83 lines
2.2 KiB
C++
83 lines
2.2 KiB
C++
#include <stdexcept>
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#include <cassert>
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#include <sys/mman.h>
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#include "mmap_manager.h"
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mmap_manager_t::mmap_manager_t(uint64_t mmap_size)
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{
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this->mmap_size = mmap_size;
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}
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mmap_manager_t::~mmap_manager_t()
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{
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for (auto & kv: past_buffers)
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{
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munmap(kv.second.addr, kv.second.size);
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}
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if (active_buffer.addr != NULL)
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{
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munmap(active_buffer.addr, active_buffer.size);
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}
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}
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void *mmap_manager_t::alloc(uint64_t size)
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{
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if (!active_buffer.addr || (active_buffer.pos + size) > active_buffer.size)
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{
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if (active_buffer.addr)
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{
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if (active_buffer.freed >= active_buffer.pos)
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munmap(active_buffer.addr, active_buffer.size);
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else
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past_buffers[active_buffer.addr] = active_buffer;
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active_buffer = { 0 };
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}
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uint64_t new_size = size < mmap_size ? mmap_size : size;
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void *buf = mmap(NULL, new_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
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if (!buf)
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throw std::runtime_error(std::string("can't mmap "+std::to_string(new_size)+" bytes"));
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active_buffer = {
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.addr = buf,
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.size = new_size,
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.freed = 0,
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.pos = 0,
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};
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}
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void *res = active_buffer.addr + active_buffer.pos;
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active_buffer.pos += size;
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return res;
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}
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void mmap_manager_t::free(void *addr, uint64_t size)
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{
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auto it = past_buffers.upper_bound(addr);
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if (it != past_buffers.begin())
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{
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if (it == past_buffers.end())
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{
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it--;
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if (addr < it->second.addr || addr >= it->second.addr+it->second.size)
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it = past_buffers.end();
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}
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else
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it--;
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}
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else
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it = past_buffers.end();
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if (it != past_buffers.end())
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{
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assert(addr >= it->second.addr && addr+size <= it->second.addr+it->second.size);
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it->second.freed += size;
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if (it->second.freed >= it->second.pos)
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{
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munmap(it->second.addr, it->second.size);
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past_buffers.erase(it);
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}
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}
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else
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{
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assert(addr < active_buffer.addr+active_buffer.size);
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active_buffer.freed += size;
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}
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}
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