openethereum/db/src/traits.rs

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// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity 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.
// Parity 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 Parity. If not, see <http://www.gnu.org/licenses/>.
//! Ethcore database trait
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use std::cell::RefCell;
pub type IteratorHandle = u32;
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pub const DEFAULT_CACHE_LEN: usize = 12288;
#[derive(Binary)]
pub struct KeyValue {
pub key: Vec<u8>,
pub value: Vec<u8>,
}
#[derive(Debug, Binary)]
pub enum Error {
AlreadyOpen,
IsClosed,
RocksDb(String),
TransactionUnknown,
IteratorUnknown,
UncommitedTransactions,
}
impl From<String> for Error {
fn from(s: String) -> Error {
Error::RocksDb(s)
}
}
/// Database configuration
#[derive(Binary)]
pub struct DatabaseConfig {
/// Optional prefix size in bytes. Allows lookup by partial key.
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pub prefix_size: Option<usize>,
/// write cache length
pub cache: usize,
}
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impl Default for DatabaseConfig {
fn default() -> DatabaseConfig {
DatabaseConfig {
prefix_size: None,
cache: DEFAULT_CACHE_LEN,
}
}
}
impl DatabaseConfig {
fn with_prefix(prefix: usize) -> DatabaseConfig {
DatabaseConfig {
prefix_size: Some(prefix),
cache: DEFAULT_CACHE_LEN,
}
}
}
pub trait DatabaseService : Sized {
/// Opens database in the specified path
fn open(&self, config: DatabaseConfig, path: String) -> Result<(), Error>;
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/// Opens database in the specified path with the default config
fn open_default(&self, path: String) -> Result<(), Error>;
/// Closes database
fn close(&self) -> Result<(), Error>;
/// Insert a key-value pair in the transaction. Any existing value value will be overwritten.
fn put(&self, key: &[u8], value: &[u8]) -> Result<(), Error>;
/// Delete value by key.
fn delete(&self, key: &[u8]) -> Result<(), Error>;
/// Get value by key.
fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>, Error>;
/// Get value by partial key. Prefix size should match configured prefix size.
fn get_by_prefix(&self, prefix: &[u8]) -> Result<Option<Vec<u8>>, Error>;
/// Check if there is anything in the database.
fn is_empty(&self) -> Result<bool, Error>;
/// Get handle to iterate through keys
fn iter(&self) -> Result<IteratorHandle, Error>;
/// Next key-value for the the given iterator
fn iter_next(&self, iterator: IteratorHandle) -> Option<KeyValue>;
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/// Dispose iteration that is no longer needed
fn dispose_iter(&self, handle: IteratorHandle) -> Result<(), Error>;
/// Write client transaction
fn write(&self, transaction: DBTransaction) -> Result<(), Error>;
}
#[derive(Binary)]
pub struct DBTransaction {
pub writes: RefCell<Vec<KeyValue>>,
pub removes: RefCell<Vec<Vec<u8>>>,
}
impl DBTransaction {
pub fn new() -> DBTransaction {
DBTransaction {
writes: RefCell::new(Vec::new()),
removes: RefCell::new(Vec::new()),
}
}
pub fn put(&self, key: &[u8], value: &[u8]) {
let mut brw = self.writes.borrow_mut();
brw.push(KeyValue { key: key.to_vec(), value: value.to_vec() });
}
pub fn delete(&self, key: &[u8]) {
let mut brw = self.removes.borrow_mut();
brw.push(key.to_vec());
}
}