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// Copyright 2018-2019 Mozilla
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
// this file except in compliance with the License. You may obtain a copy of the
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
use std::{
fs,
os::raw::c_uint,
path::{Path, PathBuf},
};
#[cfg(any(feature = "db-dup-sort", feature = "db-int-key"))]
use crate::backend::{BackendDatabaseFlags, DatabaseFlags};
use crate::{
backend::{
BackendEnvironment, BackendEnvironmentBuilder, BackendRoCursorTransaction,
BackendRwCursorTransaction, SafeModeError,
},
error::{CloseError, StoreError},
readwrite::{Reader, Writer},
store::{single::SingleStore, CloseOptions, Options as StoreOptions},
};
#[cfg(feature = "db-dup-sort")]
use crate::store::multi::MultiStore;
#[cfg(feature = "db-int-key")]
use crate::store::integer::IntegerStore;
#[cfg(feature = "db-int-key")]
use crate::store::keys::PrimitiveInt;
#[cfg(all(feature = "db-dup-sort", feature = "db-int-key"))]
use crate::store::integermulti::MultiIntegerStore;
pub static DEFAULT_MAX_DBS: c_uint = 5;
/// Wrapper around an `Environment` (e.g. such as an `LMDB` or `SafeMode` environment).
#[derive(Debug)]
pub struct Rkv<E> {
_path: PathBuf,
env: E,
}
/// Static methods.
impl<'e, E> Rkv<E>
where
E: BackendEnvironment<'e>,
{
pub fn environment_builder<B>() -> B
where
B: BackendEnvironmentBuilder<'e, Environment = E>,
{
B::new()
}
/// Return a new Rkv environment that supports up to `DEFAULT_MAX_DBS` open databases.
#[allow(clippy::new_ret_no_self)]
pub fn new<B>(path: &Path) -> Result<Rkv<E>, StoreError>
where
B: BackendEnvironmentBuilder<'e, Environment = E>,
{
Rkv::with_capacity::<B>(path, DEFAULT_MAX_DBS)
}
/// Return a new Rkv environment that supports the specified number of open databases.
pub fn with_capacity<B>(path: &Path, max_dbs: c_uint) -> Result<Rkv<E>, StoreError>
where
B: BackendEnvironmentBuilder<'e, Environment = E>,
{
let mut builder = B::new();
builder.set_max_dbs(max_dbs);
// Future: set flags, maximum size, etc. here if necessary.
Rkv::from_builder(path, builder)
}
/// Return a new Rkv environment from the provided builder.
pub fn from_builder<B>(path: &Path, builder: B) -> Result<Rkv<E>, StoreError>
where
B: BackendEnvironmentBuilder<'e, Environment = E>,
{
Ok(Rkv {
_path: path.into(),
env: builder.open(path).map_err(|e| e.into())?,
})
}
}
/// Store creation methods.
impl<'e, E> Rkv<E>
where
E: BackendEnvironment<'e>,
{
/// Return all created databases.
pub fn get_dbs(&self) -> Result<Vec<Option<String>>, StoreError> {
self.env.get_dbs().map_err(|e| e.into())
}
/// Create or Open an existing database in (&[u8] -> Single Value) mode.
/// Note: that create=true cannot be called concurrently with other operations so if
/// you are sure that the database exists, call this with create=false.
pub fn open_single<'s, T>(
&self,
name: T,
opts: StoreOptions<E::Flags>,
) -> Result<SingleStore<E::Database>, StoreError>
where
T: Into<Option<&'s str>>,
{
self.open(name, opts).map(SingleStore::new)
}
/// Create or Open an existing database in (Integer -> Single Value) mode.
/// Note: that create=true cannot be called concurrently with other operations so if
/// you are sure that the database exists, call this with create=false.
#[cfg(feature = "db-int-key")]
pub fn open_integer<'s, T, K>(
&self,
name: T,
mut opts: StoreOptions<E::Flags>,
) -> Result<IntegerStore<E::Database, K>, StoreError>
where
K: PrimitiveInt,
T: Into<Option<&'s str>>,
{
opts.flags.set(DatabaseFlags::INTEGER_KEY, true);
self.open(name, opts).map(IntegerStore::new)
}
/// Create or Open an existing database in (&[u8] -> Multiple Values) mode.
/// Note: that create=true cannot be called concurrently with other operations so if
/// you are sure that the database exists, call this with create=false.
#[cfg(feature = "db-dup-sort")]
pub fn open_multi<'s, T>(
&self,
name: T,
mut opts: StoreOptions<E::Flags>,
) -> Result<MultiStore<E::Database>, StoreError>
where
T: Into<Option<&'s str>>,
{
opts.flags.set(DatabaseFlags::DUP_SORT, true);
self.open(name, opts).map(MultiStore::new)
}
/// Create or Open an existing database in (Integer -> Multiple Values) mode.
/// Note: that create=true cannot be called concurrently with other operations so if
/// you are sure that the database exists, call this with create=false.
#[cfg(all(feature = "db-dup-sort", feature = "db-int-key"))]
pub fn open_multi_integer<'s, T, K>(
&self,
name: T,
mut opts: StoreOptions<E::Flags>,
) -> Result<MultiIntegerStore<E::Database, K>, StoreError>
where
K: PrimitiveInt,
T: Into<Option<&'s str>>,
{
opts.flags.set(DatabaseFlags::INTEGER_KEY, true);
opts.flags.set(DatabaseFlags::DUP_SORT, true);
self.open(name, opts).map(MultiIntegerStore::new)
}
fn open<'s, T>(&self, name: T, opts: StoreOptions<E::Flags>) -> Result<E::Database, StoreError>
where
T: Into<Option<&'s str>>,
{
if opts.create {
self.env
.create_db(name.into(), opts.flags)
.map_err(|e| match e.into() {
#[cfg(feature = "lmdb")]
StoreError::LmdbError(lmdb::Error::BadRslot) => {
StoreError::open_during_transaction()
}
StoreError::SafeModeError(SafeModeError::DbsIllegalOpen) => {
StoreError::open_during_transaction()
}
e => e,
})
} else {
self.env.open_db(name.into()).map_err(|e| match e.into() {
#[cfg(feature = "lmdb")]
StoreError::LmdbError(lmdb::Error::BadRslot) => {
StoreError::open_during_transaction()
}
StoreError::SafeModeError(SafeModeError::DbsIllegalOpen) => {
StoreError::open_during_transaction()
}
e => e,
})
}
}
}
/// Read and write accessors.
impl<'e, E> Rkv<E>
where
E: BackendEnvironment<'e>,
{
/// Create a read transaction. There can be multiple concurrent readers for an
/// environment, up to the maximum specified by LMDB (default 126), and you can open
/// readers while a write transaction is active.
pub fn read<T>(&'e self) -> Result<Reader<T>, StoreError>
where
E: BackendEnvironment<'e, RoTransaction = T>,
T: BackendRoCursorTransaction<'e, Database = E::Database>,
{
Ok(Reader::new(self.env.begin_ro_txn().map_err(|e| e.into())?))
}
/// Create a write transaction. There can be only one write transaction active at any
/// given time, so trying to create a second one will block until the first is
/// committed or aborted.
pub fn write<T>(&'e self) -> Result<Writer<T>, StoreError>
where
E: BackendEnvironment<'e, RwTransaction = T>,
T: BackendRwCursorTransaction<'e, Database = E::Database>,
{
Ok(Writer::new(self.env.begin_rw_txn().map_err(|e| e.into())?))
}
}
/// Other environment methods.
impl<'e, E> Rkv<E>
where
E: BackendEnvironment<'e>,
{
/// Flush the data buffers to disk. This call is only useful, when the environment was
/// open with either `NO_SYNC`, `NO_META_SYNC` or `MAP_ASYNC` (see below). The call is
/// not valid if the environment was opened with `READ_ONLY`.
///
/// Data is always written to disk when `transaction.commit()` is called, but the
/// operating system may keep it buffered. LMDB always flushes the OS buffers upon
/// commit as well, unless the environment was opened with `NO_SYNC` or in part
/// `NO_META_SYNC`.
///
/// `force`: if true, force a synchronous flush. Otherwise if the environment has the
/// `NO_SYNC` flag set the flushes will be omitted, and with `MAP_ASYNC` they will
/// be asynchronous.
pub fn sync(&self, force: bool) -> Result<(), StoreError> {
self.env.sync(force).map_err(|e| e.into())
}
/// Retrieve statistics about this environment.
///
/// It includes:
/// * Page size in bytes
/// * B-tree depth
/// * Number of internal (non-leaf) pages
/// * Number of leaf pages
/// * Number of overflow pages
/// * Number of data entries
pub fn stat(&self) -> Result<E::Stat, StoreError> {
self.env.stat().map_err(|e| e.into())
}
/// Retrieve information about this environment.
///
/// It includes:
/// * Map size in bytes
/// * The last used page number
/// * The last transaction ID
/// * Max number of readers allowed
/// * Number of readers in use
pub fn info(&self) -> Result<E::Info, StoreError> {
self.env.info().map_err(|e| e.into())
}
/// Retrieve the load ratio (# of used pages / total pages) about this environment.
///
/// With the formular: (last_page_no - freelist_pages) / total_pages.
/// A value of `None` means that the backend doesn't ever need to be resized.
pub fn load_ratio(&self) -> Result<Option<f32>, StoreError> {
self.env.load_ratio().map_err(|e| e.into())
}
/// Sets the size of the memory map to use for the environment.
///
/// This can be used to resize the map when the environment is already open. You can
/// also use `Rkv::environment_builder()` to set the map size during the `Rkv`
/// initialization.
///
/// Note:
///
/// * No active transactions allowed when performing resizing in this process. It's up
/// to the consumer to enforce that.
///
/// * The size should be a multiple of the OS page size. Any attempt to set a size
/// smaller than the space already consumed by the environment will be silently
/// changed to the current size of the used space.
///
/// * In the multi-process case, once a process resizes the map, other processes need
/// to either re-open the environment, or call set_map_size with size 0 to update
/// the environment. Otherwise, new transaction creation will fail with
/// `LmdbError::MapResized`.
pub fn set_map_size(&self, size: usize) -> Result<(), StoreError> {
self.env.set_map_size(size).map_err(Into::into)
}
/// Closes this environment and optionally deletes all its files from disk. Doesn't
/// delete the folder used when opening the environment.
pub fn close(self, options: CloseOptions) -> Result<(), CloseError> {
let files = self.env.get_files_on_disk();
drop(self);
if options.delete {
for file in files {
fs::remove_file(file)?;
}
}
Ok(())
}
}