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env.rs
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env.rs
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use std::any::TypeId;
use std::collections::hash_map::{Entry, HashMap};
use std::ffi::{c_void, CString};
use std::fs::{File, Metadata};
use std::marker::PhantomData;
#[cfg(unix)]
use std::os::unix::{
ffi::OsStrExt,
io::{AsRawFd, BorrowedFd, RawFd},
};
use std::path::{Path, PathBuf};
use std::result::Result as StdResult;
use std::sync::{Arc, RwLock};
use std::time::Duration;
#[cfg(windows)]
use std::{
ffi::OsStr,
os::windows::io::{AsRawHandle, BorrowedHandle, RawHandle},
};
use std::{fmt, io, mem, ptr, sync};
use lmdb_master3_sys::MDB_val;
use once_cell::sync::Lazy;
use synchronoise::event::SignalEvent;
use crate::mdb::error::mdb_result;
use crate::mdb::ffi;
use crate::{Database, Error, Flags, PolyDatabase, Result, RoCursor, RoTxn, RwTxn};
/// The list of opened environments, the value is an optional environment, it is None
/// when someone asks to close the environment, closing is a two-phase step, to make sure
/// no one tries to open the same environment between these two phases.
///
/// Trying to open a None marked environment returns an error to the user trying to open it.
static OPENED_ENV: Lazy<RwLock<HashMap<PathBuf, EnvEntry>>> = Lazy::new(RwLock::default);
struct EnvEntry {
env: Option<Env>,
signal_event: Arc<SignalEvent>,
options: SimplifiedOpenOptions,
}
/// A simplified version of the options that were used to open a given [`Env`].
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct SimplifiedOpenOptions {
/// The name of the checksum algorithm this [`Env`] has been opened with.
pub checksum_name: Option<String>,
/// The name of the encryption/decryption algorithm this [`Env`] has been opened with.
pub encrypt_name: Option<String>,
/// The maximum size this [`Env`] with take in bytes or [`None`] if it was not specified.
pub map_size: Option<usize>,
/// The maximum number of concurrent readers or [`None`] if it was not specified.
pub max_readers: Option<u32>,
/// The maximum number of opened database or [`None`] if it was not specified.
pub max_dbs: Option<u32>,
/// The raw flags enabled for this [`Env`] or [`None`] if it was not specified.
pub flags: u32,
}
impl<E: Encrypt, C: Checksum> From<&EnvOpenOptions<E, C>> for SimplifiedOpenOptions {
fn from(eoo: &EnvOpenOptions<E, C>) -> SimplifiedOpenOptions {
let EnvOpenOptions { checksum, encrypt, map_size, max_readers, max_dbs, flags } = eoo;
SimplifiedOpenOptions {
checksum_name: checksum.map(|_| E::name()),
encrypt_name: encrypt.as_ref().map(|_| C::name()),
map_size: *map_size,
max_readers: *max_readers,
max_dbs: *max_dbs,
flags: *flags,
}
}
}
// Thanks to the mozilla/rkv project
// Workaround the UNC path on Windows, see https://github.com/rust-lang/rust/issues/42869.
// Otherwise, `Env::from_env()` will panic with error_no(123).
#[cfg(not(windows))]
fn canonicalize_path(path: &Path) -> io::Result<PathBuf> {
path.canonicalize()
}
#[cfg(windows)]
fn canonicalize_path(path: &Path) -> io::Result<PathBuf> {
let canonical = path.canonicalize()?;
let url = url::Url::from_file_path(&canonical)
.map_err(|_e| io::Error::new(io::ErrorKind::Other, "URL passing error"))?;
url.to_file_path()
.map_err(|_e| io::Error::new(io::ErrorKind::Other, "path canonicalization error"))
}
#[cfg(windows)]
/// Adding a 'missing' trait from windows OsStrExt
trait OsStrExtLmdb {
fn as_bytes(&self) -> &[u8];
}
#[cfg(windows)]
impl OsStrExtLmdb for OsStr {
fn as_bytes(&self) -> &[u8] {
&self.to_str().unwrap().as_bytes()
}
}
#[cfg(unix)]
fn get_file_fd(file: &File) -> RawFd {
file.as_raw_fd()
}
#[cfg(windows)]
fn get_file_fd(file: &File) -> RawHandle {
file.as_raw_handle()
}
#[cfg(unix)]
/// Get metadata from a file descriptor.
unsafe fn metadata_from_fd(raw_fd: RawFd) -> io::Result<Metadata> {
let fd = BorrowedFd::borrow_raw(raw_fd);
let owned = fd.try_clone_to_owned()?;
File::from(owned).metadata()
}
#[cfg(windows)]
/// Get metadata from a file descriptor.
unsafe fn metadata_from_fd(raw_fd: RawHandle) -> io::Result<Metadata> {
let fd = BorrowedHandle::borrow_raw(raw_fd);
let owned = fd.try_clone_to_owned()?;
File::from(owned).metadata()
}
/// Describes a check-summing algorithm that ensure the correctness of the pages.
pub trait Checksum {
/// The number of bytes the checksum value takes.
const SIZE: u32;
/// The name of the check-summing algorithm, used for safety purposes.
///
/// Make sure that the name corresponds to the algorithm, it will be compared
/// whenever an [`Env`] is opened and tried to be opened a second time.
fn name() -> String;
/// Takes the input and must write in the output that is `Self::SIZE` long.
fn checksum(input: &[u8], output: &mut [u8], key: Option<&[u8]>);
}
/// A dummy check-summing algorithm that must never be used.
/// Only here for Rust API purposes.
pub enum DummyChecksum {}
impl Checksum for DummyChecksum {
const SIZE: u32 = 32 / 8;
fn name() -> String {
String::new()
}
fn checksum(_input: &[u8], _output: &mut [u8], _key: Option<&[u8]>) {}
}
/// Describes an encryption/decryption algorithm to ensure pages
/// are readable only with the right key.
pub trait Encrypt {
/// The name of the encryption/decryption algorithm, used for safety purposes.
///
/// Make sure that the name corresponds to the algorithm, it will be compared
/// whenever an [`Env`] is opened and tried to be opened a second time.
fn name() -> String;
/// Takes the input bytes and writes them in the output slice of the same length.
fn encrypt_decrypt(
action: EncryptDecrypt,
input: &[u8],
output: &mut [u8],
key: &[u8],
iv: &[u8],
auth: &[u8],
) -> StdResult<(), ()>;
}
/// The action to perform on the page.
#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub enum EncryptDecrypt {
Encrypt,
Decrypt,
}
/// A dummy encryption/decryption algorithm that must never be used.
/// Only here for Rust API purposes.
pub enum DummyEncrypt {}
impl Encrypt for DummyEncrypt {
fn name() -> String {
String::new()
}
fn encrypt_decrypt(
_action: EncryptDecrypt,
_input: &[u8],
_output: &mut [u8],
_key: &[u8],
_iv: &[u8],
_auth: &[u8],
) -> StdResult<(), ()> {
Err(())
}
}
/// Options and flags which can be used to configure how an environment is opened.
#[derive(Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct EnvOpenOptions<E: Encrypt = DummyEncrypt, C: Checksum = DummyChecksum> {
checksum: Option<PhantomData<C>>,
encrypt: Option<(PhantomData<E>, Vec<u8>, u32)>,
map_size: Option<usize>,
max_readers: Option<u32>,
max_dbs: Option<u32>,
flags: u32,
}
impl<E: Encrypt, C: Checksum> fmt::Debug for EnvOpenOptions<E, C> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let EnvOpenOptions { checksum, encrypt, map_size, max_readers, max_dbs, flags } = self;
f.debug_struct("EnvOpenOptions")
.field("checksum", &checksum.map(|_| C::name()))
.field("encrypt", &encrypt.as_ref().map(|_| E::name()))
.field("map_size", &map_size)
.field("max_readers", &max_readers)
.field("max_dbs", &max_dbs)
.field("flags", &flags)
.finish()
}
}
impl EnvOpenOptions {
/// Creates a blank new set of options ready for configuration.
pub fn new() -> EnvOpenOptions {
EnvOpenOptions {
checksum: None,
encrypt: None,
map_size: None,
max_readers: None,
max_dbs: None,
flags: 0,
}
}
}
impl<E: Encrypt, C: Checksum> EnvOpenOptions<E, C> {
/// Set the size of the memory map to use for this environment.
pub fn map_size(&mut self, size: usize) -> &mut Self {
self.map_size = Some(size);
self
}
/// Set the maximum number of threads/reader slots for the environment.
pub fn max_readers(&mut self, readers: u32) -> &mut Self {
self.max_readers = Some(readers);
self
}
/// Set the maximum number of named databases for the environment.
pub fn max_dbs(&mut self, dbs: u32) -> &mut Self {
self.max_dbs = Some(dbs);
self
}
/// Specifies that the [`Env`] will be encrypted/decrypted with this `F` algorithm,
/// with this `key` and the `auth_size` that can be zero.
///
/// It is advised to use a checksum algorithm when an encryption/decryption algorithm
/// is specified to get better error messages when the encryption key is wrong.
pub fn encrypt_with<F: Encrypt>(self, key: Vec<u8>, auth_size: u32) -> EnvOpenOptions<F, C> {
let EnvOpenOptions { checksum, encrypt: _, map_size, max_readers, max_dbs, flags } = self;
EnvOpenOptions {
checksum,
encrypt: Some((PhantomData, key, auth_size)),
map_size,
max_readers,
max_dbs,
flags,
}
}
/// Specifies that the [`Env`] will be checksum-checked with this `D` algorithm.
pub fn checksum_with<D: Checksum>(self) -> EnvOpenOptions<E, D> {
let EnvOpenOptions { checksum: _, encrypt, map_size, max_readers, max_dbs, flags } = self;
EnvOpenOptions {
checksum: Some(PhantomData),
encrypt,
map_size,
max_readers,
max_dbs,
flags,
}
}
/// Set one or [more LMDB flags](http://www.lmdb.tech/doc/group__mdb__env.html).
/// ```
/// use std::fs;
/// use std::path::Path;
/// use heed::{EnvOpenOptions, Database, Flags};
/// use heed::types::*;
///
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// fs::create_dir_all(Path::new("target").join("database.mdb"))?;
/// let mut env_builder = EnvOpenOptions::new();
/// unsafe {
/// env_builder.flag(Flags::MdbNoTls);
/// env_builder.flag(Flags::MdbNoMetaSync);
/// }
/// let dir = tempfile::tempdir().unwrap();
/// let env = env_builder.open(dir.path())?;
///
/// // we will open the default unamed database
/// let mut wtxn = env.write_txn()?;
/// let db: Database<Str, OwnedType<i32>> = env.create_database(&mut wtxn, None)?;
///
/// // opening a write transaction
/// db.put(&mut wtxn, "seven", &7)?;
/// db.put(&mut wtxn, "zero", &0)?;
/// db.put(&mut wtxn, "five", &5)?;
/// db.put(&mut wtxn, "three", &3)?;
/// wtxn.commit()?;
///
/// // Force the OS to flush the buffers (see Flags::MdbNoSync and Flags::MdbNoMetaSync).
/// env.force_sync();
///
/// // opening a read transaction
/// // to check if those values are now available
/// let mut rtxn = env.read_txn()?;
///
/// let ret = db.get(&rtxn, "zero")?;
/// assert_eq!(ret, Some(0));
///
/// let ret = db.get(&rtxn, "five")?;
/// assert_eq!(ret, Some(5));
/// # Ok(()) }
/// ```
pub unsafe fn flag(&mut self, flag: Flags) -> &mut Self {
self.flags = self.flags | flag as u32;
self
}
/// Open an environment that will be located at the specified path.
pub fn open<P: AsRef<Path>>(&self, path: P) -> Result<Env> {
let path = canonicalize_path(path.as_ref())?;
let mut lock = OPENED_ENV.write().unwrap();
let original_options = SimplifiedOpenOptions::from(self);
match lock.entry(path) {
Entry::Occupied(entry) => {
let env = entry.get().env.clone().ok_or(Error::DatabaseClosing)?;
let options = entry.get().options.clone();
if options == original_options {
return Ok(env);
} else {
return Err(Error::BadOpenOptions { env, original_options });
}
}
Entry::Vacant(entry) => {
let path = entry.key();
let path_str = CString::new(path.as_os_str().as_bytes()).unwrap();
unsafe {
let mut env: *mut ffi::MDB_env = ptr::null_mut();
mdb_result(ffi::mdb_env_create(&mut env))?;
if let Some(_marker) = &self.checksum {
mdb_result(ffi::mdb_env_set_checksum(
env,
Some(checksum_func_wrapper::<C>),
C::SIZE,
))?;
}
if let Some((_marker, key, auth_size)) = &self.encrypt {
let key = crate::into_val(key);
mdb_result(ffi::mdb_env_set_encrypt(
env,
Some(encrypt_func_wrapper::<E>),
&key,
*auth_size,
))?;
}
if let Some(size) = self.map_size {
if size % page_size::get() != 0 {
let msg = format!(
"map size ({}) must be a multiple of the system page size ({})",
size,
page_size::get()
);
return Err(Error::Io(io::Error::new(
io::ErrorKind::InvalidInput,
msg,
)));
}
mdb_result(ffi::mdb_env_set_mapsize(env, size))?;
}
if let Some(readers) = self.max_readers {
mdb_result(ffi::mdb_env_set_maxreaders(env, readers))?;
}
if let Some(dbs) = self.max_dbs {
mdb_result(ffi::mdb_env_set_maxdbs(env, dbs))?;
}
// When the `sync-read-txn` feature is enabled, we must force LMDB
// to avoid using the thread local storage, this way we allow users
// to use references of RoTxn between threads safely.
let flags = if cfg!(feature = "sync-read-txn") {
self.flags | Flags::MdbNoTls as u32
} else {
self.flags
};
let result =
mdb_result(ffi::mdb_env_open(env, path_str.as_ptr(), flags, 0o600));
match result {
Ok(()) => {
let signal_event = Arc::new(SignalEvent::manual(false));
let inner = EnvInner {
env,
dbi_open_mutex: sync::Mutex::default(),
path: path.clone(),
};
let env = Env(Arc::new(inner));
let cache_entry = EnvEntry {
env: Some(env.clone()),
options: original_options,
signal_event,
};
entry.insert(cache_entry);
Ok(env)
}
Err(e) => {
ffi::mdb_env_close(env);
Err(e.into())
}
}
}
}
}
}
}
/// The wrapper function that is called by LMDB that directly calls
/// the Rust idiomatic function internally.
unsafe extern "C" fn encrypt_func_wrapper<E: Encrypt>(
src: *const MDB_val,
dst: *mut MDB_val,
key_ptr: *const MDB_val,
encdec: i32,
) -> i32 {
let input = std::slice::from_raw_parts((*src).mv_data as *const u8, (*src).mv_size);
let output = std::slice::from_raw_parts_mut((*dst).mv_data as *mut u8, (*dst).mv_size);
let key = std::slice::from_raw_parts((*key_ptr).mv_data as *const u8, (*key_ptr).mv_size);
let iv = std::slice::from_raw_parts(
(*key_ptr.offset(1)).mv_data as *const u8,
(*key_ptr.offset(1)).mv_size,
);
let auth = std::slice::from_raw_parts(
(*key_ptr.offset(2)).mv_data as *const u8,
(*key_ptr.offset(2)).mv_size,
);
let action = if encdec == 1 { EncryptDecrypt::Encrypt } else { EncryptDecrypt::Decrypt };
E::encrypt_decrypt(action, input, output, key, iv, auth).is_err() as i32
}
/// The wrapper function that is called by LMDB that directly calls
/// the Rust idiomatic function internally.
unsafe extern "C" fn checksum_func_wrapper<C: Checksum>(
src: *const MDB_val,
dst: *mut MDB_val,
key_ptr: *const MDB_val,
) {
let input = std::slice::from_raw_parts((*src).mv_data as *const u8, (*src).mv_size);
let output = std::slice::from_raw_parts_mut((*dst).mv_data as *mut u8, (*dst).mv_size);
let key = if key_ptr.is_null() {
None
} else {
Some(std::slice::from_raw_parts((*key_ptr).mv_data as *const u8, (*key_ptr).mv_size))
};
C::checksum(input, output, key)
}
/// Returns a struct that allows to wait for the effective closing of an environment.
pub fn env_closing_event<P: AsRef<Path>>(path: P) -> Option<EnvClosingEvent> {
let lock = OPENED_ENV.read().unwrap();
lock.get(path.as_ref()).map(|e| EnvClosingEvent(e.signal_event.clone()))
}
/// An environment handle constructed by using [`EnvOpenOptions`].
#[derive(Clone)]
pub struct Env(Arc<EnvInner>);
impl fmt::Debug for Env {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let EnvInner { env: _, dbi_open_mutex: _, path } = self.0.as_ref();
f.debug_struct("Env").field("path", &path.display()).finish_non_exhaustive()
}
}
struct EnvInner {
env: *mut ffi::MDB_env,
dbi_open_mutex: sync::Mutex<HashMap<u32, Option<(TypeId, TypeId)>>>,
path: PathBuf,
}
unsafe impl Send for EnvInner {}
unsafe impl Sync for EnvInner {}
impl Drop for EnvInner {
fn drop(&mut self) {
let mut lock = OPENED_ENV.write().unwrap();
match lock.remove(&self.path) {
None => panic!("It seems another env closed this env before"),
Some(EnvEntry { signal_event, .. }) => {
unsafe {
let _ = ffi::mdb_env_close(self.env);
}
// We signal to all the waiters that we have closed the env.
signal_event.signal();
}
}
}
}
/// Whether to perform compaction while copying an environment.
#[derive(Debug, Copy, Clone)]
pub enum CompactionOption {
/// Omit free pages and sequentially renumber all pages in output.
///
/// This option consumes more CPU and runs more slowly than the default.
/// Currently it fails if the environment has suffered a page leak.
Enabled,
/// Copy everything without taking any special action about free pages.
Disabled,
}
impl Env {
pub(crate) fn env_mut_ptr(&self) -> *mut ffi::MDB_env {
self.0.env
}
/// The size of the data file on disk.
///
/// # Example
///
/// ```
/// use heed::EnvOpenOptions;
///
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let dir = tempfile::tempdir()?;
/// let size_in_bytes = 1024 * 1024;
/// let env = EnvOpenOptions::new().map_size(size_in_bytes).open(dir.path())?;
///
/// let actual_size = env.real_disk_size()? as usize;
/// assert!(actual_size < size_in_bytes);
/// # Ok(()) }
/// ```
pub fn real_disk_size(&self) -> Result<u64> {
let mut fd = std::mem::MaybeUninit::uninit();
unsafe { mdb_result(ffi::mdb_env_get_fd(self.env_mut_ptr(), fd.as_mut_ptr()))? };
let fd = unsafe { fd.assume_init() };
let metadata = unsafe { metadata_from_fd(fd)? };
Ok(metadata.len())
}
/// Check if a flag was specified when opening this environment.
pub fn contains_flag(&self, flag: Flags) -> Result<bool> {
let flags = self.raw_flags()?;
let set = flags & (flag as u32);
Ok(set != 0)
}
/// Return the raw flags the environment was opened with.
pub fn raw_flags(&self) -> Result<u32> {
let mut flags = std::mem::MaybeUninit::uninit();
unsafe { mdb_result(ffi::mdb_env_get_flags(self.env_mut_ptr(), flags.as_mut_ptr()))? };
let flags = unsafe { flags.assume_init() };
Ok(flags)
}
/// Returns some basic informations about this environment.
pub fn info(&self) -> EnvInfo {
let mut raw_info = mem::MaybeUninit::uninit();
unsafe { ffi::mdb_env_info(self.0.env, raw_info.as_mut_ptr()) };
let raw_info = unsafe { raw_info.assume_init() };
EnvInfo {
map_addr: raw_info.me_mapaddr,
map_size: raw_info.me_mapsize,
last_page_number: raw_info.me_last_pgno,
last_txn_id: raw_info.me_last_txnid,
maximum_number_of_readers: raw_info.me_maxreaders,
number_of_readers: raw_info.me_numreaders,
}
}
/// Returns the size used by all the databases in the environment without the free pages.
pub fn non_free_pages_size(&self) -> Result<u64> {
let compute_size = |stat: ffi::MDB_stat| {
(stat.ms_leaf_pages + stat.ms_branch_pages + stat.ms_overflow_pages) as u64
* stat.ms_psize as u64
};
let mut size = 0;
let mut stat = std::mem::MaybeUninit::uninit();
unsafe { mdb_result(ffi::mdb_env_stat(self.env_mut_ptr(), stat.as_mut_ptr()))? };
let stat = unsafe { stat.assume_init() };
size += compute_size(stat);
let rtxn = self.read_txn()?;
let dbi = self.raw_open_dbi(rtxn.txn, None, 0)?;
// we don’t want anyone to open an environment while we’re computing the stats
// thus we take a lock on the dbi
let dbi_open = self.0.dbi_open_mutex.lock().unwrap();
// We’re going to iterate on the unnamed database
let mut cursor = RoCursor::new(&rtxn, dbi)?;
while let Some((key, _value)) = cursor.move_on_next()? {
if key.contains(&0) {
continue;
}
let key = String::from_utf8(key.to_vec()).unwrap();
if let Ok(dbi) = self.raw_open_dbi(rtxn.txn, Some(&key), 0) {
let mut stat = std::mem::MaybeUninit::uninit();
unsafe { mdb_result(ffi::mdb_stat(rtxn.txn, dbi, stat.as_mut_ptr()))? };
let stat = unsafe { stat.assume_init() };
size += compute_size(stat);
// if the db wasn’t already opened
if !dbi_open.contains_key(&dbi) {
unsafe { ffi::mdb_dbi_close(self.env_mut_ptr(), dbi) }
}
}
}
Ok(size)
}
/// Opens a typed database that already exists in this environment.
///
/// If the database was previously opened in this program run, types will be checked.
///
/// ## Important Information
///
/// LMDB have an important restriction on the unnamed database when named ones are opened,
/// the names of the named databases are stored as keys in the unnamed one and are immutable,
/// these keys can only be read and not written.
pub fn open_database<KC, DC>(
&self,
rtxn: &RoTxn,
name: Option<&str>,
) -> Result<Option<Database<KC, DC>>>
where
KC: 'static,
DC: 'static,
{
let types = (TypeId::of::<KC>(), TypeId::of::<DC>());
match self.raw_init_database(rtxn.txn, name, Some(types), false) {
Ok(dbi) => Ok(Some(Database::new(self.env_mut_ptr() as _, dbi))),
Err(Error::Mdb(e)) if e.not_found() => Ok(None),
Err(e) => Err(e),
}
}
/// Opens an untyped database that already exists in this environment.
///
/// If the database was previously opened as a typed one, an error will be returned.
///
/// ## Important Information
///
/// LMDB have an important restriction on the unnamed database when named ones are opened,
/// the names of the named databases are stored as keys in the unnamed one and are immutable,
/// these keys can only be read and not written.
pub fn open_poly_database(
&self,
rtxn: &RoTxn,
name: Option<&str>,
) -> Result<Option<PolyDatabase>> {
match self.raw_init_database(rtxn.txn, name, None, false) {
Ok(dbi) => Ok(Some(PolyDatabase::new(self.env_mut_ptr() as _, dbi))),
Err(Error::Mdb(e)) if e.not_found() => Ok(None),
Err(e) => Err(e),
}
}
/// Creates a typed database that can already exist in this environment.
///
/// If the database was previously opened in this program run, types will be checked.
///
/// ## Important Information
///
/// LMDB have an important restriction on the unnamed database when named ones are opened,
/// the names of the named databases are stored as keys in the unnamed one and are immutable,
/// these keys can only be read and not written.
pub fn create_database<KC, DC>(
&self,
wtxn: &mut RwTxn,
name: Option<&str>,
) -> Result<Database<KC, DC>>
where
KC: 'static,
DC: 'static,
{
let types = (TypeId::of::<KC>(), TypeId::of::<DC>());
match self.raw_init_database(wtxn.txn.txn, name, Some(types), true) {
Ok(dbi) => Ok(Database::new(self.env_mut_ptr() as _, dbi)),
Err(e) => Err(e),
}
}
/// Creates a typed database that can already exist in this environment.
///
/// If the database was previously opened as a typed one, an error will be returned.
///
/// ## Important Information
///
/// LMDB have an important restriction on the unnamed database when named ones are opened,
/// the names of the named databases are stored as keys in the unnamed one and are immutable,
/// these keys can only be read and not written.
pub fn create_poly_database(
&self,
wtxn: &mut RwTxn,
name: Option<&str>,
) -> Result<PolyDatabase> {
match self.raw_init_database(wtxn.txn.txn, name, None, true) {
Ok(dbi) => Ok(PolyDatabase::new(self.env_mut_ptr() as _, dbi)),
Err(e) => Err(e),
}
}
fn raw_open_dbi(
&self,
raw_txn: *mut ffi::MDB_txn,
name: Option<&str>,
flags: u32,
) -> std::result::Result<u32, crate::mdb::lmdb_error::Error> {
let mut dbi = 0;
let name = name.map(|n| CString::new(n).unwrap());
let name_ptr = match name {
Some(ref name) => name.as_bytes_with_nul().as_ptr() as *const _,
None => ptr::null(),
};
// safety: The name cstring is cloned by LMDB, we can drop it after.
// If a read-only is used with the MDB_CREATE flag, LMDB will throw an error.
unsafe { mdb_result(ffi::mdb_dbi_open(raw_txn, name_ptr, flags, &mut dbi))? };
Ok(dbi)
}
fn raw_init_database(
&self,
raw_txn: *mut ffi::MDB_txn,
name: Option<&str>,
types: Option<(TypeId, TypeId)>,
create: bool,
) -> Result<u32> {
let mut lock = self.0.dbi_open_mutex.lock().unwrap();
let flags = if create { ffi::MDB_CREATE } else { 0 };
match self.raw_open_dbi(raw_txn, name, flags) {
Ok(dbi) => {
let old_types = lock.entry(dbi).or_insert(types);
if *old_types == types {
Ok(dbi)
} else {
Err(Error::InvalidDatabaseTyping)
}
}
Err(e) => Err(e.into()),
}
}
/// Create a transaction with read and write access for use with the environment.
pub fn write_txn(&self) -> Result<RwTxn> {
RwTxn::new(self)
}
/// Create a nested transaction with read and write access for use with the environment.
///
/// The new transaction will be a nested transaction, with the transaction indicated by parent
/// as its parent. Transactions may be nested to any level.
///
/// A parent transaction and its cursors may not issue any other operations than _commit_ and
/// _abort_ while it has active child transactions.
pub fn nested_write_txn<'e, 'p: 'e>(&'e self, parent: &'p mut RwTxn) -> Result<RwTxn<'e, 'p>> {
RwTxn::nested(self, parent)
}
/// Create a transaction with read only access for use with the environment.
pub fn read_txn(&self) -> Result<RoTxn> {
RoTxn::new(self)
}
/// Copy an LMDB environment to the specified path, with options.
///
/// This function may be used to make a backup of an existing environment.
/// No lockfile is created, since it gets recreated at need.
pub fn copy_to_file<P: AsRef<Path>>(&self, path: P, option: CompactionOption) -> Result<File> {
let file = File::options().create_new(true).write(true).open(&path)?;
let fd = get_file_fd(&file);
unsafe { self.copy_to_fd(fd, option)? };
// We reopen the file to make sure the cursor is at the start,
// even a seek to start doesn't work properly.
let file = File::open(path)?;
Ok(file)
}
/// Copy an LMDB environment to the specified file descriptor, with compaction option.
///
/// This function may be used to make a backup of an existing environment.
/// No lockfile is created, since it gets recreated at need.
pub unsafe fn copy_to_fd(
&self,
fd: ffi::mdb_filehandle_t,
option: CompactionOption,
) -> Result<()> {
let flags = if let CompactionOption::Enabled = option { ffi::MDB_CP_COMPACT } else { 0 };
mdb_result(ffi::mdb_env_copyfd2(self.0.env, fd, flags))?;
Ok(())
}
/// Flush the data buffers to disk.
pub fn force_sync(&self) -> Result<()> {
unsafe { mdb_result(ffi::mdb_env_sync(self.0.env, 1))? }
Ok(())
}
/// Returns the canonicalized path where this env lives.
pub fn path(&self) -> &Path {
&self.0.path
}
/// Returns an `EnvClosingEvent` that can be used to wait for the closing event,
/// multiple threads can wait on this event.
///
/// Make sure that you drop all the copies of `Env`s you have, env closing are triggered
/// when all references are dropped, the last one will eventually close the environment.
pub fn prepare_for_closing(self) -> EnvClosingEvent {
let mut lock = OPENED_ENV.write().unwrap();
match lock.get_mut(self.path()) {
None => panic!("cannot find the env that we are trying to close"),
Some(EnvEntry { env, signal_event, .. }) => {
// We remove the env from the global list and replace it with a None.
let _env = env.take();
let signal_event = signal_event.clone();
// we must make sure we release the lock before we drop the env
// as the drop of the EnvInner also tries to lock the OPENED_ENV
// global and we don't want to trigger a dead-lock.
drop(lock);
EnvClosingEvent(signal_event)
}
}
}
/// Check for stale entries in the reader lock table and clear them.
///
/// Returns the number of stale readers cleared.
pub fn clear_stale_readers(&self) -> Result<usize> {
let mut dead: i32 = 0;
unsafe { mdb_result(ffi::mdb_reader_check(self.0.env, &mut dead))? }
// safety: The reader_check function asks for an i32, initialize it to zero
// and never decrements it. It is safe to use either an u32 or u64 (usize).
Ok(dead as usize)
}
}
/// Contains information about the environment.
#[derive(Debug, Clone, Copy)]
pub struct EnvInfo {
/// Address of map, if fixed.
pub map_addr: *mut c_void,
/// Size of the data memory map.
pub map_size: usize,
/// ID of the last used page.
pub last_page_number: usize,
/// ID of the last committed transaction.
pub last_txn_id: usize,
/// Maximum number of reader slots in the environment.
pub maximum_number_of_readers: u32,
/// Maximum number of reader slots used in the environment.
pub number_of_readers: u32,
}
/// A structure that can be used to wait for the closing event,
/// multiple threads can wait on this event.
#[derive(Clone)]
pub struct EnvClosingEvent(Arc<SignalEvent>);
impl EnvClosingEvent {
/// Blocks this thread until the environment is effectively closed.
///
/// # Safety
///
/// Make sure that you don't have any copy of the environment in the thread
/// that is waiting for a close event, if you do, you will have a dead-lock.
pub fn wait(&self) {
self.0.wait()
}
/// Blocks this thread until either the environment has been closed
/// or until the timeout elapses, returns `true` if the environment
/// has been effectively closed.
pub fn wait_timeout(&self, timeout: Duration) -> bool {
self.0.wait_timeout(timeout)
}
}
impl fmt::Debug for EnvClosingEvent {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("EnvClosingEvent").finish()
}
}
#[cfg(test)]
mod tests {
use std::time::Duration;
use std::{fs, thread};
use crate::types::*;
use crate::{env_closing_event, EnvOpenOptions, Error};
#[test]
fn close_env() {
let dir = tempfile::tempdir().unwrap();
let env = EnvOpenOptions::new()
.map_size(10 * 1024 * 1024) // 10MB
.max_dbs(30)
.open(&dir.path())
.unwrap();
// Force a thread to keep the env for 1 second.
let env_cloned = env.clone();
thread::spawn(move || {
let _env = env_cloned;
thread::sleep(Duration::from_secs(1));
});
let mut wtxn = env.write_txn().unwrap();
let db = env.create_database::<Str, Str>(&mut wtxn, None).unwrap();
wtxn.commit().unwrap();
// Create an ordered list of keys...
let mut wtxn = env.write_txn().unwrap();
db.put(&mut wtxn, "hello", "hello").unwrap();
db.put(&mut wtxn, "world", "world").unwrap();
let mut iter = db.iter(&wtxn).unwrap();
assert_eq!(iter.next().transpose().unwrap(), Some(("hello", "hello")));
assert_eq!(iter.next().transpose().unwrap(), Some(("world", "world")));
assert_eq!(iter.next().transpose().unwrap(), None);
drop(iter);
wtxn.commit().unwrap();
let signal_event = env.prepare_for_closing();
eprintln!("waiting for the env to be closed");
signal_event.wait();
eprintln!("env closed successfully");
// Make sure we don't have a reference to the env
assert!(env_closing_event(&dir.path()).is_none());
}
#[test]
fn reopen_env_with_different_options_is_err() {
let dir = tempfile::tempdir().unwrap();
let _env = EnvOpenOptions::new()
.map_size(10 * 1024 * 1024) // 10MB
.open(&dir.path())
.unwrap();
let result = EnvOpenOptions::new()
.map_size(12 * 1024 * 1024) // 12MB
.open(&dir.path());
assert!(matches!(result, Err(Error::BadOpenOptions { .. })));
}
#[test]