mirror of
https://github.com/matrix-construct/construct
synced 2024-08-20 16:44:43 +02:00
398 lines
9.2 KiB
C++
398 lines
9.2 KiB
C++
// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk
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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.
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//
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// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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// IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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#pragma once
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#define HAVE_AIO_H
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#include <RB_INC_SYS_SYSCALL_H
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#include <RB_INC_SYS_EVENTFD_H
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#include <linux/aio_abi.h>
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/// AIO context instance. Right now this is a singleton with an extern
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/// instance at fs::aioctx.
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struct ircd::fs::aio
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{
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struct request;
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/// Maximum number of events we can submit to kernel
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static constexpr const size_t &MAX_EVENTS
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{
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64
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};
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/// The semaphore value for the eventfd which we keep here.
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uint64_t semval{0};
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/// An eventfd which will be notified by the kernel; we integrate this with
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/// the ircd io_service core epoll() event loop. The EFD_SEMAPHORE flag is
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/// not used to reduce the number of triggers. We can collect multiple AIO
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/// completions after a single trigger to this fd. With EFD_SEMAPHORE, we
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/// would collect all the completions on the first trigger and then
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/// continue to get polled. Because EFD_SEMAPHORE is not set, the semval
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/// which is kept above will reflect a hint for how many AIO's are done.
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asio::posix::stream_descriptor resfd
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{
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*ircd::ios, int(syscall(::eventfd, semval, EFD_NONBLOCK))
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};
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/// Handler to the io context we submit requests to the kernel with
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aio_context_t idp{0};
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// Callback stack invoked when the sigfd is notified of completed events.
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void handle_event(const io_event &) noexcept;
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void handle_events() noexcept;
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void handle(const error_code &, const size_t) noexcept;
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void set_handle();
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aio()
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{
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syscall<SYS_io_setup>(MAX_EVENTS, &idp);
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set_handle();
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}
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~aio() noexcept
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{
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resfd.cancel();
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syscall<SYS_io_destroy>(idp);
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}
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};
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/// Generic request control block.
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struct ircd::fs::aio::request
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:iocb
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{
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struct read;
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struct write;
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ssize_t retval {0};
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ssize_t errcode {0};
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ctx::ctx *waiter {ctx::current};
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void handle();
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public:
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size_t operator()();
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void cancel();
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request(const int &fd);
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~request() noexcept;
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};
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ircd::fs::aio::request::request(const int &fd)
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:iocb{0}
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{
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assert(aioctx);
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assert(ctx::current);
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aio_flags = IOCB_FLAG_RESFD;
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aio_resfd = aioctx->resfd.native_handle();
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aio_fildes = fd;
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aio_data = uintptr_t(this);
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}
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/// vtable base
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ircd::fs::aio::request::~request()
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noexcept
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{
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}
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/// Cancel a request. The handler callstack is invoked directly from here
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/// which means any callback will be invoked or ctx will be notified if
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/// appropriate.
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void
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ircd::fs::aio::request::cancel()
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{
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io_event result {0};
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const auto &cb{static_cast<iocb *>(this)};
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assert(aioctx);
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syscall_nointr<SYS_io_cancel>(aioctx->idp, cb, &result);
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aioctx->handle_event(result);
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}
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/// Submit a request and properly yield the ircd::ctx. When this returns the
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/// result will be available or an exception will be thrown.
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size_t
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ircd::fs::aio::request::operator()()
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try
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{
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assert(aioctx);
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assert(ctx::current);
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assert(waiter == ctx::current);
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struct iocb *const cbs[]
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{
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static_cast<iocb *>(this)
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};
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syscall<SYS_io_submit>(aioctx->idp, 1, &cbs); do
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{
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ctx::wait();
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}
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while(!retval && !errcode);
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if(retval == -1)
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throw_system_error(errcode);
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return size_t(retval);
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}
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catch(const ctx::interrupted &e)
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{
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// When the ctx is interrupted we're obligated to cancel the request.
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// The handler callstack is invoked directly from here by cancel() for
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// what it's worth but we rethrow the interrupt anyway.
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cancel();
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throw;
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}
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void
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ircd::fs::aio::request::handle()
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{
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assert(this->retval || errcode);
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if(likely(waiter && waiter != ctx::current))
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ircd::ctx::notify(*waiter);
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}
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//
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// aio
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//
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void
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ircd::fs::aio::set_handle()
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{
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semval = 0;
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const asio::mutable_buffers_1 bufs(&semval, sizeof(semval));
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auto handler{std::bind(&aio::handle, this, ph::_1, ph::_2)};
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asio::async_read(resfd, bufs, std::move(handler));
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}
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/// Handle notifications that requests are complete.
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void
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ircd::fs::aio::handle(const error_code &ec,
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const size_t bytes)
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noexcept
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{
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assert((bytes == 8 && !ec && semval >= 1) || (bytes == 0 && ec));
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assert(!ec || ec.category() == asio::error::get_system_category());
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switch(ec.value())
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{
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case boost::system::errc::success:
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handle_events();
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break;
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case boost::system::errc::operation_canceled:
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return;
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default:
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throw boost::system::system_error(ec);
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}
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set_handle();
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}
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void
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ircd::fs::aio::handle_events()
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noexcept try
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{
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std::array<io_event, MAX_EVENTS> event;
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// The number of completed requests available in events[]. This syscall
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// is restarted on EINTR. After restart, it may or may not find any ready
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// events but it never blocks to do so.
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const auto count
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{
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syscall_nointr<SYS_io_getevents>(idp, 0, event.size(), event.data(), nullptr)
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};
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// The count should be at least 1 event. The only reason to return 0 might
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// be related to an INTR; this assert will find out and may be commented.
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assert(count > 0);
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for(ssize_t i(0); i < count; ++i)
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handle_event(event[i]);
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}
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catch(const std::exception &e)
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{
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log::error("AIO(%p) handle_events: %s",
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this,
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e.what());
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}
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void
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ircd::fs::aio::handle_event(const io_event &event)
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noexcept try
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{
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// Our extended control block is passed in event.data
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auto *const &request
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{
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reinterpret_cast<aio::request *>(event.data)
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};
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// The relevant iocb is repeated back to us in the result; we assert
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// some basic sanity here about the layout of the request conglomerate.
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assert(reinterpret_cast<iocb *>(event.obj) == static_cast<iocb *>(request));
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// error conventions are like so
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assert(event.res >= -1); // unix syscall return value semantic
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assert(event.res2 >= 0); // errno code semantic
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assert(event.res == -1 || event.res2 == 0);
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// Set result indicators
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request->retval = event.res;
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request->errcode = event.res2;
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/*
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log::debug("AIO request(%p) fd:%d op:%d bytes:%lu off:%ld prio:%d ctx:%p result: bytes:%ld errno:%ld",
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request,
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request->aio_fildes,
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request->aio_lio_opcode,
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request->aio_nbytes,
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request->aio_offset,
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request->aio_reqprio,
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request->waiter,
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request->retval,
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request->errcode);
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*/
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request->handle();
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}
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catch(const std::exception &e)
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{
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log::critical("Unhandled request(%lu) event(%p) error: %s",
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event.data,
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&event,
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e.what());
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}
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///////////////////////////////////////////////////////////////////////////////
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//
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// fs/read.h
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//
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namespace ircd::fs
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{
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string_view read__aio(const string_view &path, const mutable_raw_buffer &, const read_opts &);
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std::string read__aio(const string_view &path, const read_opts &);
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}
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/// Read request control block
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struct ircd::fs::aio::request::read
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:request
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{
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read(const int &fd, const mutable_raw_buffer &buf, const read_opts &opts);
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};
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ircd::fs::aio::request::read::read(const int &fd,
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const mutable_raw_buffer &buf,
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const read_opts &opts)
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:request{fd}
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{
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aio_reqprio = opts.priority;
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aio_lio_opcode = IOCB_CMD_PREAD;
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aio_buf = uintptr_t(buffer::data(buf));
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aio_nbytes = buffer::size(buf);
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aio_offset = opts.offset;
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}
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//
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// Interface
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//
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std::string
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ircd::fs::read__aio(const string_view &path,
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const read_opts &opts)
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{
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// Path to open(2) must be null terminated;
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static thread_local char pathstr[2048];
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strlcpy(pathstr, path, sizeof(pathstr));
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const auto fd
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{
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syscall(::open, pathstr, O_CLOEXEC, O_RDONLY)
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};
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const unwind cfd{[&fd]
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{
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syscall(::close, fd);
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}};
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struct stat stat;
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syscall(::fstat, fd, &stat);
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const auto &size
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{
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stat.st_size
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};
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std::string ret(size, char{});
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const mutable_buffer buf
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{
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const_cast<char *>(ret.data()), ret.size()
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};
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aio::request::read request
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{
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int(fd), buf, opts
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};
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const size_t bytes
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{
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request()
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};
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ret.resize(bytes);
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return ret;
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}
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ircd::string_view
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ircd::fs::read__aio(const string_view &path,
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const mutable_raw_buffer &buf,
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const read_opts &opts)
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{
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// Path to open(2) must be null terminated;
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static thread_local char pathstr[2048];
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strlcpy(pathstr, path, sizeof(pathstr));
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const auto fd
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{
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syscall(::open, pathstr, O_CLOEXEC, O_RDONLY)
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};
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const unwind cfd{[&fd]
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{
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syscall(::close, fd);
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}};
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aio::request::read request
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{
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int(fd), buf, opts
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};
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const size_t bytes
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{
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request()
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};
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const string_view view
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{
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reinterpret_cast<const char *>(data(buf)), bytes
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};
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return view;
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}
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