/* Mark the set of root objects.
*
* Things we need to scan:
* - System classes defined by root classloader
* - For each thread:
* - Interpreted stack, from top to "curFrame"
* - Dalvik registers (args + local vars)
* - JNI local references
* - Automatic VM local references (TrackedAlloc)
* - Associated Thread/VMThread object
* - ThreadGroups (could track & start with these instead of working
* upward from Threads)
* - Exception currently being thrown, if present
* - JNI global references
* - Interned string table
* - Primitive classes
* - Special objects
* - gDvm.outOfMemoryObj
* - Objects allocated with ALLOC_NO_GC
* - Objects pending finalization (but not yet finalized)
* - Objects in debugger object registry
*
* Don't need:
* - Native stack (for in-progress stuff in the VM)
* - The TrackedAlloc stuff watches all native VM references.
*/
void dvmHeapMarkRootSet()
{
GcHeap *gcHeap = gDvm.gcHeap;
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_STICKY_CLASS, 0);
LOG_SCAN("immune objects");
dvmMarkImmuneObjects(gcHeap->markContext.immuneLimit);
LOG_SCAN("root class loader\n");
dvmGcScanRootClassLoader();
LOG_SCAN("primitive classes\n");
dvmGcScanPrimitiveClasses();
/* dvmGcScanRootThreadGroups() sets a bunch of
* different scan states internally.
*/
HPROF_CLEAR_GC_SCAN_STATE();
LOG_SCAN("root thread groups\n");
dvmGcScanRootThreadGroups();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_INTERNED_STRING, 0);
LOG_SCAN("interned strings\n");
dvmGcScanInternedStrings();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_JNI_GLOBAL, 0);
LOG_SCAN("JNI global refs\n");
dvmGcMarkJniGlobalRefs();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_REFERENCE_CLEANUP, 0);
LOG_SCAN("pending reference operations\n");
dvmHeapMarkLargeTableRefs(gcHeap->referenceOperations);
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_FINALIZING, 0);
LOG_SCAN("pending finalizations\n");
dvmHeapMarkLargeTableRefs(gcHeap->pendingFinalizationRefs);
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_DEBUGGER, 0);
LOG_SCAN("debugger refs\n");
dvmGcMarkDebuggerRefs();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_VM_INTERNAL, 0);
/* Mark any special objects we have sitting around.
*/
LOG_SCAN("special objects\n");
dvmMarkObjectNonNull(gDvm.outOfMemoryObj);
dvmMarkObjectNonNull(gDvm.internalErrorObj);
dvmMarkObjectNonNull(gDvm.noClassDefFoundErrorObj);
//TODO: scan object references sitting in gDvm; use pointer begin & end
HPROF_CLEAR_GC_SCAN_STATE();
}
static void
hprofDumpUnmarkedObjects(const HeapBitmap markBitmaps[],
const HeapBitmap objectBitmaps[], size_t numBitmaps)
{
hprof_context_t *hctx = gDvm.gcHeap->hprofContext;
if (hctx == NULL) {
return;
}
LOGI("hprof: dumping unreachable objects\n");
HPROF_SET_GC_SCAN_STATE(HPROF_UNREACHABLE, 0);
dvmHeapBitmapXorWalkLists(markBitmaps, objectBitmaps, numBitmaps,
hprofUnreachableBitmapCallback, hctx);
HPROF_CLEAR_GC_SCAN_STATE();
}
/* All objects for stronger reference levels have been
* marked before this is called.
*/
void dvmHeapHandleReferences(Object *refListHead, enum RefType refType)
{
Object *reference;
GcMarkContext *markContext = &gDvm.gcHeap->markContext;
const int offVmData = gDvm.offJavaLangRefReference_vmData;
const int offReferent = gDvm.offJavaLangRefReference_referent;
bool workRequired = false;
size_t numCleared = 0;
size_t numEnqueued = 0;
reference = refListHead;
while (reference != NULL) {
Object *next;
Object *referent;
/* Pull the interesting fields out of the Reference object.
*/
next = dvmGetFieldObject(reference, offVmData);
referent = dvmGetFieldObject(reference, offReferent);
//TODO: when handling REF_PHANTOM, unlink any references
// that fail this initial if(). We need to re-walk
// the list, and it would be nice to avoid the extra
// work.
if (referent != NULL && !isMarked(ptr2chunk(referent), markContext)) {
bool schedClear, schedEnqueue;
/* This is the strongest reference that refers to referent.
* Do the right thing.
*/
switch (refType) {
case REF_SOFT:
case REF_WEAK:
schedClear = clearReference(reference);
schedEnqueue = enqueueReference(reference);
break;
case REF_PHANTOM:
/* PhantomReferences are not cleared automatically.
* Until someone clears it (or the reference itself
* is collected), the referent must remain alive.
*
* It's necessary to fully mark the referent because
* it will still be present during the next GC, and
* all objects that it points to must be valid.
* (The referent will be marked outside of this loop,
* after handing all references of this strength, in
* case multiple references point to the same object.)
*/
schedClear = false;
/* A PhantomReference is only useful with a
* queue, but since it's possible to create one
* without a queue, we need to check.
*/
schedEnqueue = enqueueReference(reference);
break;
default:
assert(!"Bad reference type");
schedClear = false;
schedEnqueue = false;
break;
}
numCleared += schedClear ? 1 : 0;
numEnqueued += schedEnqueue ? 1 : 0;
if (schedClear || schedEnqueue) {
uintptr_t workBits;
/* Stuff the clear/enqueue bits in the bottom of
* the pointer. Assumes that objects are 8-byte
* aligned.
*
* Note that we are adding the *Reference* (which
* is by definition already marked at this point) to
* this list; we're not adding the referent (which
* has already been cleared).
*/
assert(((intptr_t)reference & 3) == 0);
assert(((WORKER_CLEAR | WORKER_ENQUEUE) & ~3) == 0);
workBits = (schedClear ? WORKER_CLEAR : 0) |
(schedEnqueue ? WORKER_ENQUEUE : 0);
if (!dvmHeapAddRefToLargeTable(
&gDvm.gcHeap->referenceOperations,
(Object *)((uintptr_t)reference | workBits)))
{
LOGE_HEAP("dvmMalloc(): no room for any more "
"reference operations\n");
dvmAbort();
}
workRequired = true;
}
if (refType != REF_PHANTOM) {
/* Let later GCs know not to reschedule this reference.
*/
dvmSetFieldObject(reference, offVmData,
SCHEDULED_REFERENCE_MAGIC);
} // else this is handled later for REF_PHANTOM
} // else there was a stronger reference to the referent.
reference = next;
}
#define refType2str(r) \
((r) == REF_SOFT ? "soft" : ( \
(r) == REF_WEAK ? "weak" : ( \
(r) == REF_PHANTOM ? "phantom" : "UNKNOWN" )))
LOGD_HEAP("dvmHeapHandleReferences(): cleared %zd, enqueued %zd %s references\n", numCleared, numEnqueued, refType2str(refType));
/* Walk though the reference list again, and mark any non-clear/marked
* referents. Only PhantomReferences can have non-clear referents
* at this point.
*/
if (refType == REF_PHANTOM) {
bool scanRequired = false;
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_REFERENCE_CLEANUP, 0);
reference = refListHead;
while (reference != NULL) {
Object *next;
Object *referent;
/* Pull the interesting fields out of the Reference object.
*/
next = dvmGetFieldObject(reference, offVmData);
referent = dvmGetFieldObject(reference, offReferent);
if (referent != NULL && !isMarked(ptr2chunk(referent), markContext)) {
markObjectNonNull(referent, markContext);
scanRequired = true;
/* Let later GCs know not to reschedule this reference.
*/
dvmSetFieldObject(reference, offVmData,
SCHEDULED_REFERENCE_MAGIC);
}
reference = next;
}
HPROF_CLEAR_GC_SCAN_STATE();
if (scanRequired) {
processMarkStack(markContext);
}
}
if (workRequired) {
dvmSignalHeapWorker(false);
}
}
/* Mark the set of root objects.
*
* Things we need to scan:
* - System classes defined by root classloader
* - For each thread:
* - Interpreted stack, from top to "curFrame"
* - Dalvik registers (args + local vars)
* - JNI local references
* - Automatic VM local references (TrackedAlloc)
* - Associated Thread/VMThread object
* - ThreadGroups (could track & start with these instead of working
* upward from Threads)
* - Exception currently being thrown, if present
* - JNI global references
* - Interned string table
* - Primitive classes
* - Special objects
* - gDvm.outOfMemoryObj
* - Objects allocated with ALLOC_NO_GC
* - Objects pending finalization (but not yet finalized)
* - Objects in debugger object registry
*
* Don't need:
* - Native stack (for in-progress stuff in the VM)
* - The TrackedAlloc stuff watches all native VM references.
*/
void dvmHeapMarkRootSet()
{
HeapRefTable *refs;
GcHeap *gcHeap;
Object **op;
gcHeap = gDvm.gcHeap;
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_STICKY_CLASS, 0);
LOG_SCAN("root class loader\n");
dvmGcScanRootClassLoader();
LOG_SCAN("primitive classes\n");
dvmGcScanPrimitiveClasses();
/* dvmGcScanRootThreadGroups() sets a bunch of
* different scan states internally.
*/
HPROF_CLEAR_GC_SCAN_STATE();
LOG_SCAN("root thread groups\n");
dvmGcScanRootThreadGroups();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_INTERNED_STRING, 0);
LOG_SCAN("interned strings\n");
dvmGcScanInternedStrings();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_JNI_GLOBAL, 0);
LOG_SCAN("JNI global refs\n");
dvmGcMarkJniGlobalRefs();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_REFERENCE_CLEANUP, 0);
LOG_SCAN("pending reference operations\n");
dvmHeapMarkLargeTableRefs(gcHeap->referenceOperations, true);
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_FINALIZING, 0);
LOG_SCAN("pending finalizations\n");
dvmHeapMarkLargeTableRefs(gcHeap->pendingFinalizationRefs, false);
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_DEBUGGER, 0);
LOG_SCAN("debugger refs\n");
dvmGcMarkDebuggerRefs();
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_VM_INTERNAL, 0);
/* Mark all ALLOC_NO_GC objects.
*/
LOG_SCAN("ALLOC_NO_GC objects\n");
refs = &gcHeap->nonCollectableRefs;
op = refs->table;
while ((uintptr_t)op < (uintptr_t)refs->nextEntry) {
dvmMarkObjectNonNull(*(op++));
}
/* Mark any special objects we have sitting around.
*/
LOG_SCAN("special objects\n");
dvmMarkObjectNonNull(gDvm.outOfMemoryObj);
dvmMarkObjectNonNull(gDvm.internalErrorObj);
//TODO: scan object references sitting in gDvm; use pointer begin & end
HPROF_CLEAR_GC_SCAN_STATE();
}
/* Find unreachable objects that need to be finalized,
* and schedule them for finalization.
*/
void dvmHeapScheduleFinalizations()
{
HeapRefTable newPendingRefs;
LargeHeapRefTable *finRefs = gDvm.gcHeap->finalizableRefs;
Object **ref;
Object **lastRef;
size_t totalPendCount;
GcMarkContext *markContext = &gDvm.gcHeap->markContext;
/*
* All reachable objects have been marked.
* Any unmarked finalizable objects need to be finalized.
*/
/* Create a table that the new pending refs will
* be added to.
*/
if (!dvmHeapInitHeapRefTable(&newPendingRefs, 128)) {
//TODO: mark all finalizable refs and hope that
// we can schedule them next time. Watch out,
// because we may be expecting to free up space
// by calling finalizers.
LOGE_GC("dvmHeapScheduleFinalizations(): no room for "
"pending finalizations\n");
dvmAbort();
}
/* Walk through finalizableRefs and move any unmarked references
* to the list of new pending refs.
*/
totalPendCount = 0;
while (finRefs != NULL) {
Object **gapRef;
size_t newPendCount = 0;
gapRef = ref = finRefs->refs.table;
lastRef = finRefs->refs.nextEntry;
while (ref < lastRef) {
DvmHeapChunk *hc;
hc = ptr2chunk(*ref);
if (!isMarked(hc, markContext)) {
if (!dvmHeapAddToHeapRefTable(&newPendingRefs, *ref)) {
//TODO: add the current table and allocate
// a new, smaller one.
LOGE_GC("dvmHeapScheduleFinalizations(): "
"no room for any more pending finalizations: %zd\n",
dvmHeapNumHeapRefTableEntries(&newPendingRefs));
dvmAbort();
}
newPendCount++;
} else {
/* This ref is marked, so will remain on finalizableRefs.
*/
if (newPendCount > 0) {
/* Copy it up to fill the holes.
*/
*gapRef++ = *ref;
} else {
/* No holes yet; don't bother copying.
*/
gapRef++;
}
}
ref++;
}
finRefs->refs.nextEntry = gapRef;
//TODO: if the table is empty when we're done, free it.
totalPendCount += newPendCount;
finRefs = finRefs->next;
}
LOGD_GC("dvmHeapScheduleFinalizations(): %zd finalizers triggered.\n",
totalPendCount);
if (totalPendCount == 0) {
/* No objects required finalization.
* Free the empty temporary table.
*/
dvmClearReferenceTable(&newPendingRefs);
return;
}
/* Add the new pending refs to the main list.
*/
if (!dvmHeapAddTableToLargeTable(&gDvm.gcHeap->pendingFinalizationRefs,
&newPendingRefs))
{
LOGE_GC("dvmHeapScheduleFinalizations(): can't insert new "
"pending finalizations\n");
dvmAbort();
}
//TODO: try compacting the main list with a memcpy loop
/* Mark the refs we just moved; we don't want them or their
* children to get swept yet.
*/
ref = newPendingRefs.table;
lastRef = newPendingRefs.nextEntry;
assert(ref < lastRef);
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_FINALIZING, 0);
while (ref < lastRef) {
markObjectNonNull(*ref, markContext);
ref++;
}
HPROF_CLEAR_GC_SCAN_STATE();
/* Set markAllReferents so that we don't collect referents whose
* only references are in final-reachable objects.
* TODO: eventually provide normal reference behavior by properly
* marking these references.
*/
gDvm.gcHeap->markAllReferents = true;
processMarkStack(markContext);
gDvm.gcHeap->markAllReferents = false;
dvmSignalHeapWorker(false);
}