use std::cell::RefCell;
use std::collections::hash_map::Entry;
-use std::convert::TryFrom;
-use std::rc::Rc;
use std::num::TryFromIntError;
use std::time::{Duration, Instant, SystemTime};
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def_id::DefId;
use rustc_index::vec::{Idx, IndexVec};
+use rustc_middle::mir::Mutability;
+use crate::concurrency::data_race;
use crate::sync::SynchronizationState;
use crate::*;
impl TryFrom<u64> for ThreadId {
type Error = TryFromIntError;
fn try_from(id: u64) -> Result<Self, Self::Error> {
- u32::try_from(id).map(|id_u32| Self(id_u32))
+ u32::try_from(id).map(Self)
}
}
}
impl ThreadId {
- pub fn to_u32_scalar<'tcx>(&self) -> Scalar<Tag> {
- Scalar::from_u32(u32::try_from(self.0).unwrap())
+ pub fn to_u32_scalar(&self) -> Scalar<Tag> {
+ Scalar::from_u32(self.0)
}
}
/// Get the name of the current thread, or `<unnamed>` if it was not set.
fn thread_name(&self) -> &[u8] {
- if let Some(ref thread_name) = self.thread_name {
- thread_name
- } else {
- b"<unnamed>"
- }
+ if let Some(ref thread_name) = self.thread_name { thread_name } else { b"<unnamed>" }
}
}
impl<'mir, 'tcx> std::fmt::Debug for Thread<'mir, 'tcx> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- write!(f, "{}({:?}, {:?})", String::from_utf8_lossy(self.thread_name()), self.state, self.join_status)
+ write!(
+ f,
+ "{}({:?}, {:?})",
+ String::from_utf8_lossy(self.thread_name()),
+ self.state,
+ self.join_status
+ )
}
}
pub(crate) sync: SynchronizationState,
/// A mapping from a thread-local static to an allocation id of a thread
/// specific allocation.
- thread_local_alloc_ids: RefCell<FxHashMap<(DefId, ThreadId), AllocId>>,
+ thread_local_alloc_ids: RefCell<FxHashMap<(DefId, ThreadId), Pointer<Tag>>>,
/// A flag that indicates that we should change the active thread.
yield_active_thread: bool,
/// Callbacks that are called once the specified time passes.
threads.push(main_thread);
Self {
active_thread: ThreadId::new(0),
- threads: threads,
+ threads,
sync: SynchronizationState::default(),
thread_local_alloc_ids: Default::default(),
yield_active_thread: false,
impl<'mir, 'tcx: 'mir> ThreadManager<'mir, 'tcx> {
/// Check if we have an allocation for the given thread local static for the
/// active thread.
- fn get_thread_local_alloc_id(&self, def_id: DefId) -> Option<AllocId> {
+ fn get_thread_local_alloc_id(&self, def_id: DefId) -> Option<Pointer<Tag>> {
self.thread_local_alloc_ids.borrow().get(&(def_id, self.active_thread)).cloned()
}
- /// Set the allocation id as the allocation id of the given thread local
+ /// Set the pointer for the allocation of the given thread local
/// static for the active thread.
///
/// Panics if a thread local is initialized twice for the same thread.
- fn set_thread_local_alloc_id(&self, def_id: DefId, new_alloc_id: AllocId) {
+ fn set_thread_local_alloc(&self, def_id: DefId, ptr: Pointer<Tag>) {
self.thread_local_alloc_ids
.borrow_mut()
- .try_insert((def_id, self.active_thread), new_alloc_id)
+ .try_insert((def_id, self.active_thread), ptr)
.unwrap();
}
/// Borrow the stack of the active thread.
- fn active_thread_stack(&self) -> &[Frame<'mir, 'tcx, Tag, FrameData<'tcx>>] {
+ pub fn active_thread_stack(&self) -> &[Frame<'mir, 'tcx, Tag, FrameData<'tcx>>] {
&self.threads[self.active_thread].stack
}
self.threads[thread_id].state == ThreadState::Terminated
}
+ /// Have all threads terminated?
+ fn have_all_terminated(&self) -> bool {
+ self.threads.iter().all(|thread| thread.state == ThreadState::Terminated)
+ }
+
/// Enable the thread for execution. The thread must be terminated.
fn enable_thread(&mut self, thread_id: ThreadId) {
assert!(self.has_terminated(thread_id));
}
/// Mark that the active thread tries to join the thread with `joined_thread_id`.
- fn join_thread(&mut self, joined_thread_id: ThreadId, data_race: &Option<Rc<data_race::GlobalState>>) -> InterpResult<'tcx> {
+ fn join_thread(
+ &mut self,
+ joined_thread_id: ThreadId,
+ data_race: Option<&mut data_race::GlobalState>,
+ ) -> InterpResult<'tcx> {
if self.threads[joined_thread_id].join_status != ThreadJoinStatus::Joinable {
throw_ub_format!("trying to join a detached or already joined thread");
}
}
/// Wakes up threads joining on the active one and deallocates thread-local statics.
- /// The `AllocId` that can now be freed is returned.
- fn thread_terminated(&mut self, data_race: &Option<Rc<data_race::GlobalState>>) -> Vec<AllocId> {
+ /// The `AllocId` that can now be freed are returned.
+ fn thread_terminated(
+ &mut self,
+ mut data_race: Option<&mut data_race::GlobalState>,
+ ) -> Vec<Pointer<Tag>> {
let mut free_tls_statics = Vec::new();
{
let mut thread_local_statics = self.thread_local_alloc_ids.borrow_mut();
// Delete this static from the map and from memory.
// We cannot free directly here as we cannot use `?` in this context.
free_tls_statics.push(alloc_id);
- return false;
+ false
});
}
// Set the thread into a terminated state in the data-race detector
- if let Some(data_race) = data_race {
+ if let Some(ref mut data_race) = data_race {
data_race.thread_terminated();
}
// Check if we need to unblock any threads.
for (i, thread) in self.threads.iter_enumerated_mut() {
if thread.state == ThreadState::BlockedOnJoin(self.active_thread) {
// The thread has terminated, mark happens-before edge to joining thread
- if let Some(data_race) = data_race {
+ if let Some(ref mut data_race) = data_race {
data_race.thread_joined(i, self.active_thread);
}
trace!("unblocking {:?} because {:?} terminated", i, self.active_thread);
thread.state = ThreadState::Enabled;
}
}
- return free_tls_statics;
+ free_tls_statics
}
/// Decide which action to take next and on which thread.
/// used in stateless model checkers such as Loom: run the active thread as
/// long as we can and switch only when we have to (the active thread was
/// blocked, terminated, or has explicitly asked to be preempted).
- fn schedule(&mut self, data_race: &Option<Rc<data_race::GlobalState>>) -> InterpResult<'tcx, SchedulingAction> {
+ fn schedule(
+ &mut self,
+ data_race: &Option<data_race::GlobalState>,
+ ) -> InterpResult<'tcx, SchedulingAction> {
// Check whether the thread has **just** terminated (`check_terminated`
// checks whether the thread has popped all its stack and if yes, sets
// the thread state to terminated).
if self.threads[self.active_thread].check_terminated() {
return Ok(SchedulingAction::ExecuteDtors);
}
+ // If we get here again and the thread is *still* terminated, there are no more dtors to run.
if self.threads[MAIN_THREAD].state == ThreadState::Terminated {
// The main thread terminated; stop the program.
- if self.threads.iter().any(|thread| thread.state != ThreadState::Terminated) {
- // FIXME: This check should be either configurable or just emit
- // a warning. For example, it seems normal for a program to
- // terminate without waiting for its detached threads to
- // terminate. However, this case is not trivial to support
- // because we also probably do not want to consider the memory
- // owned by these threads as leaked.
- throw_unsup_format!("the main thread terminated without waiting for other threads");
- }
+ // We do *not* run TLS dtors of remaining threads, which seems to match rustc behavior.
return Ok(SchedulingAction::Stop);
}
- // At least for `pthread_cond_timedwait` we need to report timeout when
- // the function is called already after the specified time even if a
- // signal is received before the thread gets scheduled. Therefore, we
- // need to schedule all timeout callbacks before we continue regular
- // execution.
- //
- // Documentation:
- // https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html#
- let potential_sleep_time =
- self.timeout_callbacks.values().map(|info| info.call_time.get_wait_time()).min();
- if potential_sleep_time == Some(Duration::new(0, 0)) {
- return Ok(SchedulingAction::ExecuteTimeoutCallback);
- }
- // No callbacks scheduled, pick a regular thread to execute.
+ // This thread and the program can keep going.
if self.threads[self.active_thread].state == ThreadState::Enabled
&& !self.yield_active_thread
{
// The currently active thread is still enabled, just continue with it.
return Ok(SchedulingAction::ExecuteStep);
}
- // We need to pick a new thread for execution.
- for (id, thread) in self.threads.iter_enumerated() {
+ // The active thread yielded. Let's see if there are any timeouts to take care of. We do
+ // this *before* running any other thread, to ensure that timeouts "in the past" fire before
+ // any other thread can take an action. This ensures that for `pthread_cond_timedwait`, "an
+ // error is returned if [...] the absolute time specified by abstime has already been passed
+ // at the time of the call".
+ // <https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html>
+ let potential_sleep_time =
+ self.timeout_callbacks.values().map(|info| info.call_time.get_wait_time()).min();
+ if potential_sleep_time == Some(Duration::new(0, 0)) {
+ return Ok(SchedulingAction::ExecuteTimeoutCallback);
+ }
+ // No callbacks scheduled, pick a regular thread to execute.
+ // The active thread blocked or yielded. So we go search for another enabled thread.
+ // Curcially, we start searching at the current active thread ID, rather than at 0, since we
+ // want to avoid always scheduling threads 0 and 1 without ever making progress in thread 2.
+ //
+ // `skip(N)` means we start iterating at thread N, so we skip 1 more to start just *after*
+ // the active thread. Then after that we look at `take(N)`, i.e., the threads *before* the
+ // active thread.
+ let threads = self
+ .threads
+ .iter_enumerated()
+ .skip(self.active_thread.index() + 1)
+ .chain(self.threads.iter_enumerated().take(self.active_thread.index()));
+ for (id, thread) in threads {
+ debug_assert_ne!(self.active_thread, id);
if thread.state == ThreadState::Enabled {
- if !self.yield_active_thread || id != self.active_thread {
- self.active_thread = id;
- if let Some(data_race) = data_race {
- data_race.thread_set_active(self.active_thread);
- }
- break;
+ self.active_thread = id;
+ if let Some(data_race) = data_race {
+ data_race.thread_set_active(self.active_thread);
}
+ break;
}
}
self.yield_active_thread = false;
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
/// Get a thread-specific allocation id for the given thread-local static.
/// If needed, allocate a new one.
- fn get_or_create_thread_local_alloc_id(&mut self, def_id: DefId) -> InterpResult<'tcx, AllocId> {
+ fn get_or_create_thread_local_alloc(
+ &mut self,
+ def_id: DefId,
+ ) -> InterpResult<'tcx, Pointer<Tag>> {
let this = self.eval_context_mut();
let tcx = this.tcx;
- if let Some(new_alloc_id) = this.machine.threads.get_thread_local_alloc_id(def_id) {
+ if let Some(old_alloc) = this.machine.threads.get_thread_local_alloc_id(def_id) {
// We already have a thread-specific allocation id for this
// thread-local static.
- Ok(new_alloc_id)
+ Ok(old_alloc)
} else {
// We need to allocate a thread-specific allocation id for this
// thread-local static.
throw_unsup_format!("foreign thread-local statics are not supported");
}
let allocation = tcx.eval_static_initializer(def_id)?;
+ let mut allocation = allocation.inner().clone();
+ // This allocation will be deallocated when the thread dies, so it is not in read-only memory.
+ allocation.mutability = Mutability::Mut;
// Create a fresh allocation with this content.
- let new_alloc_id = this.memory.allocate_with(allocation.clone(), MiriMemoryKind::Tls.into()).alloc_id;
- this.machine.threads.set_thread_local_alloc_id(def_id, new_alloc_id);
- Ok(new_alloc_id)
+ let new_alloc = this.allocate_raw_ptr(allocation, MiriMemoryKind::Tls.into())?;
+ this.machine.threads.set_thread_local_alloc(def_id, new_alloc);
+ Ok(new_alloc)
}
}
fn create_thread(&mut self) -> ThreadId {
let this = self.eval_context_mut();
let id = this.machine.threads.create_thread();
- if let Some(data_race) = &this.memory.extra.data_race {
+ if let Some(data_race) = &mut this.machine.data_race {
data_race.thread_created(id);
}
id
#[inline]
fn join_thread(&mut self, joined_thread_id: ThreadId) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
- let data_race = &this.memory.extra.data_race;
- this.machine.threads.join_thread(joined_thread_id, data_race)?;
+ this.machine.threads.join_thread(joined_thread_id, this.machine.data_race.as_mut())?;
Ok(())
}
#[inline]
fn set_active_thread(&mut self, thread_id: ThreadId) -> ThreadId {
let this = self.eval_context_mut();
- if let Some(data_race) = &this.memory.extra.data_race {
+ if let Some(data_race) = &this.machine.data_race {
data_race.thread_set_active(thread_id);
}
this.machine.threads.set_active_thread_id(thread_id)
this.machine.threads.has_terminated(thread_id)
}
+ #[inline]
+ fn have_all_terminated(&self) -> bool {
+ let this = self.eval_context_ref();
+ this.machine.threads.have_all_terminated()
+ }
+
#[inline]
fn enable_thread(&mut self, thread_id: ThreadId) {
let this = self.eval_context_mut();
#[inline]
fn set_active_thread_name(&mut self, new_thread_name: Vec<u8>) {
let this = self.eval_context_mut();
- if let Some(data_race) = &this.memory.extra.data_race {
+ if let Some(data_race) = &mut this.machine.data_race {
if let Ok(string) = String::from_utf8(new_thread_name.clone()) {
- data_race.thread_set_name(
- this.machine.threads.active_thread, string
- );
+ data_race.thread_set_name(this.machine.threads.active_thread, string);
}
}
this.machine.threads.set_thread_name(new_thread_name);
this.machine.threads.yield_active_thread();
}
+ #[inline]
+ fn maybe_preempt_active_thread(&mut self) {
+ use rand::Rng as _;
+
+ let this = self.eval_context_mut();
+ if this.machine.rng.get_mut().gen_bool(this.machine.preemption_rate) {
+ this.yield_active_thread();
+ }
+ }
+
#[inline]
fn register_timeout_callback(
&mut self,
fn run_timeout_callback(&mut self) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
let (thread, callback) =
- this.machine.threads.get_ready_callback().expect("no callback found");
+ if let Some((thread, callback)) = this.machine.threads.get_ready_callback() {
+ (thread, callback)
+ } else {
+ // get_ready_callback can return None if the computer's clock
+ // was shifted after calling the scheduler and before the call
+ // to get_ready_callback (see issue
+ // https://github.com/rust-lang/miri/issues/1763). In this case,
+ // just do nothing, which effectively just returns to the
+ // scheduler.
+ return Ok(());
+ };
// This back-and-forth with `set_active_thread` is here because of two
// design decisions:
// 1. Make the caller and not the callback responsible for changing
#[inline]
fn schedule(&mut self) -> InterpResult<'tcx, SchedulingAction> {
let this = self.eval_context_mut();
- let data_race = &this.memory.extra.data_race;
+ let data_race = &this.machine.data_race;
this.machine.threads.schedule(data_race)
}
#[inline]
fn thread_terminated(&mut self) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
- let data_race = &this.memory.extra.data_race;
- for alloc_id in this.machine.threads.thread_terminated(data_race) {
- let ptr = this.memory.global_base_pointer(alloc_id.into())?;
- this.memory.deallocate(ptr, None, MiriMemoryKind::Tls.into())?;
+ for ptr in this.machine.threads.thread_terminated(this.machine.data_race.as_mut()) {
+ this.deallocate_ptr(ptr.into(), None, MiriMemoryKind::Tls.into())?;
}
Ok(())
}
projects / rust.git / blobdiff