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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.h"
#include "gc/space/image_space.h"
#include "mirror/dex_cache.h"
#include "mirror/object_array-inl.h"
#include "mirror/object-inl.h"
#include "mirror/string.h"
#include "thread.h"
#include "UniquePtr.h"
#include "utf.h"
namespace art {
InternTable::InternTable()
: intern_table_lock_("InternTable lock"), is_dirty_(false), allow_new_interns_(true),
new_intern_condition_("New intern condition", intern_table_lock_) {
}
size_t InternTable::Size() const {
MutexLock mu(Thread::Current(), intern_table_lock_);
return strong_interns_.size() + weak_interns_.size();
}
void InternTable::DumpForSigQuit(std::ostream& os) const {
MutexLock mu(Thread::Current(), intern_table_lock_);
os << "Intern table: " << strong_interns_.size() << " strong; "
<< weak_interns_.size() << " weak\n";
}
void InternTable::VisitRoots(RootVisitor* visitor, void* arg,
bool only_dirty, bool clean_dirty) {
MutexLock mu(Thread::Current(), intern_table_lock_);
if (!only_dirty || is_dirty_) {
for (auto& strong_intern : strong_interns_) {
strong_intern.second = down_cast<mirror::String*>(visitor(strong_intern.second, arg));
DCHECK(strong_intern.second != nullptr);
}
if (clean_dirty) {
is_dirty_ = false;
}
}
// Note: we deliberately don't visit the weak_interns_ table and the immutable image roots.
}
mirror::String* InternTable::Lookup(Table& table, mirror::String* s, uint32_t hash_code) {
intern_table_lock_.AssertHeld(Thread::Current());
for (auto it = table.find(hash_code), end = table.end(); it != end; ++it) {
mirror::String* existing_string = it->second;
if (existing_string->Equals(s)) {
return existing_string;
}
}
return NULL;
}
mirror::String* InternTable::Insert(Table& table, mirror::String* s, uint32_t hash_code) {
intern_table_lock_.AssertHeld(Thread::Current());
table.insert(std::make_pair(hash_code, s));
return s;
}
void InternTable::Remove(Table& table, const mirror::String* s,
uint32_t hash_code) {
intern_table_lock_.AssertHeld(Thread::Current());
for (auto it = table.find(hash_code), end = table.end(); it != end; ++it) {
if (it->second == s) {
table.erase(it);
return;
}
}
}
static mirror::String* LookupStringFromImage(mirror::String* s)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
gc::space::ImageSpace* image = Runtime::Current()->GetHeap()->GetImageSpace();
if (image == NULL) {
return NULL; // No image present.
}
mirror::Object* root = image->GetImageHeader().GetImageRoot(ImageHeader::kDexCaches);
mirror::ObjectArray<mirror::DexCache>* dex_caches = root->AsObjectArray<mirror::DexCache>();
const std::string utf8 = s->ToModifiedUtf8();
for (int32_t i = 0; i < dex_caches->GetLength(); ++i) {
mirror::DexCache* dex_cache = dex_caches->Get(i);
const DexFile* dex_file = dex_cache->GetDexFile();
// Binary search the dex file for the string index.
const DexFile::StringId* string_id = dex_file->FindStringId(utf8.c_str());
if (string_id != NULL) {
uint32_t string_idx = dex_file->GetIndexForStringId(*string_id);
mirror::String* image = dex_cache->GetResolvedString(string_idx);
if (image != NULL) {
return image;
}
}
}
return NULL;
}
void InternTable::AllowNewInterns() {
Thread* self = Thread::Current();
MutexLock mu(self, intern_table_lock_);
allow_new_interns_ = true;
new_intern_condition_.Broadcast(self);
}
void InternTable::DisallowNewInterns() {
Thread* self = Thread::Current();
MutexLock mu(self, intern_table_lock_);
allow_new_interns_ = false;
}
mirror::String* InternTable::Insert(mirror::String* s, bool is_strong) {
Thread* self = Thread::Current();
MutexLock mu(self, intern_table_lock_);
DCHECK(s != NULL);
uint32_t hash_code = s->GetHashCode();
while (UNLIKELY(!allow_new_interns_)) {
new_intern_condition_.WaitHoldingLocks(self);
}
if (is_strong) {
// Check the strong table for a match.
mirror::String* strong = Lookup(strong_interns_, s, hash_code);
if (strong != NULL) {
return strong;
}
// Mark as dirty so that we rescan the roots.
is_dirty_ = true;
// Check the image for a match.
mirror::String* image = LookupStringFromImage(s);
if (image != NULL) {
return Insert(strong_interns_, image, hash_code);
}
// There is no match in the strong table, check the weak table.
mirror::String* weak = Lookup(weak_interns_, s, hash_code);
if (weak != NULL) {
// A match was found in the weak table. Promote to the strong table.
Remove(weak_interns_, weak, hash_code);
return Insert(strong_interns_, weak, hash_code);
}
// No match in the strong table or the weak table. Insert into the strong
// table.
return Insert(strong_interns_, s, hash_code);
}
// Check the strong table for a match.
mirror::String* strong = Lookup(strong_interns_, s, hash_code);
if (strong != NULL) {
return strong;
}
// Check the image for a match.
mirror::String* image = LookupStringFromImage(s);
if (image != NULL) {
return Insert(weak_interns_, image, hash_code);
}
// Check the weak table for a match.
mirror::String* weak = Lookup(weak_interns_, s, hash_code);
if (weak != NULL) {
return weak;
}
// Insert into the weak table.
return Insert(weak_interns_, s, hash_code);
}
mirror::String* InternTable::InternStrong(int32_t utf16_length,
const char* utf8_data) {
return InternStrong(mirror::String::AllocFromModifiedUtf8(
Thread::Current(), utf16_length, utf8_data));
}
mirror::String* InternTable::InternStrong(const char* utf8_data) {
return InternStrong(
mirror::String::AllocFromModifiedUtf8(Thread::Current(), utf8_data));
}
mirror::String* InternTable::InternStrong(mirror::String* s) {
if (s == NULL) {
return NULL;
}
return Insert(s, true);
}
mirror::String* InternTable::InternWeak(mirror::String* s) {
if (s == NULL) {
return NULL;
}
return Insert(s, false);
}
bool InternTable::ContainsWeak(mirror::String* s) {
MutexLock mu(Thread::Current(), intern_table_lock_);
const mirror::String* found = Lookup(weak_interns_, s, s->GetHashCode());
return found == s;
}
void InternTable::SweepInternTableWeaks(RootVisitor visitor, void* arg) {
MutexLock mu(Thread::Current(), intern_table_lock_);
for (auto it = weak_interns_.begin(), end = weak_interns_.end(); it != end;) {
mirror::Object* object = it->second;
mirror::Object* new_object = visitor(object, arg);
if (new_object == nullptr) {
// TODO: use it = weak_interns_.erase(it) when we get a c++11 stl.
weak_interns_.erase(it++);
} else {
it->second = down_cast<mirror::String*>(new_object);
++it;
}
}
}
} // namespace art