From 9bca61313ee79c05f82eea7df528aa1b34f8110a Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Wed, 1 Apr 2020 12:17:26 -0700
Subject: [PATCH] ircd::m::device: Add unconditional direct putter; setter to
 check for duplicate value.

---
 include/ircd/m/device.h |  1 +
 matrix/device.cc        | 36 ++++++++++++++++++++++++++++++------
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/include/ircd/m/device.h b/include/ircd/m/device.h
index 94ec35f81..1e41ca4c9 100644
--- a/include/ircd/m/device.h
+++ b/include/ircd/m/device.h
@@ -132,6 +132,7 @@ struct ircd::m::device
 	static bool has(const user &, const string_view &id, const string_view &prop);
 	static bool has(const user &, const string_view &id);
 	static bool del(const user &, const string_view &id);
+	static bool put(const user &, const string_view &id, const string_view &prop, const string_view &val);
 	static bool set(const user &, const string_view &id, const string_view &prop, const string_view &val);
 	static bool set(const user &, const device &);
 
diff --git a/matrix/device.cc b/matrix/device.cc
index 163d9fc92..b9c28a235 100644
--- a/matrix/device.cc
+++ b/matrix/device.cc
@@ -55,16 +55,18 @@ ircd::m::device::set(const m::user &user,
 		json::at<"device_id"_>(device)
 	};
 
-	json::for_each(device, [&user, &device_id]
+	bool ret {false};
+	json::for_each(device, [&user, &device_id, &ret]
 	(const auto &prop, auto &&val)
 	{
-		if(!json::defined(json::value(val)))
-			return;
-
-		set(user, device_id, prop, val);
+		if constexpr(std::is_assignable<string_view, decltype(val)>())
+		{
+			if(json::defined(json::value(val)))
+				ret |= set(user, device_id, prop, val);
+		}
 	});
 
-	return true;
+	return ret;
 }
 
 bool
@@ -72,6 +74,28 @@ ircd::m::device::set(const m::user &user,
                      const string_view &id,
                      const string_view &prop,
                      const string_view &val)
+{
+	bool dup {false};
+	const bool got
+	{
+		get(std::nothrow, user, id, prop, [&val, &dup]
+		(const json::string &existing)
+		{
+			dup = val == existing;
+		})
+	};
+
+	assert(!dup || got);
+	return !dup?
+		put(user, id, prop, val):
+		false;
+}
+
+bool
+ircd::m::device::put(const m::user &user,
+                     const string_view &id,
+                     const string_view &prop,
+                     const string_view &val)
 {
 	char buf[m::event::TYPE_MAX_SIZE];
 	const string_view type{fmt::sprintf