From c7a68a8cb3d51d2f33583c518fe592bc8bd4e1e4 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Fri, 12 Jul 2019 15:18:26 -0700
Subject: [PATCH] ircd::ctx: Fix ctx::parallel argument allocation assumptions.

ircd::ctx: Rename tool.
---
 include/ircd/ctx/{parallel.h => concurrent.h} | 95 +++++++++----------
 include/ircd/ctx/ctx.h                        |  2 +-
 modules/client/sync/presence.cc               | 19 ++--
 modules/client/sync/rooms/state.cc            | 16 ++--
 4 files changed, 66 insertions(+), 66 deletions(-)
 rename include/ircd/ctx/{parallel.h => concurrent.h} (56%)

diff --git a/include/ircd/ctx/parallel.h b/include/ircd/ctx/concurrent.h
similarity index 56%
rename from include/ircd/ctx/parallel.h
rename to include/ircd/ctx/concurrent.h
index f18cd6999..dce244430 100644
--- a/include/ircd/ctx/parallel.h
+++ b/include/ircd/ctx/concurrent.h
@@ -1,7 +1,7 @@
 // Matrix Construct
 //
 // Copyright (C) Matrix Construct Developers, Authors & Contributors
-// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+// 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
@@ -9,20 +9,21 @@
 // full license for this software is available in the LICENSE file.
 
 #pragma once
-#define HAVE_IRCD_CTX_PARALLEL_H
+#define HAVE_IRCD_CTX_CONCURRENT_H
 
 namespace ircd::ctx
 {
-	template<class arg> class parallel;
+	template<class arg> class concurrent;
 }
 
 template<class arg>
-struct ircd::ctx::parallel
+struct ircd::ctx::concurrent
 {
 	using closure = std::function<void (arg &)>;
 
 	pool *p {nullptr};
 	vector_view<arg> a;
+	std::vector<bool> b;
 	closure c;
 	dock d;
 	std::exception_ptr eptr;
@@ -35,34 +36,34 @@ struct ircd::ctx::parallel
 	void wait_done();
 	void wait_avail();
 	void rethrow_any_exception();
-	void receiver() noexcept;
-	void sender() noexcept;
+	void receiver(const size_t pos) noexcept;
+	void sender(const size_t pos) noexcept;
 
   public:
 	size_t nextpos() const;
 
-	void operator()();
 	void operator()(const arg &a);
 
-	parallel(pool &, const vector_view<arg> &, closure);
-	parallel(parallel &&) = delete;
-	parallel(const parallel &) = delete;
-	~parallel() noexcept;
+	concurrent(pool &, const vector_view<arg> &, closure);
+	concurrent(concurrent &&) = delete;
+	concurrent(const concurrent &) = delete;
+	~concurrent() noexcept;
 };
 
 template<class arg>
-ircd::ctx::parallel<arg>::parallel(pool &p,
-                                   const vector_view<arg> &a,
-                                   closure c)
+ircd::ctx::concurrent<arg>::concurrent(pool &p,
+                                       const vector_view<arg> &a,
+                                       closure c)
 :p{&p}
 ,a{a}
+,b(this->a.size(), false)
 ,c{std::move(c)}
 {
 	p.min(this->a.size());
 }
 
 template<class arg>
-ircd::ctx::parallel<arg>::~parallel()
+ircd::ctx::concurrent<arg>::~concurrent()
 noexcept
 {
 	const uninterruptible::nothrow ui;
@@ -71,44 +72,43 @@ noexcept
 
 template<class arg>
 void
-ircd::ctx::parallel<arg>::operator()(const arg &a)
+ircd::ctx::concurrent<arg>::operator()(const arg &a)
 {
 	const uninterruptible ui;
 	rethrow_any_exception();
 	assert(avail());
-	this->a.at(nextpos()) = a;
-	sender();
-	wait_avail();
-}
-
-template<class arg>
-void
-ircd::ctx::parallel<arg>::operator()()
-{
-	const uninterruptible ui;
-	rethrow_any_exception();
-	assert(avail());
-	sender();
+	const auto nextpos(this->nextpos());
+	assert(nextpos < b.size());
+	this->a.at(nextpos) = a;
+	assert(this->b.at(nextpos) == false);
+	this->b.at(nextpos) = true;
+	sender(nextpos);
 	wait_avail();
 }
 
 template<class arg>
 size_t
-ircd::ctx::parallel<arg>::nextpos()
+ircd::ctx::concurrent<arg>::nextpos()
 const
 {
-	return snd % a.size();
+	const auto it
+	{
+		std::find(begin(b), end(b), false)
+	};
+
+	return std::distance(begin(b), it);
 }
 
 template<class arg>
 void
-ircd::ctx::parallel<arg>::sender()
+ircd::ctx::concurrent<arg>::sender(const size_t pos)
 noexcept
 {
+	assert(pos < b.size());
 	auto &p(*this->p);
 	auto func
 	{
-		std::bind(&parallel::receiver, this)
+		std::bind(&concurrent::receiver, this, pos) //TODO: alloc
 	};
 
 	++snd;
@@ -121,15 +121,11 @@ noexcept
 
 template<class arg>
 void
-ircd::ctx::parallel<arg>::receiver()
+ircd::ctx::concurrent<arg>::receiver(const size_t pos)
 noexcept
 {
-	assert(snd > rcv);
-	const auto pos
-	{
-		rcv++ % this->a.size()
-	};
-
+	++rcv;
+	assert(snd >= rcv);
 	if(!this->eptr) try
 	{
 		c(this->a.at(pos));
@@ -139,14 +135,17 @@ noexcept
 		this->eptr = std::current_exception();
 	}
 
+	assert(pos < b.size());
+	assert(this->b.at(pos) == true);
+	this->b.at(pos) = false;
 	assert(rcv > fin);
-	fin++;
+	++fin;
 	d.notify_one();
 }
 
 template<class arg>
 void
-ircd::ctx::parallel<arg>::rethrow_any_exception()
+ircd::ctx::concurrent<arg>::rethrow_any_exception()
 {
 	if(likely(!this->eptr))
 		return;
@@ -159,7 +158,7 @@ ircd::ctx::parallel<arg>::rethrow_any_exception()
 
 template<class arg>
 void
-ircd::ctx::parallel<arg>::wait_avail()
+ircd::ctx::concurrent<arg>::wait_avail()
 {
 	d.wait([this]
 	{
@@ -169,7 +168,7 @@ ircd::ctx::parallel<arg>::wait_avail()
 
 template<class arg>
 void
-ircd::ctx::parallel<arg>::wait_done()
+ircd::ctx::concurrent<arg>::wait_done()
 {
 	d.wait([this]
 	{
@@ -179,23 +178,23 @@ ircd::ctx::parallel<arg>::wait_done()
 
 template<class arg>
 bool
-ircd::ctx::parallel<arg>::avail()
+ircd::ctx::concurrent<arg>::avail()
 const
 {
 	assert(snd >= rcv);
 	assert(rcv >= fin);
 	assert(snd - rcv <= a.size());
 	assert(snd - fin <= a.size());
-	return snd - fin < a.size();
+	return snd - fin < a.size() && nextpos() < a.size();
 }
 
 template<class arg>
 bool
-ircd::ctx::parallel<arg>::done()
+ircd::ctx::concurrent<arg>::done()
 const
 {
 	assert(snd >= rcv);
 	assert(rcv >= fin);
 	assert(snd - rcv <= a.size());
-	return snd - fin == 0;
+	return snd - fin == 0 && nextpos() == 0;
 }
diff --git a/include/ircd/ctx/ctx.h b/include/ircd/ctx/ctx.h
index cd2f84a7e..85d927857 100644
--- a/include/ircd/ctx/ctx.h
+++ b/include/ircd/ctx/ctx.h
@@ -101,7 +101,7 @@ namespace ircd::ctx
 #include "pool.h"
 #include "ole.h"
 #include "fault.h"
-#include "parallel.h"
+#include "concurrent.h"
 
 // Exports to ircd::
 namespace ircd
diff --git a/modules/client/sync/presence.cc b/modules/client/sync/presence.cc
index c9b72a549..3f5a64c3e 100644
--- a/modules/client/sync/presence.cc
+++ b/modules/client/sync/presence.cc
@@ -123,12 +123,12 @@ ircd::m::sync::presence_polylog(data &data)
 		};
 	}};
 
-	// Setup for parallelization.
+	// Setup for concurrentization.
 	static const size_t fibers(64); //TODO: conf
 	using buffer = std::array<char[m::id::MAX_SIZE+1], fibers>;
 	const auto buf(std::make_unique<buffer>());
 	std::array<string_view, fibers> q;
-	ctx::parallel<string_view> parallel
+	ctx::concurrent<string_view> concurrent
 	{
 		m::sync::pool, q, [&data, &append_event]
 		(const m::user::id user_id)
@@ -145,19 +145,18 @@ ircd::m::sync::presence_polylog(data &data)
 
 	// Iterate all of the users visible to our user in joined rooms.
 	const m::user::mitsein mitsein{data.user};
-	mitsein.for_each("join", [&parallel, &q, &buf]
+	mitsein.for_each("join", [&concurrent, &q, &buf]
 	(const m::user &user)
 	{
 		// Manual copy of the user_id string to the buffer and assignment
-		// of q at the next position. parallel.snd is the position in q
-		// which ctx::parallel wants us to store the next data at. The
-		// parallel() call doesn't return (blocks this context) until there's
+		// of q at the next position. concurrent.snd is the position in q
+		// which ctx::concurrent wants us to store the next data at. The
+		// concurrent() call doesn't return (blocks this context) until there's
 		// a next position available; propagating flow-control for the iter.
-		const auto pos(parallel.nextpos());
-		q[pos] = strlcpy(buf->at(pos), user.user_id);
-		parallel();
+		const auto pos(concurrent.nextpos());
+		concurrent(strlcpy(buf->at(pos), user.user_id));
 	});
 
-	parallel.wait_done();
+	concurrent.wait_done();
 	return ret;
 }
diff --git a/modules/client/sync/rooms/state.cc b/modules/client/sync/rooms/state.cc
index 373b56e67..d63da30b3 100644
--- a/modules/client/sync/rooms/state.cc
+++ b/modules/client/sync/rooms/state.cc
@@ -208,8 +208,8 @@ ircd::m::sync::room_state_polylog_events(data &data)
 	};
 
 	ctx::mutex mutex;
-	std::array<event::idx, 64> md; //TODO: conf
-	std::vector<event::fetch> event(md.size() * 2);
+	std::array<event::idx, 64> md;
+	std::vector<event::fetch> event(md.size() * 3);
 	for(auto &fetch : event)
 		fetch = event::fetch{_default_fopts};
 
@@ -237,19 +237,21 @@ ircd::m::sync::room_state_polylog_events(data &data)
 		ret = true;
 	}};
 
-	ctx::parallel<event::idx> parallel
+	ctx::concurrent<event::idx> concurrent
 	{
 		m::sync::pool, md, each_idx
 	};
 
-	state.for_each([&data, &parallel]
+	state.for_each([&data, &concurrent, &each_idx]
 	(const m::event::idx &event_idx)
 	{
-		if(apropos(data, event_idx))
-			parallel(event_idx);
+		if(!apropos(data, event_idx))
+			return;
+
+		concurrent(event_idx);
 	});
 
-	parallel.wait_done();
+	concurrent.wait_done();
 	return ret;
 }