Struct piecrust::VM

pub struct VM { /* private fields */ }

A handle to the piecrust virtual machine.

It is instantiated using new or ephemeral, and can be used to spawn multiple Sessions using session.

These sessions are synchronized with the help of a sync loop. Deletions and squashes are assured to not delete any commits used as a base for sessions until these are dropped. A handle to this loop is available at sync_thread.

Users are encouraged to instantiate a VM once during the lifetime of their program and spawn sessions as needed.

Implementations

impl VM

pub fn new<P: AsRef<Path>>(root_dir: P) -> Result<Self, Error>

Creates a new VM, reading the given directory for existing commits and bytecode.

The directory will be used to save any future session commits made by this VM instance.

Errors

If the directory contains unparseable or inconsistent data.

pub fn ephemeral() -> Result<Self, Error>

Creates a new VM using a new temporary directory.

Any session commits made by this machine should be considered discarded once this VM instance drops.

Errors

If creating a temporary directory fails.

pub fn register_host_query<Q, S>(&mut self, name: S, query: Q)where Q: 'static + HostQuery, S: Into<Cow<'static, str>>,

Registers a host query with the given name.

The query will be available to any session spawned after this was called.

pub fn session(&self, data: impl Into<SessionData>) -> Result<Session, Error>

Spawn a Session.

Errors

If base commit is provided but does not exist.

pub fn commits(&self) -> Vec<[u8; 32]>

Return all existing commits.

pub fn squash_commit(&self, root: [u8; 32]) -> Result<(), Error>

Remove the diff files from a commit by applying them to the base memories, and writing them back to disk.

Errors

If this function fails, it may be due to any number of reasons:

• remove_file may fail
• write may fail

Failing may result in a corrupted commit, and the user is encouraged to call delete_commit.

pub fn delete_commit(&self, root: [u8; 32]) -> Result<(), Error>

Deletes the given commit from disk.

pub fn root_dir(&self) -> &Path

Return the root directory of the virtual machine.

This is either the directory passed in by using new, or the temporary directory created using ephemeral.

pub fn sync_thread(&self) -> &Thread

Returns a reference to the synchronization thread.

Trait Implementations

impl Debug for VM

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.