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From 272c1ba11fac7a9ceede2f4f737bb27b4bbcad71 Mon Sep 17 00:00:00 2001
From: Steve Fink <sfink@mozilla.com>
Date: Thu, 19 Mar 2015 20:50:57 -0700
Subject: [PATCH] Bug 1120655 - Suppress zone/compartment collection while
iterating. r=terrence, a=bkerensa
---
js/src/gc/Zone.h | 9 ++++----
js/src/jsgc.cpp | 57 +++++++++++++++++++++++++++++++++++----------------
js/src/jsgc.h | 11 +++++++++-
js/src/vm/Runtime.cpp | 1 +
js/src/vm/Runtime.h | 3 +++
5 files changed, 58 insertions(+), 23 deletions(-)
diff --git a/js/src/gc/Zone.h b/js/src/gc/Zone.h
index e7f687a..dd058f0 100644
--- a/js/src/gc/Zone.h
+++ b/js/src/gc/Zone.h
@@ -353,10 +353,11 @@ enum ZoneSelector {
class ZonesIter {
private:
+ gc::AutoEnterIteration iterMarker;
JS::Zone **it, **end;
public:
- ZonesIter(JSRuntime *rt, ZoneSelector selector) {
+ ZonesIter(JSRuntime *rt, ZoneSelector selector) : iterMarker(rt) {
it = rt->zones.begin();
end = rt->zones.end();
@@ -427,13 +428,13 @@ struct CompartmentsInZoneIter
template<class ZonesIterT>
class CompartmentsIterT
{
- private:
+ gc::AutoEnterIteration iterMarker;
ZonesIterT zone;
mozilla::Maybe<CompartmentsInZoneIter> comp;
public:
explicit CompartmentsIterT(JSRuntime *rt)
- : zone(rt)
+ : iterMarker(rt), zone(rt)
{
if (zone.done())
comp.construct();
@@ -442,7 +443,7 @@ class CompartmentsIterT
}
CompartmentsIterT(JSRuntime *rt, ZoneSelector selector)
- : zone(rt, selector)
+ : iterMarker(rt), zone(rt, selector)
{
if (zone.done())
comp.construct();
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index 15c86c8..1dfe0ab 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -2525,7 +2525,7 @@ ReleaseObservedTypes(JSRuntime* rt)
* arbitrary compartment in the zone.
*/
static void
-SweepCompartments(FreeOp *fop, Zone *zone, bool keepAtleastOne, bool lastGC)
+SweepCompartments(FreeOp *fop, Zone *zone, bool keepAtleastOne, bool destroyingRuntime)
{
JSRuntime *rt = zone->runtimeFromMainThread();
JSDestroyCompartmentCallback callback = rt->destroyCompartmentCallback;
@@ -2543,7 +2543,7 @@ SweepCompartments(FreeOp *fop, Zone *zone, bool keepAtleastOne, bool lastGC)
* deleted and keepAtleastOne is true.
*/
bool dontDelete = read == end && !foundOne && keepAtleastOne;
- if ((!comp->marked && !dontDelete) || lastGC) {
+ if ((!comp->marked && !dontDelete) || destroyingRuntime) {
if (callback)
callback(fop, comp);
if (comp->principals)
@@ -2559,9 +2559,13 @@ SweepCompartments(FreeOp *fop, Zone *zone, bool keepAtleastOne, bool lastGC)
}
static void
-SweepZones(FreeOp *fop, bool lastGC)
+SweepZones(FreeOp *fop, bool destroyingRuntime)
{
JSRuntime *rt = fop->runtime();
+ MOZ_ASSERT_IF(destroyingRuntime, rt->numActiveZoneIters == 0);
+ if (rt->numActiveZoneIters)
+ return;
+
JSZoneCallback callback = rt->destroyZoneCallback;
/* Skip the atomsCompartment zone. */
@@ -2576,17 +2580,17 @@ SweepZones(FreeOp* fop, bool lastGC)
if (zone->wasGCStarted()) {
if ((zone->allocator.arenas.arenaListsAreEmpty() && !zone->hasMarkedCompartments()) ||
- lastGC)
+ destroyingRuntime)
{
zone->allocator.arenas.checkEmptyFreeLists();
if (callback)
callback(zone);
- SweepCompartments(fop, zone, false, lastGC);
+ SweepCompartments(fop, zone, false, destroyingRuntime);
JS_ASSERT(zone->compartments.empty());
fop->delete_(zone);
continue;
}
- SweepCompartments(fop, zone, true, lastGC);
+ SweepCompartments(fop, zone, true, destroyingRuntime);
}
*write++ = zone;
}
@@ -3787,7 +3791,7 @@ EndSweepingZoneGroup(JSRuntime *rt)
}
static void
-BeginSweepPhase(JSRuntime *rt, bool lastGC)
+BeginSweepPhase(JSRuntime *rt, bool destroyingRuntime)
{
/*
* Sweep phase.
@@ -3804,7 +3808,7 @@ BeginSweepPhase(JSRuntime *rt, bool lastGC)
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
#ifdef JS_THREADSAFE
- rt->gcSweepOnBackgroundThread = !lastGC && rt->useHelperThreads();
+ rt->gcSweepOnBackgroundThread = !destroyingRuntime && rt->useHelperThreads();
#endif
#ifdef DEBUG
@@ -3903,12 +3907,12 @@ SweepPhase(JSRuntime *rt, SliceBudget &sliceBudget)
}
static void
-EndSweepPhase(JSRuntime *rt, JSGCInvocationKind gckind, bool lastGC)
+EndSweepPhase(JSRuntime *rt, JSGCInvocationKind gckind, bool destroyingRuntime)
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
- JS_ASSERT_IF(lastGC, !rt->gcSweepOnBackgroundThread);
+ JS_ASSERT_IF(destroyingRuntime, !rt->gcSweepOnBackgroundThread);
JS_ASSERT(rt->gcMarker.isDrained());
rt->gcMarker.stop();
@@ -3959,8 +3963,8 @@ EndSweepPhase(JSRuntime *rt, JSGCInvocationKind gckind, bool lastGC)
* This removes compartments from rt->compartment, so we do it last to make
* sure we don't miss sweeping any compartments.
*/
- if (!lastGC)
- SweepZones(&fop, lastGC);
+ if (!destroyingRuntime)
+ SweepZones(&fop, destroyingRuntime);
if (!rt->gcSweepOnBackgroundThread) {
/*
@@ -4001,8 +4005,8 @@ EndSweepPhase(JSRuntime *rt, JSGCInvocationKind gckind, bool lastGC)
rt->freeLifoAlloc.freeAll();
/* Ensure the compartments get swept if it's the last GC. */
- if (lastGC)
- SweepZones(&fop, lastGC);
+ if (destroyingRuntime)
+ SweepZones(&fop, destroyingRuntime);
}
for (ZonesIter zone(rt, WithAtoms); !zone.done(); zone.next()) {
@@ -4339,7 +4343,7 @@ IncrementalCollectSlice(JSRuntime *rt,
AutoCopyFreeListToArenasForGC copy(rt);
AutoGCSlice slice(rt);
- bool lastGC = (reason == JS::gcreason::DESTROY_RUNTIME);
+ bool destroyingRuntime = (reason == JS::gcreason::DESTROY_RUNTIME);
gc::State initialState = rt->gcIncrementalState;
@@ -4384,7 +4388,7 @@ IncrementalCollectSlice(JSRuntime *rt,
return;
}
- if (!lastGC)
+ if (!destroyingRuntime)
PushZealSelectedObjects(rt);
rt->gcIncrementalState = MARK;
@@ -4426,7 +4430,7 @@ IncrementalCollectSlice(JSRuntime *rt,
* This runs to completion, but we don't continue if the budget is
* now exhasted.
*/
- BeginSweepPhase(rt, lastGC);
+ BeginSweepPhase(rt, destroyingRuntime);
if (sliceBudget.isOverBudget())
break;
@@ -4445,7 +4449,7 @@ IncrementalCollectSlice(JSRuntime *rt,
if (!finished)
break;
- EndSweepPhase(rt, gckind, lastGC);
+ EndSweepPhase(rt, gckind, destroyingRuntime);
if (rt->gcSweepOnBackgroundThread)
rt->gcHelperThread.startBackgroundSweep(gckind == GC_SHRINK);
@@ -5386,3 +5390,20 @@ JS::AutoAssertNoGC::~AutoAssertNoGC()
MOZ_ASSERT(gcNumber == runtime->gcNumber, "GC ran inside an AutoAssertNoGC scope.");
}
#endif
+
+namespace js {
+namespace gc {
+
+AutoEnterIteration::AutoEnterIteration(JSRuntime *rt_) : rt(rt_)
+{
+ ++rt->numActiveZoneIters;
+}
+
+AutoEnterIteration::~AutoEnterIteration()
+{
+ MOZ_ASSERT(rt->numActiveZoneIters);
+ --rt->numActiveZoneIters;
+}
+
+} /* namespace gc */
+} /* namespace js */
diff --git a/js/src/jsgc.h b/js/src/jsgc.h
index 825cff5..ca331c0 100644
--- a/js/src/jsgc.h
+++ b/js/src/jsgc.h
@@ -1077,7 +1077,7 @@ MaybeVerifyBarriers(JSContext* cx, bool always = false)
/*
* Instances of this class set the |JSRuntime::suppressGC| flag for the duration
* that they are live. Use of this class is highly discouraged. Please carefully
- * read the comment in jscntxt.h above |suppressGC| and take all appropriate
+ * read the comment in vm/Runtime.h above |suppressGC| and take all appropriate
* precautions before instantiating this class.
*/
class AutoSuppressGC
@@ -1113,6 +1113,15 @@ class AutoEnterOOMUnsafeRegion
class AutoEnterOOMUnsafeRegion {};
#endif /* DEBUG */
+/* Prevent compartments and zones from being collected during iteration. */
+class AutoEnterIteration {
+ JSRuntime *rt;
+
+ public:
+ AutoEnterIteration(JSRuntime *rt_);
+ ~AutoEnterIteration();
+};
+
} /* namespace gc */
#ifdef DEBUG
diff --git a/js/src/vm/Runtime.cpp b/js/src/vm/Runtime.cpp
index bb5c8680..0d8c6cd 100644
--- a/js/src/vm/Runtime.cpp
+++ b/js/src/vm/Runtime.cpp
@@ -195,6 +195,7 @@ JSRuntime::JSRuntime(JSRuntime *parentRuntime, JSUseHelperThreads useHelperThrea
gcShouldCleanUpEverything(false),
gcGrayBitsValid(false),
gcIsNeeded(0),
+ numActiveZoneIters(0),
gcStats(thisFromCtor()),
gcNumber(0),
gcStartNumber(0),
diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
index 5aeb924..ba4180e 100644
--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -1061,6 +1061,9 @@ struct JSRuntime : public JS::shadow::Runtime,
*/
volatile uintptr_t gcIsNeeded;
+ mozilla::Atomic<size_t, mozilla::ReleaseAcquire> numActiveZoneIters;
+ friend class js::gc::AutoEnterIteration;
+
js::gcstats::Statistics gcStats;
/* Incremented on every GC slice. */
--
2.2.1
|