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lnav/src/big_array.hh

106 lines
3.1 KiB
C++

/**
* Copyright (c) 2017, Timothy Stack
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither the name of Timothy Stack nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @file big_array.hh
*/
#ifndef _big_array_hh
#define _big_array_hh
#include <sys/mman.h>
#include "lnav_util.hh"
template<typename T>
struct big_array {
static const size_t DEFAULT_INCREMENT = 100 * 1000;
big_array() : ba_ptr(nullptr), ba_size(0), ba_capacity(0) {
};
bool reserve(size_t size) {
if (size < this->ba_capacity) {
return false;
}
if (this->ba_ptr) {
munmap(this->ba_ptr,
roundup_size(this->ba_capacity * sizeof(T), getpagesize()));
}
this->ba_capacity = size + DEFAULT_INCREMENT;
void *result = mmap(nullptr,
roundup_size(this->ba_capacity * sizeof(T),
getpagesize()),
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE,
-1,
0);
ensure(result != MAP_FAILED);
this->ba_ptr = (T *) result;
return true;
};
void clear() {
this->ba_size = 0;
};
size_t size() const {
return this->ba_size;
};
void push_back(const T &val) {
this->ba_ptr[this->ba_size] = val;
this->ba_size += 1;
};
T &operator[](size_t index) {
return this->ba_ptr[index];
};
typedef T *iterator;
iterator begin() {
return this->ba_ptr;
};
iterator end() {
return this->ba_ptr + this->ba_size;
};
T *ba_ptr;
size_t ba_size;
size_t ba_capacity;
};
#endif