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// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/field_table.h"
#include "platform/atomic.h"
#include "vm/flags.h"
#include "vm/growable_array.h"
#include "vm/heap/heap.h"
#include "vm/object.h"
#include "vm/object_graph.h"
#include "vm/object_store.h"
#include "vm/raw_object.h"
#include "vm/visitor.h"
namespace dart {
FieldTable::~FieldTable() {
FreeOldTables();
delete old_tables_; // Allocated in FieldTable::FieldTable()
free(table_); // Allocated in FieldTable::Grow()
}
bool FieldTable::IsReadyToUse() const {
DEBUG_ASSERT(
IsolateGroup::Current()->IsReloading() ||
IsolateGroup::Current()->program_lock()->IsCurrentThreadReader());
return is_ready_to_use_;
}
void FieldTable::MarkReadyToUse() {
// The isolate will mark it's field table ready-to-use upon initialization of
// the isolate. Only after it was marked as ready-to-use will it participate
// in new static field registrations.
//
// By requiring a read lock here we ensure no other thread is is registering a
// new static field at this moment (it would need exlusive writer lock).
DEBUG_ASSERT(
IsolateGroup::Current()->program_lock()->IsCurrentThreadReader());
ASSERT(!is_ready_to_use_);
is_ready_to_use_ = true;
}
void FieldTable::FreeOldTables() {
while (old_tables_->length() > 0) {
free(old_tables_->RemoveLast());
}
}
intptr_t FieldTable::FieldOffsetFor(intptr_t field_id) {
return field_id * sizeof(ObjectPtr); // NOLINT
}
bool FieldTable::Register(const Field& field, intptr_t expected_field_id) {
DEBUG_ASSERT(
IsolateGroup::Current()->program_lock()->IsCurrentThreadWriter());
ASSERT(is_ready_to_use_);
if (free_head_ < 0) {
bool grown_backing_store = false;
if (top_ == capacity_) {
const intptr_t new_capacity = capacity_ + kCapacityIncrement;
Grow(new_capacity);
grown_backing_store = true;
}
ASSERT(top_ < capacity_);
ASSERT(expected_field_id == -1 || expected_field_id == top_);
field.set_field_id(top_);
table_[top_] = Object::sentinel().ptr();
++top_;
return grown_backing_store;
}
// Reuse existing free element. This is "slow path" that should only be
// triggered after hot reload.
intptr_t reused_free = free_head_;
free_head_ = Smi::Value(Smi::RawCast(table_[free_head_]));
field.set_field_id(reused_free);
table_[reused_free] = Object::sentinel().ptr();
return false;
}
void FieldTable::Free(intptr_t field_id) {
table_[field_id] = Smi::New(free_head_);
free_head_ = field_id;
}
void FieldTable::SetAt(intptr_t index, ObjectPtr raw_instance) {
ASSERT(index < capacity_);
table_[index] = raw_instance;
}
void FieldTable::AllocateIndex(intptr_t index) {
if (index >= capacity_) {
const intptr_t new_capacity = index + kCapacityIncrement;
Grow(new_capacity);
}
ASSERT(table_[index] == ObjectPtr());
if (index >= top_) {
top_ = index + 1;
}
}
void FieldTable::Grow(intptr_t new_capacity) {
ASSERT(new_capacity > capacity_);
auto old_table = table_;
auto new_table = static_cast<ObjectPtr*>(
malloc(new_capacity * sizeof(ObjectPtr))); // NOLINT
intptr_t i;
for (i = 0; i < top_; i++) {
new_table[i] = old_table[i];
}
for (; i < new_capacity; i++) {
new_table[i] = ObjectPtr();
}
capacity_ = new_capacity;
old_tables_->Add(old_table);
// Ensure that new_table_ is populated before it is published
// via store to table_.
std::atomic_thread_fence(std::memory_order_release);
table_ = new_table;
if (isolate_ != nullptr) {
isolate_->mutator_thread()->field_table_values_ = table_;
}
}
FieldTable* FieldTable::Clone(Isolate* for_isolate) {
DEBUG_ASSERT(
IsolateGroup::Current()->program_lock()->IsCurrentThreadReader());
FieldTable* clone = new FieldTable(for_isolate);
auto new_table =
static_cast<ObjectPtr*>(malloc(capacity_ * sizeof(ObjectPtr))); // NOLINT
memmove(new_table, table_, capacity_ * sizeof(ObjectPtr));
ASSERT(clone->table_ == nullptr);
clone->table_ = new_table;
clone->capacity_ = capacity_;
clone->top_ = top_;
clone->free_head_ = free_head_;
return clone;
}
void FieldTable::VisitObjectPointers(ObjectPointerVisitor* visitor) {
// GC might try to visit field table before it's isolate done setting it up.
if (table_ == nullptr) {
return;
}
ASSERT(visitor != NULL);
visitor->set_gc_root_type("static fields table");
visitor->VisitPointers(&table_[0], &table_[top_ - 1]);
visitor->clear_gc_root_type();
}
} // namespace dart