445 lines
16 KiB
C++
445 lines
16 KiB
C++
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "intern_table-inl.h"
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#include <memory>
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#include "dex/utf.h"
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#include "gc/collector/garbage_collector.h"
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#include "gc/space/image_space.h"
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#include "gc/weak_root_state.h"
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#include "gc_root-inl.h"
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#include "handle_scope-inl.h"
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#include "image-inl.h"
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#include "mirror/dex_cache-inl.h"
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#include "mirror/object-inl.h"
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#include "mirror/object_array-inl.h"
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#include "mirror/string-inl.h"
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#include "object_callbacks.h"
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#include "scoped_thread_state_change-inl.h"
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#include "thread.h"
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#include "thread-inl.h"
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namespace art {
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InternTable::InternTable()
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: log_new_roots_(false),
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weak_intern_condition_("New intern condition", *Locks::intern_table_lock_),
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weak_root_state_(gc::kWeakRootStateNormal) {
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}
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size_t InternTable::Size() const {
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MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
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return strong_interns_.Size() + weak_interns_.Size();
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}
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size_t InternTable::StrongSize() const {
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MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
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return strong_interns_.Size();
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}
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size_t InternTable::WeakSize() const {
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MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
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return weak_interns_.Size();
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}
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void InternTable::DumpForSigQuit(std::ostream& os) const {
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os << "Intern table: " << StrongSize() << " strong; " << WeakSize() << " weak\n";
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}
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void InternTable::VisitRoots(RootVisitor* visitor, VisitRootFlags flags) {
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MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
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if ((flags & kVisitRootFlagAllRoots) != 0) {
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strong_interns_.VisitRoots(visitor);
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} else if ((flags & kVisitRootFlagNewRoots) != 0) {
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for (auto& root : new_strong_intern_roots_) {
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ObjPtr<mirror::String> old_ref = root.Read<kWithoutReadBarrier>();
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root.VisitRoot(visitor, RootInfo(kRootInternedString));
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ObjPtr<mirror::String> new_ref = root.Read<kWithoutReadBarrier>();
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if (new_ref != old_ref) {
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// The GC moved a root in the log. Need to search the strong interns and update the
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// corresponding object. This is slow, but luckily for us, this may only happen with a
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// concurrent moving GC.
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DCHECK(new_ref != nullptr);
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uint32_t hash = static_cast<uint32_t>(old_ref->GetStoredHashCode());
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DCHECK_EQ(hash, static_cast<uint32_t>(new_ref->GetStoredHashCode()));
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DCHECK(new_ref->Equals(old_ref));
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bool found = false;
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for (Table::InternalTable& table : strong_interns_.tables_) {
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auto it = table.set_.FindWithHash(GcRoot<mirror::String>(old_ref), hash);
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if (it != table.set_.end()) {
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*it = GcRoot<mirror::String>(new_ref);
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found = true;
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break;
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}
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}
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DCHECK(found);
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}
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}
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}
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if ((flags & kVisitRootFlagClearRootLog) != 0) {
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new_strong_intern_roots_.clear();
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}
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if ((flags & kVisitRootFlagStartLoggingNewRoots) != 0) {
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log_new_roots_ = true;
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} else if ((flags & kVisitRootFlagStopLoggingNewRoots) != 0) {
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log_new_roots_ = false;
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}
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// Note: we deliberately don't visit the weak_interns_ table and the immutable image roots.
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}
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ObjPtr<mirror::String> InternTable::LookupWeak(Thread* self, ObjPtr<mirror::String> s) {
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DCHECK(s != nullptr);
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// `String::GetHashCode()` ensures that the stored hash is calculated.
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uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
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MutexLock mu(self, *Locks::intern_table_lock_);
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return weak_interns_.Find(s, hash);
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}
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ObjPtr<mirror::String> InternTable::LookupStrong(Thread* self, ObjPtr<mirror::String> s) {
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DCHECK(s != nullptr);
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// `String::GetHashCode()` ensures that the stored hash is calculated.
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uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
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MutexLock mu(self, *Locks::intern_table_lock_);
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return strong_interns_.Find(s, hash);
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}
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ObjPtr<mirror::String> InternTable::LookupStrong(Thread* self,
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uint32_t utf16_length,
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const char* utf8_data) {
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uint32_t hash = Utf8String::Hash(utf16_length, utf8_data);
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MutexLock mu(self, *Locks::intern_table_lock_);
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return strong_interns_.Find(Utf8String(utf16_length, utf8_data), hash);
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}
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ObjPtr<mirror::String> InternTable::LookupWeakLocked(ObjPtr<mirror::String> s) {
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DCHECK(s != nullptr);
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// `String::GetHashCode()` ensures that the stored hash is calculated.
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uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
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return weak_interns_.Find(s, hash);
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}
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ObjPtr<mirror::String> InternTable::LookupStrongLocked(ObjPtr<mirror::String> s) {
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DCHECK(s != nullptr);
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// `String::GetHashCode()` ensures that the stored hash is calculated.
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uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
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return strong_interns_.Find(s, hash);
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}
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void InternTable::AddNewTable() {
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MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
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weak_interns_.AddNewTable();
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strong_interns_.AddNewTable();
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}
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ObjPtr<mirror::String> InternTable::InsertStrong(ObjPtr<mirror::String> s, uint32_t hash) {
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Runtime* runtime = Runtime::Current();
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if (runtime->IsActiveTransaction()) {
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runtime->RecordStrongStringInsertion(s);
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}
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if (log_new_roots_) {
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new_strong_intern_roots_.push_back(GcRoot<mirror::String>(s));
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}
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strong_interns_.Insert(s, hash);
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return s;
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}
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ObjPtr<mirror::String> InternTable::InsertWeak(ObjPtr<mirror::String> s, uint32_t hash) {
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Runtime* runtime = Runtime::Current();
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if (runtime->IsActiveTransaction()) {
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runtime->RecordWeakStringInsertion(s);
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}
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weak_interns_.Insert(s, hash);
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return s;
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}
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void InternTable::RemoveStrong(ObjPtr<mirror::String> s, uint32_t hash) {
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strong_interns_.Remove(s, hash);
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}
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void InternTable::RemoveWeak(ObjPtr<mirror::String> s, uint32_t hash) {
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Runtime* runtime = Runtime::Current();
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if (runtime->IsActiveTransaction()) {
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runtime->RecordWeakStringRemoval(s);
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}
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weak_interns_.Remove(s, hash);
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}
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void InternTable::BroadcastForNewInterns() {
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Thread* self = Thread::Current();
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MutexLock mu(self, *Locks::intern_table_lock_);
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weak_intern_condition_.Broadcast(self);
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}
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void InternTable::WaitUntilAccessible(Thread* self) {
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Locks::intern_table_lock_->ExclusiveUnlock(self);
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{
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ScopedThreadSuspension sts(self, ThreadState::kWaitingWeakGcRootRead);
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MutexLock mu(self, *Locks::intern_table_lock_);
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while ((!kUseReadBarrier && weak_root_state_ == gc::kWeakRootStateNoReadsOrWrites) ||
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(kUseReadBarrier && !self->GetWeakRefAccessEnabled())) {
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weak_intern_condition_.Wait(self);
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}
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}
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Locks::intern_table_lock_->ExclusiveLock(self);
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}
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ObjPtr<mirror::String> InternTable::Insert(ObjPtr<mirror::String> s,
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uint32_t hash,
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bool is_strong,
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size_t num_searched_strong_frozen_tables) {
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DCHECK(s != nullptr);
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DCHECK_EQ(hash, static_cast<uint32_t>(s->GetStoredHashCode()));
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DCHECK_IMPLIES(hash == 0u, s->ComputeHashCode() == 0);
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Thread* const self = Thread::Current();
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MutexLock mu(self, *Locks::intern_table_lock_);
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if (kDebugLocking) {
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Locks::mutator_lock_->AssertSharedHeld(self);
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CHECK_EQ(2u, self->NumberOfHeldMutexes()) << "may only safely hold the mutator lock";
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}
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while (true) {
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// Check the strong table for a match.
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ObjPtr<mirror::String> strong =
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strong_interns_.Find(s, hash, num_searched_strong_frozen_tables);
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if (strong != nullptr) {
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return strong;
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}
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if (kUseReadBarrier ? self->GetWeakRefAccessEnabled()
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: weak_root_state_ != gc::kWeakRootStateNoReadsOrWrites) {
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break;
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}
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num_searched_strong_frozen_tables = strong_interns_.tables_.size() - 1u;
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// weak_root_state_ is set to gc::kWeakRootStateNoReadsOrWrites in the GC pause but is only
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// cleared after SweepSystemWeaks has completed. This is why we need to wait until it is
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// cleared.
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StackHandleScope<1> hs(self);
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auto h = hs.NewHandleWrapper(&s);
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WaitUntilAccessible(self);
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}
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if (!kUseReadBarrier) {
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CHECK_EQ(weak_root_state_, gc::kWeakRootStateNormal);
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} else {
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CHECK(self->GetWeakRefAccessEnabled());
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}
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// There is no match in the strong table, check the weak table.
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ObjPtr<mirror::String> weak = weak_interns_.Find(s, hash);
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if (weak != nullptr) {
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if (is_strong) {
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// A match was found in the weak table. Promote to the strong table.
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RemoveWeak(weak, hash);
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return InsertStrong(weak, hash);
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}
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return weak;
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}
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// No match in the strong table or the weak table. Insert into the strong / weak table.
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return is_strong ? InsertStrong(s, hash) : InsertWeak(s, hash);
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}
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ObjPtr<mirror::String> InternTable::InternStrong(uint32_t utf16_length, const char* utf8_data) {
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DCHECK(utf8_data != nullptr);
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uint32_t hash = Utf8String::Hash(utf16_length, utf8_data);
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Thread* self = Thread::Current();
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ObjPtr<mirror::String> s;
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size_t num_searched_strong_frozen_tables;
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{
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// Try to avoid allocation. If we need to allocate, release the mutex before the allocation.
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MutexLock mu(self, *Locks::intern_table_lock_);
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DCHECK(!strong_interns_.tables_.empty());
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num_searched_strong_frozen_tables = strong_interns_.tables_.size() - 1u;
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s = strong_interns_.Find(Utf8String(utf16_length, utf8_data), hash);
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}
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if (s != nullptr) {
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return s;
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}
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bool is_ascii = (utf8_data[utf16_length] == 0);
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int32_t utf8_length = utf16_length + (LIKELY(is_ascii) ? 0 : strlen(utf8_data + utf16_length));
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DCHECK_EQ(static_cast<size_t>(utf8_length), strlen(utf8_data));
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s = mirror::String::AllocFromModifiedUtf8(self, utf16_length, utf8_data, utf8_length);
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if (UNLIKELY(s == nullptr)) {
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self->AssertPendingOOMException();
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return nullptr;
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}
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s->SetHashCode(static_cast<int32_t>(hash));
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return Insert(s, hash, /*is_strong=*/ true, num_searched_strong_frozen_tables);
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}
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ObjPtr<mirror::String> InternTable::InternStrong(const char* utf8_data) {
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DCHECK(utf8_data != nullptr);
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Thread* self = Thread::Current();
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ObjPtr<mirror::String> s = mirror::String::AllocFromModifiedUtf8(self, utf8_data);
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if (UNLIKELY(s == nullptr)) {
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self->AssertPendingOOMException();
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return nullptr;
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}
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return InternStrong(s);
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}
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ObjPtr<mirror::String> InternTable::InternStrong(ObjPtr<mirror::String> s) {
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DCHECK(s != nullptr);
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// `String::GetHashCode()` ensures that the stored hash is calculated.
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uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
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return Insert(s, hash, /*is_strong=*/ true);
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}
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ObjPtr<mirror::String> InternTable::InternWeak(const char* utf8_data) {
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DCHECK(utf8_data != nullptr);
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Thread* self = Thread::Current();
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ObjPtr<mirror::String> s = mirror::String::AllocFromModifiedUtf8(self, utf8_data);
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if (UNLIKELY(s == nullptr)) {
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self->AssertPendingOOMException();
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return nullptr;
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}
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return InternWeak(s);
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}
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ObjPtr<mirror::String> InternTable::InternWeak(ObjPtr<mirror::String> s) {
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DCHECK(s != nullptr);
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// `String::GetHashCode()` ensures that the stored hash is calculated.
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uint32_t hash = static_cast<uint32_t>(s->GetHashCode());
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return Insert(s, hash, /*is_strong=*/ false);
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}
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void InternTable::SweepInternTableWeaks(IsMarkedVisitor* visitor) {
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MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
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weak_interns_.SweepWeaks(visitor);
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}
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void InternTable::Table::Remove(ObjPtr<mirror::String> s, uint32_t hash) {
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// Note: We can remove weak interns even from frozen tables when promoting to strong interns.
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// We can remove strong interns only for a transaction rollback.
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for (InternalTable& table : tables_) {
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auto it = table.set_.FindWithHash(GcRoot<mirror::String>(s), hash);
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if (it != table.set_.end()) {
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table.set_.erase(it);
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return;
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}
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}
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LOG(FATAL) << "Attempting to remove non-interned string " << s->ToModifiedUtf8();
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}
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FLATTEN
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ObjPtr<mirror::String> InternTable::Table::Find(ObjPtr<mirror::String> s,
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uint32_t hash,
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size_t num_searched_frozen_tables) {
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Locks::intern_table_lock_->AssertHeld(Thread::Current());
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auto mid = tables_.begin() + num_searched_frozen_tables;
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for (Table::InternalTable& table : MakeIterationRange(tables_.begin(), mid)) {
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DCHECK(table.set_.FindWithHash(GcRoot<mirror::String>(s), hash) == table.set_.end());
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}
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// Search from the last table, assuming that apps shall search for their own
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// strings more often than for boot image strings.
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for (Table::InternalTable& table : ReverseRange(MakeIterationRange(mid, tables_.end()))) {
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auto it = table.set_.FindWithHash(GcRoot<mirror::String>(s), hash);
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if (it != table.set_.end()) {
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return it->Read();
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}
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}
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return nullptr;
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}
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FLATTEN
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ObjPtr<mirror::String> InternTable::Table::Find(const Utf8String& string, uint32_t hash) {
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Locks::intern_table_lock_->AssertHeld(Thread::Current());
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// Search from the last table, assuming that apps shall search for their own
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// strings more often than for boot image strings.
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for (InternalTable& table : ReverseRange(tables_)) {
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auto it = table.set_.FindWithHash(string, hash);
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if (it != table.set_.end()) {
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return it->Read();
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}
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}
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return nullptr;
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}
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void InternTable::Table::AddNewTable() {
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// Propagate the min/max load factor from the old active set.
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DCHECK(!tables_.empty());
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const UnorderedSet& last_set = tables_.back().set_;
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InternalTable new_table;
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new_table.set_.SetLoadFactor(last_set.GetMinLoadFactor(), last_set.GetMaxLoadFactor());
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tables_.push_back(std::move(new_table));
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}
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void InternTable::Table::Insert(ObjPtr<mirror::String> s, uint32_t hash) {
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// Always insert the last table, the image tables are before and we avoid inserting into these
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// to prevent dirty pages.
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DCHECK(!tables_.empty());
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tables_.back().set_.PutWithHash(GcRoot<mirror::String>(s), hash);
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}
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void InternTable::Table::VisitRoots(RootVisitor* visitor) {
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BufferedRootVisitor<kDefaultBufferedRootCount> buffered_visitor(
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visitor, RootInfo(kRootInternedString));
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for (InternalTable& table : tables_) {
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for (auto& intern : table.set_) {
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buffered_visitor.VisitRoot(intern);
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}
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}
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}
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void InternTable::Table::SweepWeaks(IsMarkedVisitor* visitor) {
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for (InternalTable& table : tables_) {
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SweepWeaks(&table.set_, visitor);
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}
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}
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void InternTable::Table::SweepWeaks(UnorderedSet* set, IsMarkedVisitor* visitor) {
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for (auto it = set->begin(), end = set->end(); it != end;) {
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// This does not need a read barrier because this is called by GC.
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mirror::Object* object = it->Read<kWithoutReadBarrier>();
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mirror::Object* new_object = visitor->IsMarked(object);
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if (new_object == nullptr) {
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it = set->erase(it);
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} else {
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*it = GcRoot<mirror::String>(new_object->AsString());
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++it;
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}
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}
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}
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size_t InternTable::Table::Size() const {
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return std::accumulate(tables_.begin(),
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tables_.end(),
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0U,
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[](size_t sum, const InternalTable& table) {
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return sum + table.Size();
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});
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}
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void InternTable::ChangeWeakRootState(gc::WeakRootState new_state) {
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MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
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ChangeWeakRootStateLocked(new_state);
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}
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void InternTable::ChangeWeakRootStateLocked(gc::WeakRootState new_state) {
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CHECK(!kUseReadBarrier);
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weak_root_state_ = new_state;
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if (new_state != gc::kWeakRootStateNoReadsOrWrites) {
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weak_intern_condition_.Broadcast(Thread::Current());
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}
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}
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InternTable::Table::Table() {
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Runtime* const runtime = Runtime::Current();
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InternalTable initial_table;
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initial_table.set_.SetLoadFactor(runtime->GetHashTableMinLoadFactor(),
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runtime->GetHashTableMaxLoadFactor());
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tables_.push_back(std::move(initial_table));
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}
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} // namespace art
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