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/*
* Copyright (C) 2011 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 "intern_table-inl.h"
#include <memory>
#include "dex/utf.h"
#include "gc/collector/garbage_collector.h"
#include "gc/space/image_space.h"
#include "gc/weak_root_state.h"
#include "gc_root-inl.h"
#include "handle_scope-inl.h"
#include "image-inl.h"
#include "mirror/dex_cache-inl.h"
#include "mirror/object-inl.h"
#include "mirror/object_array-inl.h"
#include "mirror/string-inl.h"
#include "object_callbacks.h"
#include "scoped_thread_state_change-inl.h"
#include "thread.h"
#include "thread-inl.h"
namespace art {
InternTable::InternTable()
: log_new_roots_(false),
weak_intern_condition_("New intern condition", *Locks::intern_table_lock_),
weak_root_state_(gc::kWeakRootStateNormal) {
}
size_t InternTable::Size() const {
MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
return strong_interns_.Size() + weak_interns_.Size();
}
size_t InternTable::StrongSize() const {
MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
return strong_interns_.Size();
}
size_t InternTable::WeakSize() const {
MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
return weak_interns_.Size();
}
void InternTable::DumpForSigQuit(std::ostream& os) const {
os << "Intern table: " << StrongSize() << " strong; " << WeakSize() << " weak\n";
}
void InternTable::VisitRoots(RootVisitor* visitor, VisitRootFlags flags) {
MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
if ((flags & kVisitRootFlagAllRoots) != 0) {
strong_interns_.VisitRoots(visitor);
} else if ((flags & kVisitRootFlagNewRoots) != 0) {
for (auto& root : new_strong_intern_roots_) {
ObjPtr<mirror::String> old_ref = root.Read<kWithoutReadBarrier>();
root.VisitRoot(visitor, RootInfo(kRootInternedString));
ObjPtr<mirror::String> new_ref = root.Read<kWithoutReadBarrier>();
if (new_ref != old_ref) {
// The GC moved a root in the log. Need to search the strong interns and update the
// corresponding object. This is slow, but luckily for us, this may only happen with a
// concurrent moving GC.
DCHECK(new_ref != nullptr);
uint32_t hash = static_cast<uint32_t>(old_ref->GetStoredHashCode());
DCHECK_EQ(hash, static_cast<uint32_t>(new_ref->GetStoredHashCode()));
DCHECK(new_ref->Equals(old_ref));
bool found = false;
for (Table::InternalTable& table : strong_interns_.tables_) {
auto it = table.set_.FindWithHash(GcRoot<mirror::String>(old_ref), hash);
if (it != table.set_.end()) {
*it = GcRoot<mirror::String>(new_ref);
found = true;
break;
}
}
DCHECK(found);
}
}
}
if ((flags & kVisitRootFlagClearRootLog) != 0) {
new_strong_intern_roots_.clear();
}
if ((flags & kVisitRootFlagStartLoggingNewRoots) != 0) {
log_new_roots_ = true;
} else if ((flags & kVisitRootFlagStopLoggingNewRoots) != 0) {
log_new_roots_ = false;
}
// Note: we deliberately don't visit the weak_interns_ table and the immutable image roots.
}
ObjPtr<mirror::String> InternTable::LookupWeak(Thread* self, ObjPtr<mirror::String> s) {
DCHECK(s != nullptr);
// `String::GetHashCode()` ensures that the stored hash is calculated.
uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
MutexLock mu(self, *Locks::intern_table_lock_);
return weak_interns_.Find(s, hash);
}
ObjPtr<mirror::String> InternTable::LookupStrong(Thread* self, ObjPtr<mirror::String> s) {
DCHECK(s != nullptr);
// `String::GetHashCode()` ensures that the stored hash is calculated.
uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
MutexLock mu(self, *Locks::intern_table_lock_);
return strong_interns_.Find(s, hash);
}
ObjPtr<mirror::String> InternTable::LookupStrong(Thread* self,
uint32_t utf16_length,
const char* utf8_data) {
uint32_t hash = Utf8String::Hash(utf16_length, utf8_data);
MutexLock mu(self, *Locks::intern_table_lock_);
return strong_interns_.Find(Utf8String(utf16_length, utf8_data), hash);
}
ObjPtr<mirror::String> InternTable::LookupWeakLocked(ObjPtr<mirror::String> s) {
DCHECK(s != nullptr);
// `String::GetHashCode()` ensures that the stored hash is calculated.
uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
return weak_interns_.Find(s, hash);
}
ObjPtr<mirror::String> InternTable::LookupStrongLocked(ObjPtr<mirror::String> s) {
DCHECK(s != nullptr);
// `String::GetHashCode()` ensures that the stored hash is calculated.
uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
return strong_interns_.Find(s, hash);
}
void InternTable::AddNewTable() {
MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
weak_interns_.AddNewTable();
strong_interns_.AddNewTable();
}
ObjPtr<mirror::String> InternTable::InsertStrong(ObjPtr<mirror::String> s, uint32_t hash) {
Runtime* runtime = Runtime::Current();
if (runtime->IsActiveTransaction()) {
runtime->RecordStrongStringInsertion(s);
}
if (log_new_roots_) {
new_strong_intern_roots_.push_back(GcRoot<mirror::String>(s));
}
strong_interns_.Insert(s, hash);
return s;
}
ObjPtr<mirror::String> InternTable::InsertWeak(ObjPtr<mirror::String> s, uint32_t hash) {
Runtime* runtime = Runtime::Current();
if (runtime->IsActiveTransaction()) {
runtime->RecordWeakStringInsertion(s);
}
weak_interns_.Insert(s, hash);
return s;
}
void InternTable::RemoveStrong(ObjPtr<mirror::String> s, uint32_t hash) {
strong_interns_.Remove(s, hash);
}
void InternTable::RemoveWeak(ObjPtr<mirror::String> s, uint32_t hash) {
Runtime* runtime = Runtime::Current();
if (runtime->IsActiveTransaction()) {
runtime->RecordWeakStringRemoval(s);
}
weak_interns_.Remove(s, hash);
}
void InternTable::BroadcastForNewInterns() {
Thread* self = Thread::Current();
MutexLock mu(self, *Locks::intern_table_lock_);
weak_intern_condition_.Broadcast(self);
}
void InternTable::WaitUntilAccessible(Thread* self) {
Locks::intern_table_lock_->ExclusiveUnlock(self);
{
ScopedThreadSuspension sts(self, ThreadState::kWaitingWeakGcRootRead);
MutexLock mu(self, *Locks::intern_table_lock_);
while ((!gUseReadBarrier && weak_root_state_ == gc::kWeakRootStateNoReadsOrWrites) ||
(gUseReadBarrier && !self->GetWeakRefAccessEnabled())) {
weak_intern_condition_.Wait(self);
}
}
Locks::intern_table_lock_->ExclusiveLock(self);
}
ObjPtr<mirror::String> InternTable::Insert(ObjPtr<mirror::String> s,
uint32_t hash,
bool is_strong,
size_t num_searched_strong_frozen_tables) {
DCHECK(s != nullptr);
DCHECK_EQ(hash, static_cast<uint32_t>(s->GetStoredHashCode()));
DCHECK_IMPLIES(hash == 0u, s->ComputeHashCode() == 0);
Thread* const self = Thread::Current();
MutexLock mu(self, *Locks::intern_table_lock_);
if (kDebugLocking) {
Locks::mutator_lock_->AssertSharedHeld(self);
CHECK_EQ(2u, self->NumberOfHeldMutexes()) << "may only safely hold the mutator lock";
}
while (true) {
// Check the strong table for a match.
ObjPtr<mirror::String> strong =
strong_interns_.Find(s, hash, num_searched_strong_frozen_tables);
if (strong != nullptr) {
return strong;
}
if (gUseReadBarrier ? self->GetWeakRefAccessEnabled()
: weak_root_state_ != gc::kWeakRootStateNoReadsOrWrites) {
break;
}
num_searched_strong_frozen_tables = strong_interns_.tables_.size() - 1u;
// weak_root_state_ is set to gc::kWeakRootStateNoReadsOrWrites in the GC pause but is only
// cleared after SweepSystemWeaks has completed. This is why we need to wait until it is
// cleared.
StackHandleScope<1> hs(self);
auto h = hs.NewHandleWrapper(&s);
WaitUntilAccessible(self);
}
if (!gUseReadBarrier) {
CHECK_EQ(weak_root_state_, gc::kWeakRootStateNormal);
} else {
CHECK(self->GetWeakRefAccessEnabled());
}
// There is no match in the strong table, check the weak table.
ObjPtr<mirror::String> weak = weak_interns_.Find(s, hash);
if (weak != nullptr) {
if (is_strong) {
// A match was found in the weak table. Promote to the strong table.
RemoveWeak(weak, hash);
return InsertStrong(weak, hash);
}
return weak;
}
// No match in the strong table or the weak table. Insert into the strong / weak table.
return is_strong ? InsertStrong(s, hash) : InsertWeak(s, hash);
}
ObjPtr<mirror::String> InternTable::InternStrong(uint32_t utf16_length, const char* utf8_data) {
DCHECK(utf8_data != nullptr);
uint32_t hash = Utf8String::Hash(utf16_length, utf8_data);
Thread* self = Thread::Current();
ObjPtr<mirror::String> s;
size_t num_searched_strong_frozen_tables;
{
// Try to avoid allocation. If we need to allocate, release the mutex before the allocation.
MutexLock mu(self, *Locks::intern_table_lock_);
DCHECK(!strong_interns_.tables_.empty());
num_searched_strong_frozen_tables = strong_interns_.tables_.size() - 1u;
s = strong_interns_.Find(Utf8String(utf16_length, utf8_data), hash);
}
if (s != nullptr) {
return s;
}
bool is_ascii = (utf8_data[utf16_length] == 0);
int32_t utf8_length = utf16_length + (LIKELY(is_ascii) ? 0 : strlen(utf8_data + utf16_length));
DCHECK_EQ(static_cast<size_t>(utf8_length), strlen(utf8_data));
s = mirror::String::AllocFromModifiedUtf8(self, utf16_length, utf8_data, utf8_length);
if (UNLIKELY(s == nullptr)) {
self->AssertPendingOOMException();
return nullptr;
}
s->SetHashCode(static_cast<int32_t>(hash));
return Insert(s, hash, /*is_strong=*/ true, num_searched_strong_frozen_tables);
}
ObjPtr<mirror::String> InternTable::InternStrong(const char* utf8_data) {
DCHECK(utf8_data != nullptr);
Thread* self = Thread::Current();
ObjPtr<mirror::String> s = mirror::String::AllocFromModifiedUtf8(self, utf8_data);
if (UNLIKELY(s == nullptr)) {
self->AssertPendingOOMException();
return nullptr;
}
return InternStrong(s);
}
ObjPtr<mirror::String> InternTable::InternStrong(ObjPtr<mirror::String> s) {
DCHECK(s != nullptr);
// `String::GetHashCode()` ensures that the stored hash is calculated.
uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
return Insert(s, hash, /*is_strong=*/ true);
}
ObjPtr<mirror::String> InternTable::InternWeak(const char* utf8_data) {
DCHECK(utf8_data != nullptr);
Thread* self = Thread::Current();
ObjPtr<mirror::String> s = mirror::String::AllocFromModifiedUtf8(self, utf8_data);
if (UNLIKELY(s == nullptr)) {
self->AssertPendingOOMException();
return nullptr;
}
return InternWeak(s);
}
ObjPtr<mirror::String> InternTable::InternWeak(ObjPtr<mirror::String> s) {
DCHECK(s != nullptr);
// `String::GetHashCode()` ensures that the stored hash is calculated.
uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
return Insert(s, hash, /*is_strong=*/ false);
}
void InternTable::SweepInternTableWeaks(IsMarkedVisitor* visitor) {
MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
weak_interns_.SweepWeaks(visitor);
}
void InternTable::Table::Remove(ObjPtr<mirror::String> s, uint32_t hash) {
// Note: We can remove weak interns even from frozen tables when promoting to strong interns.
// We can remove strong interns only for a transaction rollback.
for (InternalTable& table : tables_) {
auto it = table.set_.FindWithHash(GcRoot<mirror::String>(s), hash);
if (it != table.set_.end()) {
table.set_.erase(it);
return;
}
}
LOG(FATAL) << "Attempting to remove non-interned string " << s->ToModifiedUtf8();
}
FLATTEN
ObjPtr<mirror::String> InternTable::Table::Find(ObjPtr<mirror::String> s,
uint32_t hash,
size_t num_searched_frozen_tables) {
Locks::intern_table_lock_->AssertHeld(Thread::Current());
auto mid = tables_.begin() + num_searched_frozen_tables;
for (Table::InternalTable& table : MakeIterationRange(tables_.begin(), mid)) {
DCHECK(table.set_.FindWithHash(GcRoot<mirror::String>(s), hash) == table.set_.end());
}
// Search from the last table, assuming that apps shall search for their own
// strings more often than for boot image strings.
for (Table::InternalTable& table : ReverseRange(MakeIterationRange(mid, tables_.end()))) {
auto it = table.set_.FindWithHash(GcRoot<mirror::String>(s), hash);
if (it != table.set_.end()) {
return it->Read();
}
}
return nullptr;
}
FLATTEN
ObjPtr<mirror::String> InternTable::Table::Find(const Utf8String& string, uint32_t hash) {
Locks::intern_table_lock_->AssertHeld(Thread::Current());
// Search from the last table, assuming that apps shall search for their own
// strings more often than for boot image strings.
for (InternalTable& table : ReverseRange(tables_)) {
auto it = table.set_.FindWithHash(string, hash);
if (it != table.set_.end()) {
return it->Read();
}
}
return nullptr;
}
void InternTable::Table::AddNewTable() {
// Propagate the min/max load factor from the old active set.
DCHECK(!tables_.empty());
const UnorderedSet& last_set = tables_.back().set_;
InternalTable new_table;
new_table.set_.SetLoadFactor(last_set.GetMinLoadFactor(), last_set.GetMaxLoadFactor());
tables_.push_back(std::move(new_table));
}
void InternTable::Table::Insert(ObjPtr<mirror::String> s, uint32_t hash) {
// Always insert the last table, the image tables are before and we avoid inserting into these
// to prevent dirty pages.
DCHECK(!tables_.empty());
tables_.back().set_.PutWithHash(GcRoot<mirror::String>(s), hash);
}
void InternTable::Table::VisitRoots(RootVisitor* visitor) {
BufferedRootVisitor<kDefaultBufferedRootCount> buffered_visitor(
visitor, RootInfo(kRootInternedString));
for (InternalTable& table : tables_) {
for (auto& intern : table.set_) {
buffered_visitor.VisitRoot(intern);
}
}
}
void InternTable::Table::SweepWeaks(IsMarkedVisitor* visitor) {
for (InternalTable& table : tables_) {
SweepWeaks(&table.set_, visitor);
}
}
void InternTable::Table::SweepWeaks(UnorderedSet* set, IsMarkedVisitor* visitor) {
for (auto it = set->begin(), end = set->end(); it != end;) {
// This does not need a read barrier because this is called by GC.
mirror::Object* object = it->Read<kWithoutReadBarrier>();
mirror::Object* new_object = visitor->IsMarked(object);
if (new_object == nullptr) {
it = set->erase(it);
} else {
// Don't use AsString as it does IsString check in debug builds which, in
// case of userfaultfd GC, is called when the object's content isn't
// thereyet.
*it = GcRoot<mirror::String>(ObjPtr<mirror::String>::DownCast(new_object));
++it;
}
}
}
size_t InternTable::Table::Size() const {
return std::accumulate(tables_.begin(),
tables_.end(),
0U,
[](size_t sum, const InternalTable& table) {
return sum + table.Size();
});
}
void InternTable::ChangeWeakRootState(gc::WeakRootState new_state) {
MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
ChangeWeakRootStateLocked(new_state);
}
void InternTable::ChangeWeakRootStateLocked(gc::WeakRootState new_state) {
CHECK(!gUseReadBarrier);
weak_root_state_ = new_state;
if (new_state != gc::kWeakRootStateNoReadsOrWrites) {
weak_intern_condition_.Broadcast(Thread::Current());
}
}
InternTable::Table::Table() {
Runtime* const runtime = Runtime::Current();
InternalTable initial_table;
initial_table.set_.SetLoadFactor(runtime->GetHashTableMinLoadFactor(),
runtime->GetHashTableMaxLoadFactor());
tables_.push_back(std::move(initial_table));
}
} // namespace art