1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
//! # Rust Compiler Self-Profiling
//!
//! This module implements the basic framework for the compiler's self-
//! profiling support. It provides the `SelfProfiler` type which enables
//! recording "events". An event is something that starts and ends at a given
//! point in time and has an ID and a kind attached to it. This allows for
//! tracing the compiler's activity.
//!
//! Internally this module uses the custom tailored [measureme][mm] crate for
//! efficiently recording events to disk in a compact format that can be
//! post-processed and analyzed by the suite of tools in the `measureme`
//! project. The highest priority for the tracing framework is on incurring as
//! little overhead as possible.
//!
//!
//! ## Event Overview
//!
//! Events have a few properties:
//!
//! - The `event_kind` designates the broad category of an event (e.g. does it
//!   correspond to the execution of a query provider or to loading something
//!   from the incr. comp. on-disk cache, etc).
//! - The `event_id` designates the query invocation or function call it
//!   corresponds to, possibly including the query key or function arguments.
//! - Each event stores the ID of the thread it was recorded on.
//! - The timestamp stores beginning and end of the event, or the single point
//!   in time it occurred at for "instant" events.
//!
//!
//! ## Event Filtering
//!
//! Event generation can be filtered by event kind. Recording all possible
//! events generates a lot of data, much of which is not needed for most kinds
//! of analysis. So, in order to keep overhead as low as possible for a given
//! use case, the `SelfProfiler` will only record the kinds of events that
//! pass the filter specified as a command line argument to the compiler.
//!
//!
//! ## `event_id` Assignment
//!
//! As far as `measureme` is concerned, `event_id`s are just strings. However,
//! it would incur too much overhead to generate and persist each `event_id`
//! string at the point where the event is recorded. In order to make this more
//! efficient `measureme` has two features:
//!
//! - Strings can share their content, so that re-occurring parts don't have to
//!   be copied over and over again. One allocates a string in `measureme` and
//!   gets back a `StringId`. This `StringId` is then used to refer to that
//!   string. `measureme` strings are actually DAGs of string components so that
//!   arbitrary sharing of substrings can be done efficiently. This is useful
//!   because `event_id`s contain lots of redundant text like query names or
//!   def-path components.
//!
//! - `StringId`s can be "virtual" which means that the client picks a numeric
//!   ID according to some application-specific scheme and can later make that
//!   ID be mapped to an actual string. This is used to cheaply generate
//!   `event_id`s while the events actually occur, causing little timing
//!   distortion, and then later map those `StringId`s, in bulk, to actual
//!   `event_id` strings. This way the largest part of the tracing overhead is
//!   localized to one contiguous chunk of time.
//!
//! How are these `event_id`s generated in the compiler? For things that occur
//! infrequently (e.g. "generic activities"), we just allocate the string the
//! first time it is used and then keep the `StringId` in a hash table. This
//! is implemented in `SelfProfiler::get_or_alloc_cached_string()`.
//!
//! For queries it gets more interesting: First we need a unique numeric ID for
//! each query invocation (the `QueryInvocationId`). This ID is used as the
//! virtual `StringId` we use as `event_id` for a given event. This ID has to
//! be available both when the query is executed and later, together with the
//! query key, when we allocate the actual `event_id` strings in bulk.
//!
//! We could make the compiler generate and keep track of such an ID for each
//! query invocation but luckily we already have something that fits all the
//! the requirements: the query's `DepNodeIndex`. So we use the numeric value
//! of the `DepNodeIndex` as `event_id` when recording the event and then,
//! just before the query context is dropped, we walk the entire query cache
//! (which stores the `DepNodeIndex` along with the query key for each
//! invocation) and allocate the corresponding strings together with a mapping
//! for `DepNodeIndex as StringId`.
//!
//! [mm]: https://github.com/rust-lang/measureme/

use crate::fx::FxHashMap;
use crate::outline;

use std::borrow::Borrow;
use std::collections::hash_map::Entry;
use std::error::Error;
use std::fmt::Display;
use std::fs;
use std::intrinsics::unlikely;
use std::path::Path;
use std::process;
use std::sync::Arc;
use std::time::{Duration, Instant};

pub use measureme::EventId;
use measureme::{EventIdBuilder, Profiler, SerializableString, StringId};
use parking_lot::RwLock;
use smallvec::SmallVec;

bitflags::bitflags! {
    #[derive(Clone, Copy)]
    struct EventFilter: u16 {
        const GENERIC_ACTIVITIES  = 1 << 0;
        const QUERY_PROVIDERS     = 1 << 1;
        const QUERY_CACHE_HITS    = 1 << 2;
        const QUERY_BLOCKED       = 1 << 3;
        const INCR_CACHE_LOADS    = 1 << 4;

        const QUERY_KEYS          = 1 << 5;
        const FUNCTION_ARGS       = 1 << 6;
        const LLVM                = 1 << 7;
        const INCR_RESULT_HASHING = 1 << 8;
        const ARTIFACT_SIZES = 1 << 9;

        const DEFAULT = Self::GENERIC_ACTIVITIES.bits() |
                        Self::QUERY_PROVIDERS.bits() |
                        Self::QUERY_BLOCKED.bits() |
                        Self::INCR_CACHE_LOADS.bits() |
                        Self::INCR_RESULT_HASHING.bits() |
                        Self::ARTIFACT_SIZES.bits();

        const ARGS = Self::QUERY_KEYS.bits() | Self::FUNCTION_ARGS.bits();
    }
}

// keep this in sync with the `-Z self-profile-events` help message in rustc_session/options.rs
const EVENT_FILTERS_BY_NAME: &[(&str, EventFilter)] = &[
    ("none", EventFilter::empty()),
    ("all", EventFilter::all()),
    ("default", EventFilter::DEFAULT),
    ("generic-activity", EventFilter::GENERIC_ACTIVITIES),
    ("query-provider", EventFilter::QUERY_PROVIDERS),
    ("query-cache-hit", EventFilter::QUERY_CACHE_HITS),
    ("query-blocked", EventFilter::QUERY_BLOCKED),
    ("incr-cache-load", EventFilter::INCR_CACHE_LOADS),
    ("query-keys", EventFilter::QUERY_KEYS),
    ("function-args", EventFilter::FUNCTION_ARGS),
    ("args", EventFilter::ARGS),
    ("llvm", EventFilter::LLVM),
    ("incr-result-hashing", EventFilter::INCR_RESULT_HASHING),
    ("artifact-sizes", EventFilter::ARTIFACT_SIZES),
];

/// Something that uniquely identifies a query invocation.
pub struct QueryInvocationId(pub u32);

/// Which format to use for `-Z time-passes`
#[derive(Clone, Copy, PartialEq, Hash, Debug)]
pub enum TimePassesFormat {
    /// Emit human readable text
    Text,
    /// Emit structured JSON
    Json,
}

/// A reference to the SelfProfiler. It can be cloned and sent across thread
/// boundaries at will.
#[derive(Clone)]
pub struct SelfProfilerRef {
    // This field is `None` if self-profiling is disabled for the current
    // compilation session.
    profiler: Option<Arc<SelfProfiler>>,

    // We store the filter mask directly in the reference because that doesn't
    // cost anything and allows for filtering with checking if the profiler is
    // actually enabled.
    event_filter_mask: EventFilter,

    // Print verbose generic activities to stderr.
    print_verbose_generic_activities: Option<TimePassesFormat>,
}

impl SelfProfilerRef {
    pub fn new(
        profiler: Option<Arc<SelfProfiler>>,
        print_verbose_generic_activities: Option<TimePassesFormat>,
    ) -> SelfProfilerRef {
        // If there is no SelfProfiler then the filter mask is set to NONE,
        // ensuring that nothing ever tries to actually access it.
        let event_filter_mask =
            profiler.as_ref().map_or(EventFilter::empty(), |p| p.event_filter_mask);

        SelfProfilerRef { profiler, event_filter_mask, print_verbose_generic_activities }
    }

    /// This shim makes sure that calls only get executed if the filter mask
    /// lets them pass. It also contains some trickery to make sure that
    /// code is optimized for non-profiling compilation sessions, i.e. anything
    /// past the filter check is never inlined so it doesn't clutter the fast
    /// path.
    #[inline(always)]
    fn exec<F>(&self, event_filter: EventFilter, f: F) -> TimingGuard<'_>
    where
        F: for<'a> FnOnce(&'a SelfProfiler) -> TimingGuard<'a>,
    {
        #[inline(never)]
        #[cold]
        fn cold_call<F>(profiler_ref: &SelfProfilerRef, f: F) -> TimingGuard<'_>
        where
            F: for<'a> FnOnce(&'a SelfProfiler) -> TimingGuard<'a>,
        {
            let profiler = profiler_ref.profiler.as_ref().unwrap();
            f(profiler)
        }

        if self.event_filter_mask.contains(event_filter) {
            cold_call(self, f)
        } else {
            TimingGuard::none()
        }
    }

    /// Start profiling a verbose generic activity. Profiling continues until the
    /// VerboseTimingGuard returned from this call is dropped. In addition to recording
    /// a measureme event, "verbose" generic activities also print a timing entry to
    /// stderr if the compiler is invoked with -Ztime-passes.
    pub fn verbose_generic_activity(&self, event_label: &'static str) -> VerboseTimingGuard<'_> {
        let message_and_format =
            self.print_verbose_generic_activities.map(|format| (event_label.to_owned(), format));

        VerboseTimingGuard::start(message_and_format, self.generic_activity(event_label))
    }

    /// Like `verbose_generic_activity`, but with an extra arg.
    pub fn verbose_generic_activity_with_arg<A>(
        &self,
        event_label: &'static str,
        event_arg: A,
    ) -> VerboseTimingGuard<'_>
    where
        A: Borrow<str> + Into<String>,
    {
        let message_and_format = self
            .print_verbose_generic_activities
            .map(|format| (format!("{}({})", event_label, event_arg.borrow()), format));

        VerboseTimingGuard::start(
            message_and_format,
            self.generic_activity_with_arg(event_label, event_arg),
        )
    }

    /// Start profiling a generic activity. Profiling continues until the
    /// TimingGuard returned from this call is dropped.
    #[inline(always)]
    pub fn generic_activity(&self, event_label: &'static str) -> TimingGuard<'_> {
        self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
            let event_label = profiler.get_or_alloc_cached_string(event_label);
            let event_id = EventId::from_label(event_label);
            TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
        })
    }

    /// Start profiling with some event filter for a given event. Profiling continues until the
    /// TimingGuard returned from this call is dropped.
    #[inline(always)]
    pub fn generic_activity_with_event_id(&self, event_id: EventId) -> TimingGuard<'_> {
        self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
            TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
        })
    }

    /// Start profiling a generic activity. Profiling continues until the
    /// TimingGuard returned from this call is dropped.
    #[inline(always)]
    pub fn generic_activity_with_arg<A>(
        &self,
        event_label: &'static str,
        event_arg: A,
    ) -> TimingGuard<'_>
    where
        A: Borrow<str> + Into<String>,
    {
        self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
            let builder = EventIdBuilder::new(&profiler.profiler);
            let event_label = profiler.get_or_alloc_cached_string(event_label);
            let event_id = if profiler.event_filter_mask.contains(EventFilter::FUNCTION_ARGS) {
                let event_arg = profiler.get_or_alloc_cached_string(event_arg);
                builder.from_label_and_arg(event_label, event_arg)
            } else {
                builder.from_label(event_label)
            };
            TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
        })
    }

    /// Start profiling a generic activity, allowing costly arguments to be recorded. Profiling
    /// continues until the `TimingGuard` returned from this call is dropped.
    ///
    /// If the arguments to a generic activity are cheap to create, use `generic_activity_with_arg`
    /// or `generic_activity_with_args` for their simpler API. However, if they are costly or
    /// require allocation in sufficiently hot contexts, then this allows for a closure to be called
    /// only when arguments were asked to be recorded via `-Z self-profile-events=args`.
    ///
    /// In this case, the closure will be passed a `&mut EventArgRecorder`, to help with recording
    /// one or many arguments within the generic activity being profiled, by calling its
    /// `record_arg` method for example.
    ///
    /// This `EventArgRecorder` may implement more specific traits from other rustc crates, e.g. for
    /// richer handling of rustc-specific argument types, while keeping this single entry-point API
    /// for recording arguments.
    ///
    /// Note: recording at least one argument is *required* for the self-profiler to create the
    /// `TimingGuard`. A panic will be triggered if that doesn't happen. This function exists
    /// explicitly to record arguments, so it fails loudly when there are none to record.
    ///
    #[inline(always)]
    pub fn generic_activity_with_arg_recorder<F>(
        &self,
        event_label: &'static str,
        mut f: F,
    ) -> TimingGuard<'_>
    where
        F: FnMut(&mut EventArgRecorder<'_>),
    {
        // Ensure this event will only be recorded when self-profiling is turned on.
        self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
            let builder = EventIdBuilder::new(&profiler.profiler);
            let event_label = profiler.get_or_alloc_cached_string(event_label);

            // Ensure the closure to create event arguments will only be called when argument
            // recording is turned on.
            let event_id = if profiler.event_filter_mask.contains(EventFilter::FUNCTION_ARGS) {
                // Set up the builder and call the user-provided closure to record potentially
                // costly event arguments.
                let mut recorder = EventArgRecorder { profiler, args: SmallVec::new() };
                f(&mut recorder);

                // It is expected that the closure will record at least one argument. If that
                // doesn't happen, it's a bug: we've been explicitly called in order to record
                // arguments, so we fail loudly when there are none to record.
                if recorder.args.is_empty() {
                    panic!(
                        "The closure passed to `generic_activity_with_arg_recorder` needs to \
                         record at least one argument"
                    );
                }

                builder.from_label_and_args(event_label, &recorder.args)
            } else {
                builder.from_label(event_label)
            };
            TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
        })
    }

    /// Record the size of an artifact that the compiler produces
    ///
    /// `artifact_kind` is the class of artifact (e.g., query_cache, object_file, etc.)
    /// `artifact_name` is an identifier to the specific artifact being stored (usually a filename)
    #[inline(always)]
    pub fn artifact_size<A>(&self, artifact_kind: &str, artifact_name: A, size: u64)
    where
        A: Borrow<str> + Into<String>,
    {
        drop(self.exec(EventFilter::ARTIFACT_SIZES, |profiler| {
            let builder = EventIdBuilder::new(&profiler.profiler);
            let event_label = profiler.get_or_alloc_cached_string(artifact_kind);
            let event_arg = profiler.get_or_alloc_cached_string(artifact_name);
            let event_id = builder.from_label_and_arg(event_label, event_arg);
            let thread_id = get_thread_id();

            profiler.profiler.record_integer_event(
                profiler.artifact_size_event_kind,
                event_id,
                thread_id,
                size,
            );

            TimingGuard::none()
        }))
    }

    #[inline(always)]
    pub fn generic_activity_with_args(
        &self,
        event_label: &'static str,
        event_args: &[String],
    ) -> TimingGuard<'_> {
        self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
            let builder = EventIdBuilder::new(&profiler.profiler);
            let event_label = profiler.get_or_alloc_cached_string(event_label);
            let event_id = if profiler.event_filter_mask.contains(EventFilter::FUNCTION_ARGS) {
                let event_args: Vec<_> = event_args
                    .iter()
                    .map(|s| profiler.get_or_alloc_cached_string(&s[..]))
                    .collect();
                builder.from_label_and_args(event_label, &event_args)
            } else {
                builder.from_label(event_label)
            };
            TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
        })
    }

    /// Start profiling a query provider. Profiling continues until the
    /// TimingGuard returned from this call is dropped.
    #[inline(always)]
    pub fn query_provider(&self) -> TimingGuard<'_> {
        self.exec(EventFilter::QUERY_PROVIDERS, |profiler| {
            TimingGuard::start(profiler, profiler.query_event_kind, EventId::INVALID)
        })
    }

    /// Record a query in-memory cache hit.
    #[inline(always)]
    pub fn query_cache_hit(&self, query_invocation_id: QueryInvocationId) {
        #[inline(never)]
        #[cold]
        fn cold_call(profiler_ref: &SelfProfilerRef, query_invocation_id: QueryInvocationId) {
            profiler_ref.instant_query_event(
                |profiler| profiler.query_cache_hit_event_kind,
                query_invocation_id,
            );
        }

        if unlikely(self.event_filter_mask.contains(EventFilter::QUERY_CACHE_HITS)) {
            cold_call(self, query_invocation_id);
        }
    }

    /// Start profiling a query being blocked on a concurrent execution.
    /// Profiling continues until the TimingGuard returned from this call is
    /// dropped.
    #[inline(always)]
    pub fn query_blocked(&self) -> TimingGuard<'_> {
        self.exec(EventFilter::QUERY_BLOCKED, |profiler| {
            TimingGuard::start(profiler, profiler.query_blocked_event_kind, EventId::INVALID)
        })
    }

    /// Start profiling how long it takes to load a query result from the
    /// incremental compilation on-disk cache. Profiling continues until the
    /// TimingGuard returned from this call is dropped.
    #[inline(always)]
    pub fn incr_cache_loading(&self) -> TimingGuard<'_> {
        self.exec(EventFilter::INCR_CACHE_LOADS, |profiler| {
            TimingGuard::start(
                profiler,
                profiler.incremental_load_result_event_kind,
                EventId::INVALID,
            )
        })
    }

    /// Start profiling how long it takes to hash query results for incremental compilation.
    /// Profiling continues until the TimingGuard returned from this call is dropped.
    #[inline(always)]
    pub fn incr_result_hashing(&self) -> TimingGuard<'_> {
        self.exec(EventFilter::INCR_RESULT_HASHING, |profiler| {
            TimingGuard::start(
                profiler,
                profiler.incremental_result_hashing_event_kind,
                EventId::INVALID,
            )
        })
    }

    #[inline(always)]
    fn instant_query_event(
        &self,
        event_kind: fn(&SelfProfiler) -> StringId,
        query_invocation_id: QueryInvocationId,
    ) {
        let event_id = StringId::new_virtual(query_invocation_id.0);
        let thread_id = get_thread_id();
        let profiler = self.profiler.as_ref().unwrap();
        profiler.profiler.record_instant_event(
            event_kind(profiler),
            EventId::from_virtual(event_id),
            thread_id,
        );
    }

    pub fn with_profiler(&self, f: impl FnOnce(&SelfProfiler)) {
        if let Some(profiler) = &self.profiler {
            f(profiler)
        }
    }

    /// Gets a `StringId` for the given string. This method makes sure that
    /// any strings going through it will only be allocated once in the
    /// profiling data.
    /// Returns `None` if the self-profiling is not enabled.
    pub fn get_or_alloc_cached_string(&self, s: &str) -> Option<StringId> {
        self.profiler.as_ref().map(|p| p.get_or_alloc_cached_string(s))
    }

    #[inline]
    pub fn enabled(&self) -> bool {
        self.profiler.is_some()
    }

    #[inline]
    pub fn llvm_recording_enabled(&self) -> bool {
        self.event_filter_mask.contains(EventFilter::LLVM)
    }
    #[inline]
    pub fn get_self_profiler(&self) -> Option<Arc<SelfProfiler>> {
        self.profiler.clone()
    }
}

/// A helper for recording costly arguments to self-profiling events. Used with
/// `SelfProfilerRef::generic_activity_with_arg_recorder`.
pub struct EventArgRecorder<'p> {
    /// The `SelfProfiler` used to intern the event arguments that users will ask to record.
    profiler: &'p SelfProfiler,

    /// The interned event arguments to be recorded in the generic activity event.
    ///
    /// The most common case, when actually recording event arguments, is to have one argument. Then
    /// followed by recording two, in a couple places.
    args: SmallVec<[StringId; 2]>,
}

impl EventArgRecorder<'_> {
    /// Records a single argument within the current generic activity being profiled.
    ///
    /// Note: when self-profiling with costly event arguments, at least one argument
    /// needs to be recorded. A panic will be triggered if that doesn't happen.
    pub fn record_arg<A>(&mut self, event_arg: A)
    where
        A: Borrow<str> + Into<String>,
    {
        let event_arg = self.profiler.get_or_alloc_cached_string(event_arg);
        self.args.push(event_arg);
    }
}

pub struct SelfProfiler {
    profiler: Profiler,
    event_filter_mask: EventFilter,

    string_cache: RwLock<FxHashMap<String, StringId>>,

    query_event_kind: StringId,
    generic_activity_event_kind: StringId,
    incremental_load_result_event_kind: StringId,
    incremental_result_hashing_event_kind: StringId,
    query_blocked_event_kind: StringId,
    query_cache_hit_event_kind: StringId,
    artifact_size_event_kind: StringId,
}

impl SelfProfiler {
    pub fn new(
        output_directory: &Path,
        crate_name: Option<&str>,
        event_filters: Option<&[String]>,
        counter_name: &str,
    ) -> Result<SelfProfiler, Box<dyn Error + Send + Sync>> {
        fs::create_dir_all(output_directory)?;

        let crate_name = crate_name.unwrap_or("unknown-crate");
        // HACK(eddyb) we need to pad the PID, strange as it may seem, as its
        // length can behave as a source of entropy for heap addresses, when
        // ASLR is disabled and the heap is otherwise deterministic.
        let pid: u32 = process::id();
        let filename = format!("{crate_name}-{pid:07}.rustc_profile");
        let path = output_directory.join(&filename);
        let profiler =
            Profiler::with_counter(&path, measureme::counters::Counter::by_name(counter_name)?)?;

        let query_event_kind = profiler.alloc_string("Query");
        let generic_activity_event_kind = profiler.alloc_string("GenericActivity");
        let incremental_load_result_event_kind = profiler.alloc_string("IncrementalLoadResult");
        let incremental_result_hashing_event_kind =
            profiler.alloc_string("IncrementalResultHashing");
        let query_blocked_event_kind = profiler.alloc_string("QueryBlocked");
        let query_cache_hit_event_kind = profiler.alloc_string("QueryCacheHit");
        let artifact_size_event_kind = profiler.alloc_string("ArtifactSize");

        let mut event_filter_mask = EventFilter::empty();

        if let Some(event_filters) = event_filters {
            let mut unknown_events = vec![];
            for item in event_filters {
                if let Some(&(_, mask)) =
                    EVENT_FILTERS_BY_NAME.iter().find(|&(name, _)| name == item)
                {
                    event_filter_mask |= mask;
                } else {
                    unknown_events.push(item.clone());
                }
            }

            // Warn about any unknown event names
            if !unknown_events.is_empty() {
                unknown_events.sort();
                unknown_events.dedup();

                warn!(
                    "Unknown self-profiler events specified: {}. Available options are: {}.",
                    unknown_events.join(", "),
                    EVENT_FILTERS_BY_NAME
                        .iter()
                        .map(|&(name, _)| name.to_string())
                        .collect::<Vec<_>>()
                        .join(", ")
                );
            }
        } else {
            event_filter_mask = EventFilter::DEFAULT;
        }

        Ok(SelfProfiler {
            profiler,
            event_filter_mask,
            string_cache: RwLock::new(FxHashMap::default()),
            query_event_kind,
            generic_activity_event_kind,
            incremental_load_result_event_kind,
            incremental_result_hashing_event_kind,
            query_blocked_event_kind,
            query_cache_hit_event_kind,
            artifact_size_event_kind,
        })
    }

    /// Allocates a new string in the profiling data. Does not do any caching
    /// or deduplication.
    pub fn alloc_string<STR: SerializableString + ?Sized>(&self, s: &STR) -> StringId {
        self.profiler.alloc_string(s)
    }

    /// Gets a `StringId` for the given string. This method makes sure that
    /// any strings going through it will only be allocated once in the
    /// profiling data.
    pub fn get_or_alloc_cached_string<A>(&self, s: A) -> StringId
    where
        A: Borrow<str> + Into<String>,
    {
        // Only acquire a read-lock first since we assume that the string is
        // already present in the common case.
        {
            let string_cache = self.string_cache.read();

            if let Some(&id) = string_cache.get(s.borrow()) {
                return id;
            }
        }

        let mut string_cache = self.string_cache.write();
        // Check if the string has already been added in the small time window
        // between dropping the read lock and acquiring the write lock.
        match string_cache.entry(s.into()) {
            Entry::Occupied(e) => *e.get(),
            Entry::Vacant(e) => {
                let string_id = self.profiler.alloc_string(&e.key()[..]);
                *e.insert(string_id)
            }
        }
    }

    pub fn map_query_invocation_id_to_string(&self, from: QueryInvocationId, to: StringId) {
        let from = StringId::new_virtual(from.0);
        self.profiler.map_virtual_to_concrete_string(from, to);
    }

    pub fn bulk_map_query_invocation_id_to_single_string<I>(&self, from: I, to: StringId)
    where
        I: Iterator<Item = QueryInvocationId> + ExactSizeIterator,
    {
        let from = from.map(|qid| StringId::new_virtual(qid.0));
        self.profiler.bulk_map_virtual_to_single_concrete_string(from, to);
    }

    pub fn query_key_recording_enabled(&self) -> bool {
        self.event_filter_mask.contains(EventFilter::QUERY_KEYS)
    }

    pub fn event_id_builder(&self) -> EventIdBuilder<'_> {
        EventIdBuilder::new(&self.profiler)
    }
}

#[must_use]
pub struct TimingGuard<'a>(Option<measureme::TimingGuard<'a>>);

impl<'a> TimingGuard<'a> {
    #[inline]
    pub fn start(
        profiler: &'a SelfProfiler,
        event_kind: StringId,
        event_id: EventId,
    ) -> TimingGuard<'a> {
        let thread_id = get_thread_id();
        let raw_profiler = &profiler.profiler;
        let timing_guard =
            raw_profiler.start_recording_interval_event(event_kind, event_id, thread_id);
        TimingGuard(Some(timing_guard))
    }

    #[inline]
    pub fn finish_with_query_invocation_id(self, query_invocation_id: QueryInvocationId) {
        if let Some(guard) = self.0 {
            outline(|| {
                let event_id = StringId::new_virtual(query_invocation_id.0);
                let event_id = EventId::from_virtual(event_id);
                guard.finish_with_override_event_id(event_id);
            });
        }
    }

    #[inline]
    pub fn none() -> TimingGuard<'a> {
        TimingGuard(None)
    }

    #[inline(always)]
    pub fn run<R>(self, f: impl FnOnce() -> R) -> R {
        let _timer = self;
        f()
    }
}

struct VerboseInfo {
    start_time: Instant,
    start_rss: Option<usize>,
    message: String,
    format: TimePassesFormat,
}

#[must_use]
pub struct VerboseTimingGuard<'a> {
    info: Option<VerboseInfo>,
    _guard: TimingGuard<'a>,
}

impl<'a> VerboseTimingGuard<'a> {
    pub fn start(
        message_and_format: Option<(String, TimePassesFormat)>,
        _guard: TimingGuard<'a>,
    ) -> Self {
        VerboseTimingGuard {
            _guard,
            info: message_and_format.map(|(message, format)| VerboseInfo {
                start_time: Instant::now(),
                start_rss: get_resident_set_size(),
                message,
                format,
            }),
        }
    }

    #[inline(always)]
    pub fn run<R>(self, f: impl FnOnce() -> R) -> R {
        let _timer = self;
        f()
    }
}

impl Drop for VerboseTimingGuard<'_> {
    fn drop(&mut self) {
        if let Some(info) = &self.info {
            let end_rss = get_resident_set_size();
            let dur = info.start_time.elapsed();
            print_time_passes_entry(&info.message, dur, info.start_rss, end_rss, info.format);
        }
    }
}

struct JsonTimePassesEntry<'a> {
    pass: &'a str,
    time: f64,
    start_rss: Option<usize>,
    end_rss: Option<usize>,
}

impl Display for JsonTimePassesEntry<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let Self { pass: what, time, start_rss, end_rss } = self;
        write!(f, r#"{{"pass":"{what}","time":{time},"rss_start":"#).unwrap();
        match start_rss {
            Some(rss) => write!(f, "{rss}")?,
            None => write!(f, "null")?,
        }
        write!(f, r#","rss_end":"#)?;
        match end_rss {
            Some(rss) => write!(f, "{rss}")?,
            None => write!(f, "null")?,
        }
        write!(f, "}}")?;
        Ok(())
    }
}

pub fn print_time_passes_entry(
    what: &str,
    dur: Duration,
    start_rss: Option<usize>,
    end_rss: Option<usize>,
    format: TimePassesFormat,
) {
    match format {
        TimePassesFormat::Json => {
            let entry =
                JsonTimePassesEntry { pass: what, time: dur.as_secs_f64(), start_rss, end_rss };

            eprintln!(r#"time: {entry}"#);
            return;
        }
        TimePassesFormat::Text => (),
    }

    // Print the pass if its duration is greater than 5 ms, or it changed the
    // measured RSS.
    let is_notable = || {
        if dur.as_millis() > 5 {
            return true;
        }

        if let (Some(start_rss), Some(end_rss)) = (start_rss, end_rss) {
            let change_rss = end_rss.abs_diff(start_rss);
            if change_rss > 0 {
                return true;
            }
        }

        false
    };
    if !is_notable() {
        return;
    }

    let rss_to_mb = |rss| (rss as f64 / 1_000_000.0).round() as usize;
    let rss_change_to_mb = |rss| (rss as f64 / 1_000_000.0).round() as i128;

    let mem_string = match (start_rss, end_rss) {
        (Some(start_rss), Some(end_rss)) => {
            let change_rss = end_rss as i128 - start_rss as i128;

            format!(
                "; rss: {:>4}MB -> {:>4}MB ({:>+5}MB)",
                rss_to_mb(start_rss),
                rss_to_mb(end_rss),
                rss_change_to_mb(change_rss),
            )
        }
        (Some(start_rss), None) => format!("; rss start: {:>4}MB", rss_to_mb(start_rss)),
        (None, Some(end_rss)) => format!("; rss end: {:>4}MB", rss_to_mb(end_rss)),
        (None, None) => String::new(),
    };

    eprintln!("time: {:>7}{}\t{}", duration_to_secs_str(dur), mem_string, what);
}

// Hack up our own formatting for the duration to make it easier for scripts
// to parse (always use the same number of decimal places and the same unit).
pub fn duration_to_secs_str(dur: std::time::Duration) -> String {
    format!("{:.3}", dur.as_secs_f64())
}

fn get_thread_id() -> u32 {
    std::thread::current().id().as_u64().get() as u32
}

// Memory reporting
cfg_match! {
    cfg(windows) => {
        pub fn get_resident_set_size() -> Option<usize> {
            use std::mem;

            use windows::{
                // FIXME: change back to K32GetProcessMemoryInfo when windows crate
                // updated to 0.49.0+ to drop dependency on psapi.dll
                Win32::System::ProcessStatus::{GetProcessMemoryInfo, PROCESS_MEMORY_COUNTERS},
                Win32::System::Threading::GetCurrentProcess,
            };

            let mut pmc = PROCESS_MEMORY_COUNTERS::default();
            let pmc_size = mem::size_of_val(&pmc);
            unsafe {
                GetProcessMemoryInfo(
                    GetCurrentProcess(),
                    &mut pmc,
                    pmc_size as u32,
                )
            }
            .ok()
            .ok()?;

            Some(pmc.WorkingSetSize)
        }
    }
    cfg(target_os = "macos")  => {
        pub fn get_resident_set_size() -> Option<usize> {
            use libc::{c_int, c_void, getpid, proc_pidinfo, proc_taskinfo, PROC_PIDTASKINFO};
            use std::mem;
            const PROC_TASKINFO_SIZE: c_int = mem::size_of::<proc_taskinfo>() as c_int;

            unsafe {
                let mut info: proc_taskinfo = mem::zeroed();
                let info_ptr = &mut info as *mut proc_taskinfo as *mut c_void;
                let pid = getpid() as c_int;
                let ret = proc_pidinfo(pid, PROC_PIDTASKINFO, 0, info_ptr, PROC_TASKINFO_SIZE);
                if ret == PROC_TASKINFO_SIZE {
                    Some(info.pti_resident_size as usize)
                } else {
                    None
                }
            }
        }
    }
    cfg(unix) => {
        pub fn get_resident_set_size() -> Option<usize> {
            let field = 1;
            let contents = fs::read("/proc/self/statm").ok()?;
            let contents = String::from_utf8(contents).ok()?;
            let s = contents.split_whitespace().nth(field)?;
            let npages = s.parse::<usize>().ok()?;
            Some(npages * 4096)
        }
    }
    _ => {
        pub fn get_resident_set_size() -> Option<usize> {
            None
        }
    }
}

#[cfg(test)]
mod tests;