Trait Storage

pub trait Storage {
    type Error: Error;

    // Required methods
    fn get_string<'a>(&'a self, key: &'a str) -> BoxFuture<'_, Option<String>>;
    fn get_int<'a>(&'a self, key: &'a str) -> BoxFuture<'_, Option<i64>>;
    fn get_bool<'a>(&'a self, key: &'a str) -> BoxFuture<'_, Option<bool>>;
    fn set_string<'a>(
        &'a mut self,
        key: &'a str,
        value: &'a str,
    ) -> BoxFuture<'_, Result<(), Self::Error>>;
    fn set_int<'a>(
        &'a mut self,
        key: &'a str,
        value: i64,
    ) -> BoxFuture<'_, Result<(), Self::Error>>;
    fn set_bool<'a>(
        &'a mut self,
        key: &'a str,
        value: bool,
    ) -> BoxFuture<'_, Result<(), Self::Error>>;
    fn remove<'a>(
        &'a mut self,
        key: &'a str,
    ) -> BoxFuture<'_, Result<(), Self::Error>>;
    fn commit(&mut self) -> BoxFuture<'_, Result<(), Self::Error>>;
}

The Storage trait is used to access typed key=value storage, for persisting protocol state and other data between runs of the update check process.

Implementations of this trait should cache values until commit() is called, and then perform an atomic committing of all outstanding value changes. On a given instance of Storage, a get() following a set(), but before a commit() should also return the set() value (not the previous value).

However, the expected usage of this trait within the library is to perform a series of get()’s at startup, and then only set()+commit() after that. The expectation being that this is being used to persist state that needs to be maintained for continuity over a reboot (or power outage).

A note on using the wrong type with a key: the result should be as if there is no value for the key. This is so that the Result::uwrap_or(<…default…>) pattern will work.

use omaha_client::storage::{MemStorage, Storage};
use omaha_client::unless::Unless;
let mut storage = MemStorage::new();
storage.set_int("key", 345);

// value should be None:
let value: Option<String> = storage.get_string("key").await;
assert_eq!(None, value);


// value should be "default":
let value: String = storage.get_string("key").await.unwrap_or("default".to_string());
assert_eq!("default", value);

Required Associated Types

type Error: Error

Required Methods

fn get_string<'a>(&'a self, key: &'a str) -> BoxFuture<'_, Option<String>>

Get a string from the backing store. Returns None if there is no value for the given key, or if the value for the key has a different type.

fn get_int<'a>(&'a self, key: &'a str) -> BoxFuture<'_, Option<i64>>

Get an int from the backing store. Returns None if there is no value for the given key, or if the value for the key has a different type.

fn get_bool<'a>(&'a self, key: &'a str) -> BoxFuture<'_, Option<bool>>

Get a boolean from the backing store. Returns None if there is no value for the given key, or if the value for the key has a different type.

fn set_string<'a>( &'a mut self, key: &'a str, value: &'a str, ) -> BoxFuture<'_, Result<(), Self::Error>>

Set a value to be stored in the backing store. The implementation should cache the value until the |commit()| fn is called, and then persist all cached values at that time.

fn set_int<'a>( &'a mut self, key: &'a str, value: i64, ) -> BoxFuture<'_, Result<(), Self::Error>>

Set a value to be stored in the backing store. The implementation should cache the value until the |commit()| fn is called, and then persist all cached values at that time.

fn set_bool<'a>( &'a mut self, key: &'a str, value: bool, ) -> BoxFuture<'_, Result<(), Self::Error>>

Set a value to be stored in the backing store. The implementation should cache the value until the |commit()| fn is called, and then persist all cached values at that time.

fn remove<'a>( &'a mut self, key: &'a str, ) -> BoxFuture<'_, Result<(), Self::Error>>

Remove the value for |key| from the backing store. The implementation should cache that the value has been removed until the |commit()| fn is called, and then persist all changes at that time.

If there is no value for the key, this should return without error.

fn commit(&mut self) -> BoxFuture<'_, Result<(), Self::Error>>

Persist all cached values to storage.

Implementors

impl Storage for MemStorage

type Error = StorageErrors