Crate mmap_io 

mmap-io: memory-mapped file I/O for Rust

Safe, zero-copy memory-mapped file operations with concurrent access, segmented views, runtime-agnostic async, and atomic memory views.

What you get

• Zero-copy reads on read-only, read-write, and copy-on-write mappings.
• Thread-safe interior mutability via parking_lot::RwLock.
• Segmented and chunked access without loading whole files.
• Cross-platform: Linux, macOS, Windows, with per-platform fast paths.
• Anonymous mappings via AnonymousMmap for shared scratch memory.
• Atomic views (feature = "atomic") for lock-free counters in mapped memory.
• Runtime-agnostic async (feature = "async") on tokio, smol, async-std, or any executor.
• bytes::Bytes integration (feature = "bytes") for the hyper/tower/tonic/axum/reqwest ecosystem.
• Native file watching (feature = "watch") via inotify / FSEvents / ReadDirectoryChangesW.

Quick start

use mmap_io::MemoryMappedFile;

// Opens "data.bin" if it exists; creates it at 1 MiB otherwise.
let mmap = MemoryMappedFile::open_or_create("data.bin", 1024 * 1024)?;
mmap.update_region(0, b"Hello, mmap!")?;
mmap.flush()?;

Modules

• mmap: Core MemoryMappedFile implementation.
• anonymous: Process-local file-less AnonymousMmap.
• segment: Segmented views for working with file regions.
• manager: High-level convenience functions (create_mmap, load_mmap, etc.).
• errors: Error types (MmapIoError).
• utils: Alignment and bounds-checking helpers.
• flush: flush::FlushPolicy and time-based flushing.

Feature flags

All optional features are off by default except advise and iterator. See the README for the full feature table.

Re-exports

pub use anonymous::AnonymousMmap;

pub use errors::MmapIoError;

pub use manager::copy_mmap;

pub use manager::create_mmap;

pub use manager::delete_mmap;

pub use manager::flush;

pub use manager::load_mmap;

pub use manager::update_region;

pub use manager::write_mmap;

pub use mmap::MappedSlice;

pub use mmap::MappedSliceMut;

pub use mmap::MemoryMappedFile;

pub use mmap::MmapMode;

pub use mmap::TouchHint;

pub use advise::MmapAdvice;

pub use iterator::ChunkIterator;

pub use iterator::PageIterator;

pub use watch::ChangeEvent;

pub use watch::ChangeKind;

pub use watch::WatchHandle;

Modules

advise

Memory advise operations for optimizing OS behavior.

anonymous

Anonymous (file-less) memory mappings. Anonymous (file-less) memory mappings.

atomic

Atomic memory views for lock-free concurrent access to specific data types.

errors

Crate-specific error types for mmap-io.

flush

Provides functions for flushing memory-mapped file changes to disk. Flush policy configuration for MemoryMappedFile.

iterator

Zero-copy iterator-based access to a memory-mapped file.

lock

Memory locking operations to prevent pages from being swapped out.

manager

High-level API for managing memory-mapped files.

mmap

Memory-mapped file support.

segment

Zero-copy segment views into a memory-mapped file.

utils

Utility helpers for alignment, page size, and safe range calculations.

watch

Native file-change watching, backed by the notify crate.