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construct/include/ircd/fs/opts.h

76 lines
2.8 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_FS_SYNC_OPTS_H
namespace ircd::fs
{
struct opts extern const opts_default;
int reqprio(int) noexcept __attribute__((const));
}
/// Options common to all operations
struct ircd::fs::opts
{
static const int highest_priority;
/// Offset in the file. If this is -1, for writes, it indicates an append
/// at the end of the file (RWF_APPEND or legacy non-atomic lseek()).
off_t offset {0};
/// Request priority. Lower value takes priority over higher. The lowest
/// possible priority value is special, on supporting platforms (RWF_HIPRI).
/// One can either simply set the integer minimum or use the extern value.
int8_t priority {0};
/// Submits the I/O request immediately rather than allowing IRCd to
/// queue requests for a few iterations of the ircd::ios event loop.
/// (only relevant to aio).
bool nodelay {false};
/// Setting this to false enables non-blocking behavior. If the operation
/// would block, EAGAIN is returned. This is only available with RWF_NOWAIT
/// on newer systems, otherwise this value is ignored and is always true.
/// This feature makes up for the fact that O_NONBLOCK when opening the
/// file is ineffective for regular files.
bool blocking {true};
/// Determines whether this operation is conducted via AIO/io_uring. If
/// not, a direct syscall is made. Using AIO will only block one ircd::ctx
/// while a direct syscall will block the thread (all contexts). If AIO is
/// not available or not enabled, or doesn't support this operation,
/// setting this has no effect. If this system supports io_uring this
/// option is reused to indicate use of io_uring (as AIO and io_uring are
/// not used simultaneously).
bool aio {true};
/// The enumerated operation code to identify the type of request being
/// made at runtime from any abstract list of requests. This is set by
/// the fs:: interface call and not the user in most cases. The user
/// should not rely on this value being preserved if, e.g. they set a read
/// opcode and then pass the opts structure to write().
enum op op {op::NOOP};
/// Suppress logging of some expected/tolerated failures. Set to false
/// if the call should just silently rethrow.
bool errlog {true};
opts(const off_t &, const enum op & = op::NOOP);
opts() = default;
};
inline
ircd::fs::opts::opts(const off_t &offset,
const enum op &op)
:offset{offset}
,op{op}
{}