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ircd::ctx: Default to DISPATCH method to wrap context switch spawn; simplify stack.

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This commit is contained in:
Jason Volk 2020-09-08 22:25:22 -07:00
parent b738d95330
commit 98dd705de9
1 changed files with 24 additions and 32 deletions
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56
ircd/ctx.cc
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@ -92,6 +92,7 @@ noexcept
assert(yc == nullptr); // Check that the context isn't active.
}
/// Internal wrapper for asio::spawn; never call directly.
void
IRCD_CTX_STACK_PROTECT
ircd::ctx::ctx::spawn(context::function func)
@ -120,8 +121,8 @@ ircd::ctx::ctx::spawn(context::function func)
ircd::ios::handler::current
};
mark(prof::event::SPAWN);
if(!parent_context) try
assert(!parent_context);
assert(parent_handler); try
{
ios::handler::leave(parent_handler);
boost::asio::spawn(ios::get(), std::move(bound), attrs);
@ -132,14 +133,6 @@ ircd::ctx::ctx::spawn(context::function func)
ios::handler::enter(parent_handler);
throw;
}
else continuation
{
continuation::false_predicate, continuation::noop_interruptor, [&attrs, &bound]
(auto &yield)
{
boost::asio::spawn(ios::get(), std::move(bound), attrs);
}
};
}
/// Base frame for a context.
@ -1205,32 +1198,31 @@ ircd::ctx::context::context(const string_view &name,
this->detach();
}};
// Indicates to the profiler that this context is spawning a child.
if(likely(ircd::ctx::current))
mark(prof::event::SPAWN);
// Branch to spawn via POST mechanism. This is an asynchronous method which
// returns immediately so this context doesn't yield. The spawning occurs
// sometime after this context next yields. This is the primary method to
// spawn contexts. Note: This is the method to spawn contexts when this
// parent is not itself a context as yielding is not possible anyway.
assert(c->flags & POST || ircd::ctx::current);
if(c->flags & POST)
{
ios::post(desc[0], std::move(spawn));
return;
}
continuation
{
continuation::false_predicate, continuation::noop_interruptor, [&spawn, this]
(auto &yield)
{
if(c->flags & DISPATCH)
{
ios::dispatch(desc[2], std::move(spawn));
return;
}
// (experimental) Branch to spawn via defer mechanism.
else if(c->flags & DEFER)
ios::defer(desc[1], ios::synchronous, std::move(spawn));
if(c->flags & DEFER)
{
ios::defer(desc[1], std::move(spawn));
return;
}
spawn();
}
};
// Branch to spawn via dispatch mechanism. This context will yield while
// the spawning takes place on this stack. This is the closest to a direct
// context switch since we don't call spawn() directly from this frame
// which allows the ctx/ios infrastructure to account for the context
// switch. Note: This is also the default method when no flags are given
// and this parent is another context.
else if(c->flags & DISPATCH || (true))
ios::dispatch(desc[2], ios::synchronous, std::move(spawn));
}
ircd::ctx::context::context(context &&other)