snarkos-storage 2.0.2

Storage for a decentralized operating system
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// Copyright (C) 2019-2022 Aleo Systems Inc.
// This file is part of the snarkOS library.

// The snarkOS library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The snarkOS library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the snarkOS library. If not, see <https://www.gnu.org/licenses/>.

use super::{DataMap, MapId};

use anyhow::Result;
use serde::{de::DeserializeOwned, Deserializer, Serialize};
use std::{borrow::Borrow, path::Path};

pub trait Storage: Serialize {
    ///
    /// Opens storage at the given `path` and `context`.
    ///
    fn open<P: AsRef<Path>>(path: P, context: u16, is_read_only: bool) -> Result<Self>
    where
        Self: Sized;

    ///
    /// Opens a map with the given `context` from storage.
    ///
    fn open_map<K: Serialize + DeserializeOwned, V: Serialize + DeserializeOwned>(&self, map_id: MapId) -> Result<DataMap<K, V>>;

    ///
    /// Imports the given serialized bytes to reconstruct storage.
    ///
    fn import<'de, D: Deserializer<'de>>(&self, deserializer: D) -> Result<(), D::Error>;

    ///
    /// Exports the current state of storage into serialized bytes.
    ///
    fn export(&self) -> Result<serde_json::Value>;
}

pub trait Map<'a, K: Serialize + DeserializeOwned, V: Serialize + DeserializeOwned> {
    type Iterator: Iterator<Item = (K, V)>;
    type Keys: Iterator<Item = K>;
    type Values: Iterator<Item = V>;

    ///
    /// Returns `true` if the given key exists in the map.
    ///
    fn contains_key<Q>(&self, key: &Q) -> Result<bool>
    where
        K: Borrow<Q>,
        Q: Serialize + ?Sized;

    ///
    /// Returns the value for the given key from the map, if it exists.
    ///
    fn get<Q>(&self, key: &Q) -> Result<Option<V>>
    where
        K: Borrow<Q>,
        Q: Serialize + ?Sized;

    ///
    /// Inserts the given key-value pair into the map.
    ///
    fn insert<Q>(&self, key: &Q, value: &V) -> Result<()>
    where
        K: Borrow<Q>,
        Q: Serialize + ?Sized;

    ///
    /// Removes the key-value pair for the given key from the map.
    ///
    fn remove<Q>(&self, key: &Q) -> Result<()>
    where
        K: Borrow<Q>,
        Q: Serialize + ?Sized;

    ///
    /// Returns an iterator visiting each key-value pair in the map.
    ///
    fn iter(&'a self) -> Self::Iterator;

    ///
    /// Returns an iterator over each key in the map.
    ///
    fn keys(&'a self) -> Self::Keys;

    ///
    /// Returns an iterator over each value in the map.
    ///
    fn values(&'a self) -> Self::Values;

    ///
    /// Performs a refresh operation for implementations of `Map` that perform periodic operations.
    /// Returns `true` if the database state has been updated.
    ///
    fn refresh(&self) -> bool {
        // Currently, this method is implemented for RocksDB to catch up a reader (secondary) database.
        true
    }
}