63 lines
2.5 KiB
C++
63 lines
2.5 KiB
C++
/** @file CircularBufferConfig.hpp
|
|
*
|
|
* @author Roland Conybeare, Jan 2026
|
|
**/
|
|
|
|
#pragma once
|
|
|
|
#include <string>
|
|
|
|
namespace xo {
|
|
namespace mm {
|
|
/** @class CircularBufferConfig
|
|
*
|
|
* @brief configuration for a @ref DCircularBuffer instance
|
|
**/
|
|
struct CircularBufferConfig {
|
|
/** @defgroup mm-circularbufferconfig-instance-vars CircularBufferConfig members **/
|
|
///@{
|
|
|
|
/** optional name, for diagnostics **/
|
|
std::string name_;
|
|
/** hard maximum buffer size = reserved virtual memory.
|
|
* However actual max will be this value rounded up to at least page size.
|
|
* Buffer will generally map much less than this amount of memory
|
|
**/
|
|
std::size_t max_capacity_ = 0;
|
|
/** hugepage size -- using huge pages relieves some TLB pressure,
|
|
* at expense of inefficient memory consumption for (up to two)
|
|
* partially used superpages.
|
|
**/
|
|
std::size_t hugepage_z_ = 2 * 1024 * 1024;
|
|
/** Threshold 'move efficeincy' = (move_distance / move_qty)
|
|
* applies to moving unread input to the beginning of mapped range,
|
|
* when not prevented by pinned ranges.
|
|
*
|
|
* Higher numbers reduce cpu consumption but increase memory consumption
|
|
* Reciprocal loose ceiling on relative effort that may be spent on
|
|
* moving fractional input
|
|
**/
|
|
float threshold_move_efficiency_ = 50.0;
|
|
/** lower bound for hard maximum number of capture spans.
|
|
*
|
|
* Expected use case is to track spans that are currently referenced
|
|
* (rather than copied) from outside a DCircularBuffer instance.
|
|
* Circular buffer will not unmap or overwrite memory for such spans.
|
|
*
|
|
* Expect to generally release captured spans in the same order they
|
|
* were captured. Out of order release is supported, but cost
|
|
* of out-of-order release grows
|
|
* like O(r) for r remembered spans.
|
|
*
|
|
* A typical parser will need spans to remember one line of input
|
|
**/
|
|
std::size_t max_captured_span_ = 0;
|
|
/** true to enable debug logging **/
|
|
bool debug_flag_ = false;
|
|
|
|
///@}
|
|
};
|
|
} /*namespace mm*/
|
|
} /*namespace xo*/
|
|
|
|
/* end CircularBufferConfig.hpp */
|