A write transaction also supports reading, and the version of the store that it +//! // reads includes the changes it has made regardless of the commit state of that +//! // transaction. + +//! // In the code above, "foo" and "bar" were put into the store, then "foo" was +//! // deleted so only "bar" will return a result when the database is queried via the +//! // writer. +//! println!("It should be None! ({:?})", store.get(&writer, "foo").unwrap()); +//! println!("Get bar ({:?})", store.get(&writer, "bar").unwrap()); +//! +//! // But a reader won't see that change until the write transaction is committed. +//! { +//! let reader = env.read().expect("reader"); +//! println!("Get foo {:?}", store.get(&reader, "foo").unwrap()); +//! println!("Get bar {:?}", store.get(&reader, "bar").unwrap()); +//! } +//! writer.commit().unwrap(); +//! { +//! let reader = env.read().expect("reader"); +//! println!("It should be None! ({:?})", store.get(&reader, "foo").unwrap()); +//! println!("Get bar {:?}", store.get(&reader, "bar").unwrap()); +//! } +//! +//! // Committing a transaction consumes the writer, preventing you from reusing it by +//! // failing at compile time with an error. This line would report "error[E0382]: +//! // borrow of moved value: `writer`". +//! // store.put(&mut writer, "baz", &Value::Str("buz")).unwrap(); +//! } +//! +//! { +//! // Clearing all the entries in the store with a write transaction. +//! { +//! let mut writer = env.write().unwrap(); +//! store.put(&mut writer, "foo", &Value::Str("bar")).unwrap(); +//! store.put(&mut writer, "bar", &Value::Str("baz")).unwrap(); +//! writer.commit().unwrap(); +//! } +//! +//! { +//! let mut writer = env.write().unwrap(); +//! store.clear(&mut writer).unwrap(); +//! writer.commit().unwrap(); +//! } +//! +//! { +//! let reader = env.read().expect("reader"); +//! println!("It should be None! ({:?})", store.get(&reader, "foo").unwrap()); +//! println!("It should be None! ({:?})", store.get(&reader, "bar").unwrap()); +//! } +//! +//! } +//! +//! ``` + +mod env; +mod error; +mod helpers; +mod manager; +mod readwrite; + +pub mod backend; +#[cfg(feature = "lmdb")] +pub mod migrator; +pub mod store; +pub mod value; + +pub use backend::{DatabaseFlags, EnvironmentFlags, WriteFlags}; +pub use env::Rkv; +pub use error::{DataError, MigrateError, StoreError}; +pub use manager::Manager; +#[cfg(feature = "lmdb")] +pub use migrator::Migrator; +pub use readwrite::{Readable, Reader, Writer}; +pub use store::{keys::EncodableKey, single::SingleStore, CloseOptions, Options as StoreOptions}; +pub use value::{OwnedValue, Value}; + +#[cfg(feature = "db-dup-sort")] +pub use store::multi::MultiStore; + +#[cfg(feature = "db-int-key")] +pub use store::integer::IntegerStore; +#[cfg(feature = "db-int-key")] +pub use store::keys::PrimitiveInt; + +#[cfg(all(feature = "db-dup-sort", feature = "db-int-key"))] +pub use store::integermulti::MultiIntegerStore; |