zeux · September 5, 2024 20:24 · Sep 1, 2022 · Sep 1, 2022 · Sep 1, 2022 · Sep 1, 2022
diff --git a/gctracker.lua b/gctracker.lua
@@ -19,6 +19,7 @@ PERFORMANCE OF THIS SOFTWARE.
 
 export type GCTracker = {
     -- track the lifetime of object obj; update will call dtor when obj is dead
+    -- note: dtor should not reference obj directly or transitively since tracker keeps a strong reference to it
     track: (obj: any, dtor: () -> ()) -> any,
     -- forget previously tracked object; note, this needs to be passed the token that was returned by track
     forget: (token: any) -> (),

diff --git a/gctracker.lua b/gctracker.lua
@@ -17,7 +17,7 @@ OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 PERFORMANCE OF THIS SOFTWARE.
 ]]--
 
-type GCTracker = {
+export type GCTracker = {
     -- track the lifetime of object obj; update will call dtor when obj is dead
     track: (obj: any, dtor: () -> ()) -> any,
     -- forget previously tracked object; note, this needs to be passed the token that was returned by track
@@ -94,4 +94,6 @@ local function GCTracker(): GCTracker
     end
 
     return self
-end
+end
+
+return { new = GCTracker }
diff --git a/gctracker.lua b/gctracker.lua
@@ -18,102 +18,80 @@ PERFORMANCE OF THIS SOFTWARE.
 ]]--
 
 type GCTracker = {
-	-- track the lifetime of object obj; update will call dtor when obj is dead
-	track: (obj: any, dtor: () -> ()) -> any,
-	-- forget previously tracked object; note, this needs to be passed the token that was returned by track
-	forget: (token: any) -> (),
-	-- update tracker, calling destructors for dead objects; if n is specified, do at most n iterations to amortize cost
-	update: (n: number?) -> ()
+    -- track the lifetime of object obj; update will call dtor when obj is dead
+    track: (obj: any, dtor: () -> ()) -> any,
+    -- forget previously tracked object; note, this needs to be passed the token that was returned by track
+    forget: (token: any) -> (),
+    -- update tracker, calling destructors for dead objects; if n is specified, do at most n iterations to amortize cost
+    update: (n: number?) -> ()
 }
 
 local function GCTracker(): GCTracker
-	-- key: token
-	-- value: tracked object (weak)
-	local tobj = {}
-	setmetatable(tobj, { __mode = "vs" })
-
-	-- key: token
-	-- value: destructor
-	local tdtor = {}
-
-	local self = { lasttoken = nil }
-
-	function self.track(obj, dtor)
-		assert(type(dtor) == "function")
-
-		local token = newproxy()
-
-		tobj[token] = obj
-		tdtor[token] = dtor
-
-		return token
-	end
-
-	function self.forget(token)
-		assert(type(token) == "userdata")
-		assert(tdtor[token] ~= nil)
-
-		tobj[token] = nil
-		tdtor[token] = nil
-	end
-
-	function self.update(n: number?)
-		assert(n == nil or type(n) == "number")
-
-		if n then
-			local lt = self.lasttoken
-			if lt ~= nil and tdtor[lt] == nil then
-				lt = nil
-			end
-
-			for i=1,n do
-				local k, v = next(tdtor, lt)
-
-				if k == nil then
-					lt = nil
-					break
-				end
-
-				if tobj[k] == nil then
-					pcall(v)
-					tdtor[k] = nil
-				end
-
-				lt = k
-			end
-
-			self.lasttoken = lt
-		else
-			for k,v in tdtor do
-				if tobj[k] == nil then
-					pcall(v)
-					tdtor[k] = nil
-				end
-			end
-		end
-	end
-
-	return self
-end
-
---[[ Example, requires collectgarbage() (Luau REPL)
-
-local tracker = GCTracker()
-
-tracker.track({ x = 1 }, function() print("he's dead jim") end)
-local T = {x=2}
-tracker.track(T, function() print("he's also dead jim") end)
-
-tracker.update(1)
-tracker.update(2)
-
-print("first")
-collectgarbage()
-tracker.update()
-
-T = nil
-
-print("second")
-collectgarbage()
-tracker.update()
-]]--
+    -- key: token
+    -- value: tracked object (weak)
+    local tobj = {}
+    setmetatable(tobj, { __mode = "vs" })
+
+    -- key: token
+    -- value: destructor
+    local tdtor = {}
+
+    local self = { lasttoken = nil }
+
+    function self.track(obj, dtor)
+        assert(type(dtor) == "function")
+
+        local token = newproxy()
+
+        tobj[token] = obj
+        tdtor[token] = dtor
+
+        return token
+    end
+
+    function self.forget(token)
+        assert(type(token) == "userdata")
+        assert(tdtor[token] ~= nil)
+
+        tobj[token] = nil
+        tdtor[token] = nil
+    end
+
+    function self.update(n: number?)
+        assert(n == nil or type(n) == "number")
+
+        if n then
+            local lt = self.lasttoken
+            if lt ~= nil and tdtor[lt] == nil then
+                lt = nil
+            end
+
+            for i=1,n do
+                local k, v = next(tdtor, lt)
+
+                if k == nil then
+                    lt = nil
+                    break
+                end
+
+                if tobj[k] == nil then
+                    pcall(v)
+                    tdtor[k] = nil
+                end
+
+                lt = k
+            end
+
+            self.lasttoken = lt
+        else
+            for k,v in tdtor do
+                if tobj[k] == nil then
+                    pcall(v)
+                    tdtor[k] = nil
+                end
+            end
+        end
+    end
+
+    return self
+end
diff --git a/gctracker.lua b/gctracker.lua
@@ -0,0 +1,119 @@
+--!strict
+
+--[[
+BSD Zero Clause License
+
+Copyright (c) 2022 Arseny Kapoulkine
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.
+]]--
+
+type GCTracker = {
+	-- track the lifetime of object obj; update will call dtor when obj is dead
+	track: (obj: any, dtor: () -> ()) -> any,
+	-- forget previously tracked object; note, this needs to be passed the token that was returned by track
+	forget: (token: any) -> (),
+	-- update tracker, calling destructors for dead objects; if n is specified, do at most n iterations to amortize cost
+	update: (n: number?) -> ()
+}
+
+local function GCTracker(): GCTracker
+	-- key: token
+	-- value: tracked object (weak)
+	local tobj = {}
+	setmetatable(tobj, { __mode = "vs" })
+
+	-- key: token
+	-- value: destructor
+	local tdtor = {}
+
+	local self = { lasttoken = nil }
+
+	function self.track(obj, dtor)
+		assert(type(dtor) == "function")
+
+		local token = newproxy()
+
+		tobj[token] = obj
+		tdtor[token] = dtor
+
+		return token
+	end
+
+	function self.forget(token)
+		assert(type(token) == "userdata")
+		assert(tdtor[token] ~= nil)
+
+		tobj[token] = nil
+		tdtor[token] = nil
+	end
+
+	function self.update(n: number?)
+		assert(n == nil or type(n) == "number")
+
+		if n then
+			local lt = self.lasttoken
+			if lt ~= nil and tdtor[lt] == nil then
+				lt = nil
+			end
+
+			for i=1,n do
+				local k, v = next(tdtor, lt)
+
+				if k == nil then
+					lt = nil
+					break
+				end
+
+				if tobj[k] == nil then
+					pcall(v)
+					tdtor[k] = nil
+				end
+
+				lt = k
+			end
+
+			self.lasttoken = lt
+		else
+			for k,v in tdtor do
+				if tobj[k] == nil then
+					pcall(v)
+					tdtor[k] = nil
+				end
+			end
+		end
+	end
+
+	return self
+end
+
+--[[ Example, requires collectgarbage() (Luau REPL)
+
+local tracker = GCTracker()
+
+tracker.track({ x = 1 }, function() print("he's dead jim") end)
+local T = {x=2}
+tracker.track(T, function() print("he's also dead jim") end)
+
+tracker.update(1)
+tracker.update(2)
+
+print("first")
+collectgarbage()
+tracker.update()
+
+T = nil
+
+print("second")
+collectgarbage()
+tracker.update()
+]]--