MeiliSearch/http-ui/src/update_store.rs
2021-06-16 18:33:33 +02:00

362 lines
13 KiB
Rust

#![allow(unused)]
use std::path::Path;
use std::sync::Arc;
use crossbeam_channel::Sender;
use heed::types::{ByteSlice, DecodeIgnore, OwnedType, SerdeJson};
use heed::{Database, Env, EnvOpenOptions};
use serde::{Deserialize, Serialize};
pub type BEU64 = heed::zerocopy::U64<heed::byteorder::BE>;
#[derive(Clone)]
pub struct UpdateStore<M, N> {
env: Env,
pending_meta: Database<OwnedType<BEU64>, SerdeJson<M>>,
pending: Database<OwnedType<BEU64>, ByteSlice>,
processed_meta: Database<OwnedType<BEU64>, SerdeJson<N>>,
aborted_meta: Database<OwnedType<BEU64>, SerdeJson<M>>,
notification_sender: Sender<()>,
}
pub trait UpdateHandler<M, N> {
fn handle_update(&mut self, update_id: u64, meta: M, content: &[u8]) -> heed::Result<N>;
}
impl<M, N, F> UpdateHandler<M, N> for F
where
F: FnMut(u64, M, &[u8]) -> heed::Result<N> + Send + 'static,
{
fn handle_update(&mut self, update_id: u64, meta: M, content: &[u8]) -> heed::Result<N> {
self(update_id, meta, content)
}
}
impl<M: 'static, N: 'static> UpdateStore<M, N> {
pub fn open<P, U>(
mut options: EnvOpenOptions,
path: P,
mut update_handler: U,
) -> heed::Result<Arc<UpdateStore<M, N>>>
where
P: AsRef<Path>,
U: UpdateHandler<M, N> + Send + 'static,
M: for<'a> Deserialize<'a>,
N: Serialize,
{
options.max_dbs(4);
let env = options.open(path)?;
let pending_meta = env.create_database(Some("pending-meta"))?;
let pending = env.create_database(Some("pending"))?;
let processed_meta = env.create_database(Some("processed-meta"))?;
let aborted_meta = env.create_database(Some("aborted-meta"))?;
let (notification_sender, notification_receiver) = crossbeam_channel::bounded(1);
// Send a first notification to trigger the process.
let _ = notification_sender.send(());
let update_store = Arc::new(UpdateStore {
env,
pending,
pending_meta,
processed_meta,
aborted_meta,
notification_sender,
});
let update_store_cloned = update_store.clone();
std::thread::spawn(move || {
// Block and wait for something to process.
for () in notification_receiver {
loop {
match update_store_cloned.process_pending_update(&mut update_handler) {
Ok(Some(_)) => (),
Ok(None) => break,
Err(e) => eprintln!("error while processing update: {}", e),
}
}
}
});
Ok(update_store)
}
/// Returns the new biggest id to use to store the new update.
fn new_update_id(&self, txn: &heed::RoTxn) -> heed::Result<u64> {
let last_pending =
self.pending_meta.remap_data_type::<DecodeIgnore>().last(txn)?.map(|(k, _)| k.get());
let last_processed =
self.processed_meta.remap_data_type::<DecodeIgnore>().last(txn)?.map(|(k, _)| k.get());
let last_aborted =
self.aborted_meta.remap_data_type::<DecodeIgnore>().last(txn)?.map(|(k, _)| k.get());
let last_update_id =
[last_pending, last_processed, last_aborted].iter().copied().flatten().max();
match last_update_id {
Some(last_id) => Ok(last_id + 1),
None => Ok(0),
}
}
/// Registers the update content in the pending store and the meta
/// into the pending-meta store. Returns the new unique update id.
pub fn register_update(&self, meta: &M, content: &[u8]) -> heed::Result<u64>
where
M: Serialize,
{
let mut wtxn = self.env.write_txn()?;
// We ask the update store to give us a new update id, this is safe,
// no other update can have the same id because we use a write txn before
// asking for the id and registering it so other update registering
// will be forced to wait for a new write txn.
let update_id = self.new_update_id(&wtxn)?;
let update_key = BEU64::new(update_id);
self.pending_meta.put(&mut wtxn, &update_key, meta)?;
self.pending.put(&mut wtxn, &update_key, content)?;
wtxn.commit()?;
if let Err(e) = self.notification_sender.try_send(()) {
assert!(!e.is_disconnected(), "update notification channel is disconnected");
}
Ok(update_id)
}
/// Executes the user provided function on the next pending update (the one with the lowest id).
/// This is asynchronous as it let the user process the update with a read-only txn and
/// only writing the result meta to the processed-meta store *after* it has been processed.
fn process_pending_update<U>(&self, handler: &mut U) -> heed::Result<Option<(u64, N)>>
where
U: UpdateHandler<M, N>,
M: for<'a> Deserialize<'a>,
N: Serialize,
{
// Create a read transaction to be able to retrieve the pending update in order.
let rtxn = self.env.read_txn()?;
let first_meta = self.pending_meta.first(&rtxn)?;
// If there is a pending update we process and only keep
// a reader while processing it, not a writer.
match first_meta {
Some((first_id, first_meta)) => {
let first_content =
self.pending.get(&rtxn, &first_id)?.expect("associated update content");
// Process the pending update using the provided user function.
let new_meta = handler.handle_update(first_id.get(), first_meta, first_content)?;
drop(rtxn);
// Once the pending update have been successfully processed
// we must remove the content from the pending stores and
// write the *new* meta to the processed-meta store and commit.
let mut wtxn = self.env.write_txn()?;
self.pending_meta.delete(&mut wtxn, &first_id)?;
self.pending.delete(&mut wtxn, &first_id)?;
self.processed_meta.put(&mut wtxn, &first_id, &new_meta)?;
wtxn.commit()?;
Ok(Some((first_id.get(), new_meta)))
}
None => Ok(None),
}
}
/// The id and metadata of the update that is currently being processed,
/// `None` if no update is being processed.
pub fn processing_update(&self) -> heed::Result<Option<(u64, M)>>
where
M: for<'a> Deserialize<'a>,
{
let rtxn = self.env.read_txn()?;
match self.pending_meta.first(&rtxn)? {
Some((key, meta)) => Ok(Some((key.get(), meta))),
None => Ok(None),
}
}
/// Execute the user defined function with the meta-store iterators, the first
/// iterator is the *processed* meta one, the second the *aborted* meta one
/// and, the last is the *pending* meta one.
pub fn iter_metas<F, T>(&self, mut f: F) -> heed::Result<T>
where
M: for<'a> Deserialize<'a>,
N: for<'a> Deserialize<'a>,
F: for<'a> FnMut(
heed::RoIter<'a, OwnedType<BEU64>, SerdeJson<N>>,
heed::RoIter<'a, OwnedType<BEU64>, SerdeJson<M>>,
heed::RoIter<'a, OwnedType<BEU64>, SerdeJson<M>>,
) -> heed::Result<T>,
{
let rtxn = self.env.read_txn()?;
// We get the pending, processed and aborted meta iterators.
let processed_iter = self.processed_meta.iter(&rtxn)?;
let aborted_iter = self.aborted_meta.iter(&rtxn)?;
let pending_iter = self.pending_meta.iter(&rtxn)?;
// We execute the user defined function with both iterators.
(f)(processed_iter, aborted_iter, pending_iter)
}
/// Returns the update associated meta or `None` if the update doesn't exist.
pub fn meta(&self, update_id: u64) -> heed::Result<Option<UpdateStatusMeta<M, N>>>
where
M: for<'a> Deserialize<'a>,
N: for<'a> Deserialize<'a>,
{
let rtxn = self.env.read_txn()?;
let key = BEU64::new(update_id);
if let Some(meta) = self.pending_meta.get(&rtxn, &key)? {
return Ok(Some(UpdateStatusMeta::Pending(meta)));
}
if let Some(meta) = self.processed_meta.get(&rtxn, &key)? {
return Ok(Some(UpdateStatusMeta::Processed(meta)));
}
if let Some(meta) = self.aborted_meta.get(&rtxn, &key)? {
return Ok(Some(UpdateStatusMeta::Aborted(meta)));
}
Ok(None)
}
/// Aborts an update, an aborted update content is deleted and
/// the meta of it is moved into the aborted updates database.
///
/// Trying to abort an update that is currently being processed, an update
/// that as already been processed or which doesn't actually exist, will
/// return `None`.
pub fn abort_update(&self, update_id: u64) -> heed::Result<Option<M>>
where
M: Serialize + for<'a> Deserialize<'a>,
{
let mut wtxn = self.env.write_txn()?;
let key = BEU64::new(update_id);
// We cannot abort an update that is currently being processed.
if self.pending_meta.first(&wtxn)?.map(|(key, _)| key.get()) == Some(update_id) {
return Ok(None);
}
let meta = match self.pending_meta.get(&wtxn, &key)? {
Some(meta) => meta,
None => return Ok(None),
};
self.aborted_meta.put(&mut wtxn, &key, &meta)?;
self.pending_meta.delete(&mut wtxn, &key)?;
self.pending.delete(&mut wtxn, &key)?;
wtxn.commit()?;
Ok(Some(meta))
}
/// Aborts all the pending updates, and not the one being currently processed.
/// Returns the update metas and ids that were successfully aborted.
pub fn abort_pendings(&self) -> heed::Result<Vec<(u64, M)>>
where
M: Serialize + for<'a> Deserialize<'a>,
{
let mut wtxn = self.env.write_txn()?;
let mut aborted_updates = Vec::new();
// We skip the first pending update as it is currently being processed.
for result in self.pending_meta.iter(&wtxn)?.skip(1) {
let (key, meta) = result?;
let id = key.get();
aborted_updates.push((id, meta));
}
for (id, meta) in &aborted_updates {
let key = BEU64::new(*id);
self.aborted_meta.put(&mut wtxn, &key, &meta)?;
self.pending_meta.delete(&mut wtxn, &key)?;
self.pending.delete(&mut wtxn, &key)?;
}
wtxn.commit()?;
Ok(aborted_updates)
}
}
#[derive(Debug, PartialEq, Eq, Hash)]
pub enum UpdateStatusMeta<M, N> {
Pending(M),
Processed(N),
Aborted(M),
}
#[cfg(test)]
mod tests {
use std::thread;
use std::time::{Duration, Instant};
use super::*;
#[test]
fn simple() {
let dir = tempfile::tempdir().unwrap();
let options = EnvOpenOptions::new();
let update_store = UpdateStore::open(options, dir, |_id, meta: String, _content: &_| {
Ok(meta + " processed")
})
.unwrap();
let meta = String::from("kiki");
let update_id = update_store.register_update(&meta, &[]).unwrap();
thread::sleep(Duration::from_millis(100));
let meta = update_store.meta(update_id).unwrap().unwrap();
assert_eq!(meta, UpdateStatusMeta::Processed(format!("kiki processed")));
}
#[test]
#[ignore]
fn long_running_update() {
let dir = tempfile::tempdir().unwrap();
let options = EnvOpenOptions::new();
let update_store = UpdateStore::open(options, dir, |_id, meta: String, _content: &_| {
thread::sleep(Duration::from_millis(400));
Ok(meta + " processed")
})
.unwrap();
let before_register = Instant::now();
let meta = String::from("kiki");
let update_id_kiki = update_store.register_update(&meta, &[]).unwrap();
assert!(before_register.elapsed() < Duration::from_millis(200));
let meta = String::from("coco");
let update_id_coco = update_store.register_update(&meta, &[]).unwrap();
assert!(before_register.elapsed() < Duration::from_millis(200));
let meta = String::from("cucu");
let update_id_cucu = update_store.register_update(&meta, &[]).unwrap();
assert!(before_register.elapsed() < Duration::from_millis(200));
thread::sleep(Duration::from_millis(400 * 3 + 100));
let meta = update_store.meta(update_id_kiki).unwrap().unwrap();
assert_eq!(meta, UpdateStatusMeta::Processed(format!("kiki processed")));
let meta = update_store.meta(update_id_coco).unwrap().unwrap();
assert_eq!(meta, UpdateStatusMeta::Processed(format!("coco processed")));
let meta = update_store.meta(update_id_cucu).unwrap().unwrap();
assert_eq!(meta, UpdateStatusMeta::Processed(format!("cucu processed")));
}
}