nghttp2/src/memchunk.h

262 lines
6.0 KiB
C++

/*
* nghttp2 - HTTP/2 C Library
*
* Copyright (c) 2014 Tatsuhiro Tsujikawa
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef MEMCHUNK_H
#define MEMCHUNK_H
#include "nghttp2_config.h"
#include <limits.h>
#include <sys/uio.h>
#include <cassert>
#include <cstring>
#include <memory>
#include <array>
#include <algorithm>
#include "template.h"
namespace nghttp2 {
template <size_t N> struct Memchunk {
Memchunk(std::unique_ptr<Memchunk> next_chunk)
: pos(std::begin(buf)), last(pos), knext(std::move(next_chunk)),
kprev(nullptr), next(nullptr) {
if (knext) {
knext->kprev = this;
}
}
size_t len() const { return last - pos; }
size_t left() const { return std::end(buf) - last; }
void reset() { pos = last = std::begin(buf); }
std::array<uint8_t, N> buf;
uint8_t *pos, *last;
std::unique_ptr<Memchunk> knext;
Memchunk *kprev;
Memchunk *next;
static const size_t size = N;
};
template <typename T> struct Pool {
Pool() : pool(nullptr), freelist(nullptr), poolsize(0) {}
T *get() {
if (freelist) {
auto m = freelist;
freelist = freelist->next;
m->next = nullptr;
m->reset();
return m;
}
pool = make_unique<T>(std::move(pool));
poolsize += T::size;
return pool.get();
}
void recycle(T *m) {
if (freelist) {
m->next = freelist;
} else {
m->next = nullptr;
}
freelist = m;
}
void shrink(size_t max) {
auto m = freelist;
for (; m && poolsize > max;) {
auto next = m->next;
poolsize -= T::size;
auto p = m->kprev;
if (p) {
p->knext = std::move(m->knext);
if (p->knext) {
p->knext->kprev = p;
}
} else {
pool = std::move(m->knext);
if (pool) {
pool->kprev = nullptr;
}
}
m = next;
}
freelist = m;
}
void clear() {
freelist = nullptr;
pool = nullptr;
poolsize = 0;
}
using value_type = T;
std::unique_ptr<T> pool;
T *freelist;
size_t poolsize;
};
template <typename Memchunk> struct Memchunks {
Memchunks(Pool<Memchunk> *pool)
: pool(pool), head(nullptr), tail(nullptr), len(0) {}
~Memchunks() {
if (!pool) {
return;
}
for (auto m = head; m;) {
auto next = m->next;
pool->recycle(m);
m = next;
}
}
size_t append(const void *src, size_t count) {
if (count == 0) {
return 0;
}
auto first = static_cast<const uint8_t *>(src);
auto last = first + count;
if (!tail) {
head = tail = pool->get();
}
for (;;) {
auto n = std::min(static_cast<size_t>(last - first), tail->left());
tail->last = std::copy_n(first, n, tail->last);
first += n;
len += n;
if (first == last) {
break;
}
tail->next = pool->get();
tail = tail->next;
}
return count;
}
template <size_t N> size_t append(const char (&s)[N]) {
return append(s, N - 1);
}
size_t remove(void *dest, size_t count) {
if (!tail || count == 0) {
return 0;
}
auto first = static_cast<uint8_t *>(dest);
auto last = first + count;
auto m = head;
while (m) {
auto next = m->next;
auto n = std::min(static_cast<size_t>(last - first), m->len());
assert(m->len());
first = std::copy_n(m->pos, n, first);
m->pos += n;
len -= n;
if (m->len() > 0) {
break;
}
pool->recycle(m);
m = next;
}
head = m;
if (head == nullptr) {
tail = nullptr;
}
return first - static_cast<uint8_t *>(dest);
}
size_t drain(size_t count) {
auto ndata = count;
auto m = head;
while (m) {
auto next = m->next;
auto n = std::min(count, m->len());
m->pos += n;
count -= n;
len -= n;
if (m->len() > 0) {
break;
}
pool->recycle(m);
m = next;
}
head = m;
if (head == nullptr) {
tail = nullptr;
}
return ndata - count;
}
int riovec(struct iovec *iov, int iovcnt) {
if (!head) {
return 0;
}
auto m = head;
int i;
for (i = 0; i < iovcnt && m; ++i, m = m->next) {
iov[i].iov_base = m->pos;
iov[i].iov_len = m->len();
}
return i;
}
size_t rleft() const { return len; }
Pool<Memchunk> *pool;
Memchunk *head, *tail;
size_t len;
};
using Memchunk16K = Memchunk<16_k>;
using MemchunkPool = Pool<Memchunk16K>;
using DefaultMemchunks = Memchunks<Memchunk16K>;
#define DEFAULT_WR_IOVCNT 16
#if defined(IOV_MAX) && IOV_MAX < DEFAULT_WR_IOVCNT
#define MAX_WR_IOVCNT IOV_MAX
#else // !defined(IOV_MAX) || IOV_MAX >= DEFAULT_WR_IOVCNT
#define MAX_WR_IOVCNT DEFAULT_WR_IOVCNT
#endif // !defined(IOV_MAX) || IOV_MAX >= DEFAULT_WR_IOVCNT
inline int limit_iovec(struct iovec *iov, int iovcnt, size_t max) {
if (max == 0) {
return 0;
}
for (int i = 0; i < iovcnt; ++i) {
auto d = std::min(max, iov[i].iov_len);
iov[i].iov_len = d;
max -= d;
if (max == 0) {
return i + 1;
}
}
return iovcnt;
}
} // namespace nghttp2
#endif // MEMCHUNK_H