Crate checkpoint

Provides checkpointing of application data for the Rust Programming Language.

This library provides functionality to create checkpoints of application data and to restore application data from existing checkpoints.

This library is built around three traits: Storage, UncommittedCheckpoint, and CommittedCheckpoint.

Types which implement Storage are responsible for managing the medium in which checkpointed data is stored. Associated with each Storage type are two additional types, which implement UncommittedCheckpoint and CommittedCheckpoint respectively. These types allow data to be inserted into checkpoint storage, read from checkpoint storage, and removed from checkpoint storage.

This library currently provides FileStorage and MemoryStorage to store checkpoint data in the file system and in memory.

The wrappers module provides types that can add functionality to Storage types. This library currently provides the following wrappers:

• ChecksumWrapper - Adds checksum verification to checkpoint data.
• GuardWrapper - Ensures that multiple uncommitted checkpoints are not given the same identifier and that committed checkpoints are not in use before they are removed.
• HmacWrapper - Adds HMAC verification to checkpoint data.

Note: Care must be taken to ensure that wrappers are applied in the desired order, as wrapper ordering matters.

Example Usage:

// Checkpoint data is serialized and deserialized with the Serde library.
extern crate serde;
#[macro_use] extern crate serde_derive;

use serde::de::DeserializeOwned;
use serde::ser::Serialize;

extern crate checkpoint;

use checkpoint::Result;
use checkpoint::storage::{
    CommittedCheckpoint, Storage, MemoryStorage, UncommittedCheckpoint};
use checkpoint::wrappers::ChecksumWrapper;

// Any type implementing the Serialize and DeserializeOwned traits can be checkpointed.
#[derive(Deserialize, Serialize)]
struct Person {
    name: String,
    age: u8
}

// Create the data that will be stored in a checkpoint.
let person = Person {
    name: String::from("John Smith"),
    age: 50
};

// Create a MemoryStorage object to hold checkpoint data.
let storage = MemoryStorage::new()?;

// Add integrity checks to checkpoint data with a ChecksumWrapper.
let mut wrapped_storage = ChecksumWrapper::wrap(storage);

// Create a new checkpoint.
let mut uncommitted_checkpoint = wrapped_storage.create_checkpoint("Checkpoint")?;

// Add data to the checkpoint.
uncommitted_checkpoint.put("Person", &person)?;

// Commit the checkpoint.
let mut committed_checkpoint = wrapped_storage.commit_checkpoint(uncommitted_checkpoint)?;

// Retrieve the checkpoint data.
let stored_person: Person = committed_checkpoint.get("Person")?;

// The data retrieved from the checkpoint is the same as what was put in.
assert_eq!(person.name, stored_person.name);
assert_eq!(person.age, stored_person.age);

Modules

error
storage
wrappers

Structs

Error

The error type for Checkpoint operations.

Traits

CommittedCheckpoint	The CommittedCheckpoint trait allows checkpoint data to be retrieved from the storage backing a checkpoint object.
Storage	The Storage trait allows checkpoints to be created, committed, loaded, and removed from the underlying storage medium.
UncommittedCheckpoint	The UncommittedCheckpoint trait allows checkpoint data to be modified and retrieved from the storage backing a checkpoint object.

Type Definitions

Result

A Result type specifically for the checkpoint library.