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construct/matrix/fetch.cc

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// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2019 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.
namespace ircd::m::fetch
{
static bool operator==(const opts &a, const opts &b) noexcept;
static bool operator==(const request &a, const opts &b) noexcept;
static bool operator==(const opts &a, const request &b) noexcept;
static bool operator==(const request &a, const request &b) noexcept;
static bool operator<(const opts &a, const opts &b) noexcept;
static bool operator<(const request &a, const opts &b) noexcept;
static bool operator<(const opts &a, const request &b) noexcept;
static bool operator<(const request &a, const request &b) noexcept;
extern ctx::dock dock;
extern ctx::mutex requests_mutex;
extern std::set<request, std::less<>> requests;
extern ctx::context request_context;
extern conf::item<size_t> backfill_limit_default;
extern conf::item<size_t> requests_max;
extern conf::item<seconds> timeout;
extern conf::item<bool> enable;
extern log::log log;
static bool timedout(const request &, const system_point &now);
extern void check_response(const request &, const json::object &);
static bool proffer_remote(request &, const string_view &);
static bool select_remote(request &, const string_view &);
static bool select_random_remote(request &);
static void finish(request &);
static void retry(request &);
static bool start(request &, const string_view &remote);
static bool start(request &);
static void handle_result(request &);
static bool handle(request &);
static bool request_handle(const decltype(requests)::iterator &);
static void request_handle();
static size_t request_cleanup();
static void request_worker();
}
decltype(ircd::m::fetch::log)
ircd::m::fetch::log
{
"m.fetch"
};
decltype(ircd::m::fetch::enable)
ircd::m::fetch::enable
{
{ "name", "ircd.m.fetch.enable" },
{ "default", true },
};
decltype(ircd::m::fetch::timeout)
ircd::m::fetch::timeout
{
{ "name", "ircd.m.fetch.timeout" },
{ "default", 5L },
};
decltype(ircd::m::fetch::requests_max)
ircd::m::fetch::requests_max
{
{ "name", "ircd.m.fetch.requests.max" },
{ "default", 2048L },
};
decltype(ircd::m::fetch::backfill_limit_default)
ircd::m::fetch::backfill_limit_default
{
{ "name", "ircd.m.fetch.backfill.limit.default" },
{ "default", 96L },
};
decltype(ircd::m::fetch::dock)
ircd::m::fetch::dock;
decltype(ircd::m::fetch::requests)
ircd::m::fetch::requests;
decltype(ircd::m::fetch::requests_mutex)
ircd::m::fetch::requests_mutex;
decltype(ircd::m::fetch::request_context)
ircd::m::fetch::request_context
{
"m.fetch.req",
1_MiB,
&request_worker,
context::POST
};
//
// init
//
ircd::m::fetch::init::init()
{
assert(requests.empty());
}
ircd::m::fetch::init::~init()
noexcept
{
request_context.terminate();
request_context.join();
requests.clear();
assert(requests.empty());
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}
//
// <ircd/m/fetch.h>
//
ircd::ctx::future<ircd::m::fetch::result>
ircd::m::fetch::start(opts opts)
{
assert(opts.room_id && opts.event_id);
if(unlikely(run::level == run::level::QUIT))
throw m::UNAVAILABLE
{
"Cannot start fetch requests at this time."
};
// in case requests are started before runlevel RUN they are stalled here
run::barrier<m::UNAVAILABLE>
{
"The fetch unit is unavailable to start requests."
};
// in case the fetch unit has reached capacity the context will yield.
dock.wait([]
{
return count() < size_t(requests_max);
});
// the state in this unit is primarily driven by the fetch::context; in
// some cases it may want to prevent others from changing this state until
// it's ready to accept.
std::unique_lock lock
{
requests_mutex
};
const scope_notify dock
{
fetch::dock
};
auto it
{
requests.lower_bound(opts)
};
const bool exists
{
it != end(requests) && *it == opts
};
assert(!exists || it->opts.room_id == opts.room_id);
if(!exists)
it = requests.emplace_hint(it, std::move(opts));
auto &request
{
const_cast<fetch::request &>(*it)
};
ctx::future<result> ret
{
request.promise
};
if(!exists)
start(request);
return ret;
}
size_t
ircd::m::fetch::count()
{
return requests.size();
}
bool
ircd::m::fetch::exists(const opts &opts)
{
return requests.count(opts);
}
bool
ircd::m::fetch::for_each(const std::function<bool (request &)> &closure)
{
for(auto &request : requests)
if(!closure(const_cast<fetch::request &>(request)))
return false;
return true;
}
ircd::string_view
ircd::m::fetch::reflect(const op &op)
{
switch(op)
{
case op::noop: return "noop";
case op::auth: return "auth";
case op::event: return "event";
case op::backfill: return "backfill";
}
return "?????";
}
//
// internal
//
//
// request worker
//
void
ircd::m::fetch::request_worker()
try
{
while(1)
{
dock.wait([]
{
return std::any_of(begin(requests), end(requests), []
(const auto &request)
{
return !request.finished;
});
});
request_handle();
}
}
catch(const std::exception &e)
{
log::critical
{
log, "fetch request worker :%s",
e.what()
};
throw;
}
void
ircd::m::fetch::request_handle()
{
std::unique_lock lock
{
requests_mutex
};
const scope_notify notify
{
fetch::dock
};
static const auto dereferencer{[]
(auto &it) -> server::request &
{
// If the request doesn't have a server::request future attached
// during this pass we reference this default constructed static
// instance which when_any() will treat as a no-op.
static server::request request_skip;
auto &request(mutable_cast(*it));
return request.future?
*request.future:
request_skip;
}};
auto next
{
ctx::when_any(requests.begin(), requests.end(), dereferencer)
};
bool timedout{true};
{
const unlock_guard unlock
{
lock
};
timedout = !next.wait(seconds(timeout), std::nothrow);
};
if(likely(!timedout))
{
const auto it
{
next.get()
};
if(it != end(requests))
if(!request_handle(it))
return;
}
request_cleanup();
}
bool
ircd::m::fetch::request_handle(const decltype(requests)::iterator &it)
{
auto &request
{
mutable_cast(*it)
};
if(!request.finished)
if(!handle(request))
return false;
requests.erase(it);
return true;
}
size_t
ircd::m::fetch::request_cleanup()
try
{
const auto now
{
ircd::now<system_point>()
};
size_t ret(0);
for(auto it(begin(requests)); it != end(requests); ++it)
{
auto &request(mutable_cast(*it));
if(!!request.finished || !request.promise)
continue;
else if(!request.started)
start(request);
else if(timedout(request, now))
retry(request);
}
auto it(begin(requests)); while(it != end(requests))
{
auto &request(mutable_cast(*it));
if(!!request.finished || !request.promise)
{
it = requests.erase(it);
++ret;
}
else ++it;
}
return ret;
}
catch(const std::exception &e)
{
log::critical
{
log, "request_cleanup(): %s",
e.what(),
};
throw;
}
//
// fetch::request
//
bool
ircd::m::fetch::start(request &request)
try
{
assert(request.promise);
assert(!request.finished);
// Attempt the user's hint first
if(!request.started && !request.origin && request.opts.hint)
if(proffer_remote(request, request.opts.hint))
select_remote(request, request.opts.hint);
// When no user hint, use legacy event_id hostpart as hint.
if(!request.started && !request.origin)
if(proffer_remote(request, request.opts.event_id.host()))
select_remote(request, request.opts.event_id.host());
if(!!request.started)
if(!request.opts.attempt_limit || request.attempted.size() < request.opts.attempt_limit)
select_random_remote(request);
if(!request.started && !request.origin)
select_random_remote(request);
if(!request.started)
request.started = ircd::now<system_point>();
while(request.origin)
{
if(unlikely(!request.promise))
throw ctx::broken_promise
{
"Fetch interrupted."
};
if(start(request, request.origin))
return true;
if(request.opts.attempt_limit)
if(request.attempted.size() >= request.opts.attempt_limit)
break;
select_random_remote(request);
}
throw m::NOT_FOUND
{
"Cannot find any server to fetch %s in %s in %zu attempts",
string_view{request.opts.event_id},
string_view{request.opts.room_id},
request.attempted.size(),
};
}
catch(...)
{
assert(!request.finished);
request.eptr = std::current_exception();
finish(request);
return false;
}
bool
ircd::m::fetch::start(request &request,
const string_view &remote)
try
{
if(unlikely(run::level != run::level::RUN))
throw m::UNAVAILABLE
{
"Cannot start fetch requests in runlevel."
};
assert(request.promise);
assert(!request.finished);
request.last = ircd::now<system_point>();
if(!request.started)
request.started = request.last;
switch(request.opts.op)
{
case op::noop:
break;
case op::auth:
{
fed::event_auth::opts opts;
opts.remote = remote;
request.future = std::make_unique<fed::event_auth>
(
request.opts.room_id,
request.opts.event_id,
request.buf,
std::move(opts)
);
break;
}
case op::event:
{
fed::event::opts opts;
opts.remote = remote;
request.future = std::make_unique<fed::event>
(
request.opts.event_id,
request.buf,
std::move(opts)
);
break;
}
case op::backfill:
{
fed::backfill::opts opts;
opts.remote = remote;
opts.limit = request.opts.backfill_limit;
opts.limit = opts.limit?: size_t(backfill_limit_default);
opts.event_id = request.opts.event_id;
request.future = std::make_unique<fed::backfill>
(
request.opts.room_id,
request.buf,
std::move(opts)
);
break;
}
}
log::debug
{
log, "Starting %s request for %s in %s from '%s'",
reflect(request.opts.op),
string_view{request.opts.event_id},
string_view{request.opts.room_id},
string_view{request.origin},
};
dock.notify_all();
return true;
}
catch(const m::UNAVAILABLE &e)
{
throw;
}
catch(const ctx::interrupted &e)
{
throw;
}
catch(const http::error &e)
{
log::derror
{
log, "Starting %s request for %s in %s to '%s' :%s %s",
reflect(request.opts.op),
string_view{request.opts.event_id},
string_view{request.opts.room_id},
string_view{request.origin},
e.what(),
e.content,
};
return false;
}
catch(const server::error &e)
{
log::derror
{
log, "Starting %s request for %s in %s to '%s' :%s",
reflect(request.opts.op),
string_view{request.opts.event_id},
string_view{request.opts.room_id},
string_view{request.origin},
e.what(),
};
return false;
}
catch(const std::exception &e)
{
log::error
{
log, "Starting %s request for %s in %s to '%s' :%s",
reflect(request.opts.op),
string_view{request.opts.event_id},
string_view{request.opts.room_id},
string_view{request.origin},
e.what()
};
return false;
}
bool
ircd::m::fetch::select_random_remote(request &request)
{
// Tests if remote is potentially viable
const auto proffer{[&request](const string_view &remote)
{
return proffer_remote(request, remote);
}};
// copies randomly selected remote into the attempted set.
const auto closure{[&request](const string_view &remote)
{
select_remote(request, remote);
}};
const m::room::origins origins
{
request.opts.room_id
};
// Select a random server in the room
request.origin = {};
if(origins.random(closure, proffer))
return true;
// If nothing found attempt hosts from mxids
const string_view mxid[2]
{
request.opts.event_id.host(),
request.opts.room_id.host(),
};
for(const auto &remote : mxid)
if(proffer_remote(request, remote))
if(select_remote(request, remote))
return true;
return false;
}
bool
ircd::m::fetch::select_remote(request &request,
const string_view &remote)
{
const auto it
{
request.attempted.lower_bound(remote)
};
if(it != request.attempted.end() && *it == remote)
return false;
const auto iit
{
request.attempted.emplace_hint(it, remote)
};
request.origin = *iit;
return true;
}
bool
ircd::m::fetch::proffer_remote(request &request,
const string_view &remote)
{
// Case sentinel false.
if(!remote)
return false;
// Don't want to request from myself.
if(my_host(remote))
return false;
// Don't want to use a peer we already tried and failed with.
if(request.attempted.count(remote))
return false;
// Don't want to use a peer marked with an error by ircd::server
if(fed::errant(remote))
return false;
return true;
}
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bool
ircd::m::fetch::handle(request &request)
{
if(likely(request.future))
handle_result(request);
if(!request.eptr || !request.promise)
finish(request);
else
retry(request);
return !!request.finished;
}
void
ircd::m::fetch::handle_result(request &request)
try
{
assert(request.future);
const auto code
{
request.future->get()
};
const string_view content
{
request.future->in.content
};
check_response(request, content);
if(unlikely(!request.promise))
throw ctx::broken_promise
{
"Fetch response check interrupted."
};
assert(request.promise);
char pbuf[48];
log::debug
{
log, "Received %u %s good %s %s in %s from '%s' %s",
uint(code),
status(code),
reflect(request.opts.op),
string_view{request.opts.event_id},
string_view{request.opts.room_id},
string_view{request.origin},
pretty(pbuf, iec(size(content))),
};
}
catch(...)
{
request.eptr = std::current_exception();
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log::derror
{
log, "%s error for %s %s in %s :%s",
string_view{request.origin},
reflect(request.opts.op),
string_view{request.opts.event_id},
string_view{request.opts.room_id},
what(request.eptr),
};
}
void
ircd::m::fetch::retry(request &request)
try
{
assert(request.promise);
assert(!request.finished);
assert(!!request.started && !!request.last);
if(request.future)
{
server::cancel(*request.future);
request.future.reset(nullptr);
}
request.eptr = std::exception_ptr{};
request.origin = {};
start(request);
}
catch(...)
{
request.eptr = std::current_exception();
finish(request);
}
void
ircd::m::fetch::finish(request &request)
{
request.finished = ircd::now<system_point>();
#if 0
log::logf
{
log, request.eptr? log::DERROR: log::DEBUG,
"Finished %s in %s started:%ld finished:%d attempted:%zu abandon:%b %s%s",
string_view{request.opts.event_id},
string_view{request.opts.room_id},
duration_cast<seconds>(tse(request.started)).count(),
duration_cast<seconds>(tse(request.finished)).count(),
request.attempted.size(),
!request.promise,
request.eptr? " :" : "",
what(request.eptr),
};
#endif
if(!request.promise)
return;
if(request.eptr)
{
request.promise.set_exception(std::move(request.eptr));
return;
}
result res;
res.buf = std::move(request.future->in.dynamic);
res.content = res.buf;
strlcpy(res.origin, request.origin);
assert(request.origin == res.origin);
request.promise.set_value(std::move(res));
}
bool
ircd::m::fetch::timedout(const request &request,
const system_point &now)
{
assert(!!request.started && !request.finished && !!request.last);
return request.last + seconds(timeout) < now;
}
bool
ircd::m::fetch::operator<(const request &a, const request &b)
noexcept
{
return a.opts < b.opts;
}
bool
ircd::m::fetch::operator<(const opts &a, const request &b)
noexcept
{
return a < b.opts;
}
bool
ircd::m::fetch::operator<(const request &a, const opts &b)
noexcept
{
return a.opts < b;
}
bool
ircd::m::fetch::operator<(const opts &a, const opts &b)
noexcept
{
if(uint(a.op) < uint(b.op))
return true;
else if(uint(a.op) > uint(b.op))
return false;
else if(a.room_id < b.room_id)
return true;
else if(a.room_id > b.room_id)
return false;
else if(a.event_id < b.event_id)
return true;
else if(a.event_id > b.event_id)
return false;
assert(operator==(a, b));
return false;
}
bool
ircd::m::fetch::operator==(const request &a, const request &b)
noexcept
{
return a.opts == b.opts;
}
bool
ircd::m::fetch::operator==(const opts &a, const request &b)
noexcept
{
return a == b.opts;
}
bool
ircd::m::fetch::operator==(const request &a, const opts &b)
noexcept
{
return a.opts == b;
}
bool
ircd::m::fetch::operator==(const opts &a, const opts &b)
noexcept
{
return uint(a.op) == uint(b.op) &&
a.event_id == b.event_id &&
a.room_id == b.room_id;
}
//
// request::request
//
ircd::m::fetch::request::request(fetch::opts opts)
:opts
{
std::move(opts)
}
,buf
{
this->opts.bufsz?: 16_KiB
}
,event_id
{
this->opts.event_id
}
,room_id
{
this->opts.room_id
}
{
this->opts.event_id = this->event_id;
this->opts.room_id = this->room_id;
}
ircd::m::fetch::request::~request()
noexcept
{
//TODO: bad things unless this first here
future.reset(nullptr);
}