Talking Tock 53

Key-Value Store Updates

Sept. 15th 2023 by Brad

With TicKV, Tock supports running a key-value store on top of flash storage. Recently, the stack has been updated with a new interface trait and interface for userspace.

The basic KV trait looks roughly like the following:

pub trait KV {
    /// Retrieve a value from the store.
    fn get(&self, key: [u8], value: [u8]) -> Result<(), ([u8], [u8], ErrorCode)>;

    /// Insert a key-value object into the store. Overwrite if needed.
    fn set(&self, key: [u8], value: [u8]) -> Result<(), ([u8], [u8], ErrorCode)>;

    /// Insert a key-value object into the store if it doesn't exist.
    fn add(&self, key: [u8], value: [u8]) -> Result<(), ([u8], [u8], ErrorCode)>;

    /// Modify a key-value object into the store if it already exists.
    fn update(&self, key: [u8], value: [u8]) -> Result<(), ([u8], [u8], ErrorCode)>;

    /// Remove a key-value object from the store.
    fn update(&self, key: [u8]) -> Result<(), ([u8], ErrorCode)>;
}

Tock also supports a permissions layer where all KV operations require permissions to complete. This allows for restricting applications and which KV objects they can access.

For more information, see TicKV on Tock Book.