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aosp12/art/runtime/reference_table.cc

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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "reference_table.h"
#include "android-base/stringprintf.h"
#include "base/mutex.h"
#include "base/utils.h"
#include "gc/allocation_record.h"
#include "gc/heap.h"
#include "indirect_reference_table.h"
#include "mirror/array-inl.h"
#include "mirror/array.h"
#include "mirror/class-inl.h"
#include "mirror/class.h"
#include "mirror/object-inl.h"
#include "mirror/string-inl.h"
#include "runtime-inl.h"
#include "thread.h"
namespace art {
using android::base::StringAppendF;
using android::base::StringPrintf;
ReferenceTable::ReferenceTable(const char* name, size_t initial_size, size_t max_size)
: name_(name), max_size_(max_size) {
CHECK_LE(initial_size, max_size);
entries_.reserve(initial_size);
}
ReferenceTable::~ReferenceTable() {
}
void ReferenceTable::Add(ObjPtr<mirror::Object> obj) {
DCHECK(obj != nullptr);
VerifyObject(obj);
if (entries_.size() >= max_size_) {
LOG(FATAL) << "ReferenceTable '" << name_ << "' "
<< "overflowed (" << max_size_ << " entries)";
}
entries_.push_back(GcRoot<mirror::Object>(obj));
}
void ReferenceTable::Remove(ObjPtr<mirror::Object> obj) {
// We iterate backwards on the assumption that references are LIFO.
for (int i = entries_.size() - 1; i >= 0; --i) {
ObjPtr<mirror::Object> entry = entries_[i].Read();
if (entry == obj) {
entries_.erase(entries_.begin() + i);
return;
}
}
}
// If "obj" is an array, return the number of elements in the array.
// Otherwise, return zero.
static size_t GetElementCount(ObjPtr<mirror::Object> obj) REQUIRES_SHARED(Locks::mutator_lock_) {
// We assume the special cleared value isn't an array in the if statement below.
DCHECK(!Runtime::Current()->GetClearedJniWeakGlobal()->IsArrayInstance());
if (obj == nullptr || !obj->IsArrayInstance()) {
return 0;
}
return obj->AsArray()->GetLength();
}
// Log an object with some additional info.
//
// Pass in the number of elements in the array (or 0 if this is not an
// array object), and the number of additional objects that are identical
// or equivalent to the original.
static void DumpSummaryLine(std::ostream& os, ObjPtr<mirror::Object> obj, size_t element_count,
int identical, int equiv)
REQUIRES_SHARED(Locks::mutator_lock_) {
if (obj == nullptr) {
os << " null reference (count=" << equiv << ")\n";
return;
}
if (Runtime::Current()->IsClearedJniWeakGlobal(obj)) {
os << " cleared jweak (count=" << equiv << ")\n";
return;
}
std::string className(obj->PrettyTypeOf());
if (obj->IsClass()) {
// We're summarizing multiple instances, so using the exemplar
// Class' type parameter here would be misleading.
className = "java.lang.Class";
}
if (element_count != 0) {
StringAppendF(&className, " (%zd elements)", element_count);
}
size_t total = identical + equiv + 1;
std::string msg(StringPrintf("%5zd of %s", total, className.c_str()));
if (identical + equiv != 0) {
StringAppendF(&msg, " (%d unique instances)", equiv + 1);
}
os << " " << msg << "\n";
}
size_t ReferenceTable::Size() const {
return entries_.size();
}
void ReferenceTable::Dump(std::ostream& os) {
os << name_ << " reference table dump:\n";
Dump(os, entries_);
}
void ReferenceTable::Dump(std::ostream& os, Table& entries) {
// Compare GC roots, first by class, then size, then address.
struct GcRootComparator {
bool operator()(GcRoot<mirror::Object> root1, GcRoot<mirror::Object> root2) const
// TODO: enable analysis when analysis can work with the STL.
NO_THREAD_SAFETY_ANALYSIS {
Locks::mutator_lock_->AssertSharedHeld(Thread::Current());
// These GC roots are already forwarded in ReferenceTable::Dump. We sort by class since there
// are no suspend points which can happen during the sorting process. This works since
// we are guaranteed that the addresses of obj1, obj2, obj1->GetClass, obj2->GetClass wont
// change during the sorting process. The classes are forwarded by ref->GetClass().
ObjPtr<mirror::Object> obj1 = root1.Read<kWithoutReadBarrier>();
ObjPtr<mirror::Object> obj2 = root2.Read<kWithoutReadBarrier>();
DCHECK(obj1 != nullptr);
DCHECK(obj2 != nullptr);
Runtime* runtime = Runtime::Current();
DCHECK(!runtime->IsClearedJniWeakGlobal(obj1));
DCHECK(!runtime->IsClearedJniWeakGlobal(obj2));
// Sort by class...
if (obj1->GetClass() != obj2->GetClass()) {
return obj1->GetClass() < obj2->GetClass();
}
// ...then by size...
const size_t size1 = obj1->SizeOf();
const size_t size2 = obj2->SizeOf();
if (size1 != size2) {
return size1 < size2;
}
// ...and finally by address.
return obj1.Ptr() < obj2.Ptr();
}
};
if (entries.empty()) {
os << " (empty)\n";
return;
}
// Dump the most recent N entries.
const size_t kLast = 10;
size_t count = entries.size();
int first = count - kLast;
if (first < 0) {
first = 0;
}
os << " Last " << (count - first) << " entries (of " << count << "):\n";
Runtime* runtime = Runtime::Current();
for (int idx = count - 1; idx >= first; --idx) {
ObjPtr<mirror::Object> ref = entries[idx].Read();
if (ref == nullptr) {
continue;
}
if (runtime->IsClearedJniWeakGlobal(ref)) {
os << StringPrintf(" %5d: cleared jweak\n", idx);
continue;
}
if (ref->GetClass() == nullptr) {
// should only be possible right after a plain dvmMalloc().
size_t size = ref->SizeOf();
os << StringPrintf(" %5d: %p (raw) (%zd bytes)\n", idx, ref.Ptr(), size);
continue;
}
std::string className(ref->PrettyTypeOf());
std::string extras;
size_t element_count = GetElementCount(ref);
if (element_count != 0) {
StringAppendF(&extras, " (%zd elements)", element_count);
} else if (ref->GetClass()->IsStringClass()) {
ObjPtr<mirror::String> s = ref->AsString();
std::string utf8(s->ToModifiedUtf8());
if (s->GetLength() <= 16) {
StringAppendF(&extras, " \"%s\"", utf8.c_str());
} else {
StringAppendF(&extras, " \"%.16s... (%d chars)", utf8.c_str(), s->GetLength());
}
} else if (ref->IsReferenceInstance()) {
ObjPtr<mirror::Object> referent = ref->AsReference()->GetReferent();
if (referent == nullptr) {
extras = " (referent is null)";
} else {
extras = StringPrintf(" (referent is a %s)", referent->PrettyTypeOf().c_str());
}
}
os << StringPrintf(" %5d: ", idx) << ref << " " << className << extras << "\n";
if (runtime->GetHeap()->IsAllocTrackingEnabled()) {
MutexLock mu(Thread::Current(), *Locks::alloc_tracker_lock_);
gc::AllocRecordObjectMap* records = runtime->GetHeap()->GetAllocationRecords();
DCHECK(records != nullptr);
// It's annoying that this is a list. But this code should be very uncommon to be executed.
auto print_stack = [&](ObjPtr<mirror::Object> to_print, const std::string& msg)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(Locks::alloc_tracker_lock_) {
for (auto it = records->Begin(), end = records->End(); it != end; ++it) {
GcRoot<mirror::Object>& stack_for_object = it->first;
gc::AllocRecord& record = it->second;
if (stack_for_object.Read() == to_print.Ptr()) {
os << " " << msg << "\n";
const gc::AllocRecordStackTrace* trace = record.GetStackTrace();
size_t depth = trace->GetDepth();
if (depth == 0) {
os << " (No managed frames)\n";
} else {
for (size_t i = 0; i < depth; ++i) {
const gc::AllocRecordStackTraceElement& frame = trace->GetStackElement(i);
os << " ";
if (frame.GetMethod() == nullptr) {
os << "(missing method data)\n";
continue;
}
os << frame.GetMethod()->PrettyMethod(true)
<< ":"
<< frame.ComputeLineNumber()
<< "\n";
}
}
break;
}
}
};
// Print the stack trace of the ref.
print_stack(ref, "Allocated at:");
// If it's a reference, see if we have data about the referent.
if (ref->IsReferenceInstance()) {
ObjPtr<mirror::Object> referent = ref->AsReference()->GetReferent();
if (referent != nullptr) {
print_stack(referent, "Referent allocated at:");
}
}
}
}
// Make a copy of the table and sort it, only adding non null and not cleared elements.
Table sorted_entries;
for (GcRoot<mirror::Object>& root : entries) {
if (!root.IsNull() && !runtime->IsClearedJniWeakGlobal(root.Read())) {
sorted_entries.push_back(root);
}
}
if (sorted_entries.empty()) {
return;
}
std::sort(sorted_entries.begin(), sorted_entries.end(), GcRootComparator());
class SummaryElement {
public:
GcRoot<mirror::Object> root;
size_t equiv;
size_t identical;
SummaryElement() : equiv(0), identical(0) {}
SummaryElement(SummaryElement&& ref) noexcept {
root = ref.root;
equiv = ref.equiv;
identical = ref.identical;
}
SummaryElement(const SummaryElement&) = default;
SummaryElement& operator=(SummaryElement&&) = default;
void Reset(GcRoot<mirror::Object>& _root) {
root = _root;
equiv = 0;
identical = 0;
}
};
std::vector<SummaryElement> sorted_summaries;
{
SummaryElement prev;
for (GcRoot<mirror::Object>& root : sorted_entries) {
ObjPtr<mirror::Object> current = root.Read<kWithoutReadBarrier>();
if (UNLIKELY(prev.root.IsNull())) {
prev.Reset(root);
continue;
}
ObjPtr<mirror::Object> prevObj = prev.root.Read<kWithoutReadBarrier>();
if (current == prevObj) {
// Same reference, added more than once.
++prev.identical;
} else if (current->GetClass() == prevObj->GetClass() &&
GetElementCount(current) == GetElementCount(prevObj)) {
// Same class / element count, different object.
++prev.equiv;
} else {
sorted_summaries.push_back(prev);
prev.Reset(root);
}
prev.root = root;
}
sorted_summaries.push_back(prev);
// Compare summary elements, first by combined count, then by identical (indicating leaks),
// then by class (and size and address).
struct SummaryElementComparator {
GcRootComparator gc_root_cmp;
bool operator()(SummaryElement& elem1, SummaryElement& elem2) const
NO_THREAD_SAFETY_ANALYSIS {
Locks::mutator_lock_->AssertSharedHeld(Thread::Current());
size_t count1 = elem1.equiv + elem1.identical;
size_t count2 = elem2.equiv + elem2.identical;
if (count1 != count2) {
return count1 > count2;
}
if (elem1.identical != elem2.identical) {
return elem1.identical > elem2.identical;
}
// Otherwise, compare the GC roots as before.
return gc_root_cmp(elem1.root, elem2.root);
}
};
std::sort(sorted_summaries.begin(), sorted_summaries.end(), SummaryElementComparator());
}
// Dump a summary of the whole table.
os << " Summary:\n";
for (SummaryElement& elem : sorted_summaries) {
ObjPtr<mirror::Object> elemObj = elem.root.Read<kWithoutReadBarrier>();
DumpSummaryLine(os, elemObj, GetElementCount(elemObj), elem.identical, elem.equiv);
}
}
void ReferenceTable::VisitRoots(RootVisitor* visitor, const RootInfo& root_info) {
BufferedRootVisitor<kDefaultBufferedRootCount> buffered_visitor(visitor, root_info);
for (GcRoot<mirror::Object>& root : entries_) {
buffered_visitor.VisitRoot(root);
}
}
} // namespace art
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