From d456a42cdd27ba9b814f76bf96b7f5da9d05ae37 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Wed, 24 Jun 2020 08:59:26 -0700
Subject: [PATCH] ircd::json: Add stats items counting calls and cycles on
 input and output.

---
 include/ircd/json/util.h | 10 ++++++++++
 ircd/json.cc             |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/include/ircd/json/util.h b/include/ircd/json/util.h
index 6e432b505..b8ff96542 100644
--- a/include/ircd/json/util.h
+++ b/include/ircd/json/util.h
@@ -35,8 +35,18 @@ namespace ircd::json
 	bool valid(const string_view &, std::nothrow_t) noexcept;
 	void valid(const string_view &);
 	std::string why(const string_view &);
+
+	struct stats extern stats;
 }
 
+/// Statistics counter access; unfortunately these cannot participate as
+/// ircd::stats items right now.
+struct ircd::json::stats
+{
+	uint64_t print_calls {0}, print_cycles {0};
+	uint64_t parse_calls {0}, parse_cycles {0};
+};
+
 /// Alternative to `json::strung` which uses a fixed array rather than an
 /// allocated string as the target.
 template<size_t SIZE>
diff --git a/ircd/json.cc b/ircd/json.cc
index 3a8180b28..cc4bfe2ad 100644
--- a/ircd/json.cc
+++ b/ircd/json.cc
@@ -19,6 +19,9 @@ namespace ircd::json
 }
 #pragma GCC visibility pop
 
+decltype(ircd::json::stats)
+ircd::json::stats;
+
 #pragma GCC visibility push(internal)
 BOOST_FUSION_ADAPT_STRUCT
 (
@@ -489,6 +492,8 @@ ircd::json::printer::operator()(mutable_buffer &out,
                                 attr&&... a)
 const
 {
+	++stats.print_calls;
+	const prof::scope_cycles timer{stats.print_cycles};
 	if(unlikely(!ircd::generate(out, std::forward<gen>(g), std::forward<attr>(a)...)))
 		throw print_error
 		{
@@ -542,6 +547,8 @@ ircd::json::parser::operator()(const char *&start,
                                attr&&...a)
 const
 {
+	++stats.parse_calls;
+	const prof::scope_cycles timer{stats.parse_cycles};
 	return ircd::parse<parse_error>(start, stop, std::forward<gen>(g), std::forward<attr>(a)...);
 }