mirror of
https://github.com/mozilla/gecko-dev.git
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4d0783188e
Backed out changeset 4feee07c34ad (bug 1117098) Backed out changeset 168e5b9bf198 (bug 1099152) Backed out changeset 9192d432d87e (bug 1099152) Backed out changeset 8b891ebcd21f (bug 1099152) Backed out changeset 24dae3ce853d (bug 1099152)
578 lines
18 KiB
C++
578 lines
18 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sts=4 et sw=4 tw=99:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef js_GCAPI_h
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#define js_GCAPI_h
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#include "mozilla/NullPtr.h"
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#include "js/HeapAPI.h"
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namespace js {
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namespace gc {
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class GCRuntime;
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}
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}
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typedef enum JSGCMode {
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/* Perform only global GCs. */
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JSGC_MODE_GLOBAL = 0,
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/* Perform per-compartment GCs until too much garbage has accumulated. */
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JSGC_MODE_COMPARTMENT = 1,
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/*
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* Collect in short time slices rather than all at once. Implies
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* JSGC_MODE_COMPARTMENT.
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*/
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JSGC_MODE_INCREMENTAL = 2
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} JSGCMode;
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namespace JS {
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#define GCREASONS(D) \
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/* Reasons internal to the JS engine */ \
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D(API) \
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D(MAYBEGC) \
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D(DESTROY_RUNTIME) \
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D(DESTROY_CONTEXT) \
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D(LAST_DITCH) \
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D(TOO_MUCH_MALLOC) \
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D(ALLOC_TRIGGER) \
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D(DEBUG_GC) \
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D(COMPARTMENT_REVIVED) \
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D(RESET) \
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D(OUT_OF_NURSERY) \
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D(EVICT_NURSERY) \
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D(FULL_STORE_BUFFER) \
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D(SHARED_MEMORY_LIMIT) \
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\
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/* These are reserved for future use. */ \
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D(RESERVED0) \
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D(RESERVED1) \
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D(RESERVED2) \
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D(RESERVED3) \
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D(RESERVED4) \
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D(RESERVED5) \
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D(RESERVED6) \
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D(RESERVED7) \
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D(RESERVED8) \
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D(RESERVED9) \
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D(RESERVED10) \
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D(RESERVED11) \
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D(RESERVED12) \
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D(RESERVED13) \
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D(RESERVED14) \
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D(RESERVED15) \
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D(RESERVED16) \
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D(RESERVED17) \
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D(RESERVED18) \
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\
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/* Reasons from Firefox */ \
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D(DOM_WINDOW_UTILS) \
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D(COMPONENT_UTILS) \
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D(MEM_PRESSURE) \
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D(CC_WAITING) \
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D(CC_FORCED) \
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D(LOAD_END) \
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D(POST_COMPARTMENT) \
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D(PAGE_HIDE) \
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D(NSJSCONTEXT_DESTROY) \
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D(SET_NEW_DOCUMENT) \
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D(SET_DOC_SHELL) \
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D(DOM_UTILS) \
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D(DOM_IPC) \
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D(DOM_WORKER) \
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D(INTER_SLICE_GC) \
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D(REFRESH_FRAME) \
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D(FULL_GC_TIMER) \
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D(SHUTDOWN_CC) \
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D(FINISH_LARGE_EVALUATE)
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namespace gcreason {
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/* GCReasons will end up looking like JSGC_MAYBEGC */
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enum Reason {
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#define MAKE_REASON(name) name,
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GCREASONS(MAKE_REASON)
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#undef MAKE_REASON
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NO_REASON,
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NUM_REASONS,
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/*
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* For telemetry, we want to keep a fixed max bucket size over time so we
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* don't have to switch histograms. 100 is conservative; as of this writing
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* there are 52. But the cost of extra buckets seems to be low while the
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* cost of switching histograms is high.
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*/
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NUM_TELEMETRY_REASONS = 100
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};
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} /* namespace gcreason */
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/*
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* Zone GC:
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*
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* SpiderMonkey's GC is capable of performing a collection on an arbitrary
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* subset of the zones in the system. This allows an embedding to minimize
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* collection time by only collecting zones that have run code recently,
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* ignoring the parts of the heap that are unlikely to have changed.
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*
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* When triggering a GC using one of the functions below, it is first necessary
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* to select the zones to be collected. To do this, you can call
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* PrepareZoneForGC on each zone, or you can call PrepareForFullGC to select
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* all zones. Failing to select any zone is an error.
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*/
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/*
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* Schedule the given zone to be collected as part of the next GC.
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*/
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extern JS_FRIEND_API(void)
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PrepareZoneForGC(Zone *zone);
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/*
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* Schedule all zones to be collected in the next GC.
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*/
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extern JS_FRIEND_API(void)
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PrepareForFullGC(JSRuntime *rt);
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/*
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* When performing an incremental GC, the zones that were selected for the
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* previous incremental slice must be selected in subsequent slices as well.
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* This function selects those slices automatically.
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*/
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extern JS_FRIEND_API(void)
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PrepareForIncrementalGC(JSRuntime *rt);
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/*
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* Returns true if any zone in the system has been scheduled for GC with one of
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* the functions above or by the JS engine.
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*/
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extern JS_FRIEND_API(bool)
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IsGCScheduled(JSRuntime *rt);
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/*
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* Undoes the effect of the Prepare methods above. The given zone will not be
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* collected in the next GC.
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*/
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extern JS_FRIEND_API(void)
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SkipZoneForGC(Zone *zone);
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/*
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* Non-Incremental GC:
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*
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* The following functions perform a non-incremental GC.
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*/
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/*
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* Performs a non-incremental collection of all selected zones. Some objects
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* that are unreachable from the program may still be alive afterwards because
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* of internal references.
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*/
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extern JS_FRIEND_API(void)
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GCForReason(JSRuntime *rt, gcreason::Reason reason);
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/*
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* Perform a non-incremental collection after clearing caches and other
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* temporary references to objects. This will remove all unreferenced objects
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* in the system.
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*/
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extern JS_FRIEND_API(void)
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ShrinkingGC(JSRuntime *rt, gcreason::Reason reason);
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/*
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* Incremental GC:
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*
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* Incremental GC divides the full mark-and-sweep collection into multiple
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* slices, allowing client JavaScript code to run between each slice. This
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* allows interactive apps to avoid long collection pauses. Incremental GC does
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* not make collection take less time, it merely spreads that time out so that
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* the pauses are less noticable.
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*
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* For a collection to be carried out incrementally the following conditions
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* must be met:
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* - The collection must be run by calling JS::IncrementalGC() rather than
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* JS_GC().
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* - The GC mode must have been set to JSGC_MODE_INCREMENTAL with
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* JS_SetGCParameter().
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* - All native objects that have their own trace hook must indicate that they
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* implement read and write barriers with the JSCLASS_IMPLEMENTS_BARRIERS
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* flag.
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*
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* Note: Even if incremental GC is enabled and working correctly,
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* non-incremental collections can still happen when low on memory.
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*/
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/*
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* Begin an incremental collection and perform one slice worth of work or
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* perform a slice of an ongoing incremental collection. When this function
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* returns, the collection is not complete. This function must be called
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* repeatedly until !IsIncrementalGCInProgress(rt).
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*
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* Note: SpiderMonkey's GC is not realtime. Slices in practice may be longer or
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* shorter than the requested interval.
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*/
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extern JS_FRIEND_API(void)
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IncrementalGC(JSRuntime *rt, gcreason::Reason reason, int64_t millis = 0);
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/*
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* If IsIncrementalGCInProgress(rt), this call finishes the ongoing collection
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* by performing an arbitrarily long slice. If !IsIncrementalGCInProgress(rt),
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* this is equivalent to GCForReason. When this function returns,
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* IsIncrementalGCInProgress(rt) will always be false.
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*/
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extern JS_FRIEND_API(void)
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FinishIncrementalGC(JSRuntime *rt, gcreason::Reason reason);
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enum GCProgress {
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/*
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* During non-incremental GC, the GC is bracketed by JSGC_CYCLE_BEGIN/END
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* callbacks. During an incremental GC, the sequence of callbacks is as
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* follows:
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* JSGC_CYCLE_BEGIN, JSGC_SLICE_END (first slice)
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* JSGC_SLICE_BEGIN, JSGC_SLICE_END (second slice)
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* ...
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* JSGC_SLICE_BEGIN, JSGC_CYCLE_END (last slice)
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*/
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GC_CYCLE_BEGIN,
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GC_SLICE_BEGIN,
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GC_SLICE_END,
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GC_CYCLE_END
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};
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struct JS_FRIEND_API(GCDescription) {
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bool isCompartment_;
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explicit GCDescription(bool isCompartment)
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: isCompartment_(isCompartment) {}
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char16_t *formatMessage(JSRuntime *rt) const;
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char16_t *formatJSON(JSRuntime *rt, uint64_t timestamp) const;
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};
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typedef void
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(* GCSliceCallback)(JSRuntime *rt, GCProgress progress, const GCDescription &desc);
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/*
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* The GC slice callback is called at the beginning and end of each slice. This
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* callback may be used for GC notifications as well as to perform additional
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* marking.
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*/
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extern JS_FRIEND_API(GCSliceCallback)
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SetGCSliceCallback(JSRuntime *rt, GCSliceCallback callback);
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/*
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* Incremental GC defaults to enabled, but may be disabled for testing or in
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* embeddings that have not yet implemented barriers on their native classes.
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* There is not currently a way to re-enable incremental GC once it has been
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* disabled on the runtime.
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*/
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extern JS_FRIEND_API(void)
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DisableIncrementalGC(JSRuntime *rt);
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/*
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* Returns true if incremental GC is enabled. Simply having incremental GC
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* enabled is not sufficient to ensure incremental collections are happening.
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* See the comment "Incremental GC" above for reasons why incremental GC may be
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* suppressed. Inspection of the "nonincremental reason" field of the
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* GCDescription returned by GCSliceCallback may help narrow down the cause if
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* collections are not happening incrementally when expected.
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*/
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extern JS_FRIEND_API(bool)
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IsIncrementalGCEnabled(JSRuntime *rt);
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/*
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* Compacting GC defaults to enabled, but may be disabled for testing or in
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* embeddings that have not implemented the necessary object moved hooks or weak
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* pointer callbacks. There is not currently a way to re-enable compacting GC
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* once it has been disabled on the runtime.
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*/
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extern JS_FRIEND_API(void)
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DisableCompactingGC(JSRuntime *rt);
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/*
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* Returns true if compacting GC is enabled.
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*/
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extern JS_FRIEND_API(bool)
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IsCompactingGCEnabled(JSRuntime *rt);
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/*
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* Returns true while an incremental GC is ongoing, both when actively
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* collecting and between slices.
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*/
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JS_FRIEND_API(bool)
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IsIncrementalGCInProgress(JSRuntime *rt);
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/*
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* Returns true when writes to GC things must call an incremental (pre) barrier.
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* This is generally only true when running mutator code in-between GC slices.
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* At other times, the barrier may be elided for performance.
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*/
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extern JS_FRIEND_API(bool)
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IsIncrementalBarrierNeeded(JSRuntime *rt);
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extern JS_FRIEND_API(bool)
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IsIncrementalBarrierNeeded(JSContext *cx);
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/*
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* Notify the GC that a reference to a GC thing is about to be overwritten.
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* These methods must be called if IsIncrementalBarrierNeeded.
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*/
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extern JS_FRIEND_API(void)
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IncrementalReferenceBarrier(GCCellPtr thing);
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extern JS_FRIEND_API(void)
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IncrementalValueBarrier(const Value &v);
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extern JS_FRIEND_API(void)
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IncrementalObjectBarrier(JSObject *obj);
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/*
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* Returns true if the most recent GC ran incrementally.
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*/
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extern JS_FRIEND_API(bool)
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WasIncrementalGC(JSRuntime *rt);
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/*
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* Generational GC:
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*
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* Note: Generational GC is not yet enabled by default. The following class
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* is non-functional unless SpiderMonkey was configured with
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* --enable-gcgenerational.
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*/
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/* Ensure that generational GC is disabled within some scope. */
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class JS_FRIEND_API(AutoDisableGenerationalGC)
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{
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js::gc::GCRuntime *gc;
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#ifdef JS_GC_ZEAL
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bool restartVerifier;
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#endif
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public:
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explicit AutoDisableGenerationalGC(JSRuntime *rt);
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~AutoDisableGenerationalGC();
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};
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/*
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* Returns true if generational allocation and collection is currently enabled
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* on the given runtime.
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*/
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extern JS_FRIEND_API(bool)
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IsGenerationalGCEnabled(JSRuntime *rt);
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/*
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* Returns the GC's "number". This does not correspond directly to the number
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* of GCs that have been run, but is guaranteed to be monotonically increasing
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* with GC activity.
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*/
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extern JS_FRIEND_API(size_t)
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GetGCNumber();
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/*
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* The GC does not immediately return the unused memory freed by a collection
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* back to the system incase it is needed soon afterwards. This call forces the
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* GC to return this memory immediately.
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*/
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extern JS_FRIEND_API(void)
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ShrinkGCBuffers(JSRuntime *rt);
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/*
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* Assert if a GC occurs while this class is live. This class does not disable
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* the static rooting hazard analysis.
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*/
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class JS_PUBLIC_API(AutoAssertOnGC)
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{
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#ifdef DEBUG
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js::gc::GCRuntime *gc;
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size_t gcNumber;
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public:
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AutoAssertOnGC();
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explicit AutoAssertOnGC(JSRuntime *rt);
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~AutoAssertOnGC();
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static void VerifyIsSafeToGC(JSRuntime *rt);
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#else
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public:
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AutoAssertOnGC() {}
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explicit AutoAssertOnGC(JSRuntime *rt) {}
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~AutoAssertOnGC() {}
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static void VerifyIsSafeToGC(JSRuntime *rt) {}
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#endif
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};
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/*
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* Assert if an allocation of a GC thing occurs while this class is live. This
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* class does not disable the static rooting hazard analysis.
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*/
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class JS_PUBLIC_API(AutoAssertNoAlloc)
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{
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#ifdef JS_DEBUG
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js::gc::GCRuntime *gc;
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public:
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AutoAssertNoAlloc() : gc(nullptr) {}
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explicit AutoAssertNoAlloc(JSRuntime *rt);
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void disallowAlloc(JSRuntime *rt);
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~AutoAssertNoAlloc();
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#else
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public:
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AutoAssertNoAlloc() {}
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explicit AutoAssertNoAlloc(JSRuntime *rt) {}
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void disallowAlloc(JSRuntime *rt) {}
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#endif
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};
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/*
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* Disable the static rooting hazard analysis in the live region and assert if
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* any allocation that could potentially trigger a GC occurs while this guard
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* object is live. This is most useful to help the exact rooting hazard analysis
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* in complex regions, since it cannot understand dataflow.
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*
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* Note: GC behavior is unpredictable even when deterministic and is generally
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* non-deterministic in practice. The fact that this guard has not
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* asserted is not a guarantee that a GC cannot happen in the guarded
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* region. As a rule, anyone performing a GC unsafe action should
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* understand the GC properties of all code in that region and ensure
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* that the hazard analysis is correct for that code, rather than relying
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* on this class.
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*/
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class JS_PUBLIC_API(AutoSuppressGCAnalysis) : public AutoAssertNoAlloc
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{
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public:
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AutoSuppressGCAnalysis() : AutoAssertNoAlloc() {}
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explicit AutoSuppressGCAnalysis(JSRuntime *rt) : AutoAssertNoAlloc(rt) {}
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};
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/*
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* Assert that code is only ever called from a GC callback, disable the static
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* rooting hazard analysis and assert if any allocation that could potentially
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* trigger a GC occurs while this guard object is live.
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*
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* This is useful to make the static analysis ignore code that runs in GC
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* callbacks.
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*/
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class JS_PUBLIC_API(AutoAssertGCCallback) : public AutoSuppressGCAnalysis
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{
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public:
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explicit AutoAssertGCCallback(JSObject *obj);
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};
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/*
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* Place AutoCheckCannotGC in scopes that you believe can never GC. These
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* annotations will be verified both dynamically via AutoAssertOnGC, and
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* statically with the rooting hazard analysis (implemented by making the
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* analysis consider AutoCheckCannotGC to be a GC pointer, and therefore
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* complain if it is live across a GC call.) It is useful when dealing with
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* internal pointers to GC things where the GC thing itself may not be present
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* for the static analysis: e.g. acquiring inline chars from a JSString* on the
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* heap.
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*/
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class JS_PUBLIC_API(AutoCheckCannotGC) : public AutoAssertOnGC
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{
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public:
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AutoCheckCannotGC() : AutoAssertOnGC() {}
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explicit AutoCheckCannotGC(JSRuntime *rt) : AutoAssertOnGC(rt) {}
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};
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/*
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* Unsets the gray bit for anything reachable from |thing|. |kind| should not be
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* JSTRACE_SHAPE. |thing| should be non-null.
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*/
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extern JS_FRIEND_API(bool)
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UnmarkGrayGCThingRecursively(GCCellPtr thing);
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} /* namespace JS */
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namespace js {
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namespace gc {
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static MOZ_ALWAYS_INLINE void
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ExposeGCThingToActiveJS(JS::GCCellPtr thing)
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{
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MOZ_ASSERT(thing.kind() != JSTRACE_SHAPE);
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/*
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* GC things residing in the nursery cannot be gray: they have no mark bits.
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* All live objects in the nursery are moved to tenured at the beginning of
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* each GC slice, so the gray marker never sees nursery things.
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*/
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if (IsInsideNursery(thing.asCell()))
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return;
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JS::shadow::Runtime *rt = detail::GetGCThingRuntime(thing.unsafeAsUIntPtr());
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if (IsIncrementalBarrierNeededOnTenuredGCThing(rt, thing))
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|
JS::IncrementalReferenceBarrier(thing);
|
|
else if (JS::GCThingIsMarkedGray(thing))
|
|
JS::UnmarkGrayGCThingRecursively(thing);
|
|
}
|
|
|
|
static MOZ_ALWAYS_INLINE void
|
|
MarkGCThingAsLive(JSRuntime *aRt, JS::GCCellPtr thing)
|
|
{
|
|
JS::shadow::Runtime *rt = JS::shadow::Runtime::asShadowRuntime(aRt);
|
|
/*
|
|
* Any object in the nursery will not be freed during any GC running at that time.
|
|
*/
|
|
if (IsInsideNursery(thing.asCell()))
|
|
return;
|
|
if (IsIncrementalBarrierNeededOnTenuredGCThing(rt, thing))
|
|
JS::IncrementalReferenceBarrier(thing);
|
|
}
|
|
|
|
} /* namespace gc */
|
|
} /* namespace js */
|
|
|
|
namespace JS {
|
|
|
|
/*
|
|
* This should be called when an object that is marked gray is exposed to the JS
|
|
* engine (by handing it to running JS code or writing it into live JS
|
|
* data). During incremental GC, since the gray bits haven't been computed yet,
|
|
* we conservatively mark the object black.
|
|
*/
|
|
static MOZ_ALWAYS_INLINE void
|
|
ExposeObjectToActiveJS(JSObject *obj)
|
|
{
|
|
js::gc::ExposeGCThingToActiveJS(GCCellPtr(obj));
|
|
}
|
|
|
|
static MOZ_ALWAYS_INLINE void
|
|
ExposeScriptToActiveJS(JSScript *script)
|
|
{
|
|
js::gc::ExposeGCThingToActiveJS(GCCellPtr(script));
|
|
}
|
|
|
|
/*
|
|
* If a GC is currently marking, mark the string black.
|
|
*/
|
|
static MOZ_ALWAYS_INLINE void
|
|
MarkStringAsLive(Zone *zone, JSString *string)
|
|
{
|
|
JSRuntime *rt = JS::shadow::Zone::asShadowZone(zone)->runtimeFromMainThread();
|
|
js::gc::MarkGCThingAsLive(rt, GCCellPtr(string));
|
|
}
|
|
|
|
/*
|
|
* Internal to Firefox.
|
|
*
|
|
* Note: this is not related to the PokeGC in nsJSEnvironment.
|
|
*/
|
|
extern JS_FRIEND_API(void)
|
|
PokeGC(JSRuntime *rt);
|
|
|
|
/*
|
|
* Internal to Firefox.
|
|
*/
|
|
extern JS_FRIEND_API(void)
|
|
NotifyDidPaint(JSRuntime *rt);
|
|
|
|
} /* namespace JS */
|
|
|
|
#endif /* js_GCAPI_h */
|