Move the call_arena to the page.

The call_arena was previously owned by the js.Context, but it has to exist on
the page, and the page is created before the context, so it's set to undefined
on the page. While this has never caused an issue, there's no reason for the
page not to own this, and the context to simply reference it.

Also, renamed the js.Context.context_arena to simply `arena`, which is more
consistent with other arena names (e.g. page.arena).

Author: karlseguin

src/browser/browser.zig

@@ -39,6 +39,7 @@ pub const Browser = struct {
     session: ?Session,
     allocator: Allocator,
     http_client: *HttpClient,
+    call_arena: ArenaAllocator,
     page_arena: ArenaAllocator,
     session_arena: ArenaAllocator,
     transfer_arena: ArenaAllocator,
@@ -63,6 +64,7 @@ pub const Browser = struct {
             .allocator = allocator,
             .notification = notification,
             .http_client = app.http.client,
+            .call_arena = ArenaAllocator.init(allocator),
             .page_arena = ArenaAllocator.init(allocator),
             .session_arena = ArenaAllocator.init(allocator),
             .transfer_arena = ArenaAllocator.init(allocator),
@@ -73,6 +75,7 @@ pub const Browser = struct {
     pub fn deinit(self: *Browser) void {
         self.closeSession();
         self.env.deinit();
+        self.call_arena.deinit();
         self.page_arena.deinit();
         self.session_arena.deinit();
         self.transfer_arena.deinit();

src/browser/js/Context.zig

@@ -35,12 +35,11 @@ templates: []v8.FunctionTemplate,
 // references the Env.meta_lookup
 meta_lookup: []types.Meta,
 
-// An arena for the lifetime of a call-group. Gets reset whenever
-// call_depth reaches 0.
-call_arena: Allocator,
+// Arena for the lifetime of the context
+arena: Allocator,
 
-// An arena for the lifetime of the context
-context_arena: Allocator,
+// The page.call_arena
+call_arena: Allocator,
 
 // Because calls can be nested (i.e.a function calling a callback),
 // we can only reset the call_arena when call_depth == 0. If we were
@@ -179,7 +178,7 @@ pub fn deinit(self: *Context) void {
 }
 
 fn trackCallback(self: *Context, pf: PersistentFunction) !void {
-    return self.callbacks.append(self.context_arena, pf);
+    return self.callbacks.append(self.arena, pf);
 }
 
 // Given an anytype, turns it into a v8.Object. The anytype could be:
@@ -236,7 +235,7 @@ pub fn module(self: *Context, comptime want_result: bool, src: []const u8, url:
 
     const m = try compileModule(self.isolate, src, url);
 
-    const arena = self.context_arena;
+    const arena = self.arena;
     const owned_url = try arena.dupe(u8, url);
 
     try self.module_identifier.putNoClobber(arena, m.getIdentityHash(), owned_url);
@@ -258,9 +257,9 @@ pub fn module(self: *Context, comptime want_result: bool, src: []const u8, url:
                 owned_url,
                 .{ .alloc = .if_needed, .null_terminated = true },
             );
-            const gop = try self.module_cache.getOrPut(self.context_arena, normalized_specifier);
+            const gop = try self.module_cache.getOrPut(self.arena, normalized_specifier);
             if (!gop.found_existing) {
-                const owned_specifier = try self.context_arena.dupeZ(u8, normalized_specifier);
+                const owned_specifier = try self.arena.dupeZ(u8, normalized_specifier);
                 gop.key_ptr.* = owned_specifier;
                 gop.value_ptr.* = .{};
                 try self.script_manager.?.getModule(owned_specifier);
@@ -522,26 +521,26 @@ pub fn zigValueToJs(self: *Context, value: anytype) !v8.Value {
 //      we can just grab it from the identity_map)
 pub fn mapZigInstanceToJs(self: *Context, js_obj_or_template: anytype, value: anytype) !PersistentObject {
     const v8_context = self.v8_context;
-    const context_arena = self.context_arena;
+    const arena = self.arena;
 
     const T = @TypeOf(value);
     switch (@typeInfo(T)) {
         .@"struct" => {
             // Struct, has to be placed on the heap
-            const heap = try context_arena.create(T);
+            const heap = try arena.create(T);
             heap.* = value;
             return self.mapZigInstanceToJs(js_obj_or_template, heap);
         },
         .pointer => |ptr| {
-            const gop = try self.identity_map.getOrPut(context_arena, @intFromPtr(value));
+            const gop = try self.identity_map.getOrPut(arena, @intFromPtr(value));
             if (gop.found_existing) {
                 // we've seen this instance before, return the same
                 // PersistentObject.
                 return gop.value_ptr.*;
             }
 
             if (comptime @hasDecl(ptr.child, "destructor")) {
-                try self.destructor_callbacks.append(context_arena, DestructorCallback.init(value));
+                try self.destructor_callbacks.append(arena, DestructorCallback.init(value));
             }
 
             // Sometimes we're creating a new v8.Object, like when
@@ -563,7 +562,7 @@ pub fn mapZigInstanceToJs(self: *Context, js_obj_or_template: anytype, value: an
                 // The TAO contains the pointer ot our Zig instance as
                 // well as any meta data we'll need to use it later.
                 // See the TaggedAnyOpaque struct for more details.
-                const tao = try context_arena.create(TaggedAnyOpaque);
+                const tao = try arena.create(TaggedAnyOpaque);
                 const meta_index = @field(types.LOOKUP, @typeName(ptr.child));
                 const meta = self.meta_lookup[meta_index];
 
@@ -768,7 +767,7 @@ fn jsValueToStruct(self: *Context, comptime named_function: NamedFunction, compt
     }
 
     if (T == js.String) {
-        return .{ .string = try self.valueToString(js_value, .{ .allocator = self.context_arena }) };
+        return .{ .string = try self.valueToString(js_value, .{ .allocator = self.arena }) };
     }
 
     const js_obj = js_value.castTo(v8.Object);
@@ -1062,7 +1061,7 @@ pub fn createPromiseResolver(self: *Context, comptime lifetime: PromiseResolverL
     const persisted = v8.Persistent(v8.PromiseResolver).init(self.isolate, resolver);
 
     if (comptime lifetime == .page) {
-        try self.persisted_promise_resolvers.append(self.context_arena, persisted);
+        try self.persisted_promise_resolvers.append(self.arena, persisted);
     }
 
     return .{
@@ -1122,7 +1121,7 @@ pub fn dynamicModuleCallback(
     };
 
     const normalized_specifier = @import("../../url.zig").stitch(
-        self.context_arena, // might need to survive until the module is loaded
+        self.arena, // might need to survive until the module is loaded
         specifier,
         resource,
         .{ .alloc = .if_needed, .null_terminated = true },
@@ -1172,7 +1171,7 @@ fn _resolveModuleCallback(self: *Context, referrer: v8.Module, specifier: []cons
         .{ .alloc = .if_needed, .null_terminated = true },
     );
 
-    const gop = try self.module_cache.getOrPut(self.context_arena, normalized_specifier);
+    const gop = try self.module_cache.getOrPut(self.arena, normalized_specifier);
     if (gop.found_existing) {
         if (gop.value_ptr.module) |m| {
             return m.handle;
@@ -1229,7 +1228,7 @@ const DynamicModuleResolveState = struct {
 
 fn _dynamicModuleCallback(self: *Context, specifier: [:0]const u8) !v8.Promise {
     const isolate = self.isolate;
-    const gop = try self.module_cache.getOrPut(self.context_arena, specifier);
+    const gop = try self.module_cache.getOrPut(self.arena, specifier);
     if (gop.found_existing and gop.value_ptr.resolver_promise != null) {
         // This is easy, there's already something responsible
         // for loading the module. Maybe it's still loading, maybe
@@ -1238,10 +1237,10 @@ fn _dynamicModuleCallback(self: *Context, specifier: [:0]const u8) !v8.Promise {
     }
 
     const persistent_resolver = v8.Persistent(v8.PromiseResolver).init(isolate, v8.PromiseResolver.init(self.v8_context));
-    try self.persisted_promise_resolvers.append(self.context_arena, persistent_resolver);
+    try self.persisted_promise_resolvers.append(self.arena, persistent_resolver);
     var resolver = persistent_resolver.castToPromiseResolver();
 
-    const state = try self.context_arena.create(DynamicModuleResolveState);
+    const state = try self.arena.create(DynamicModuleResolveState);
     state.* = .{
         .module = null,
         .context = self,

src/browser/js/Env.zig

@@ -178,7 +178,6 @@ pub fn newExecutionWorld(self: *Env) !ExecutionWorld {
     return .{
         .env = self,
         .context = null,
-        .call_arena = ArenaAllocator.init(self.allocator),
         .context_arena = ArenaAllocator.init(self.allocator),
     };
 }

src/browser/js/ExecutionWorld.zig

@@ -21,13 +21,6 @@ const CONTEXT_ARENA_RETAIN = 1024 * 64;
 const ExecutionWorld = @This();
 env: *Env,
 
-// Arena whose lifetime is for a single getter/setter/function/etc.
-// Largely used to get strings out of V8, like a stack trace from
-// a TryCatch. The allocator will be owned by the Context, but the
-// arena itself is owned by the ExecutionWorld so that we can re-use it
-// from context to context.
-call_arena: ArenaAllocator,
-
 // Arena whose lifetime is for a single page load. Where
 // the call_arena lives for a single function call, the context_arena
 // lives for the lifetime of the entire page. The allocator will be
@@ -48,7 +41,6 @@ pub fn deinit(self: *ExecutionWorld) void {
         self.removeContext();
     }
 
-    self.call_arena.deinit();
     self.context_arena.deinit();
 }
 
@@ -178,8 +170,8 @@ pub fn createContext(self: *ExecutionWorld, page: *Page, enter: bool, global_cal
         .meta_lookup = &env.meta_lookup,
         .handle_scope = handle_scope,
         .script_manager = &page.script_manager,
-        .call_arena = self.call_arena.allocator(),
-        .context_arena = self.context_arena.allocator(),
+        .call_arena = page.call_arena,
+        .arena = self.context_arena.allocator(),
         .global_callback = global_callback,
     };
 
@@ -191,8 +183,6 @@ pub fn createContext(self: *ExecutionWorld, page: *Page, enter: bool, global_cal
         v8_context.setEmbedderData(1, data);
     }
 
-    page.call_arena = context.call_arena;
-
     // Custom exception
     // NOTE: there is no way in v8 to subclass the Error built-in type
     // TODO: this is an horrible hack

src/browser/js/Object.zig

@@ -22,7 +22,7 @@ pub fn setIndex(self: Object, index: u32, value: anytype, opts: SetOpts) !void {
     @setEvalBranchQuota(10000);
     const key = switch (index) {
         inline 0...20 => |i| std.fmt.comptimePrint("{d}", .{i}),
-        else => try std.fmt.allocPrint(self.context.context_arena, "{d}", .{index}),
+        else => try std.fmt.allocPrint(self.context.arena, "{d}", .{index}),
     };
     return self.set(key, value, opts);
 }
@@ -76,7 +76,7 @@ pub fn persist(self: Object) !Object {
     const js_obj = self.js_obj;
 
     const persisted = PersistentObject.init(context.isolate, js_obj);
-    try context.js_object_list.append(context.context_arena, persisted);
+    try context.js_object_list.append(context.arena, persisted);
 
     return .{
         .context = context,

src/browser/page.zig

@@ -121,7 +121,7 @@ pub const Page = struct {
         complete,
     };
 
-    pub fn init(self: *Page, arena: Allocator, session: *Session) !void {
+    pub fn init(self: *Page, arena: Allocator, call_arena: Allocator, session: *Session) !void {
         const browser = session.browser;
         const script_manager = ScriptManager.init(browser, self);
 
@@ -131,7 +131,7 @@ pub const Page = struct {
             .window = try Window.create(null, null),
             .arena = arena,
             .session = session,
-            .call_arena = undefined,
+            .call_arena = call_arena,
             .renderer = Renderer.init(arena),
             .state_pool = &browser.state_pool,
             .cookie_jar = &session.cookie_jar,

src/browser/session.zig

@@ -106,7 +106,7 @@ pub const Session = struct {
 
         self.page = @as(Page, undefined);
         const page = &self.page.?;
-        try Page.init(page, page_arena.allocator(), self);
+        try Page.init(page, page_arena.allocator(), self.browser.call_arena.allocator(), self);
 
         log.debug(.browser, "create page", .{});
         // start JS env

src/http/Http.zig

@@ -443,7 +443,6 @@ const LineWriter = struct {
     }
 };
 
-
 pub fn debugCallback(_: *c.CURL, msg_type: c.curl_infotype, raw: [*c]u8, len: usize, _: *anyopaque) callconv(.c) void {
     const data = raw[0..len];
     switch (msg_type) {