Crate vmap

A cross-platform library for fast and safe memory-mapped IO

This library defines a convenient API for reading and writing to files using the hosts virtual memory system. The design of the API strives to both minimize the frequency of mapping system calls while still retaining safe access.

Additionally, a variety of buffer implementations are provided in the vmap::io module.

Example

use vmap::Map;
use std::io::Write;
use std::fs::OpenOptions;
use std::path::PathBuf;

let path: PathBuf = /* path to file */
let file = OpenOptions::new().read(true).write(true).open(&path)?;

// Map the beginning of the file
let map = Map::file(&file, 0, 14)?;
assert_eq!(b"this is a test", &map[..]);

// Move the Map into a MapMut
// ... we could have started with MapMut::file(...)
let mut map = map.make_mut()?;
{
    let mut data = &mut map[..];
    data.write_all(b"that")?;
}

// Move the MapMut back into a Map
let map = map.make_read_only()?;
assert_eq!(b"that is a test", &map[..]);

Modules

io	Read/Write types for buffering.
os	Low-level cross-platform virtual memory functions

Structs

AllocSize	Type for calculation page size information.
Map	Allocation of one or more read-only sequential pages.
MapMut	Allocation of one or more read-write sequential pages.

Enums

AdviseAccess	Hint for the access pattern of the underlying mapping.
AdviseUsage	Hint for the immediacy of accessing the underlying mapping.
Flush	Desired behavior when flushing write changes.
Protect	Protection level for a page.

Functions

allocation_size	Gets a cached version of the system allocation granularity size.
page_size	Gets a cached version of the system page size.

Type Definitions

Pgno	Type to represent whole page offsets and counts.