Add syncback rate limits, ignore CurrentCamera, fix service writing

CHANGELOG.md

@@ -6,6 +6,19 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ## [Unreleased]
 
+### Added
+
+- "Creating" services is now possible via hydration
+
+### Fixed
+
+- `workspace.Camera` is now ignored by syncback so HTTP request limit no longer gets exceeded
+- Removing services no longer causes Argon to crash, instead the user receives a warning
+
+### Changed
+
+- Two-way sync is now rate limited to a maximum of 2 requests per second
+
 ## [2.0.3] - 2024-05-04
 
 ### Fixed
@@ -79,12 +92,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Fixed
 
-- Locked property error ([#1])
+- Locked property error ([#1](https://github.com/argon-rbx/argon-roblox/issues/1))
 - Sync confirmation cancellation not working
 - Text inputs in the Settings widget
 
-[#1]: https://github.com/argon-rbx/argon-roblox/issues/1
-
 ## [2.0.0-pre2] - 2024-03-19
 
 ### Fixed

src/App/.src.lua

@@ -333,8 +333,8 @@ function App:connect()
 	self.core:onSync(function(kind, data)
 		self.lastSync:set(os.time())
 		self.lastSyncKind:set(
-			kind == ('SyncChanges' or 'SyncDetails') and 'Server'
-				or (kind == 'Add' or kind == 'Change' or kind == 'Remove') and 'Client'
+			(kind == 'SyncChanges' or kind == 'SyncDetails') and 'Server'
+				or kind == 'SyncbackChanges' and 'Client'
 				or 'Unknown'
 		)
 

src/Core/.src.lua

@@ -21,6 +21,7 @@ local Tree = require(script.Tree)
 local Error = require(script.Error)
 
 local CHANGES_TRESHOLD = 5
+local SYNCBACK_RATE = 0.5
 
 local Core = {
 	Status = {
@@ -285,9 +286,30 @@ function Core:__startSyncLoop()
 end
 
 function Core:__startSyncbackLoop()
+	local aggregateChanges = Changes.new()
+
 	return Promise.new(function(resolve)
+		task.spawn(function()
+			while self.status == Core.Status.Connected do
+				task.wait(SYNCBACK_RATE)
+
+				if aggregateChanges:isEmpty() then
+					continue
+				end
+
+				local changes = aggregateChanges
+				aggregateChanges = Changes.new()
+
+				self.client:write(changes):catch(function(err)
+					Log.warn('Failed to write changes to the server:', err)
+				end)
+
+				self.__sync('kind', changes)
+			end
+		end)
+
 		while self.status == Core.Status.Connected do
-			local event = self.watcher:awaitEvent() :: Types.WatcherEvent
+			local event = self.watcher:listen() :: Types.WatcherEvent
 
 			if self.processor.read.isPaused then
 				continue
@@ -318,13 +340,7 @@ function Core:__startSyncbackLoop()
 				end
 			end
 
-			if not changes:isEmpty() then
-				self.client:write(changes):catch(function(err)
-					Log.warn('Failed to write changes to the server:', err)
-				end)
-
-				self.__sync(kind, changes)
-			end
+			aggregateChanges:join(changes)
 		end
 
 		resolve()

src/Core/Error.lua

@@ -27,6 +27,9 @@ local Error = {
 	NoInstanceAdd = 'Tried to add an instance whose parent that does not exist in the tree: $1',
 	NoInstanceUpdate = 'Tried to update an instance that does not exist in the tree: $1',
 	NoInstanceRemove = 'Tried to remove an instance that does not exist in the tree: $1',
+	NotCreatable = 'Tried to create an instance of class: $1 that is not creatable',
+	NotRemovable = 'Tried to remove an instance of class: $1 that is not removable',
+	HydrationFailed = 'Failed to hydrate root service, snapshot: $1',
 }
 
 local function eq(self: Error, other: Error): boolean

src/Core/Processor/Write.lua

@@ -54,7 +54,28 @@ function WriteProcessor:applyAddition(snapshot: Types.AddedSnapshot)
 		return
 	end
 
-	local instance = Instance.new(snapshot.class)
+	local instance
+
+	if Dom.isCreatable(snapshot.class) then
+		instance = Instance.new(snapshot.class)
+	elseif parent == game then
+		local service = game:FindFirstChildOfClass(snapshot.class)
+
+		if service then
+			instance = service
+		else
+			local err = Error.new(Error.HydrationFailed, snapshot)
+			Log.warn(err)
+
+			return
+		end
+	else
+		local err = Error.new(Error.NotCreatable, snapshot.class)
+		Log.warn(err)
+
+		return
+	end
+
 	instance.Name = snapshot.name
 
 	for property, value in pairs(snapshot.properties) do
@@ -217,6 +238,13 @@ function WriteProcessor:applyRemoval(object: Types.Ref | Instance)
 			return
 		end
 
+		if not Dom.isCreatable(instance.ClassName) then
+			local err = Error.new(Error.NotRemovable, instance.ClassName)
+			Log.warn(err)
+
+			return
+		end
+
 		self.lastRemovedInstance = {
 			instance = instance:Clone(),
 			parent = instance.Parent,

src/Watcher.lua

@@ -47,11 +47,15 @@ function Watcher:stop()
 	self.connections = {}
 end
 
-function Watcher:awaitEvent(): Types.WatcherEvent
+function Watcher:listen(): Types.WatcherEvent
 	return self.signal:Wait()
 end
 
 function Watcher:__connectEvents(instance: Instance)
+	if instance == workspace.CurrentCamera then
+		return
+	end
+
 	local connections = {}
 
 	table.insert(