1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "scoped_arena_allocator.h"
18
19#include "arena_allocator.h"
20#include "base/memory_tool.h"
21
22namespace art {
23
24static constexpr size_t kMemoryToolRedZoneBytes = 8;
25
26ArenaStack::ArenaStack(ArenaPool* arena_pool)
27  : DebugStackRefCounter(),
28    stats_and_pool_(arena_pool),
29    bottom_arena_(nullptr),
30    top_arena_(nullptr),
31    top_ptr_(nullptr),
32    top_end_(nullptr) {
33}
34
35ArenaStack::~ArenaStack() {
36  DebugStackRefCounter::CheckNoRefs();
37  stats_and_pool_.pool->FreeArenaChain(bottom_arena_);
38}
39
40void ArenaStack::Reset() {
41  DebugStackRefCounter::CheckNoRefs();
42  stats_and_pool_.pool->FreeArenaChain(bottom_arena_);
43  bottom_arena_ = nullptr;
44  top_arena_  = nullptr;
45  top_ptr_ = nullptr;
46  top_end_ = nullptr;
47}
48
49MemStats ArenaStack::GetPeakStats() const {
50  DebugStackRefCounter::CheckNoRefs();
51  return MemStats("ArenaStack peak", static_cast<const TaggedStats<Peak>*>(&stats_and_pool_),
52                  bottom_arena_);
53}
54
55uint8_t* ArenaStack::AllocateFromNextArena(size_t rounded_bytes) {
56  UpdateBytesAllocated();
57  size_t allocation_size = std::max(Arena::kDefaultSize, rounded_bytes);
58  if (UNLIKELY(top_arena_ == nullptr)) {
59    top_arena_ = bottom_arena_ = stats_and_pool_.pool->AllocArena(allocation_size);
60    top_arena_->next_ = nullptr;
61  } else if (top_arena_->next_ != nullptr && top_arena_->next_->Size() >= allocation_size) {
62    top_arena_ = top_arena_->next_;
63  } else {
64    Arena* tail = top_arena_->next_;
65    top_arena_->next_ = stats_and_pool_.pool->AllocArena(allocation_size);
66    top_arena_ = top_arena_->next_;
67    top_arena_->next_ = tail;
68  }
69  top_end_ = top_arena_->End();
70  // top_ptr_ shall be updated by ScopedArenaAllocator.
71  return top_arena_->Begin();
72}
73
74void ArenaStack::UpdatePeakStatsAndRestore(const ArenaAllocatorStats& restore_stats) {
75  if (PeakStats()->BytesAllocated() < CurrentStats()->BytesAllocated()) {
76    PeakStats()->Copy(*CurrentStats());
77  }
78  CurrentStats()->Copy(restore_stats);
79}
80
81void ArenaStack::UpdateBytesAllocated() {
82  if (top_arena_ != nullptr) {
83    // Update how many bytes we have allocated into the arena so that the arena pool knows how
84    // much memory to zero out. Though ScopedArenaAllocator doesn't guarantee the memory is
85    // zero-initialized, the Arena may be reused by ArenaAllocator which does guarantee this.
86    size_t allocated = static_cast<size_t>(top_ptr_ - top_arena_->Begin());
87    if (top_arena_->bytes_allocated_ < allocated) {
88      top_arena_->bytes_allocated_ = allocated;
89    }
90  }
91}
92
93void* ArenaStack::AllocWithMemoryTool(size_t bytes, ArenaAllocKind kind) {
94  // We mark all memory for a newly retrieved arena as inaccessible and then
95  // mark only the actually allocated memory as defined. That leaves red zones
96  // and padding between allocations marked as inaccessible.
97  size_t rounded_bytes = RoundUp(bytes + kMemoryToolRedZoneBytes, 8);
98  uint8_t* ptr = top_ptr_;
99  if (UNLIKELY(static_cast<size_t>(top_end_ - ptr) < rounded_bytes)) {
100    ptr = AllocateFromNextArena(rounded_bytes);
101    CHECK(ptr != nullptr) << "Failed to allocate memory";
102    MEMORY_TOOL_MAKE_NOACCESS(ptr, top_end_ - ptr);
103  }
104  CurrentStats()->RecordAlloc(bytes, kind);
105  top_ptr_ = ptr + rounded_bytes;
106  MEMORY_TOOL_MAKE_UNDEFINED(ptr, bytes);
107  return ptr;
108}
109
110ScopedArenaAllocator::ScopedArenaAllocator(ArenaStack* arena_stack)
111  : DebugStackReference(arena_stack),
112    DebugStackRefCounter(),
113    ArenaAllocatorStats(*arena_stack->CurrentStats()),
114    arena_stack_(arena_stack),
115    mark_arena_(arena_stack->top_arena_),
116    mark_ptr_(arena_stack->top_ptr_),
117    mark_end_(arena_stack->top_end_) {
118}
119
120ScopedArenaAllocator::~ScopedArenaAllocator() {
121  DoReset();
122}
123
124void ScopedArenaAllocator::Reset() {
125  DoReset();
126  // If this allocator was Create()d, we need to move the arena_stack_->top_ptr_ past *this.
127  if (mark_ptr_ == reinterpret_cast<uint8_t*>(this)) {
128    arena_stack_->top_ptr_ = mark_ptr_ + RoundUp(sizeof(ScopedArenaAllocator), 8);
129  }
130}
131
132void ScopedArenaAllocator::DoReset() {
133  DebugStackReference::CheckTop();
134  DebugStackRefCounter::CheckNoRefs();
135  arena_stack_->UpdatePeakStatsAndRestore(*this);
136  arena_stack_->UpdateBytesAllocated();
137  if (LIKELY(mark_arena_ != nullptr)) {
138    arena_stack_->top_arena_ = mark_arena_;
139    arena_stack_->top_ptr_ = mark_ptr_;
140    arena_stack_->top_end_ = mark_end_;
141  } else if (arena_stack_->bottom_arena_ != nullptr) {
142    mark_arena_ = arena_stack_->top_arena_ = arena_stack_->bottom_arena_;
143    mark_ptr_ = arena_stack_->top_ptr_ = mark_arena_->Begin();
144    mark_end_ = arena_stack_->top_end_ = mark_arena_->End();
145  }
146}
147
148}  // namespace art
149