1 | use super::*; |
2 | |
3 | use indexmap::{self, IndexMap}; |
4 | |
5 | use std::convert::Infallible; |
6 | use std::fmt; |
7 | use std::marker::PhantomData; |
8 | use std::ops; |
9 | |
10 | /// Storage for streams |
11 | #[derive (Debug)] |
12 | pub(super) struct Store { |
13 | slab: slab::Slab<Stream>, |
14 | ids: IndexMap<StreamId, SlabIndex>, |
15 | } |
16 | |
17 | /// "Pointer" to an entry in the store |
18 | pub(super) struct Ptr<'a> { |
19 | key: Key, |
20 | store: &'a mut Store, |
21 | } |
22 | |
23 | /// References an entry in the store. |
24 | #[derive (Debug, Clone, Copy, PartialEq, Eq)] |
25 | pub(crate) struct Key { |
26 | index: SlabIndex, |
27 | /// Keep the stream ID in the key as an ABA guard, since slab indices |
28 | /// could be re-used with a new stream. |
29 | stream_id: StreamId, |
30 | } |
31 | |
32 | // We can never have more than `StreamId::MAX` streams in the store, |
33 | // so we can save a smaller index (u32 vs usize). |
34 | #[derive (Debug, Clone, Copy, PartialEq, Eq)] |
35 | struct SlabIndex(u32); |
36 | |
37 | #[derive (Debug)] |
38 | pub(super) struct Queue<N> { |
39 | indices: Option<store::Indices>, |
40 | _p: PhantomData<N>, |
41 | } |
42 | |
43 | pub(super) trait Next { |
44 | fn next(stream: &Stream) -> Option<Key>; |
45 | |
46 | fn set_next(stream: &mut Stream, key: Option<Key>); |
47 | |
48 | fn take_next(stream: &mut Stream) -> Option<Key>; |
49 | |
50 | fn is_queued(stream: &Stream) -> bool; |
51 | |
52 | fn set_queued(stream: &mut Stream, val: bool); |
53 | } |
54 | |
55 | /// A linked list |
56 | #[derive (Debug, Clone, Copy)] |
57 | struct Indices { |
58 | pub head: Key, |
59 | pub tail: Key, |
60 | } |
61 | |
62 | pub(super) enum Entry<'a> { |
63 | Occupied(OccupiedEntry<'a>), |
64 | Vacant(VacantEntry<'a>), |
65 | } |
66 | |
67 | pub(super) struct OccupiedEntry<'a> { |
68 | ids: indexmap::map::OccupiedEntry<'a, StreamId, SlabIndex>, |
69 | } |
70 | |
71 | pub(super) struct VacantEntry<'a> { |
72 | ids: indexmap::map::VacantEntry<'a, StreamId, SlabIndex>, |
73 | slab: &'a mut slab::Slab<Stream>, |
74 | } |
75 | |
76 | pub(super) trait Resolve { |
77 | fn resolve(&mut self, key: Key) -> Ptr; |
78 | } |
79 | |
80 | // ===== impl Store ===== |
81 | |
82 | impl Store { |
83 | pub fn new() -> Self { |
84 | Store { |
85 | slab: slab::Slab::new(), |
86 | ids: IndexMap::new(), |
87 | } |
88 | } |
89 | |
90 | pub fn find_mut(&mut self, id: &StreamId) -> Option<Ptr> { |
91 | let index = match self.ids.get(id) { |
92 | Some(key) => *key, |
93 | None => return None, |
94 | }; |
95 | |
96 | Some(Ptr { |
97 | key: Key { |
98 | index, |
99 | stream_id: *id, |
100 | }, |
101 | store: self, |
102 | }) |
103 | } |
104 | |
105 | pub fn insert(&mut self, id: StreamId, val: Stream) -> Ptr { |
106 | let index = SlabIndex(self.slab.insert(val) as u32); |
107 | assert!(self.ids.insert(id, index).is_none()); |
108 | |
109 | Ptr { |
110 | key: Key { |
111 | index, |
112 | stream_id: id, |
113 | }, |
114 | store: self, |
115 | } |
116 | } |
117 | |
118 | pub fn find_entry(&mut self, id: StreamId) -> Entry { |
119 | use self::indexmap::map::Entry::*; |
120 | |
121 | match self.ids.entry(id) { |
122 | Occupied(e) => Entry::Occupied(OccupiedEntry { ids: e }), |
123 | Vacant(e) => Entry::Vacant(VacantEntry { |
124 | ids: e, |
125 | slab: &mut self.slab, |
126 | }), |
127 | } |
128 | } |
129 | |
130 | pub(crate) fn for_each<F>(&mut self, mut f: F) |
131 | where |
132 | F: FnMut(Ptr), |
133 | { |
134 | match self.try_for_each(|ptr| { |
135 | f(ptr); |
136 | Ok::<_, Infallible>(()) |
137 | }) { |
138 | Ok(()) => (), |
139 | Err(infallible) => match infallible {}, |
140 | } |
141 | } |
142 | |
143 | pub fn try_for_each<F, E>(&mut self, mut f: F) -> Result<(), E> |
144 | where |
145 | F: FnMut(Ptr) -> Result<(), E>, |
146 | { |
147 | let mut len = self.ids.len(); |
148 | let mut i = 0; |
149 | |
150 | while i < len { |
151 | // Get the key by index, this makes the borrow checker happy |
152 | let (stream_id, index) = { |
153 | let entry = self.ids.get_index(i).unwrap(); |
154 | (*entry.0, *entry.1) |
155 | }; |
156 | |
157 | f(Ptr { |
158 | key: Key { index, stream_id }, |
159 | store: self, |
160 | })?; |
161 | |
162 | // TODO: This logic probably could be better... |
163 | let new_len = self.ids.len(); |
164 | |
165 | if new_len < len { |
166 | debug_assert!(new_len == len - 1); |
167 | len -= 1; |
168 | } else { |
169 | i += 1; |
170 | } |
171 | } |
172 | |
173 | Ok(()) |
174 | } |
175 | } |
176 | |
177 | impl Resolve for Store { |
178 | fn resolve(&mut self, key: Key) -> Ptr { |
179 | Ptr { key, store: self } |
180 | } |
181 | } |
182 | |
183 | impl ops::Index<Key> for Store { |
184 | type Output = Stream; |
185 | |
186 | fn index(&self, key: Key) -> &Self::Output { |
187 | self.slab |
188 | .get(key:key.index.0 as usize) |
189 | .filter(|s: &&Stream| s.id == key.stream_id) |
190 | .unwrap_or_else(|| { |
191 | panic!("dangling store key for stream_id= {:?}" , key.stream_id); |
192 | }) |
193 | } |
194 | } |
195 | |
196 | impl ops::IndexMut<Key> for Store { |
197 | fn index_mut(&mut self, key: Key) -> &mut Self::Output { |
198 | self.slab |
199 | .get_mut(key:key.index.0 as usize) |
200 | .filter(|s: &&mut Stream| s.id == key.stream_id) |
201 | .unwrap_or_else(|| { |
202 | panic!("dangling store key for stream_id= {:?}" , key.stream_id); |
203 | }) |
204 | } |
205 | } |
206 | |
207 | impl Store { |
208 | #[cfg (feature = "unstable" )] |
209 | pub fn num_active_streams(&self) -> usize { |
210 | self.ids.len() |
211 | } |
212 | |
213 | #[cfg (feature = "unstable" )] |
214 | pub fn num_wired_streams(&self) -> usize { |
215 | self.slab.len() |
216 | } |
217 | } |
218 | |
219 | // While running h2 unit/integration tests, enable this debug assertion. |
220 | // |
221 | // In practice, we don't need to ensure this. But the integration tests |
222 | // help to make sure we've cleaned up in cases where we could (like, the |
223 | // runtime isn't suddenly dropping the task for unknown reasons). |
224 | #[cfg (feature = "unstable" )] |
225 | impl Drop for Store { |
226 | fn drop(&mut self) { |
227 | use std::thread; |
228 | |
229 | if !thread::panicking() { |
230 | debug_assert!(self.slab.is_empty()); |
231 | } |
232 | } |
233 | } |
234 | |
235 | // ===== impl Queue ===== |
236 | |
237 | impl<N> Queue<N> |
238 | where |
239 | N: Next, |
240 | { |
241 | pub fn new() -> Self { |
242 | Queue { |
243 | indices: None, |
244 | _p: PhantomData, |
245 | } |
246 | } |
247 | |
248 | pub fn take(&mut self) -> Self { |
249 | Queue { |
250 | indices: self.indices.take(), |
251 | _p: PhantomData, |
252 | } |
253 | } |
254 | |
255 | /// Queue the stream. |
256 | /// |
257 | /// If the stream is already contained by the list, return `false`. |
258 | pub fn push(&mut self, stream: &mut store::Ptr) -> bool { |
259 | tracing::trace!("Queue::push_back" ); |
260 | |
261 | if N::is_queued(stream) { |
262 | tracing::trace!(" -> already queued" ); |
263 | return false; |
264 | } |
265 | |
266 | N::set_queued(stream, true); |
267 | |
268 | // The next pointer shouldn't be set |
269 | debug_assert!(N::next(stream).is_none()); |
270 | |
271 | // Queue the stream |
272 | match self.indices { |
273 | Some(ref mut idxs) => { |
274 | tracing::trace!(" -> existing entries" ); |
275 | |
276 | // Update the current tail node to point to `stream` |
277 | let key = stream.key(); |
278 | N::set_next(&mut stream.resolve(idxs.tail), Some(key)); |
279 | |
280 | // Update the tail pointer |
281 | idxs.tail = stream.key(); |
282 | } |
283 | None => { |
284 | tracing::trace!(" -> first entry" ); |
285 | self.indices = Some(store::Indices { |
286 | head: stream.key(), |
287 | tail: stream.key(), |
288 | }); |
289 | } |
290 | } |
291 | |
292 | true |
293 | } |
294 | |
295 | /// Queue the stream |
296 | /// |
297 | /// If the stream is already contained by the list, return `false`. |
298 | pub fn push_front(&mut self, stream: &mut store::Ptr) -> bool { |
299 | tracing::trace!("Queue::push_front" ); |
300 | |
301 | if N::is_queued(stream) { |
302 | tracing::trace!(" -> already queued" ); |
303 | return false; |
304 | } |
305 | |
306 | N::set_queued(stream, true); |
307 | |
308 | // The next pointer shouldn't be set |
309 | debug_assert!(N::next(stream).is_none()); |
310 | |
311 | // Queue the stream |
312 | match self.indices { |
313 | Some(ref mut idxs) => { |
314 | tracing::trace!(" -> existing entries" ); |
315 | |
316 | // Update the provided stream to point to the head node |
317 | let head_key = stream.resolve(idxs.head).key(); |
318 | N::set_next(stream, Some(head_key)); |
319 | |
320 | // Update the head pointer |
321 | idxs.head = stream.key(); |
322 | } |
323 | None => { |
324 | tracing::trace!(" -> first entry" ); |
325 | self.indices = Some(store::Indices { |
326 | head: stream.key(), |
327 | tail: stream.key(), |
328 | }); |
329 | } |
330 | } |
331 | |
332 | true |
333 | } |
334 | |
335 | pub fn pop<'a, R>(&mut self, store: &'a mut R) -> Option<store::Ptr<'a>> |
336 | where |
337 | R: Resolve, |
338 | { |
339 | if let Some(mut idxs) = self.indices { |
340 | let mut stream = store.resolve(idxs.head); |
341 | |
342 | if idxs.head == idxs.tail { |
343 | assert!(N::next(&stream).is_none()); |
344 | self.indices = None; |
345 | } else { |
346 | idxs.head = N::take_next(&mut stream).unwrap(); |
347 | self.indices = Some(idxs); |
348 | } |
349 | |
350 | debug_assert!(N::is_queued(&stream)); |
351 | N::set_queued(&mut stream, false); |
352 | |
353 | return Some(stream); |
354 | } |
355 | |
356 | None |
357 | } |
358 | |
359 | pub fn is_empty(&self) -> bool { |
360 | self.indices.is_none() |
361 | } |
362 | |
363 | pub fn pop_if<'a, R, F>(&mut self, store: &'a mut R, f: F) -> Option<store::Ptr<'a>> |
364 | where |
365 | R: Resolve, |
366 | F: Fn(&Stream) -> bool, |
367 | { |
368 | if let Some(idxs) = self.indices { |
369 | let should_pop = f(&store.resolve(idxs.head)); |
370 | if should_pop { |
371 | return self.pop(store); |
372 | } |
373 | } |
374 | |
375 | None |
376 | } |
377 | } |
378 | |
379 | // ===== impl Ptr ===== |
380 | |
381 | impl<'a> Ptr<'a> { |
382 | /// Returns the Key associated with the stream |
383 | pub fn key(&self) -> Key { |
384 | self.key |
385 | } |
386 | |
387 | pub fn store_mut(&mut self) -> &mut Store { |
388 | self.store |
389 | } |
390 | |
391 | /// Remove the stream from the store |
392 | pub fn remove(self) -> StreamId { |
393 | // The stream must have been unlinked before this point |
394 | debug_assert!(!self.store.ids.contains_key(&self.key.stream_id)); |
395 | |
396 | // Remove the stream state |
397 | let stream = self.store.slab.remove(self.key.index.0 as usize); |
398 | assert_eq!(stream.id, self.key.stream_id); |
399 | stream.id |
400 | } |
401 | |
402 | /// Remove the StreamId -> stream state association. |
403 | /// |
404 | /// This will effectively remove the stream as far as the H2 protocol is |
405 | /// concerned. |
406 | pub fn unlink(&mut self) { |
407 | let id = self.key.stream_id; |
408 | self.store.ids.swap_remove(&id); |
409 | } |
410 | } |
411 | |
412 | impl<'a> Resolve for Ptr<'a> { |
413 | fn resolve(&mut self, key: Key) -> Ptr { |
414 | Ptr { |
415 | key, |
416 | store: &mut *self.store, |
417 | } |
418 | } |
419 | } |
420 | |
421 | impl<'a> ops::Deref for Ptr<'a> { |
422 | type Target = Stream; |
423 | |
424 | fn deref(&self) -> &Stream { |
425 | &self.store[self.key] |
426 | } |
427 | } |
428 | |
429 | impl<'a> ops::DerefMut for Ptr<'a> { |
430 | fn deref_mut(&mut self) -> &mut Stream { |
431 | &mut self.store[self.key] |
432 | } |
433 | } |
434 | |
435 | impl<'a> fmt::Debug for Ptr<'a> { |
436 | fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { |
437 | (**self).fmt(fmt) |
438 | } |
439 | } |
440 | |
441 | // ===== impl OccupiedEntry ===== |
442 | |
443 | impl<'a> OccupiedEntry<'a> { |
444 | pub fn key(&self) -> Key { |
445 | let stream_id: StreamId = *self.ids.key(); |
446 | let index: SlabIndex = *self.ids.get(); |
447 | Key { index, stream_id } |
448 | } |
449 | } |
450 | |
451 | // ===== impl VacantEntry ===== |
452 | |
453 | impl<'a> VacantEntry<'a> { |
454 | pub fn insert(self, value: Stream) -> Key { |
455 | // Insert the value in the slab |
456 | let stream_id: StreamId = value.id; |
457 | let index: SlabIndex = SlabIndex(self.slab.insert(val:value) as u32); |
458 | |
459 | // Insert the handle in the ID map |
460 | self.ids.insert(index); |
461 | |
462 | Key { index, stream_id } |
463 | } |
464 | } |
465 | |