2020-03-16 18:48:44 -05:00
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//! Implements threads.
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use std::cell::RefCell;
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2020-04-07 22:20:41 -05:00
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use std::convert::TryFrom;
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2020-04-15 23:25:12 -05:00
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use std::num::NonZeroU32;
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2020-03-16 18:48:44 -05:00
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use log::trace;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_index::vec::{Idx, IndexVec};
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use crate::*;
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/// A thread identifier.
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#[derive(Clone, Copy, Debug, PartialOrd, Ord, PartialEq, Eq, Hash)]
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pub struct ThreadId(usize);
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impl Idx for ThreadId {
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fn new(idx: usize) -> Self {
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ThreadId(idx)
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}
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fn index(self) -> usize {
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self.0
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}
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}
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impl From<u64> for ThreadId {
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fn from(id: u64) -> Self {
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Self(id as usize)
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}
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}
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2020-04-07 22:20:41 -05:00
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impl From<u32> for ThreadId {
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fn from(id: u32) -> Self {
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Self(id as usize)
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}
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}
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impl ThreadId {
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pub fn to_u32_scalar<'tcx>(&self) -> Scalar<Tag> {
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Scalar::from_u32(u32::try_from(self.0).unwrap())
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}
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}
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/// An identifier of a set of blocked threads.
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#[derive(Clone, Copy, Debug, PartialOrd, Ord, PartialEq, Eq, Hash)]
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pub struct BlockSetId(NonZeroU32);
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impl From<u32> for BlockSetId {
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fn from(id: u32) -> Self {
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Self(NonZeroU32::new(id).expect("0 is not a valid blockset id"))
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2020-04-07 22:20:41 -05:00
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}
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}
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impl BlockSetId {
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pub fn to_u32_scalar<'tcx>(&self) -> Scalar<Tag> {
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2020-04-15 23:25:12 -05:00
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Scalar::from_u32(self.0.get())
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2020-04-07 22:20:41 -05:00
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}
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}
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2020-03-16 18:48:44 -05:00
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/// The state of a thread.
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
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pub enum ThreadState {
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/// The thread is enabled and can be executed.
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Enabled,
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/// The thread tried to join the specified thread and is blocked until that
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/// thread terminates.
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BlockedOnJoin(ThreadId),
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/// The thread is blocked and belongs to the given blockset..
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Blocked(BlockSetId),
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/// The thread has terminated its execution (we do not delete terminated
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/// threads.)
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Terminated,
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}
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/// A thread.
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pub struct Thread<'mir, 'tcx> {
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state: ThreadState,
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/// Name of the thread.
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thread_name: Option<Vec<u8>>,
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/// The virtual call stack.
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stack: Vec<Frame<'mir, 'tcx, Tag, FrameData<'tcx>>>,
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/// Is the thread detached?
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///
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/// A thread is detached if its join handle was destroyed and no other
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/// thread can join it.
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detached: bool,
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}
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impl<'mir, 'tcx> Thread<'mir, 'tcx> {
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/// Check if the thread terminated. If yes, change the state to terminated
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/// and return `true`.
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fn check_terminated(&mut self) -> bool {
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if self.state == ThreadState::Enabled {
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if self.stack.is_empty() {
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self.state = ThreadState::Terminated;
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return true;
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}
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}
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false
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}
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}
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impl<'mir, 'tcx> std::fmt::Debug for Thread<'mir, 'tcx> {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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write!(f, "{:?}", self.state)
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}
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}
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impl<'mir, 'tcx> Default for Thread<'mir, 'tcx> {
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fn default() -> Self {
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Self { state: ThreadState::Enabled, thread_name: None, stack: Vec::new(), detached: false }
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}
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}
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/// A set of threads.
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#[derive(Debug)]
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pub struct ThreadManager<'mir, 'tcx> {
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/// Identifier of the currently active thread.
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active_thread: ThreadId,
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/// Threads used in the program.
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///
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/// Note that this vector also contains terminated threads.
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threads: IndexVec<ThreadId, Thread<'mir, 'tcx>>,
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/// A counter used to generate unique identifiers for blocksets.
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blockset_counter: u32,
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/// A mapping from an allocation id of a thread-local static to an
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/// allocation id of a thread specific allocation.
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thread_local_alloc_ids: RefCell<FxHashMap<(AllocId, ThreadId), AllocId>>,
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2020-03-16 18:48:44 -05:00
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}
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2020-04-09 14:06:33 -05:00
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impl<'mir, 'tcx> Default for ThreadManager<'mir, 'tcx> {
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fn default() -> Self {
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let mut threads = IndexVec::new();
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threads.push(Default::default());
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Self {
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active_thread: ThreadId::new(0),
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threads: threads,
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blockset_counter: 0,
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thread_local_alloc_ids: Default::default(),
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}
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2020-03-16 18:48:44 -05:00
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}
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}
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2020-04-09 14:06:33 -05:00
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impl<'mir, 'tcx: 'mir> ThreadManager<'mir, 'tcx> {
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2020-04-15 16:34:34 -05:00
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/// Check if we have an allocation for the given thread local static for the
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/// active thread.
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pub fn get_thread_local_alloc_id(&self, static_alloc_id: AllocId) -> Option<AllocId> {
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self.thread_local_alloc_ids.borrow().get(&(static_alloc_id, self.active_thread)).cloned()
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}
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2020-04-15 16:34:34 -05:00
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/// Set the allocation id as the allocation id of the given thread local
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/// static for the active thread.
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pub fn set_thread_local_alloc_id(&self, static_alloc_id: AllocId, new_alloc_id: AllocId) {
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assert!(
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self.thread_local_alloc_ids
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.borrow_mut()
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.insert((static_alloc_id, self.active_thread), new_alloc_id)
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.is_none(),
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"Bug: a thread local initialized twice for the same thread."
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);
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}
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2020-03-16 18:48:44 -05:00
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/// Borrow the stack of the active thread.
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fn active_thread_stack(&self) -> &[Frame<'mir, 'tcx, Tag, FrameData<'tcx>>] {
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&self.threads[self.active_thread].stack
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}
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2020-03-16 18:48:44 -05:00
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/// Mutably borrow the stack of the active thread.
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fn active_thread_stack_mut(&mut self) -> &mut Vec<Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
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&mut self.threads[self.active_thread].stack
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}
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2020-03-16 18:48:44 -05:00
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/// Create a new thread and returns its id.
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fn create_thread(&mut self) -> ThreadId {
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let new_thread_id = ThreadId::new(self.threads.len());
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self.threads.push(Default::default());
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new_thread_id
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}
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/// Set an active thread and return the id of the thread that was active before.
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fn set_active_thread_id(&mut self, id: ThreadId) -> ThreadId {
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let active_thread_id = self.active_thread;
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self.active_thread = id;
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assert!(self.active_thread.index() < self.threads.len());
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active_thread_id
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}
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/// Get the id of the currently active thread.
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fn get_active_thread_id(&self) -> ThreadId {
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self.active_thread
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}
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/// Get the borrow of the currently active thread.
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fn active_thread_mut(&mut self) -> &mut Thread<'mir, 'tcx> {
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&mut self.threads[self.active_thread]
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}
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/// Mark the thread as detached, which means that no other thread will try
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/// to join it and the thread is responsible for cleaning up.
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fn detach_thread(&mut self, id: ThreadId) {
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self.threads[id].detached = true;
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}
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/// Mark that the active thread tries to join the thread with `joined_thread_id`.
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fn join_thread(&mut self, joined_thread_id: ThreadId) {
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assert!(!self.threads[joined_thread_id].detached, "Bug: trying to join a detached thread.");
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assert_ne!(joined_thread_id, self.active_thread, "Bug: trying to join itself");
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assert!(
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self.threads
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.iter()
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.all(|thread| thread.state != ThreadState::BlockedOnJoin(joined_thread_id)),
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"Bug: multiple threads try to join the same thread."
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);
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if self.threads[joined_thread_id].state != ThreadState::Terminated {
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// The joined thread is still running, we need to wait for it.
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self.active_thread_mut().state = ThreadState::BlockedOnJoin(joined_thread_id);
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trace!(
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"{:?} blocked on {:?} when trying to join",
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self.active_thread,
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joined_thread_id
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);
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}
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}
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2020-04-06 18:12:13 -05:00
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/// Set the name of the active thread.
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fn set_thread_name(&mut self, new_thread_name: Vec<u8>) {
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self.active_thread_mut().thread_name = Some(new_thread_name);
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}
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2020-04-15 23:25:12 -05:00
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2020-04-07 22:20:41 -05:00
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/// Get ids and states of all threads ever allocated.
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fn get_all_thread_ids_with_states(&self) -> Vec<(ThreadId, ThreadState)> {
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self.threads.iter_enumerated().map(|(id, thread)| (id, thread.state)).collect()
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}
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/// Allocate a new blockset id.
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fn create_blockset(&mut self) -> BlockSetId {
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self.blockset_counter = self.blockset_counter.checked_add(1).unwrap();
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self.blockset_counter.into()
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}
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/// Block the currently active thread and put it into the given blockset.
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fn block_active_thread(&mut self, set: BlockSetId) {
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let state = &mut self.active_thread_mut().state;
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assert_eq!(*state, ThreadState::Enabled);
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*state = ThreadState::Blocked(set);
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}
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/// Unblock any one thread from the given blockset if it contains at least
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/// one. Return the id of the unblocked thread.
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fn unblock_random_thread(&mut self, set: BlockSetId) -> Option<ThreadId> {
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for (id, thread) in self.threads.iter_enumerated_mut() {
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if thread.state == ThreadState::Blocked(set) {
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trace!("unblocking {:?} in blockset {:?}", id, set);
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thread.state = ThreadState::Enabled;
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return Some(id);
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}
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}
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None
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}
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/// Decide which thread to run next.
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///
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/// Returns `false` if all threads terminated.
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fn schedule(&mut self) -> InterpResult<'tcx, bool> {
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if self.threads[self.active_thread].check_terminated() {
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// Check if we need to unblock any threads.
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for (i, thread) in self.threads.iter_enumerated_mut() {
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if thread.state == ThreadState::BlockedOnJoin(self.active_thread) {
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trace!("unblocking {:?} because {:?} terminated", i, self.active_thread);
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thread.state = ThreadState::Enabled;
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}
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}
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}
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if self.threads[self.active_thread].state == ThreadState::Enabled {
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return Ok(true);
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}
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if let Some(enabled_thread) =
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self.threads.iter().position(|thread| thread.state == ThreadState::Enabled)
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{
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self.active_thread = ThreadId::new(enabled_thread);
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return Ok(true);
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}
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if self.threads.iter().all(|thread| thread.state == ThreadState::Terminated) {
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Ok(false)
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} else {
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throw_machine_stop!(TerminationInfo::Deadlock);
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}
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}
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}
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impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
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pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
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fn get_thread_local_alloc_id(&self, static_alloc_id: AllocId) -> Option<AllocId> {
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let this = self.eval_context_ref();
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this.machine.threads.get_thread_local_alloc_id(static_alloc_id)
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}
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2020-04-15 16:34:34 -05:00
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fn set_thread_local_alloc_id(&self, static_alloc_id: AllocId, thread_local_alloc_id: AllocId) {
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let this = self.eval_context_ref();
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this.machine.threads.set_thread_local_alloc_id(static_alloc_id, thread_local_alloc_id)
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}
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fn create_thread(&mut self) -> InterpResult<'tcx, ThreadId> {
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let this = self.eval_context_mut();
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|
Ok(this.machine.threads.create_thread())
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-03-16 18:48:44 -05:00
|
|
|
fn detach_thread(&mut self, thread_id: ThreadId) -> InterpResult<'tcx> {
|
|
|
|
let this = self.eval_context_mut();
|
|
|
|
this.machine.threads.detach_thread(thread_id);
|
|
|
|
Ok(())
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-03-16 18:48:44 -05:00
|
|
|
fn join_thread(&mut self, joined_thread_id: ThreadId) -> InterpResult<'tcx> {
|
|
|
|
let this = self.eval_context_mut();
|
|
|
|
this.machine.threads.join_thread(joined_thread_id);
|
|
|
|
Ok(())
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-03-16 18:48:44 -05:00
|
|
|
fn set_active_thread(&mut self, thread_id: ThreadId) -> InterpResult<'tcx, ThreadId> {
|
|
|
|
let this = self.eval_context_mut();
|
2020-04-06 18:12:13 -05:00
|
|
|
Ok(this.machine.threads.set_active_thread_id(thread_id))
|
2020-03-16 18:48:44 -05:00
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-03-16 18:48:44 -05:00
|
|
|
fn get_active_thread(&self) -> InterpResult<'tcx, ThreadId> {
|
|
|
|
let this = self.eval_context_ref();
|
2020-04-06 18:12:13 -05:00
|
|
|
Ok(this.machine.threads.get_active_thread_id())
|
2020-03-16 18:48:44 -05:00
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-03-16 18:48:44 -05:00
|
|
|
fn active_thread_stack(&self) -> &[Frame<'mir, 'tcx, Tag, FrameData<'tcx>>] {
|
|
|
|
let this = self.eval_context_ref();
|
|
|
|
this.machine.threads.active_thread_stack()
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-03-16 18:48:44 -05:00
|
|
|
fn active_thread_stack_mut(&mut self) -> &mut Vec<Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
|
|
|
|
let this = self.eval_context_mut();
|
|
|
|
this.machine.threads.active_thread_stack_mut()
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-04-06 18:12:13 -05:00
|
|
|
fn set_active_thread_name(&mut self, new_thread_name: Vec<u8>) -> InterpResult<'tcx, ()> {
|
|
|
|
let this = self.eval_context_mut();
|
|
|
|
Ok(this.machine.threads.set_thread_name(new_thread_name))
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-04-06 16:41:05 -05:00
|
|
|
fn get_all_thread_ids_with_states(&mut self) -> Vec<(ThreadId, ThreadState)> {
|
2020-03-16 18:48:44 -05:00
|
|
|
let this = self.eval_context_mut();
|
2020-04-06 16:41:05 -05:00
|
|
|
this.machine.threads.get_all_thread_ids_with_states()
|
2020-03-16 18:48:44 -05:00
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-04-07 22:20:41 -05:00
|
|
|
fn create_blockset(&mut self) -> InterpResult<'tcx, BlockSetId> {
|
|
|
|
let this = self.eval_context_mut();
|
|
|
|
Ok(this.machine.threads.create_blockset())
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-04-07 22:20:41 -05:00
|
|
|
fn block_active_thread(&mut self, set: BlockSetId) -> InterpResult<'tcx> {
|
|
|
|
let this = self.eval_context_mut();
|
|
|
|
Ok(this.machine.threads.block_active_thread(set))
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-04-07 22:20:41 -05:00
|
|
|
fn unblock_random_thread(&mut self, set: BlockSetId) -> InterpResult<'tcx, Option<ThreadId>> {
|
|
|
|
let this = self.eval_context_mut();
|
|
|
|
Ok(this.machine.threads.unblock_random_thread(set))
|
|
|
|
}
|
2020-04-15 23:25:12 -05:00
|
|
|
|
2020-03-16 18:48:44 -05:00
|
|
|
/// Decide which thread to run next.
|
|
|
|
///
|
|
|
|
/// Returns `false` if all threads terminated.
|
|
|
|
fn schedule(&mut self) -> InterpResult<'tcx, bool> {
|
|
|
|
let this = self.eval_context_mut();
|
2020-04-15 16:34:34 -05:00
|
|
|
this.machine.threads.schedule()
|
2020-03-16 18:48:44 -05:00
|
|
|
}
|
|
|
|
}
|