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Diffstat (limited to 'lib/esan')
-rw-r--r-- | lib/esan/esan_circular_buffer.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/lib/esan/esan_circular_buffer.h b/lib/esan/esan_circular_buffer.h new file mode 100644 index 000000000..98891109c --- /dev/null +++ b/lib/esan/esan_circular_buffer.h @@ -0,0 +1,92 @@ +//===-- esan_circular_buffer.h ----------------------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file is a part of EfficiencySanitizer, a family of performance tuners. +// +// Circular buffer data structure. +//===----------------------------------------------------------------------===// + +#include "sanitizer_common/sanitizer_common.h" + +namespace __esan { + +// A circular buffer for POD data whose memory is allocated using mmap. +// There are two usage models: one is to use initialize/free (for global +// instances) and the other is to use placement new with the +// constructor and to call the destructor or free (they are equivalent). +template<typename T> +class CircularBuffer { + public: + // To support global instances we cannot initialize any field in the + // default constructor. + explicit CircularBuffer() {} + CircularBuffer(uptr BufferCapacity) { + initialize(BufferCapacity); + } + ~CircularBuffer() { + free(); + } + void initialize(uptr BufferCapacity) { + Capacity = BufferCapacity; + // MmapOrDie rounds up to the page size for us. + Data = (T *)MmapOrDie(Capacity * sizeof(T), "CircularBuffer"); + StartIdx = 0; + Count = 0; + } + void free() { + UnmapOrDie(Data, Capacity * sizeof(T)); + } + T &operator[](uptr Idx) { + CHECK_LT(Idx, Count); + uptr ArrayIdx = (StartIdx + Idx) % Capacity; + return Data[ArrayIdx]; + } + const T &operator[](uptr Idx) const { + CHECK_LT(Idx, Count); + uptr ArrayIdx = (StartIdx + Idx) % Capacity; + return Data[ArrayIdx]; + } + void push_back(const T &Item) { + CHECK_GT(Capacity, 0); + uptr ArrayIdx = (StartIdx + Count) % Capacity; + Data[ArrayIdx] = Item; + if (Count < Capacity) + ++Count; + else + StartIdx = (StartIdx + 1) % Capacity; + } + T &back() { + CHECK_GT(Count, 0); + uptr ArrayIdx = (StartIdx + Count - 1) % Capacity; + return Data[ArrayIdx]; + } + void pop_back() { + CHECK_GT(Count, 0); + --Count; + } + uptr size() const { + return Count; + } + void clear() { + StartIdx = 0; + Count = 0; + } + bool empty() const { return size() == 0; } + + private: + CircularBuffer(const CircularBuffer&); + void operator=(const CircularBuffer&); + + T *Data; + uptr Capacity; + uptr StartIdx; + uptr Count; +}; + +} // namespace __esan |