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| 1 | +// Copyright Joyent, Inc. and other Node contributors. |
| 2 | +// |
| 3 | +// Permission is hereby granted, free of charge, to any person obtaining a |
| 4 | +// copy of this software and associated documentation files (the |
| 5 | +// "Software"), to deal in the Software without restriction, including |
| 6 | +// without limitation the rights to use, copy, modify, merge, publish, |
| 7 | +// distribute, sublicense, and/or sell copies of the Software, and to permit |
| 8 | +// persons to whom the Software is furnished to do so, subject to the |
| 9 | +// following conditions: |
| 10 | +// |
| 11 | +// The above copyright notice and this permission notice shall be included |
| 12 | +// in all copies or substantial portions of the Software. |
| 13 | +// |
| 14 | +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
| 15 | +// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 16 | +// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN |
| 17 | +// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, |
| 18 | +// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
| 19 | +// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE |
| 20 | +// USE OR OTHER DEALINGS IN THE SOFTWARE. |
| 21 | + |
| 22 | +#ifndef SRC_UTIL_LOCAL_VECTOR_H_ |
| 23 | +#define SRC_UTIL_LOCAL_VECTOR_H_ |
| 24 | + |
| 25 | +#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS |
| 26 | + |
| 27 | +#include "util.h" |
| 28 | +#include "v8.h" |
| 29 | + |
| 30 | +namespace node { |
| 31 | + |
| 32 | +// Template specialization for MaybeStackBuffer<v8::Local<T>> that uses |
| 33 | +// v8::LocalVector<T> for heap allocations instead of malloc/free. |
| 34 | +template <typename T, size_t kStackStorageSize> |
| 35 | +class MaybeStackBuffer<v8::Local<T>, kStackStorageSize> { |
| 36 | + public: |
| 37 | + // Disallow copy constructor |
| 38 | + MaybeStackBuffer(const MaybeStackBuffer&) = delete; |
| 39 | + // Disallow copy assignment operator |
| 40 | + MaybeStackBuffer& operator=(const MaybeStackBuffer& other) = delete; |
| 41 | + |
| 42 | + const v8::Local<T>* out() const { return buf_; } |
| 43 | + |
| 44 | + v8::Local<T>* out() { return buf_; } |
| 45 | + |
| 46 | + // operator* for compatibility with `v8::String::(Utf8)Value` |
| 47 | + v8::Local<T>* operator*() { return buf_; } |
| 48 | + |
| 49 | + const v8::Local<T>* operator*() const { return buf_; } |
| 50 | + |
| 51 | + v8::Local<T>& operator[](size_t index) { |
| 52 | + CHECK_LT(index, length()); |
| 53 | + return buf_[index]; |
| 54 | + } |
| 55 | + |
| 56 | + const v8::Local<T>& operator[](size_t index) const { |
| 57 | + CHECK_LT(index, length()); |
| 58 | + return buf_[index]; |
| 59 | + } |
| 60 | + |
| 61 | + size_t length() const { return length_; } |
| 62 | + |
| 63 | + // Current maximum capacity of the buffer with which SetLength() can be used |
| 64 | + // without first calling AllocateSufficientStorage(). |
| 65 | + size_t capacity() const { return capacity_; } |
| 66 | + |
| 67 | + // Make sure enough space for `storage` entries is available. |
| 68 | + // This method can be called multiple times throughout the lifetime of the |
| 69 | + // buffer, but once this has been called Invalidate() cannot be used. |
| 70 | + // Content of the buffer in the range [0, length()) is preserved. |
| 71 | + void AllocateSufficientStorage(size_t storage) { |
| 72 | + CHECK(!IsInvalidated()); |
| 73 | + if (storage > capacity()) { |
| 74 | + bool was_allocated = IsAllocated(); |
| 75 | + |
| 76 | + if (was_allocated) { |
| 77 | + // Copy from existing LocalVector to a new one |
| 78 | + v8::Isolate* isolate = v8::Isolate::GetCurrent(); |
| 79 | + auto new_vec = std::make_unique<v8::LocalVector<T>>(isolate, storage); |
| 80 | + for (size_t i = 0; i < length_; i++) { |
| 81 | + (*new_vec)[i] = buf_[i]; |
| 82 | + } |
| 83 | + vector_buf_ = std::move(new_vec); |
| 84 | + buf_ = vector_buf_->data(); |
| 85 | + } else { |
| 86 | + // First allocation or switching from stack to heap |
| 87 | + v8::Isolate* isolate = v8::Isolate::GetCurrent(); |
| 88 | + vector_buf_ = std::make_unique<v8::LocalVector<T>>(isolate, storage); |
| 89 | + |
| 90 | + // Copy from stack to LocalVector if needed |
| 91 | + if (length_ > 0) { |
| 92 | + for (size_t i = 0; i < length_; i++) { |
| 93 | + (*vector_buf_)[i] = buf_st_[i]; |
| 94 | + } |
| 95 | + } |
| 96 | + buf_ = vector_buf_->data(); |
| 97 | + } |
| 98 | + capacity_ = storage; |
| 99 | + } |
| 100 | + |
| 101 | + length_ = storage; |
| 102 | + } |
| 103 | + |
| 104 | + void SetLength(size_t length) { |
| 105 | + // capacity() returns how much memory is actually available. |
| 106 | + CHECK_LE(length, capacity()); |
| 107 | + length_ = length; |
| 108 | + } |
| 109 | + |
| 110 | + void SetLengthAndZeroTerminate(size_t length) { |
| 111 | + // capacity() returns how much memory is actually available. |
| 112 | + CHECK_LE(length + 1, capacity()); |
| 113 | + SetLength(length); |
| 114 | + |
| 115 | + // Set null for the last element |
| 116 | + buf_[length] = v8::Local<T>(); |
| 117 | + } |
| 118 | + |
| 119 | + // Make dereferencing this object return nullptr. |
| 120 | + // This method can be called multiple times throughout the lifetime of the |
| 121 | + // buffer, but once this has been called AllocateSufficientStorage() cannot |
| 122 | + // be used. |
| 123 | + void Invalidate() { |
| 124 | + CHECK(!IsAllocated()); |
| 125 | + capacity_ = 0; |
| 126 | + length_ = 0; |
| 127 | + buf_ = nullptr; |
| 128 | + } |
| 129 | + |
| 130 | + // If the buffer is stored in the heap rather than on the stack. |
| 131 | + bool IsAllocated() const { return !IsInvalidated() && buf_ != buf_st_; } |
| 132 | + |
| 133 | + // If Invalidate() has been called. |
| 134 | + bool IsInvalidated() const { return buf_ == nullptr; } |
| 135 | + |
| 136 | + // Release ownership of the LocalVector buffer. |
| 137 | + void Release() { |
| 138 | + CHECK(IsAllocated()); |
| 139 | + vector_buf_.reset(); |
| 140 | + buf_ = buf_st_; |
| 141 | + length_ = 0; |
| 142 | + capacity_ = arraysize(buf_st_); |
| 143 | + } |
| 144 | + |
| 145 | + MaybeStackBuffer() |
| 146 | + : length_(0), |
| 147 | + capacity_(arraysize(buf_st_)), |
| 148 | + buf_(buf_st_), |
| 149 | + vector_buf_(nullptr) { |
| 150 | + // Default to a zero-length buffer. |
| 151 | + } |
| 152 | + |
| 153 | + explicit MaybeStackBuffer(size_t storage) : MaybeStackBuffer() { |
| 154 | + AllocateSufficientStorage(storage); |
| 155 | + } |
| 156 | + |
| 157 | + ~MaybeStackBuffer() { |
| 158 | + // LocalVector manages its own memory |
| 159 | + vector_buf_.reset(); |
| 160 | + } |
| 161 | + |
| 162 | + private: |
| 163 | + size_t length_; |
| 164 | + // capacity of the vector_buf_ or stack buffer |
| 165 | + size_t capacity_; |
| 166 | + v8::Local<T>* buf_; |
| 167 | + v8::Local<T> buf_st_[kStackStorageSize]; |
| 168 | + // Used when we allocate on the heap |
| 169 | + std::unique_ptr<v8::LocalVector<T>> vector_buf_; |
| 170 | +}; |
| 171 | + |
| 172 | +} // namespace node |
| 173 | + |
| 174 | +#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS |
| 175 | + |
| 176 | +#endif // SRC_UTIL_LOCAL_VECTOR_H_ |
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