This library implements a FUSE filesystem that uses event sourcing to store data. This approach provides visibility into filesystem changes and allows restoring the filesystem to any previous point. In particular this library supports branching from specific points in the event history (see examples).

Example

use std::{fs, path::PathBuf};

use eventfs::{EventPageLimit, Filesystem, FilesystemConfiguration};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create the local mount point used by FUSE.
    let mount_point = PathBuf::from("eventfs.mount");

    fs::create_dir_all(&mount_point)?;

    // Open the filesystem and mount it in the background.
    let configuration = FilesystemConfiguration::new("eventfs.db", mount_point.clone())?;

    let filesystem = Filesystem::open(configuration)?;

    let _ = filesystem.spawn_mount()?;

    // Write a file through the mounted filesystem.
    fs::write(mount_point.join("hello.txt"), "Hello from eventfs!")?;

    // Print the events created by filesystem changes.
    for event in filesystem.events(EventPageLimit::new(10)?) {
        println!("{:?}", event?);
    }

    Ok(())
}

FUSE operation support

• lookup
• getattr
• setattr
• readlink
• mknod
• mkdir
• unlink
• rmdir
• symlink
• rename
• link
• open
• read
• write
• flush
• release
• fsync
• opendir
• readdir
• releasedir
• fsyncdir
• statfs
• setxattr
• getxattr
• listxattr
• removexattr
• access
• create
• readdirplus
• getlk
• setlk
• bmap
• ioctl
• poll
• fallocate
• lseek
• copy_file_range

Benchmarks

• Measured with ./dev.sh bench on July 9, 2026.
• Apple M4 Pro host, macOS 26.2 25C56.
• Apple container Linux VM, Linux 6.18.15 aarch64.
• 14 CPUs and 49.3 GB RAM exposed to the container.
• FUSE 3.14.0.

Benchmark	Host	eventfs	Overhead
Read metadata by path	215 ns	226 ns	1.1x
Read metadata from an open file	128 ns	128 ns	1.0x
Change file permissions	280 ns	38.91 µs	139.2x
Resize a file between 2 KiB and 4 KiB	523 ns	62.03 µs	118.6x
Check file read access	198 ns	211 ns	1.1x
Read filesystem statistics	282 ns	23.71 µs	83.9x
Create a named pipe	772 ns	81.73 µs	105.9x
Create a directory	51.42 µs	82.45 µs	1.6x
Create a file	886 ns	87.43 µs	98.7x
Delete a file	1.008 µs	67.49 µs	66.9x
Remove an empty directory	1.307 µs	66.4 µs	50.8x
Rename a file	874 ns	84.57 µs	96.8x
Rename a file without replacing the destination	885 ns	84.26 µs	95.3x
Create a hard link	576 ns	84.61 µs	146.8x
Create a symbolic link	830 ns	84.34 µs	101.6x
Read a symbolic link target	247 ns	22.44 µs	90.7x
Open a file	253 ns	24.1 µs	95.4x
Read 4 KiB	201 ns	27.67 µs	137.4x
Overwrite 4 KiB	241 ns	56.77 µs	235.6x
Flush a file	104 ns	106 ns	1.0x
Close a file	156 ns	2.699 µs	17.3x
Synchronize a file	27.35 µs	54.79 µs	2.0x
Open a directory containing 16 files	392 ns	25.57 µs	65.2x
Read a directory containing 16 files	538 ns	51.12 µs	95.1x
Read a directory and metadata for its 16 files	4.353 µs	108.4 µs	24.9x
Synchronize a directory	26.36 µs	53.42 µs	2.0x
Close a directory	158 ns	2.624 µs	16.7x
Set a 5-byte extended attribute	370 ns	56.76 µs	153.5x
Read a 5-byte extended attribute	292 ns	23.13 µs	79.2x
List extended attributes	261 ns	24.28 µs	93.0x
Remove an extended attribute	364 ns	56.21 µs	154.4x
Write a new 256 MiB file sequentially	32.5 ms	407.1 ms	12.5x
Write the first 64 MiB of a new file	7.471 ms	95.7 ms	12.8x
Append 64 MiB to a 192 MiB file	6.538 ms	97.66 ms	14.9x
Overwrite the middle 64 MiB of a 256 MiB file	3.694 ms	133.8 ms	36.2x
Write 64 MiB at a 512 MiB offset in a sparse file	6.929 ms	96.24 ms	13.9x
Truncate a 256 MiB file to 128 MiB, then extend it to 320 MiB	4.629 ms	61.8 ms	13.4x
Write and synchronize a new 256 MiB file	194.7 ms	407 ms	2.1x
Write, synchronize, and rename a 256 MiB file	510.1 ms	403.8 ms	0.8x