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lib.rs
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#![deny(
missing_docs,
non_camel_case_types,
non_snake_case,
path_statements,
trivial_casts,
trivial_numeric_casts,
unsafe_code,
unstable_features,
unused_allocation,
unused_import_braces,
unused_imports,
unused_must_use,
unused_mut,
while_true,
clippy::panic,
clippy::print_stdout,
clippy::todo,
//clippy::unwrap_used, // not yet in stable
clippy::wrong_pub_self_convention
)]
#![warn(clippy::pedantic)]
// part of `clippy::pedantic`, causing many warnings
#![allow(clippy::missing_errors_doc, clippy::module_name_repetitions)]
//! # Rustbreak
//!
//! Rustbreak was a [Daybreak][daybreak] inspired single file Database.
//! It has now since evolved into something else. Please check v1 for a more
//! similar version.
//!
//! You will find an overview here in the docs, but to give you a more complete
//! tale of how this is used please check the [examples][examples].
//!
//! At its core, Rustbreak is an attempt at making a configurable
//! general-purpose store Database. It features the possibility of:
//!
//! - Choosing what kind of Data is stored in it
//! - Which kind of Serialization is used for persistence
//! - Which kind of persistence is used
//!
//! This means you can take any struct you can serialize and deserialize and
//! stick it into this Database. It is then encoded with Ron, Yaml, JSON,
//! Bincode, anything really that uses Serde operations!
//!
//! There are three helper type aliases [`MemoryDatabase`], [`FileDatabase`],
//! and [`PathDatabase`], each backed by their respective backend.
//!
//! The [`MemoryBackend`] saves its data into a `Vec<u8>`, which is not that
//! useful on its own, but is needed for compatibility with the rest of the
//! Library.
//!
//! The [`FileDatabase`] is a classical file based database. You give it a path
//! or a file, and it will use it as its storage. You still get to pick what
//! encoding it uses.
//!
//! The [`PathDatabase`] is very similar, but always requires a path for
//! creation. It features atomic saves, so that the old database contents won't
//! be lost when panicing during the save. It should therefore be preferred to a
//! [`FileDatabase`].
//!
//! Using the [`Database::with_deser`] and [`Database::with_backend`] one can
//! switch between the representations one needs. Even at runtime! However this
//! is only useful in a few scenarios.
//!
//! If you have any questions feel free to ask at the main [repo][repo].
//!
//! ## Quickstart
//!
//! Add this to your `Cargo.toml`:
//!
//! ```toml
//! [dependencies.rustbreak]
//! version = "2"
//! features = ["ron_enc"] # You can also use "yaml_enc" or "bin_enc"
//! # Check the documentation to add your own!
//! ```
//!
//! ```rust
//! # extern crate rustbreak;
//! # use std::collections::HashMap;
//! use rustbreak::{deser::Ron, MemoryDatabase};
//!
//! # fn main() {
//! # let func = || -> Result<(), Box<dyn std::error::Error>> {
//! let db = MemoryDatabase::<HashMap<u32, String>, Ron>::memory(HashMap::new())?;
//!
//! println!("Writing to Database");
//! db.write(|db| {
//! db.insert(0, String::from("world"));
//! db.insert(1, String::from("bar"));
//! });
//!
//! db.read(|db| {
//! // db.insert("foo".into(), String::from("bar"));
//! // The above line will not compile since we are only reading
//! println!("Hello: {:?}", db.get(&0));
//! })?;
//! # return Ok(()); };
//! # func().unwrap();
//! # }
//! ```
//!
//! Or alternatively:
//! ```rust
//! # extern crate rustbreak;
//! # use std::collections::HashMap;
//! use rustbreak::{deser::Ron, MemoryDatabase};
//!
//! # fn main() {
//! # let func = || -> Result<(), Box<dyn std::error::Error>> {
//! let db = MemoryDatabase::<HashMap<u32, String>, Ron>::memory(HashMap::new())?;
//!
//! println!("Writing to Database");
//! {
//! let mut data = db.borrow_data_mut()?;
//! data.insert(0, String::from("world"));
//! data.insert(1, String::from("bar"));
//! }
//!
//! let data = db.borrow_data()?;
//! println!("Hello: {:?}", data.get(&0));
//! # return Ok(()); };
//! # func().unwrap();
//! # }
//! ```
//!
//! ## Error Handling
//!
//! Handling errors in Rustbreak is straightforward. Every `Result` has as its
//! fail case as [`error::RustbreakError`]. This means that you can now either
//! continue bubbling up said error case, or handle it yourself.
//!
//! ```rust
//! use rustbreak::{deser::Ron, error::RustbreakError, MemoryDatabase};
//! let db = match MemoryDatabase::<usize, Ron>::memory(0) {
//! Ok(db) => db,
//! Err(e) => {
//! // Do something with `e` here
//! std::process::exit(1);
//! }
//! };
//! ```
//!
//! ## Panics
//!
//! This Database implementation uses [`RwLock`] and [`Mutex`] under the hood.
//! If either the closures given to [`Database::write`] or any of the Backend
//! implementation methods panic the respective objects are then poisoned. This
//! means that you *cannot panic* under any circumstances in your closures or
//! custom backends.
//!
//! Currently there is no way to recover from a poisoned `Database` other than
//! re-creating it.
//!
//! ## Examples
//!
//! There are several more or less in-depth example programs you can check out!
//! Check them out here: [Examples][examples]
//!
//! - `config.rs` shows you how a possible configuration file could be managed
//! with rustbreak
//! - `full.rs` shows you how the database can be used as a hashmap store
//! - `switching.rs` show you how you can easily swap out different parts of the
//! Database *Note*: To run this example you need to enable the feature `yaml`
//! like so: `cargo run --example switching --features yaml`
//! - `server/` is a fully fledged example app written with the Rocket framework
//! to make a form of micro-blogging website. You will need rust nightly to
//! start it.
//!
//! ## Features
//!
//! Rustbreak comes with following optional features:
//!
//! - `ron_enc` which enables the [Ron][ron] de/serialization
//! - `yaml_enc` which enables the Yaml de/serialization
//! - `bin_enc` which enables the Bincode de/serialization
//! - 'mmap' whhich enables memory map backend.
//!
//! [Enable them in your `Cargo.toml` file to use them.][features] You can
//! safely have them all turned on per-default.
//!
//!
//! [repo]: https://github.com/TheNeikos/rustbreak
//! [daybreak]: https://propublica.github.io/daybreak
//! [examples]: https://github.com/TheNeikos/rustbreak/tree/master/examples
//! [ron]: https://github.com/ron-rs/ron
//! [features]: https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#choosing-features
pub mod backend;
/// Different serialization and deserialization methods one can use
pub mod deser;
/// The rustbreak errors that can be returned
pub mod error;
/// The `DeSerializer` trait used by serialization structs
pub use crate::deser::DeSerializer;
/// The general error used by the Rustbreak Module
use std::fmt::Debug;
use std::ops::Deref;
use std::path::PathBuf;
use std::sync::{Mutex, RwLock, RwLockReadGuard, RwLockWriteGuard};
use serde::de::DeserializeOwned;
use serde::Serialize;
#[cfg(feature = "mmap")]
use crate::backend::MmapStorage;
use crate::backend::{Backend, FileBackend, MemoryBackend, PathBackend};
pub use crate::error::*;
/// The Central Database to Rustbreak.
///
/// It has 3 Type Generics:
///
/// - `Data`: Is the Data, you must specify this
/// - `Back`: The storage backend.
/// - `DeSer`: The Serializer/Deserializer or short `DeSer`. Check the [`deser`]
/// module for other strategies.
///
/// # Panics
///
/// If the backend or the de/serialization panics, the database is poisoned.
/// This means that any subsequent writes/reads will fail with an
/// [`error::RustbreakError::Poison`]. You can only recover from this by
/// re-creating the Database Object.
#[derive(Debug)]
pub struct Database<Data, Back, DeSer> {
data: RwLock<Data>,
backend: Mutex<Back>,
deser: DeSer,
}
impl<Data, Back, DeSer> Database<Data, Back, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send,
Back: Backend,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Write lock the database and get write access to the `Data` container.
///
/// This gives you an exclusive lock on the memory object. Trying to open
/// the database in writing will block if it is currently being written
/// to.
///
/// # Panics
///
/// If you panic in the closure, the database is poisoned. This means that
/// any subsequent writes/reads will fail with an
/// [`error::RustbreakError::Poison`]. You can only recover from
/// this by re-creating the Database Object.
///
/// If you do not have full control over the code being written, and cannot
/// incur the cost of having a single operation panicking then use
/// [`Database::write_safe`].
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate serde_derive;
/// # extern crate rustbreak;
/// # extern crate serde;
/// # extern crate tempfile;
/// use rustbreak::{deser::Ron, FileDatabase};
///
/// #[derive(Debug, Serialize, Deserialize, Clone)]
/// struct Data {
/// level: u32,
/// }
///
/// # fn main() {
/// # let func = || -> Result<(), Box<dyn std::error::Error>> {
/// # let file = tempfile::tempfile()?;
/// let db = FileDatabase::<Data, Ron>::from_file(file, Data { level: 0 })?;
///
/// db.write(|db| {
/// db.level = 42;
/// })?;
///
/// // You can also return from a `.read()`. But don't forget that you cannot return references
/// // into the structure
/// let value = db.read(|db| db.level)?;
/// assert_eq!(42, value);
/// # return Ok(());
/// # };
/// # func().unwrap();
/// # }
/// ```
pub fn write<T, R>(&self, task: T) -> error::Result<R>
where
T: FnOnce(&mut Data) -> R,
{
let mut lock = self.data.write().map_err(|_| RustbreakError::Poison)?;
Ok(task(&mut lock))
}
/// Write lock the database and get write access to the `Data` container in
/// a safe way.
///
/// This gives you an exclusive lock on the memory object. Trying to open
/// the database in writing will block if it is currently being written
/// to.
///
/// This differs to `Database::write` in that a clone of the internal data
/// is made, which is then passed to the closure. Only if the closure
/// doesn't panic is the internal model updated.
///
/// Depending on the size of the database this can be very costly. This is a
/// tradeoff to make for panic safety.
///
/// You should read the documentation about this:
/// [`UnwindSafe`](https://doc.rust-lang.org/std/panic/trait.UnwindSafe.html)
///
/// # Panics
///
/// When the closure panics, it is caught and a
/// [`error::RustbreakError::WritePanic`] will be returned.
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate serde_derive;
/// # extern crate rustbreak;
/// # extern crate serde;
/// # extern crate tempfile;
/// use rustbreak::{
/// deser::Ron,
/// error::RustbreakError,
/// FileDatabase,
/// };
///
/// #[derive(Debug, Serialize, Deserialize, Clone)]
/// struct Data {
/// level: u32,
/// }
///
/// # fn main() {
/// # let func = || -> Result<(), Box<dyn std::error::Error>> {
/// # let file = tempfile::tempfile()?;
/// let db = FileDatabase::<Data, Ron>::from_file(file, Data { level: 0 })?;
///
/// let result = db
/// .write_safe(|db| {
/// db.level = 42;
/// panic!("We panic inside the write code.");
/// })
/// .expect_err("This should have been caught");
///
/// match result {
/// RustbreakError::WritePanic => {
/// // We can now handle this, in this example we will just ignore it
/// }
/// e => {
/// println!("{:#?}", e);
/// // You should always have generic error catching here.
/// // This future-proofs your code, and makes your code more robust.
/// // In this example this is unreachable though, and to assert that we have this
/// // macro here
/// unreachable!();
/// }
/// }
///
/// // We read it back out again, it has not changed
/// let value = db.read(|db| db.level)?;
/// assert_eq!(0, value);
/// # return Ok(());
/// # };
/// # func().unwrap();
/// # }
/// ```
pub fn write_safe<T>(&self, task: T) -> error::Result<()>
where
T: FnOnce(&mut Data) + std::panic::UnwindSafe,
{
let mut lock = self.data.write().map_err(|_| RustbreakError::Poison)?;
let mut data = lock.clone();
std::panic::catch_unwind(::std::panic::AssertUnwindSafe(|| {
task(&mut data);
}))
.map_err(|_| RustbreakError::WritePanic)?;
*lock = data;
Ok(())
}
/// Read lock the database and get read access to the `Data` container.
///
/// This gives you a read-only lock on the database. You can have as many
/// readers in parallel as you wish.
///
/// # Errors
///
/// May return:
///
/// - [`error::RustbreakError::Backend`]
///
/// # Panics
///
/// If you panic in the closure, the database is poisoned. This means that
/// any subsequent writes/reads will fail with an
/// [`error::RustbreakError::Poison`]. You can only recover from
/// this by re-creating the Database Object.
pub fn read<T, R>(&self, task: T) -> error::Result<R>
where
T: FnOnce(&Data) -> R,
{
let mut lock = self.data.read().map_err(|_| RustbreakError::Poison)?;
Ok(task(&mut lock))
}
/// Read lock the database and get access to the underlying struct.
///
/// This gives you access to the underlying struct, allowing for simple read
/// only operations on it.
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate serde_derive;
/// # extern crate rustbreak;
/// # extern crate serde;
/// # extern crate tempfile;
/// use rustbreak::{deser::Ron, FileDatabase};
///
/// #[derive(Debug, Serialize, Deserialize, Clone)]
/// struct Data {
/// level: u32,
/// }
///
/// # fn main() {
/// # let func = || -> Result<(), Box<dyn std::error::Error>> {
/// # let file = tempfile::tempfile()?;
/// let db = FileDatabase::<Data, Ron>::from_file(file, Data { level: 0 })?;
///
/// db.write(|db| {
/// db.level = 42;
/// })?;
///
/// let data = db.borrow_data()?;
///
/// assert_eq!(42, data.level);
/// # return Ok(());
/// # };
/// # func().unwrap();
/// # }
/// ```
pub fn borrow_data<'a>(&'a self) -> error::Result<RwLockReadGuard<'a, Data>> {
self.data.read().map_err(|_| RustbreakError::Poison)
}
/// Write lock the database and get access to the underlying struct.
///
/// This gives you access to the underlying struct, allowing you to modify
/// it.
///
/// # Panics
///
/// If you panic while holding this reference, the database is poisoned.
/// This means that any subsequent writes/reads will fail with an
/// [`error::RustbreakError::Poison`]. You can only recover from
/// this by re-creating the Database Object.
///
/// If you do not have full control over the code being written, and cannot
/// incur the cost of having a single operation panicking then use
/// [`Database::write_safe`].
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate serde_derive;
/// # extern crate rustbreak;
/// # extern crate serde;
/// # extern crate tempfile;
/// use rustbreak::{deser::Ron, FileDatabase};
///
/// #[derive(Debug, Serialize, Deserialize, Clone)]
/// struct Data {
/// level: u32,
/// }
///
/// # fn main() {
/// # let func = || -> Result<(), Box<dyn std::error::Error>> {
/// # let file = tempfile::tempfile()?;
/// let db = FileDatabase::<Data, Ron>::from_file(file, Data { level: 0 })?;
///
/// {
/// let mut data = db.borrow_data_mut()?;
/// data.level = 42;
/// }
///
/// let data = db.borrow_data()?;
///
/// assert_eq!(42, data.level);
/// # return Ok(());
/// # };
/// # func().unwrap();
/// # }
/// ```
pub fn borrow_data_mut<'a>(&'a self) -> error::Result<RwLockWriteGuard<'a, Data>> {
self.data.write().map_err(|_| RustbreakError::Poison)
}
/// Load data from backend and return this data.
fn load_from_backend(backend: &mut Back, deser: &DeSer) -> error::Result<Data> {
let new_data = deser.deserialize(&backend.get_data()?[..])?;
Ok(new_data)
}
/// Like [`Self::load`] but returns the write lock to data it used.
fn load_get_data_lock(&self) -> error::Result<RwLockWriteGuard<'_, Data>> {
let mut backend_lock = self.backend.lock().map_err(|_| RustbreakError::Poison)?;
let fresh_data = Self::load_from_backend(&mut backend_lock, &self.deser)?;
drop(backend_lock);
let mut data_write_lock = self.data.write().map_err(|_| RustbreakError::Poison)?;
*data_write_lock = fresh_data;
Ok(data_write_lock)
}
/// Load the data from the backend.
pub fn load(&self) -> error::Result<()> {
self.load_get_data_lock().map(|_| ())
}
/// Like [`Self::save`] but with explicit read (or write) lock to data.
fn save_data_locked<L: Deref<Target = Data>>(&self, lock: L) -> error::Result<()> {
let ser = self.deser.serialize(lock.deref())?;
drop(lock);
let mut backend = self.backend.lock().map_err(|_| RustbreakError::Poison)?;
backend.put_data(&ser)?;
Ok(())
}
/// Flush the data structure to the backend.
pub fn save(&self) -> error::Result<()> {
let data = self.data.read().map_err(|_| RustbreakError::Poison)?;
self.save_data_locked(data)
}
/// Get a clone of the data as it is in memory right now.
///
/// To make sure you have the latest data, call this method with `load`
/// true.
pub fn get_data(&self, load: bool) -> error::Result<Data> {
let data = if load {
self.load_get_data_lock()?
} else {
self.data.write().map_err(|_| RustbreakError::Poison)?
};
Ok(data.clone())
}
/// Puts the data as is into memory.
///
/// To save the data afterwards, call with `save` true.
pub fn put_data(&self, new_data: Data, save: bool) -> error::Result<()> {
let mut data = self.data.write().map_err(|_| RustbreakError::Poison)?;
*data = new_data;
if save {
self.save_data_locked(data)
} else {
Ok(())
}
}
/// Create a database from its constituents.
pub fn from_parts(data: Data, backend: Back, deser: DeSer) -> Self {
Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
}
}
/// Break a database into its individual parts.
pub fn into_inner(self) -> error::Result<(Data, Back, DeSer)> {
Ok((
self.data.into_inner().map_err(|_| RustbreakError::Poison)?,
self.backend
.into_inner()
.map_err(|_| RustbreakError::Poison)?,
self.deser,
))
}
/// Tries to clone the Data in the Database.
///
/// This method returns a `MemoryDatabase` which has an empty vector as a
/// backend initially. This means that the user is responsible for assigning
/// a new backend if an alternative is wanted.
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate serde_derive;
/// # extern crate rustbreak;
/// # extern crate serde;
/// # extern crate tempfile;
/// use rustbreak::{deser::Ron, FileDatabase};
///
/// #[derive(Debug, Serialize, Deserialize, Clone)]
/// struct Data {
/// level: u32,
/// }
///
/// # fn main() {
/// # let func = || -> Result<(), Box<dyn std::error::Error>> {
/// # let file = tempfile::tempfile()?;
/// let db = FileDatabase::<Data, Ron>::from_file(file, Data { level: 0 })?;
///
/// db.write(|db| {
/// db.level = 42;
/// })?;
///
/// db.save()?;
///
/// let other_db = db.try_clone()?;
///
/// // You can also return from a `.read()`. But don't forget that you cannot return references
/// // into the structure
/// let value = other_db.read(|db| db.level)?;
/// assert_eq!(42, value);
/// # return Ok(());
/// # };
/// # func().unwrap();
/// # }
/// ```
pub fn try_clone(&self) -> error::Result<MemoryDatabase<Data, DeSer>> {
let lock = self.data.read().map_err(|_| RustbreakError::Poison)?;
Ok(Database {
data: RwLock::new(lock.clone()),
backend: Mutex::new(MemoryBackend::new()),
deser: self.deser.clone(),
})
}
}
/// A database backed by a file.
pub type FileDatabase<D, DS> = Database<D, FileBackend, DS>;
impl<Data, DeSer> Database<Data, FileBackend, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Create new [`FileDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents.
pub fn load_from_path<S>(path: S) -> error::Result<Self>
where
S: AsRef<std::path::Path>,
{
let mut backend = FileBackend::from_path_or_fail(path)?;
let deser = DeSer::default();
let data = Self::load_from_backend(&mut backend, &deser)?;
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
Ok(db)
}
/// Load [`FileDatabase`] at `path` or initialise with `data`.
///
/// Create new [`FileDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents. If the file does not exist, initialise with
/// `data`.
pub fn load_from_path_or<S>(path: S, data: Data) -> error::Result<Self>
where
S: AsRef<std::path::Path>,
{
let (mut backend, exists) = FileBackend::from_path_or_create(path)?;
let deser = DeSer::default();
if !exists {
let ser = deser.serialize(&data)?;
backend.put_data(&ser)?;
}
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
if exists {
db.load()?;
}
Ok(db)
}
/// Load [`FileDatabase`] at `path` or initialise with `closure`.
///
/// Create new [`FileDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents. If the file does not exist, `closure` is
/// called and the database is initialised with it's return value.
pub fn load_from_path_or_else<S, C>(path: S, closure: C) -> error::Result<Self>
where
S: AsRef<std::path::Path>,
C: FnOnce() -> Data,
{
let (mut backend, exists) = FileBackend::from_path_or_create(path)?;
let deser = DeSer::default();
let data = if exists {
Self::load_from_backend(&mut backend, &deser)?
} else {
let data = closure();
let ser = deser.serialize(&data)?;
backend.put_data(&ser)?;
data
};
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
Ok(db)
}
/// Create [`FileDatabase`] at `path`. Initialise with `data` if the file
/// doesn't exist.
///
/// Create new [`FileDatabase`] from the file at [`Path`](std::path::Path).
/// Contents are not loaded. If the file does not exist, it is
/// initialised with `data`. Frontend is always initialised with `data`.
pub fn create_at_path<S>(path: S, data: Data) -> error::Result<Self>
where
S: AsRef<std::path::Path>,
{
let (mut backend, exists) = FileBackend::from_path_or_create(path)?;
let deser = DeSer::default();
if !exists {
let ser = deser.serialize(&data)?;
backend.put_data(&ser)?;
}
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
Ok(db)
}
/// Create new [`FileDatabase`] from a file.
pub fn from_file(file: std::fs::File, data: Data) -> error::Result<Self> {
let backend = FileBackend::from_file(file);
Ok(Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser: DeSer::default(),
})
}
}
impl<Data, DeSer> Database<Data, FileBackend, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send + Default,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Load [`FileDatabase`] at `path` or initialise with `Data::default()`.
///
/// Create new [`FileDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents. If the file does not exist, initialise with
/// `Data::default`.
pub fn load_from_path_or_default<S>(path: S) -> error::Result<Self>
where
S: AsRef<std::path::Path>,
{
Self::load_from_path_or_else(path, Data::default)
}
}
/// A database backed by a file, using atomic saves.
pub type PathDatabase<D, DS> = Database<D, PathBackend, DS>;
impl<Data, DeSer> Database<Data, PathBackend, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Create new [`PathDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents.
pub fn load_from_path(path: PathBuf) -> error::Result<Self> {
let mut backend = PathBackend::from_path_or_fail(path)?;
let deser = DeSer::default();
let data = Self::load_from_backend(&mut backend, &deser)?;
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
Ok(db)
}
/// Load [`PathDatabase`] at `path` or initialise with `data`.
///
/// Create new [`PathDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents. If the file does not exist, initialise with
/// `data`.
pub fn load_from_path_or(path: PathBuf, data: Data) -> error::Result<Self> {
let (mut backend, exists) = PathBackend::from_path_or_create(path)?;
let deser = DeSer::default();
if !exists {
let ser = deser.serialize(&data)?;
backend.put_data(&ser)?;
}
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
if exists {
db.load()?;
}
Ok(db)
}
/// Load [`PathDatabase`] at `path` or initialise with `closure`.
///
/// Create new [`PathDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents. If the file does not exist, `closure` is
/// called and the database is initialised with it's return value.
pub fn load_from_path_or_else<C>(path: PathBuf, closure: C) -> error::Result<Self>
where
C: FnOnce() -> Data,
{
let (mut backend, exists) = PathBackend::from_path_or_create(path)?;
let deser = DeSer::default();
let data = if exists {
Self::load_from_backend(&mut backend, &deser)?
} else {
let data = closure();
let ser = deser.serialize(&data)?;
backend.put_data(&ser)?;
data
};
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
Ok(db)
}
/// Create [`PathDatabase`] at `path`. Initialise with `data` if the file
/// doesn't exist.
///
/// Create new [`PathDatabase`] from the file at [`Path`](std::path::Path).
/// Contents are not loaded. If the file does not exist, it is
/// initialised with `data`. Frontend is always initialised with `data`.
pub fn create_at_path(path: PathBuf, data: Data) -> error::Result<Self> {
let (mut backend, exists) = PathBackend::from_path_or_create(path)?;
let deser = DeSer::default();
if !exists {
let ser = deser.serialize(&data)?;
backend.put_data(&ser)?;
}
let db = Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser,
};
Ok(db)
}
}
impl<Data, DeSer> Database<Data, PathBackend, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send + Default,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Load [`PathDatabase`] at `path` or initialise with `Data::default()`.
///
/// Create new [`PathDatabase`] from the file at [`Path`](std::path::Path),
/// and load the contents. If the file does not exist, initialise with
/// `Data::default`.
pub fn load_from_path_or_default(path: PathBuf) -> error::Result<Self> {
Self::load_from_path_or_else(path, Data::default)
}
}
/// A database backed by a byte vector (`Vec<u8>`).
pub type MemoryDatabase<D, DS> = Database<D, MemoryBackend, DS>;
impl<Data, DeSer> Database<Data, MemoryBackend, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Create new in-memory database.
pub fn memory(data: Data) -> error::Result<Self> {
let backend = MemoryBackend::new();
Ok(Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser: DeSer::default(),
})
}
}
/// A database backed by anonymous memory map.
#[cfg(feature = "mmap")]
pub type MmapDatabase<D, DS> = Database<D, MmapStorage, DS>;
#[cfg(feature = "mmap")]
impl<Data, DeSer> Database<Data, MmapStorage, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Create new [`MmapDatabase`].
pub fn mmap(data: Data) -> error::Result<Self> {
let backend = MmapStorage::new()?;
Ok(Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser: DeSer::default(),
})
}
/// Create new [`MmapDatabase`] with specified initial size.
pub fn mmap_with_size(data: Data, size: usize) -> error::Result<Self> {
let backend = MmapStorage::with_size(size)?;
Ok(Self {
data: RwLock::new(data),
backend: Mutex::new(backend),
deser: DeSer::default(),
})
}
}
impl<Data, Back, DeSer> Database<Data, Back, DeSer> {
/// Exchanges the `DeSerialization` strategy with the new one.
pub fn with_deser<T>(self, deser: T) -> Database<Data, Back, T> {
Database {
backend: self.backend,
data: self.data,
deser,
}
}
}
impl<Data, Back, DeSer> Database<Data, Back, DeSer> {
/// Exchanges the `Backend` with the new one.
///
/// The new backend does not necessarily have the latest data saved to it,
/// so a `.save` should be called to make sure that it is saved.
pub fn with_backend<T>(self, backend: T) -> Database<Data, T, DeSer> {
Database {
backend: Mutex::new(backend),
data: self.data,
deser: self.deser,
}
}
}
impl<Data, Back, DeSer> Database<Data, Back, DeSer>
where
Data: Serialize + DeserializeOwned + Clone + Send,
Back: Backend,
DeSer: DeSerializer<Data> + Send + Sync + Clone,
{
/// Converts from one data type to another.
///
/// This method is useful to migrate from one datatype to another.
pub fn convert_data<C, OutputData>(
self,
convert: C,
) -> error::Result<Database<OutputData, Back, DeSer>>
where
OutputData: Serialize + DeserializeOwned + Clone + Send,
C: FnOnce(Data) -> OutputData,
DeSer: DeSerializer<OutputData> + Send + Sync,
{
let (data, backend, deser) = self.into_inner()?;