mariadb/tpool/aio_simulated.cc
Vladislav Vaintroub 00ee8d85c9 MDEV-16264: Add threadpool library
The library is capable of
- asynchronous execution of tasks (and optionally waiting for them)
- asynchronous file IO
  This is implemented using libaio on Linux and completion ports on
  Windows. Elsewhere, async io is "simulated", which means worker threads
  are performing synchronous IO.
- timers, scheduling work asynchronously in some point of the future.
  Also periodic timers are implemented.
2019-11-15 16:50:22 +01:00

180 lines
No EOL
4.1 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/* Copyright(C) 2019 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*/
#ifndef _WIN32
#include <unistd.h> /* pread(), pwrite() */
#endif
#include "tpool.h"
#include "tpool_structs.h"
#include <stdlib.h>
#include <string.h>
namespace tpool
{
#ifdef _WIN32
/*
In order to be able to execute synchronous IO even on file opened
with FILE_FLAG_OVERLAPPED, and to bypass to completion port,
we use valid event handle for the hEvent member of the OVERLAPPED structure,
with its low-order bit set.
´See MSDN docs for GetQueuedCompletionStatus() for description of this trick.
*/
static DWORD fls_sync_io= FLS_OUT_OF_INDEXES;
HANDLE win_get_syncio_event()
{
HANDLE h;
h= (HANDLE) FlsGetValue(fls_sync_io);
if (h)
{
return h;
}
h= CreateEventA(NULL, FALSE, FALSE, NULL);
/* Set low-order bit to keeps I/O completion from being queued */
h= (HANDLE)((uintptr_t) h | 1);
FlsSetValue(fls_sync_io, h);
return h;
}
#include <WinIoCtl.h>
static void __stdcall win_free_syncio_event(void *data)
{
if (data)
{
CloseHandle((HANDLE) data);
}
}
struct WinIoInit
{
WinIoInit()
{
fls_sync_io= FlsAlloc(win_free_syncio_event);
if(fls_sync_io == FLS_OUT_OF_INDEXES)
abort();
}
~WinIoInit() { FlsFree(fls_sync_io); }
};
static WinIoInit win_io_init;
int pread(const native_file_handle &h, void *buf, size_t count,
unsigned long long offset)
{
OVERLAPPED ov{};
ULARGE_INTEGER uli;
uli.QuadPart= offset;
ov.Offset= uli.LowPart;
ov.OffsetHigh= uli.HighPart;
ov.hEvent= win_get_syncio_event();
if (ReadFile(h, buf, (DWORD) count, 0, &ov) ||
(GetLastError() == ERROR_IO_PENDING))
{
DWORD n_bytes;
if (GetOverlappedResult(h, &ov, &n_bytes, TRUE))
return n_bytes;
}
return -1;
}
int pwrite(const native_file_handle &h, void *buf, size_t count,
unsigned long long offset)
{
OVERLAPPED ov{};
ULARGE_INTEGER uli;
uli.QuadPart= offset;
ov.Offset= uli.LowPart;
ov.OffsetHigh= uli.HighPart;
ov.hEvent= win_get_syncio_event();
if (WriteFile(h, buf, (DWORD) count, 0, &ov) ||
(GetLastError() == ERROR_IO_PENDING))
{
DWORD n_bytes;
if (GetOverlappedResult(h, &ov, &n_bytes, TRUE))
return n_bytes;
}
return -1;
}
#endif
/**
Simulated AIO.
Executes IO synchronously in worker pool
and then calls the completion routine.
*/
class simulated_aio : public aio
{
thread_pool *m_pool;
public:
simulated_aio(thread_pool *tp)
: m_pool(tp)
{
}
static void simulated_aio_callback(void *param)
{
aiocb *cb= (aiocb *) param;
int ret_len;
int err= 0;
switch (cb->m_opcode)
{
case aio_opcode::AIO_PREAD:
ret_len= pread(cb->m_fh, cb->m_buffer, cb->m_len, cb->m_offset);
break;
case aio_opcode::AIO_PWRITE:
ret_len= pwrite(cb->m_fh, cb->m_buffer, cb->m_len, cb->m_offset);
break;
default:
abort();
}
if (ret_len < 0)
{
#ifdef _WIN32
err= GetLastError();
#else
err= errno;
#endif
}
cb->m_ret_len = ret_len;
cb->m_err = err;
cb->m_callback(cb);
}
virtual int submit_io(aiocb *aiocb) override
{
aiocb->m_internal_task.m_func = simulated_aio_callback;
aiocb->m_internal_task.m_arg = aiocb;
aiocb->m_internal_task.m_group = aiocb->m_group;
m_pool->submit_task(&aiocb->m_internal_task);
return 0;
}
virtual int bind(native_file_handle &fd) override { return 0; }
virtual int unbind(const native_file_handle &fd) override { return 0; }
};
aio *create_simulated_aio(thread_pool *tp)
{
return new simulated_aio(tp);
}
} // namespace tpool