From ac03c9a13bc934f55076e27a5c45aae09b50d1f3 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 19 Aug 2019 21:17:42 -0700
Subject: [PATCH] ircd: Use bool return values through prefetching stack.

---
 include/ircd/db/column.h        |  2 +-
 include/ircd/m/event/prefetch.h |  8 ++++----
 ircd/db.cc                      |  9 ++++++---
 ircd/m_event.cc                 | 34 +++++++++++++++++++++++----------
 ircd/m_room.cc                  |  3 +--
 5 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/include/ircd/db/column.h b/include/ircd/db/column.h
index 5dd203238..08e5edf22 100644
--- a/include/ircd/db/column.h
+++ b/include/ircd/db/column.h
@@ -42,7 +42,7 @@ namespace ircd::db
 	// [GET] Tests if key exists
 	bool has(column &, const string_view &key, const gopts & = {});
 	bool cached(column &, const string_view &key, const gopts & = {});
-	void prefetch(column &, const string_view &key, const gopts & = {});
+	bool prefetch(column &, const string_view &key, const gopts & = {});
 
 	// [GET] Query space usage
 	size_t bytes(column &, const std::pair<string_view, string_view> &range, const gopts & = {});
diff --git a/include/ircd/m/event/prefetch.h b/include/ircd/m/event/prefetch.h
index 238ae21ee..b4ac4b244 100644
--- a/include/ircd/m/event/prefetch.h
+++ b/include/ircd/m/event/prefetch.h
@@ -13,9 +13,9 @@
 
 namespace ircd::m
 {
-	void prefetch(const event::idx &, const event::fetch::opts & = event::fetch::default_opts);
-	void prefetch(const event::idx &, const string_view &key);
+	bool prefetch(const event::idx &, const event::fetch::opts & = event::fetch::default_opts);
+	bool prefetch(const event::idx &, const string_view &key);
 
-	void prefetch(const event::id &, const event::fetch::opts & = event::fetch::default_opts);
-	void prefetch(const event::id &, const string_view &key);
+	bool prefetch(const event::id &, const event::fetch::opts & = event::fetch::default_opts);
+	bool prefetch(const event::id &, const string_view &key);
 }
diff --git a/ircd/db.cc b/ircd/db.cc
index a54bba1f1..4f38f6363 100644
--- a/ircd/db.cc
+++ b/ircd/db.cc
@@ -5784,22 +5784,25 @@ ircd::db::bytes(column &column,
 	return ret[0];
 }
 
-void
+bool
 ircd::db::prefetch(column &column,
                    const string_view &key,
                    const gopts &gopts)
 {
 	if(cached(column, key, gopts))
-		return;
+		return false;
 
 	if(!request.avail())
-		return;
+		return false;
 
 	request([column(column), key(std::string(key)), gopts]
 	() mutable
 	{
 		has(column, key, gopts);
 	});
+
+	ctx::yield();
+	return true;
 }
 
 #if 0
diff --git a/ircd/m_event.cc b/ircd/m_event.cc
index 2b5972bb0..1472bab91 100644
--- a/ircd/m_event.cc
+++ b/ircd/m_event.cc
@@ -789,32 +789,46 @@ const
 // event/prefetch.h
 //
 
-void
+bool
 ircd::m::prefetch(const event::id &event_id,
                   const event::fetch::opts &opts)
 {
-	prefetch(index(event_id), opts);
+	return prefetch(index(event_id), opts);
 }
 
-void
+bool
 ircd::m::prefetch(const event::id &event_id,
                   const string_view &key)
 {
-	prefetch(index(event_id), key);
+	return prefetch(index(event_id), key);
 }
 
-void
+bool
 ircd::m::prefetch(const event::idx &event_idx,
                   const event::fetch::opts &opts)
 {
-	const event::keys keys{opts.keys};
-	const vector_view<const string_view> cols{keys};
+	if(event::fetch::should_seek_json(opts))
+		return db::prefetch(dbs::event_json, byte_view<string_view>{event_idx});
+
+	const event::keys keys
+	{
+		opts.keys
+	};
+
+	const vector_view<const string_view> cols
+	{
+		keys
+	};
+
+	bool ret{false};
 	for(const auto &col : cols)
 		if(col)
-			prefetch(event_idx, col);
+			ret |= prefetch(event_idx, col);
+
+	return ret;
 }
 
-void
+bool
 ircd::m::prefetch(const event::idx &event_idx,
                   const string_view &key)
 {
@@ -828,7 +842,7 @@ ircd::m::prefetch(const event::idx &event_idx,
 		dbs::event_column.at(column_idx)
 	};
 
-	db::prefetch(column, byte_view<string_view>{event_idx});
+	return db::prefetch(column, byte_view<string_view>{event_idx});
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/ircd/m_room.cc b/ircd/m_room.cc
index 2ffe88049..327232131 100644
--- a/ircd/m_room.cc
+++ b/ircd/m_room.cc
@@ -192,8 +192,7 @@ ircd::m::room::state::prefetch(const state &state,
 		if(range.second && event_idx > range.second)
 			return;
 
-		m::prefetch(event_idx, fopts);
-		++ret;
+		ret += m::prefetch(event_idx, fopts);
 	}});
 
 	return ret;