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use std::cell::{Cell, UnsafeCell, RefCell};
use std::mem::ManuallyDrop;
use std::fmt::{self, Debug, Formatter};
use std::marker::PhantomData;
use slog::{Logger, FnValue, trace, o};
use crate::{CollectorRef, ShadowStack, ContextState};
use crate::collector::RawCollectorImpl;
pub struct CollectionManager<C: RawCollectorImpl> {
_marker: PhantomData<CollectorRef<C>>,
state: RefCell<CollectorState>,
collecting: Cell<bool>,
has_existing_context: Cell<bool>,
}
impl<C: RawCollectorImpl> super::sealed::Sealed for CollectionManager<C> {}
unsafe impl<C> super::CollectionManager<C> for CollectionManager<C>
where C: RawCollectorImpl<Manager=Self, RawContext=RawContext<C>> {
type Context = RawContext<C>;
fn new() -> Self {
assert!(!C::SYNC);
CollectionManager {
_marker: PhantomData,
state: RefCell::new(CollectorState::new()),
collecting: Cell::new(false),
has_existing_context: Cell::new(false)
}
}
#[inline]
fn is_collecting(&self) -> bool {
self.collecting.get()
}
#[inline]
fn should_trigger_collection(&self) -> bool {
false
}
unsafe fn freeze_context(&self, context: &RawContext<C>) {
debug_assert_eq!(context.state.get(), ContextState::Active);
unimplemented!("Freezing single-threaded contexts")
}
unsafe fn unfreeze_context(&self, _context: &RawContext<C>) {
unreachable!("Can't unfreeze a single-threaded context")
}
fn prevent_collection<R>(_collector: &C, _func: impl FnOnce() -> R) -> R {
unimplemented!("Preventing collections for non-sync collectors")
}
#[inline]
unsafe fn free_context(_collector: &C, _context: *mut Self::Context) {
assert!(!C::SYNC);
}
}
pub struct RawContext<C: RawCollectorImpl> {
pub(crate) collector: CollectorRef<C>,
pub(super) shadow_stack: UnsafeCell<ShadowStack<C>>,
pub(super) state: Cell<ContextState>,
logger: Logger
}
impl<C: RawCollectorImpl> Debug for RawContext<C> {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.debug_struct("RawContext")
.field(
"collector",
&format_args!("{:p}", &self.collector)
)
.field(
"shadow_stacks",
unsafe { &*self.shadow_stack.get() }
)
.field("state", &self.state.get())
.finish()
}
}
impl<C: RawCollectorImpl> super::sealed::Sealed for RawContext<C> {}
unsafe impl<C> super::RawContext<C> for RawContext<C>
where C: RawCollectorImpl<RawContext=Self, Manager=CollectionManager<C>> {
unsafe fn register_new(collector: &CollectorRef<C>) -> ManuallyDrop<Box<Self>> {
assert!(!C::SYNC);
assert!(
!collector.as_raw().manager().has_existing_context
.replace(true),
"Already created a context for the collector!"
);
let collector = collector.clone_internal();
let logger = collector.as_raw().logger().new(o!());
let context = ManuallyDrop::new(Box::new(RawContext {
logger: logger.clone(), collector,
shadow_stack: UnsafeCell::new(ShadowStack {
last: std::ptr::null_mut(),
}),
state: Cell::new(ContextState::Active)
}));
trace!(
logger, "Initializing context";
"ptr" => format_args!("{:p}", &**context),
);
context
}
#[cold]
#[inline(never)]
unsafe fn trigger_safepoint(&self) {
assert!(!self.collector.as_raw().manager().collecting.get());
self.collector.as_raw().manager().collecting.set(true);
let collection_id = self.collector.as_raw().manager().state.borrow_mut()
.next_pending_id();
trace!(
self.logger,
"Creating collector";
"id" => collection_id,
"ctx_ptr" => format_args!("{:?}", self)
);
let shadow_stack = &*self.shadow_stack.get();
let ptr = self as *const RawContext<C> as *mut RawContext<C>;
assert_eq!(self.state.replace(ContextState::SafePoint {
collection_id,
}), ContextState::Active);
trace!(
self.logger, "Beginning collection";
"ptr" => ?ptr,
"shadow_stack" => FnValue(|_| format!("{:?}", shadow_stack.as_vec())),
"state" => ?self.state,
"collection_id" => collection_id,
"original_size" => %self.collector.as_raw().allocated_size(),
);
self.collector.as_raw().perform_raw_collection(&[ptr]);
assert_eq!(
self.state.replace(ContextState::Active),
ContextState::SafePoint { collection_id }
);
assert!(self.collector.as_raw().manager().collecting.replace(false));
}
#[inline]
fn shadow_stack_ptr(&self) -> *mut ShadowStack<C> {
self.shadow_stack.get()
}
#[inline]
unsafe fn collector(&self) -> &C {
self.collector.as_raw()
}
#[inline]
fn state(&self) -> ContextState {
self.state.get()
}
}
pub struct CollectorState {
next_pending_id: u64
}
impl CollectorState {
pub fn new() -> Self {
CollectorState {
next_pending_id: 0
}
}
fn next_pending_id(&mut self) -> u64 {
let id = self.next_pending_id;
self.next_pending_id = id.checked_add(1)
.expect("Overflow");
id
}
}