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/* 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
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