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/* Copyright (C) 2021, 2022, MariaDB Corporation.
This program is free software; you can redistribute itand /or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111 - 1301 USA*/
#include "tpool_structs.h"
#include "tpool.h"
#include "mysql/service_my_print_error.h"
#include "mysqld_error.h"
#include <liburing.h>
#include <pthread.h>
#include <algorithm>
#include <vector>
#include <thread>
#include <mutex>
#include <stdexcept>
#include <my_sys.h>
namespace
{
class aio_uring final : public tpool::aio
{
public:
aio_uring(tpool::thread_pool *tpool, int max_aio) : tpool_(tpool)
{
if (const auto e= io_uring_queue_init(max_aio, &uring_, 0))
{
switch (-e) {
case ENOMEM:
my_printf_error(ER_UNKNOWN_ERROR,
"io_uring_queue_init() failed with ENOMEM:"
" try larger memory locked limit, ulimit -l"
", or https://mariadb.com/kb/en/systemd/#configuring-limitmemlock"
" under systemd"
#ifdef HAVE_IO_URING_MLOCK_SIZE
" (%zd bytes required)", ME_ERROR_LOG | ME_WARNING,
io_uring_mlock_size(max_aio, 0));
#else
, ME_ERROR_LOG | ME_WARNING);
#endif
break;
case ENOSYS:
my_printf_error(ER_UNKNOWN_ERROR,
"io_uring_queue_init() failed with ENOSYS:"
" check seccomp filters, and the kernel version "
"(newer than 5.1 required)",
ME_ERROR_LOG | ME_WARNING);
break;
case EPERM:
my_printf_error(ER_UNKNOWN_ERROR,
"io_uring_queue_init() failed with EPERM:"
" sysctl kernel.io_uring_disabled has the value 2, "
"or 1 and the user of the process is not a member of "
"sysctl kernel.io_uring_group. (see man 2 "
"io_uring_setup).",
ME_ERROR_LOG | ME_WARNING);
break;
default:
my_printf_error(ER_UNKNOWN_ERROR,
"io_uring_queue_init() failed with errno %d",
ME_ERROR_LOG | ME_WARNING, e);
}
throw std::runtime_error("aio_uring()");
}
if (io_uring_ring_dontfork(&uring_) != 0)
{
my_printf_error(ER_UNKNOWN_ERROR,
"io_uring_dontfork() failed with errno %d (continuing)",
ME_ERROR_LOG | ME_WARNING, errno);
}
thread_= std::thread(thread_routine, this);
}
const char *get_implementation() const override { return "io_uring"; };
~aio_uring() noexcept override
{
{
std::lock_guard<std::mutex> _(mutex_);
io_uring_sqe *sqe= io_uring_get_sqe(&uring_);
io_uring_prep_nop(sqe);
io_uring_sqe_set_data(sqe, nullptr);
auto ret= io_uring_submit(&uring_);
if (ret != 1)
{
my_printf_error(ER_UNKNOWN_ERROR,
"io_uring_submit() returned %d during shutdown:"
" this may cause a hang",
ME_ERROR_LOG | ME_FATAL, ret);
abort();
}
}
thread_.join();
io_uring_queue_exit(&uring_);
}
int submit_io(tpool::aiocb *cb) final
{
cb->m_iovec.iov_base= cb->m_buffer;
cb->m_iovec.iov_len= cb->m_len;
// The whole operation since io_uring_get_sqe() and till io_uring_submit()
// must be atomical. This is because liburing provides thread-unsafe calls.
std::lock_guard<std::mutex> _(mutex_);
io_uring_sqe *sqe= io_uring_get_sqe(&uring_);
if (cb->m_opcode == tpool::aio_opcode::AIO_PREAD)
io_uring_prep_readv(sqe, cb->m_fh, &cb->m_iovec, 1, cb->m_offset);
else
io_uring_prep_writev(sqe, cb->m_fh, &cb->m_iovec, 1, cb->m_offset);
io_uring_sqe_set_data(sqe, cb);
return io_uring_submit(&uring_) == 1 ? 0 : -1;
}
int bind(native_file_handle &fd) final
{
std::lock_guard<std::mutex> _(files_mutex_);
auto it= std::lower_bound(files_.begin(), files_.end(), fd);
assert(it == files_.end() || *it != fd);
files_.insert(it, fd);
return io_uring_register_files_update(&uring_, 0, files_.data(),
files_.size());
}
int unbind(const native_file_handle &fd) final
{
std::lock_guard<std::mutex> _(files_mutex_);
auto it= std::lower_bound(files_.begin(), files_.end(), fd);
assert(*it == fd);
files_.erase(it);
return io_uring_register_files_update(&uring_, 0, files_.data(),
files_.size());
}
private:
static void thread_routine(aio_uring *aio)
{
my_thread_set_name("io_uring_wait");
for (;;)
{
io_uring_cqe *cqe;
if (int ret= io_uring_wait_cqe(&aio->uring_, &cqe))
{
if (ret == -EINTR)
continue;
my_printf_error(ER_UNKNOWN_ERROR,
"io_uring_wait_cqe() returned %d",
ME_ERROR_LOG | ME_FATAL, ret);
abort();
}
auto *iocb= static_cast<tpool::aiocb*>(io_uring_cqe_get_data(cqe));
if (!iocb)
break; // ~aio_uring() told us to terminate
int res= cqe->res;
if (res < 0)
{
iocb->m_err= -res;
iocb->m_ret_len= 0;
}
else
{
iocb->m_err= 0;
iocb->m_ret_len= res;
}
io_uring_cqe_seen(&aio->uring_, cqe);
finish_synchronous(iocb);
// If we need to resubmit the IO operation, but the ring is full,
// we will follow the same path as for any other error codes.
if (res == -EAGAIN && !aio->submit_io(iocb))
continue;
iocb->m_internal_task.m_func= iocb->m_callback;
iocb->m_internal_task.m_arg= iocb;
iocb->m_internal_task.m_group= iocb->m_group;
aio->tpool_->submit_task(&iocb->m_internal_task);
}
}
io_uring uring_;
std::mutex mutex_;
tpool::thread_pool *tpool_;
std::thread thread_;
std::vector<native_file_handle> files_;
std::mutex files_mutex_;
};
} // namespace
namespace tpool
{
aio *create_uring(thread_pool *pool, int max_aio)
{
try {
return new aio_uring(pool, max_aio);
} catch (std::runtime_error&) {
return nullptr;
}
}
} // namespace tpool
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