next.js/turbopack/crates/turbopack-trace-server/src/store_container.rs

use std::{
    ops::{Deref, DerefMut},
    sync::{
        RwLock, RwLockReadGuard, RwLockWriteGuard,
        atomic::{AtomicBool, Ordering},
    },
};

use crate::store::Store;

pub struct StoreContainer {
    store: RwLock<StoreWithGeneration>,
    want_to_read: AtomicBool,
}

struct StoreWithGeneration {
    store: Store,
    generation: usize,
}

impl StoreContainer {
    pub fn new() -> Self {
        Self {
            store: RwLock::new(StoreWithGeneration {
                store: Store::new(),
                generation: 0,
            }),
            want_to_read: AtomicBool::new(false),
        }
    }

    pub fn read(&self) -> StoreReadGuard<'_> {
        if let Ok(guard) = self.store.try_read() {
            return StoreReadGuard { guard };
        }
        self.want_to_read.store(true, Ordering::Relaxed);
        let guard = StoreReadGuard {
            guard: self.store.read().unwrap(),
        };
        self.want_to_read.store(false, Ordering::Relaxed);
        guard
    }

    pub fn write(&self) -> StoreWriteGuard<'_> {
        let mut guard = self.store.write().unwrap();
        guard.generation += 1;
        StoreWriteGuard { guard }
    }

    pub fn want_to_read(&self) -> bool {
        self.want_to_read.load(Ordering::Relaxed)
    }
}

pub struct StoreReadGuard<'a> {
    guard: RwLockReadGuard<'a, StoreWithGeneration>,
}

impl StoreReadGuard<'_> {
    pub fn generation(&self) -> usize {
        self.guard.generation
    }
}

impl Deref for StoreReadGuard<'_> {
    type Target = Store;

    fn deref(&self) -> &Self::Target {
        &self.guard.store
    }
}

pub struct StoreWriteGuard<'a> {
    guard: RwLockWriteGuard<'a, StoreWithGeneration>,
}

impl Deref for StoreWriteGuard<'_> {
    type Target = Store;

    fn deref(&self) -> &Self::Target {
        &self.guard.store
    }
}

impl DerefMut for StoreWriteGuard<'_> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.guard.store
    }
}