68 lines
2.0 KiB
C++
68 lines
2.0 KiB
C++
// The Construct
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//
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// Copyright (C) The Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2023 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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decltype(ircd::m::room::iterate::prefetch)
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ircd::m::room::iterate::prefetch
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{
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{ "name", "ircd.m.room.iterate.prefetch" },
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{ "default", 512L },
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};
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bool
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ircd::m::room::iterate::for_each(const closure &closure)
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const
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{
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entry *const __restrict__ queue
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{
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buf.get()
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};
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// ring queue state
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size_t i{0}; // monotonic
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size_t pos{0}; // modulated index of the current ring head.
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bool ret{true};
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const auto call_user
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{
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[&closure, &queue, &pos, &ret](const string_view &val)
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{
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ret = closure(val, queue[pos].first, queue[pos].second);
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}
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};
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m::room::events it{room};
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for(; it && ret; --it, ++i, pos = i % queue_max)
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{
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// Entry at the current ring head. A prefetch has been for this entry
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// during the last iteration and the fetch will be made this iteration.
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auto &[depth, event_idx]
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{
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queue[pos]
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};
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// Fetch the content for the event at the current queue pos; this will
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// be a no-op on the first iteration when the entries are all zero.
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m::get(std::nothrow, event_idx, column, call_user);
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// After the user consumed the fetched entry, overwrite it with the
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// next prefetch and continue the iteration.
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depth = it.depth();
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event_idx = it.event_idx();
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m::prefetch(event_idx, column);
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}
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// The primary loop completes when there's no more events left to
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// prefetch, but another loop around the queue needs to be made for
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// any fetches still in flight.
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for(size_t j(i); ret && i < j + queue_max; ++i, pos = i % queue_max)
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m::get(std::nothrow, queue[pos].second, column, call_user);
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return ret;
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}
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