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construct/include/ircd/fs/write.h

96 lines
4.3 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_WRITE_H
namespace ircd::fs
{
struct write_opts extern const write_opts_default;
// Yields ircd::ctx for write from buffers; returns bytes written
size_t write(const fd &, const const_buffers &, const write_opts & = write_opts_default);
size_t write(const string_view &path, const const_buffers &, const write_opts & = write_opts_default);
// Yields ircd::ctx for write from buffer; returns view of written portion
const_buffer write(const fd &, const const_buffer &, const write_opts & = write_opts_default);
const_buffer write(const string_view &path, const const_buffer &, const write_opts & = write_opts_default);
// Yields ircd::ctx to append to file from buffers; returns bytes appended
size_t append(const fd &, const const_buffers &, const write_opts & = write_opts_default);
size_t append(const string_view &path, const const_buffers &, const write_opts & = write_opts_default);
// Yields ircd::ctx to append to file from buffer; returns view of written portion
const_buffer append(const fd &, const const_buffer &, const write_opts & = write_opts_default);
const_buffer append(const string_view &path, const const_buffer &, const write_opts & = write_opts_default);
// Yields ircd::ctx to overwrite (trunc) file from buffers; returns bytes written
size_t overwrite(const fd &, const const_buffers &, const write_opts & = write_opts_default);
size_t overwrite(const string_view &path, const const_buffers &, const write_opts & = write_opts_default);
// Yields ircd::ctx to overwrite (trunc) file from buffer; returns view of written portion
const_buffer overwrite(const fd &, const const_buffer & = {}, const write_opts & = write_opts_default);
const_buffer overwrite(const string_view &path, const const_buffer & = {}, const write_opts & = write_opts_default);
// Truncate file to explicit size
void truncate(const fd &, const size_t &, const write_opts & = write_opts_default);
void truncate(const string_view &path, const size_t &, const write_opts & = write_opts_default);
// Allocate
void allocate(const fd &, const size_t &size, const write_opts & = write_opts_default);
}
/// Options for a write operation
struct ircd::fs::write_opts
{
write_opts() = default;
write_opts(const off_t &);
/// Offset in the file to start the write from. For append() if this zero
/// then it will be internally set to the end of the file; otherwise if
/// this is set it will write to that offset, even for append(), unless
/// the host system later ignores the offset due to the file's openmode.
off_t offset {0};
/// Request priority. Lower value request will take priority over higher.
int8_t priority {0};
/// for allocate()
bool keep_size {false};
/// Determines whether this operation is conducted via AIO. 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.
bool aio {true};
/// Yields the ircd::ctx until the buffers are written. This performs
/// the unix incremental write loop internally. When this option is true,
/// any return value from a function in the write() suite will not be a
/// partial value requiring another invocation of write().
bool all {true};
/// Whether to propagate an EINTR; otherwise we reinvoke the syscall. For a
/// write(2) family call this can only happen before any data was written;
/// an exception will be thrown. We default to true because we have faith
/// in the useful propagation of an exception for this event.
bool interruptible {true};
/// 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};
};
inline
ircd::fs::write_opts::write_opts(const off_t &offset)
:offset{offset}
{}