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construct/matrix/room_content.cc

67 lines
2 KiB
C++

// The Construct
//
// Copyright (C) The Construct Developers, Authors & Contributors
// Copyright (C) 2016-2020 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.
decltype(ircd::m::room::content::prefetch)
ircd::m::room::content::prefetch
{
{ "name", "ircd.m.room.content.prefetch" },
{ "default", 512L },
};
bool
ircd::m::room::content::for_each(const closure &closure)
const
{
entry *const __restrict__ queue
{
buf.get()
};
// ring queue state
size_t i{0}; // monotonic
size_t pos{0}; // modulated index of the current ring head.
bool ret{true};
const auto call_user
{
[&closure, &queue, &pos, &ret](const json::object &content)
{
ret = closure(content, queue[pos].first, queue[pos].second);
}
};
m::room::events it{room};
for(; it && ret; --it, ++i, pos = i % queue_max)
{
// Entry at the current ring head. A prefetch has been for this entry
// during the last iteration and the fetch will be made this iteration.
auto &[depth, event_idx]
{
queue[pos]
};
// Fetch the content for the event at the current queue pos; this will
// be a no-op on the first iteration when the entries are all zero.
m::get(std::nothrow, event_idx, "content", call_user);
// After the user consumed the fetched entry, overwrite it with the
// next prefetch and continue the iteration.
depth = it.depth();
event_idx = it.event_idx();
m::prefetch(event_idx, "content");
}
// The primary loop completes when there's no more events left to
// prefetch, but another loop around the queue needs to be made for
// any fetches still in flight.
for(size_t j(i); ret && i < j + queue_max; ++i, pos = i % queue_max)
m::get(std::nothrow, queue[pos].second, "content", call_user);
return ret;
}