2946cd7010
to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
96 lines
2.6 KiB
C++
96 lines
2.6 KiB
C++
//===-- esan_circular_buffer.h ----------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of EfficiencySanitizer, a family of performance tuners.
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//
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// Circular buffer data structure.
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//===----------------------------------------------------------------------===//
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#include "sanitizer_common/sanitizer_common.h"
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namespace __esan {
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// A circular buffer for POD data whose memory is allocated using mmap.
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// There are two usage models: one is to use initialize/free (for global
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// instances) and the other is to use placement new with the
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// constructor and to call the destructor or free (they are equivalent).
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template<typename T>
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class CircularBuffer {
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public:
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// To support global instances we cannot initialize any field in the
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// default constructor.
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explicit CircularBuffer() {}
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CircularBuffer(uptr BufferCapacity) {
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initialize(BufferCapacity);
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WasConstructed = true;
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}
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~CircularBuffer() {
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if (WasConstructed) // Else caller will call free() explicitly.
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free();
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}
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void initialize(uptr BufferCapacity) {
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Capacity = BufferCapacity;
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// MmapOrDie rounds up to the page size for us.
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Data = (T *)MmapOrDie(Capacity * sizeof(T), "CircularBuffer");
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StartIdx = 0;
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Count = 0;
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WasConstructed = false;
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}
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void free() {
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UnmapOrDie(Data, Capacity * sizeof(T));
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}
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T &operator[](uptr Idx) {
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CHECK_LT(Idx, Count);
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uptr ArrayIdx = (StartIdx + Idx) % Capacity;
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return Data[ArrayIdx];
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}
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const T &operator[](uptr Idx) const {
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CHECK_LT(Idx, Count);
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uptr ArrayIdx = (StartIdx + Idx) % Capacity;
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return Data[ArrayIdx];
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}
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void push_back(const T &Item) {
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CHECK_GT(Capacity, 0);
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uptr ArrayIdx = (StartIdx + Count) % Capacity;
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Data[ArrayIdx] = Item;
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if (Count < Capacity)
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++Count;
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else
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StartIdx = (StartIdx + 1) % Capacity;
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}
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T &back() {
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CHECK_GT(Count, 0);
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uptr ArrayIdx = (StartIdx + Count - 1) % Capacity;
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return Data[ArrayIdx];
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}
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void pop_back() {
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CHECK_GT(Count, 0);
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--Count;
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}
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uptr size() const {
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return Count;
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}
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void clear() {
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StartIdx = 0;
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Count = 0;
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}
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bool empty() const { return size() == 0; }
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private:
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CircularBuffer(const CircularBuffer&);
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void operator=(const CircularBuffer&);
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bool WasConstructed;
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T *Data;
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uptr Capacity;
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uptr StartIdx;
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uptr Count;
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};
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} // namespace __esan
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