From 767322dc376085c5d65d45c3420c7351f2bff147 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Tue, 6 Oct 2020 15:46:36 -0700
Subject: [PATCH] ircd::rand: Simplify interface; comments/cleanup.

---
 include/ircd/rand.h     | 24 ++++++++++++++++++------
 ircd/rand.cc            | 18 +++---------------
 matrix/id.cc            |  6 ++++--
 matrix/user_tokens.cc   |  4 ++--
 modules/media/upload.cc |  2 +-
 5 files changed, 28 insertions(+), 26 deletions(-)

diff --git a/include/ircd/rand.h b/include/ircd/rand.h
index bfe625e78..ba06d8ad1 100644
--- a/include/ircd/rand.h
+++ b/include/ircd/rand.h
@@ -24,36 +24,48 @@ namespace ircd::rand::dict
 /// Tools for randomization
 namespace ircd::rand
 {
+	// Interface state.
 	extern std::random_device device;
 	extern std::mt19937_64 mt;
 
+	// Random integer
 	uint64_t integer();
 	uint64_t integer(const uint64_t &min, const uint64_t &max); // inclusive
 
 	// Random character from dictionary
 	char character(const std::string &dict = dict::alnum);
 
-	// Random string from dictionary
-	string_view string(const std::string &dict, const mutable_buffer &out);
-	std::string string(const std::string &dict, const size_t &len);
+	// Random string from dictionary, fills buffer
+	string_view string(const mutable_buffer &out, const std::string &dict);
 }
 
-// Random character from dictionary
+/// Random character from dictionary
 inline char
 ircd::rand::character(const std::string &dict)
 {
 	assert(!dict.empty());
-	return dict.at(integer(0, dict.size() - 1));
+	const auto pos
+	{
+		integer(0, dict.size() - 1)
+	};
+
+	return dict.at(pos);
 }
 
+/// Random integer in range (inclusive)
 inline uint64_t
 ircd::rand::integer(const uint64_t &min,
                     const uint64_t &max)
 {
-	std::uniform_int_distribution<uint64_t> dist{min, max};
+	std::uniform_int_distribution<uint64_t> dist
+	{
+		min, max
+	};
+
 	return dist(mt);
 }
 
+/// Random 64-bits
 inline uint64_t
 ircd::rand::integer()
 {
diff --git a/ircd/rand.cc b/ircd/rand.cc
index 4ffd97327..ed5d1e75a 100644
--- a/ircd/rand.cc
+++ b/ircd/rand.cc
@@ -44,20 +44,9 @@ decltype(ircd::rand::dict::numeric) ircd::rand::dict::numeric
 	"0123456789"
 };
 
-std::string
-ircd::rand::string(const std::string &dict,
-                   const size_t &len)
-{
-	return ircd::util::string(len, [&dict]
-	(const mutable_buffer &buf)
-	{
-		return string(dict, buf);
-	});
-}
-
 ircd::string_view
-ircd::rand::string(const std::string &dict,
-                   const mutable_buffer &out)
+ircd::rand::string(const mutable_buffer &out,
+                   const std::string &dict)
 {
 	std::uniform_int_distribution<size_t> dist
 	{
@@ -65,9 +54,8 @@ ircd::rand::string(const std::string &dict,
 	};
 
 	std::generate(data(out), data(out) + size(out), [&dict, &dist]
-	() -> char
 	{
-		return dict.at(dist(mt));
+		return char(dict.at(dist(mt)));
 	});
 
 	return out;
diff --git a/matrix/id.cc b/matrix/id.cc
index 417b5069e..3fdee9b01 100644
--- a/matrix/id.cc
+++ b/matrix/id.cc
@@ -527,14 +527,16 @@ ircd::m::id::id(const enum sigil &sigil,
 		case sigil::ROOM:
 		{
 			static const auto &dict{rand::dict::alnum};
-			name = rand::string(dict, mutable_buffer{namebuf, 18});
+			const mutable_buffer dst{namebuf, 18};
+			name = rand::string(dst, dict);
 			break;
 		}
 
 		case sigil::DEVICE:
 		{
 			static const auto &dict{rand::dict::alnum};
-			name = rand::string(dict, mutable_buffer{namebuf, 10});
+			const mutable_buffer dst{namebuf, 10};
+			name = rand::string(dst, dict);
 			break;
 		}
 
diff --git a/matrix/user_tokens.cc b/matrix/user_tokens.cc
index 260c898c2..3e83cbb07 100644
--- a/matrix/user_tokens.cc
+++ b/matrix/user_tokens.cc
@@ -249,8 +249,8 @@ ircd::m::user::tokens::generate(const mutable_buffer &buf)
 
 	const mutable_buffer out
 	{
-		data(buf), std::min(token_max, size(buf))
+		buf, token_max
 	};
 
-	return rand::string(token_dict, out);
+	return rand::string(out, token_dict);
 }
diff --git a/modules/media/upload.cc b/modules/media/upload.cc
index 195b798ae..040cc5b38 100644
--- a/modules/media/upload.cc
+++ b/modules/media/upload.cc
@@ -52,7 +52,7 @@ post__upload(client &client,
 	char randbuf[32];
 	const auto randstr
 	{
-		rand::string(rand::dict::alpha, randbuf)
+		rand::string(randbuf, rand::dict::alpha)
 	};
 
 	const m::media::mxc mxc