Merge commit 'ddf105b646' into sync-from-ra

crates/salsa/tests/parallel/setup.rs

@@ -0,0 +1,197 @@
+use crate::signal::Signal;
+use salsa::Database;
+use salsa::ParallelDatabase;
+use salsa::Snapshot;
+use std::sync::Arc;
+use std::{
+    cell::Cell,
+    panic::{catch_unwind, resume_unwind, AssertUnwindSafe},
+};
+
+#[salsa::query_group(Par)]
+pub(crate) trait ParDatabase: Knobs {
+    #[salsa::input]
+    fn input(&self, key: char) -> usize;
+
+    fn sum(&self, key: &'static str) -> usize;
+
+    /// Invokes `sum`
+    fn sum2(&self, key: &'static str) -> usize;
+
+    /// Invokes `sum` but doesn't really care about the result.
+    fn sum2_drop_sum(&self, key: &'static str) -> usize;
+
+    /// Invokes `sum2`
+    fn sum3(&self, key: &'static str) -> usize;
+
+    /// Invokes `sum2_drop_sum`
+    fn sum3_drop_sum(&self, key: &'static str) -> usize;
+}
+
+/// Various "knobs" and utilities used by tests to force
+/// a certain behavior.
+pub(crate) trait Knobs {
+    fn knobs(&self) -> &KnobsStruct;
+
+    fn signal(&self, stage: usize);
+
+    fn wait_for(&self, stage: usize);
+}
+
+pub(crate) trait WithValue<T> {
+    fn with_value<R>(&self, value: T, closure: impl FnOnce() -> R) -> R;
+}
+
+impl<T> WithValue<T> for Cell<T> {
+    fn with_value<R>(&self, value: T, closure: impl FnOnce() -> R) -> R {
+        let old_value = self.replace(value);
+
+        let result = catch_unwind(AssertUnwindSafe(closure));
+
+        self.set(old_value);
+
+        match result {
+            Ok(r) => r,
+            Err(payload) => resume_unwind(payload),
+        }
+    }
+}
+
+#[derive(Default, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum CancellationFlag {
+    #[default]
+    Down,
+    Panic,
+}
+
+/// Various "knobs" that can be used to customize how the queries
+/// behave on one specific thread. Note that this state is
+/// intentionally thread-local (apart from `signal`).
+#[derive(Clone, Default)]
+pub(crate) struct KnobsStruct {
+    /// A kind of flexible barrier used to coordinate execution across
+    /// threads to ensure we reach various weird states.
+    pub(crate) signal: Arc<Signal>,
+
+    /// When this database is about to block, send a signal.
+    pub(crate) signal_on_will_block: Cell<usize>,
+
+    /// Invocations of `sum` will signal this stage on entry.
+    pub(crate) sum_signal_on_entry: Cell<usize>,
+
+    /// Invocations of `sum` will wait for this stage on entry.
+    pub(crate) sum_wait_for_on_entry: Cell<usize>,
+
+    /// If true, invocations of `sum` will panic before they exit.
+    pub(crate) sum_should_panic: Cell<bool>,
+
+    /// If true, invocations of `sum` will wait for cancellation before
+    /// they exit.
+    pub(crate) sum_wait_for_cancellation: Cell<CancellationFlag>,
+
+    /// Invocations of `sum` will wait for this stage prior to exiting.
+    pub(crate) sum_wait_for_on_exit: Cell<usize>,
+
+    /// Invocations of `sum` will signal this stage prior to exiting.
+    pub(crate) sum_signal_on_exit: Cell<usize>,
+
+    /// Invocations of `sum3_drop_sum` will panic unconditionally
+    pub(crate) sum3_drop_sum_should_panic: Cell<bool>,
+}
+
+fn sum(db: &dyn ParDatabase, key: &'static str) -> usize {
+    let mut sum = 0;
+
+    db.signal(db.knobs().sum_signal_on_entry.get());
+
+    db.wait_for(db.knobs().sum_wait_for_on_entry.get());
+
+    if db.knobs().sum_should_panic.get() {
+        panic!("query set to panic before exit")
+    }
+
+    for ch in key.chars() {
+        sum += db.input(ch);
+    }
+
+    match db.knobs().sum_wait_for_cancellation.get() {
+        CancellationFlag::Down => (),
+        CancellationFlag::Panic => {
+            tracing::debug!("waiting for cancellation");
+            loop {
+                db.unwind_if_cancelled();
+                std::thread::yield_now();
+            }
+        }
+    }
+
+    db.wait_for(db.knobs().sum_wait_for_on_exit.get());
+
+    db.signal(db.knobs().sum_signal_on_exit.get());
+
+    sum
+}
+
+fn sum2(db: &dyn ParDatabase, key: &'static str) -> usize {
+    db.sum(key)
+}
+
+fn sum2_drop_sum(db: &dyn ParDatabase, key: &'static str) -> usize {
+    let _ = db.sum(key);
+    22
+}
+
+fn sum3(db: &dyn ParDatabase, key: &'static str) -> usize {
+    db.sum2(key)
+}
+
+fn sum3_drop_sum(db: &dyn ParDatabase, key: &'static str) -> usize {
+    if db.knobs().sum3_drop_sum_should_panic.get() {
+        panic!("sum3_drop_sum executed")
+    }
+    db.sum2_drop_sum(key)
+}
+
+#[salsa::database(
+    Par,
+    crate::parallel_cycle_all_recover::ParallelCycleAllRecover,
+    crate::parallel_cycle_none_recover::ParallelCycleNoneRecover,
+    crate::parallel_cycle_mid_recover::ParallelCycleMidRecovers,
+    crate::parallel_cycle_one_recovers::ParallelCycleOneRecovers
+)]
+#[derive(Default)]
+pub(crate) struct ParDatabaseImpl {
+    storage: salsa::Storage<Self>,
+    knobs: KnobsStruct,
+}
+
+impl Database for ParDatabaseImpl {
+    fn salsa_event(&self, event: salsa::Event) {
+        if let salsa::EventKind::WillBlockOn { .. } = event.kind {
+            self.signal(self.knobs().signal_on_will_block.get());
+        }
+    }
+}
+
+impl ParallelDatabase for ParDatabaseImpl {
+    fn snapshot(&self) -> Snapshot<Self> {
+        Snapshot::new(ParDatabaseImpl {
+            storage: self.storage.snapshot(),
+            knobs: self.knobs.clone(),
+        })
+    }
+}
+
+impl Knobs for ParDatabaseImpl {
+    fn knobs(&self) -> &KnobsStruct {
+        &self.knobs
+    }
+
+    fn signal(&self, stage: usize) {
+        self.knobs.signal.signal(stage);
+    }
+
+    fn wait_for(&self, stage: usize) {
+        self.knobs.signal.wait_for(stage);
+    }
+}