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1b355d8a87
Introduces a `SyncReadAsyncWriteLock` to make it harder to write to the npm resolution without first waiting async in a queue. For the npm resolution, reading synchronously is fine, but when updating, someone should wait async, clone the data, then write the data at the end back.
62 lines
1.6 KiB
Rust
62 lines
1.6 KiB
Rust
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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use deno_core::parking_lot::RwLock;
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use deno_core::parking_lot::RwLockReadGuard;
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use deno_core::parking_lot::RwLockWriteGuard;
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use super::TaskQueue;
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use super::TaskQueuePermit;
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/// A lock that can be read synchronously at any time (including when
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/// being written to), but must write asynchronously.
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pub struct SyncReadAsyncWriteLockWriteGuard<'a, T: Send + Sync> {
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_update_permit: TaskQueuePermit<'a>,
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data: &'a RwLock<T>,
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}
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impl<'a, T: Send + Sync> SyncReadAsyncWriteLockWriteGuard<'a, T> {
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pub fn read(&self) -> RwLockReadGuard<'_, T> {
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self.data.read()
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}
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/// Warning: Only `write()` with data you created within this
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/// write this `SyncReadAsyncWriteLockWriteGuard`.
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///
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/// ```rs
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/// let mut data = lock.write().await;
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///
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/// let mut data = data.read().clone();
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/// data.value = 2;
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/// *data.write() = data;
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/// ```
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pub fn write(&self) -> RwLockWriteGuard<'_, T> {
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self.data.write()
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}
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}
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/// A lock that can only be
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pub struct SyncReadAsyncWriteLock<T: Send + Sync> {
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data: RwLock<T>,
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update_queue: TaskQueue,
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}
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impl<T: Send + Sync> SyncReadAsyncWriteLock<T> {
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pub fn new(data: T) -> Self {
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Self {
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data: RwLock::new(data),
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update_queue: TaskQueue::default(),
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}
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}
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pub fn read(&self) -> RwLockReadGuard<'_, T> {
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self.data.read()
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}
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pub async fn acquire(&self) -> SyncReadAsyncWriteLockWriteGuard<'_, T> {
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let update_permit = self.update_queue.acquire().await;
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SyncReadAsyncWriteLockWriteGuard {
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_update_permit: update_permit,
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data: &self.data,
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}
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}
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}
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