mirror of
https://github.com/matrix-construct/construct
synced 2024-11-16 23:10:54 +01:00
76 lines
3 KiB
C++
76 lines
3 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_FS_READ_H
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namespace ircd::fs
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{
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struct read_opts extern const read_opts_default;
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// Yields ircd::ctx for read into buffers; returns bytes read
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size_t read(const fd &, const mutable_buffers &, const read_opts & = read_opts_default);
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size_t read(const string_view &path, const mutable_buffers &, const read_opts & = read_opts_default);
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// Yields ircd::ctx for read into buffer; returns view of read portion.
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const_buffer read(const fd &, const mutable_buffer &, const read_opts & = read_opts_default);
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const_buffer read(const string_view &path, const mutable_buffer &, const read_opts & = read_opts_default);
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// Yields ircd::ctx for read into allocated string; returns that string
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std::string read(const fd &, const read_opts & = read_opts_default);
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std::string read(const string_view &path, const read_opts & = read_opts_default);
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// Prefetch bytes for subsequent read(); offset is given in opts.
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void prefetch(const fd &, const size_t &, const read_opts & = read_opts_default);
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}
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/// Options for a read operation
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struct ircd::fs::read_opts
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{
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read_opts() = default;
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read_opts(const off_t &);
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/// Offset in the file to start the read from.
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off_t offset {0};
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/// Request priority. Higher value request will take priority over lower
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/// value. Lowest value is zero. Negative value will receive a contextual
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/// value internally (generally just zero). Default is -1.
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int8_t priority {-1};
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/// Determines whether this operation is conducted via AIO. If not, a
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/// direct syscall is made. Using AIO will only block one ircd::ctx while
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/// a direct syscall will block the thread (all contexts). If AIO is not
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/// available or not enabled, or doesn't support this operation, setting
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/// this has no effect.
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bool aio {true};
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/// Yields the ircd::ctx until the buffers are full or EOF. This performs
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/// the unix incremental read loop internally. When this option is true,
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/// any return value from a function in the read suite will not be a
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/// partial value requiring another invocation of read.
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bool all {true};
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/// Whether to propagate an EINTR; otherwise we reinvoke the syscall. For a
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/// read(2) family call this can only happen before any data was read;
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/// an exception will be thrown. We default to true because we have faith
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/// in the useful propagation of an exception for this event.
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bool interruptible {true};
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/// Submits the I/O request immediately rather than allowing IRCd to
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/// queue requests for a few iterations of the ircd::ios event loop.
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/// (only relevant to aio).
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bool nodelay {false};
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};
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inline
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ircd::fs::read_opts::read_opts(const off_t &offset)
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:offset{offset}
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{}
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