mirror of
https://github.com/matrix-construct/construct
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76 lines
2.6 KiB
C++
76 lines
2.6 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_op;
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struct read_opts extern const read_opts_default;
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// Yields ircd::ctx for parallel reads into buffers; total bytes read
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size_t read(const vector_view<read_op> &);
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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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// 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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// 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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// Test whether bytes in the specified range are cached and should not block
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bool incore(const fd &, const size_t &, const read_opts & = read_opts_default);
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// Prefetch data for subsequent read(); offset given in opts (WILLNEED).
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size_t prefetch(const fd &, const size_t &, const read_opts & = read_opts_default);
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// Evict data which won't be read anymore (DONTNEED).
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size_t evict(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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:opts
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{
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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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read_opts(const off_t & = 0);
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};
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/// Convenience aggregation for the parallel read() overload.
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struct ircd::fs::read_op
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{
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// request
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const fs::fd *fd {nullptr};
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const read_opts *opts {nullptr};
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mutable_buffers bufs;
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// result
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std::exception_ptr eptr;
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size_t ret {0};
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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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:opts{offset, op::READ}
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{}
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