Merge pull request #1091 from lightpanda-io/concurrent_blocking_imports

Concurrent blocking imports

src/browser/ScriptManager.zig

@@ -67,8 +67,18 @@ client: *Http.Client,
 allocator: Allocator,
 buffer_pool: BufferPool,
 script_pool: std.heap.MemoryPool(PendingScript),
+sync_module_pool: std.heap.MemoryPool(SyncModule),
 async_module_pool: std.heap.MemoryPool(AsyncModule),
 
+// We can download multiple sync modules in parallel, but we want to process
+// then in order. We can't use an OrderList, like the other script types,
+// because the order we load them might not be the order we want to process
+// them in (I'm not sure this is true, but as far as I can tell, v8 doesn't
+// make any guarantees about the list of sub-module dependencies it gives us
+// So this is more like a cache. When a SyncModule is complete, it's put here
+// and can be requested as needed.
+sync_modules: std.StringHashMapUnmanaged(*SyncModule),
+
 const OrderList = std.DoublyLinkedList;
 
 pub fn init(browser: *Browser, page: *Page) ScriptManager {
@@ -80,24 +90,42 @@ pub fn init(browser: *Browser, page: *Page) ScriptManager {
         .scripts = .{},
         .deferreds = .{},
         .asyncs_ready = .{},
+        .sync_modules = .empty,
         .is_evaluating = false,
         .allocator = allocator,
         .client = browser.http_client,
         .static_scripts_done = false,
         .buffer_pool = BufferPool.init(allocator, 5),
         .script_pool = std.heap.MemoryPool(PendingScript).init(allocator),
+        .sync_module_pool = std.heap.MemoryPool(SyncModule).init(allocator),
         .async_module_pool = std.heap.MemoryPool(AsyncModule).init(allocator),
     };
 }
 
 pub fn deinit(self: *ScriptManager) void {
     self.reset();
+    var it = self.sync_modules.valueIterator();
+    while (it.next()) |value_ptr| {
+        value_ptr.*.buffer.deinit(self.allocator);
+        self.sync_module_pool.destroy(value_ptr.*);
+    }
+
     self.buffer_pool.deinit();
     self.script_pool.deinit();
+    self.sync_module_pool.deinit();
     self.async_module_pool.deinit();
+
+    self.sync_modules.deinit(self.allocator);
 }
 
 pub fn reset(self: *ScriptManager) void {
+    var it = self.sync_modules.valueIterator();
+    while (it.next()) |value_ptr| {
+        value_ptr.*.buffer.deinit(self.allocator);
+        self.sync_module_pool.destroy(value_ptr.*);
+    }
+    self.sync_modules.clearRetainingCapacity();
+
     self.clearList(&self.asyncs);
     self.clearList(&self.scripts);
     self.clearList(&self.deferreds);
@@ -260,49 +288,70 @@ pub fn addFromElement(self: *ScriptManager, element: *parser.Element) !void {
 // Unlike external modules which can only ever be executed after releasing an
 // http handle, these are executed without there necessarily being a free handle.
 // Thus, Http/Client.zig maintains a dedicated handle for these calls.
-pub fn blockingGet(self: *ScriptManager, url: [:0]const u8) !GetResult {
-    std.debug.assert(self.is_blocking == false);
-
-    self.is_blocking = true;
-    defer {
-        self.is_blocking = false;
-
-        // we blocked evaluation while loading this script, there could be
-        // scripts ready to process.
-        self.evaluate();
+pub fn getModule(self: *ScriptManager, url: [:0]const u8) !void {
+    const gop = try self.sync_modules.getOrPut(self.allocator, url);
+    if (gop.found_existing) {
+        // already requested
+        return;
     }
+    errdefer _ = self.sync_modules.remove(url);
 
-    var blocking = Blocking{
-        .allocator = self.allocator,
-        .buffer_pool = &self.buffer_pool,
-    };
+    const sync = try self.sync_module_pool.create();
+    errdefer self.sync_module_pool.destroy(sync);
+
+    sync.* = .{ .manager = self };
+    gop.value_ptr.* = sync;
 
     var headers = try self.client.newHeaders();
     try self.page.requestCookie(.{}).headersForRequest(self.page.arena, url, &headers);
 
-    var client = self.client;
-    try client.blockingRequest(.{
+    try self.client.request(.{
         .url = url,
+        .ctx = sync,
         .method = .GET,
         .headers = headers,
         .cookie_jar = self.page.cookie_jar,
-        .ctx = &blocking,
         .resource_type = .script,
-        .start_callback = if (log.enabled(.http, .debug)) Blocking.startCallback else null,
-        .header_callback = Blocking.headerCallback,
-        .data_callback = Blocking.dataCallback,
-        .done_callback = Blocking.doneCallback,
-        .error_callback = Blocking.errorCallback,
+        .start_callback = if (log.enabled(.http, .debug)) SyncModule.startCallback else null,
+        .header_callback = SyncModule.headerCallback,
+        .data_callback = SyncModule.dataCallback,
+        .done_callback = SyncModule.doneCallback,
+        .error_callback = SyncModule.errorCallback,
     });
+}
 
-    // rely on http's timeout settings to avoid an endless/long loop.
+pub fn waitForModule(self: *ScriptManager, url: [:0]const u8) !GetResult {
+    std.debug.assert(self.is_blocking == false);
+    self.is_blocking = true;
+    defer self.is_blocking = false;
+
+    // Normally it's dangerous to hold on to map pointers. But here, the map
+    // can't change. It's possible that by calling `tick`, other entries within
+    // the map will have their value change, but the map itself is immutable
+    // during this tick.
+    const entry = self.sync_modules.getEntry(url) orelse {
+        return error.UnknownModule;
+    };
+    const sync = entry.value_ptr.*;
+
+    var client = self.client;
     while (true) {
-        _ = try client.tick(200);
-        switch (blocking.state) {
-            .running => {},
-            .done => |result| return result,
+        switch (sync.state) {
+            .loading => {},
+            .done => {
+                // Our caller has its own higher level cache (caching the
+                // actual compiled module). There's no reason for us to keep this
+                defer self.sync_module_pool.destroy(sync);
+                defer self.sync_modules.removeByPtr(entry.key_ptr);
+                return .{
+                    .buffer = sync.buffer,
+                    .buffer_pool = &self.buffer_pool,
+                };
+            },
             .err => |err| return err,
         }
+        // rely on http's timeout settings to avoid an endless/long loop.
+        _ = try client.tick(200);
     }
 }
 
@@ -333,7 +382,6 @@ pub fn getAsyncModule(self: *ScriptManager, url: [:0]const u8, cb: AsyncModule.C
         .error_callback = AsyncModule.errorCallback,
     });
 }
-
 pub fn staticScriptsDone(self: *ScriptManager) void {
     std.debug.assert(self.static_scripts_done == false);
     self.static_scripts_done = true;
@@ -783,16 +831,15 @@ const BufferPool = struct {
     }
 };
 
-const Blocking = struct {
-    allocator: Allocator,
-    buffer_pool: *BufferPool,
-    state: State = .{ .running = {} },
+const SyncModule = struct {
+    manager: *ScriptManager,
     buffer: std.ArrayListUnmanaged(u8) = .{},
+    state: State = .loading,
 
     const State = union(enum) {
-        running: void,
+        done,
+        loading,
         err: anyerror,
-        done: GetResult,
     };
 
     fn startCallback(transfer: *Http.Transfer) !void {
@@ -808,12 +855,13 @@ const Blocking = struct {
             .content_type = header.contentType(),
         });
 
+        var self: *SyncModule = @ptrCast(@alignCast(transfer.ctx));
         if (header.status != 200) {
+            self.finished(.{ .err = error.InvalidStatusCode });
             return error.InvalidStatusCode;
         }
 
-        var self: *Blocking = @ptrCast(@alignCast(transfer.ctx));
-        self.buffer = self.buffer_pool.get();
+        self.buffer = self.manager.buffer_pool.get();
     }
 
     fn dataCallback(transfer: *Http.Transfer, data: []const u8) !void {
@@ -823,8 +871,8 @@ const Blocking = struct {
         //     .blocking = true,
         // });
 
-        var self: *Blocking = @ptrCast(@alignCast(transfer.ctx));
-        self.buffer.appendSlice(self.allocator, data) catch |err| {
+        var self: *SyncModule = @ptrCast(@alignCast(transfer.ctx));
+        self.buffer.appendSlice(self.manager.allocator, data) catch |err| {
             log.err(.http, "SM.dataCallback", .{
                 .err = err,
                 .len = data.len,
@@ -836,19 +884,17 @@ const Blocking = struct {
     }
 
     fn doneCallback(ctx: *anyopaque) !void {
-        var self: *Blocking = @ptrCast(@alignCast(ctx));
-        self.state = .{ .done = .{
-            .buffer = self.buffer,
-            .buffer_pool = self.buffer_pool,
-        } };
+        var self: *SyncModule = @ptrCast(@alignCast(ctx));
+        self.finished(.done);
     }
 
     fn errorCallback(ctx: *anyopaque, err: anyerror) void {
-        var self: *Blocking = @ptrCast(@alignCast(ctx));
-        self.state = .{ .err = err };
-        if (self.buffer.items.len > 0) {
-            self.buffer_pool.release(self.buffer);
-        }
+        var self: *SyncModule = @ptrCast(@alignCast(ctx));
+        self.finished(.{ .err = err });
+    }
+
+    fn finished(self: *SyncModule, state: State) void {
+        self.state = state;
     }
 };
 

src/browser/page.zig

@@ -143,7 +143,7 @@ pub const Page = struct {
             .main_context = undefined,
         };
 
-        self.main_context = try session.executor.createJsContext(&self.window, self, self, true, Env.GlobalMissingCallback.init(&self.polyfill_loader));
+        self.main_context = try session.executor.createJsContext(&self.window, self, &self.script_manager, true, Env.GlobalMissingCallback.init(&self.polyfill_loader));
         try polyfill.preload(self.arena, self.main_context);
 
         try self.scheduler.add(self, runMicrotasks, 5, .{ .name = "page.microtasks" });
@@ -255,16 +255,6 @@ pub const Page = struct {
         try Node.prepend(head, &[_]Node.NodeOrText{.{ .node = parser.elementToNode(base) }});
     }
 
-    pub fn fetchModuleSource(ctx: *anyopaque, url: [:0]const u8) !ScriptManager.GetResult {
-        const self: *Page = @ptrCast(@alignCast(ctx));
-        return self.script_manager.blockingGet(url);
-    }
-
-    pub fn fetchAsyncModuleSource(ctx: *anyopaque, url: [:0]const u8, cb: ScriptManager.AsyncModule.Callback, cb_data: *anyopaque) !void {
-        const self: *Page = @ptrCast(@alignCast(ctx));
-        return self.script_manager.getAsyncModule(url, cb, cb_data);
-    }
-
     pub fn wait(self: *Page, wait_ms: i32) Session.WaitResult {
         return self._wait(wait_ms) catch |err| {
             switch (err) {

src/cdp/cdp.zig

@@ -693,7 +693,7 @@ const IsolatedWorld = struct {
         _ = try self.executor.createJsContext(
             &page.window,
             page,
-            {},
+            null,
             false,
             Env.GlobalMissingCallback.init(&self.polyfill_loader),
         );

src/http/Client.zig

@@ -86,9 +86,6 @@ allocator: Allocator,
 // request. These wil come and go with each request.
 transfer_pool: std.heap.MemoryPool(Transfer),
 
-// see ScriptManager.blockingGet
-blocking: Handle,
-
 // To notify registered subscribers of events, the browser sets/nulls this for us.
 notification: ?*Notification = null,
 
@@ -121,16 +118,12 @@ pub fn init(allocator: Allocator, ca_blob: ?c.curl_blob, opts: Http.Opts) !*Clie
     var handles = try Handles.init(allocator, client, ca_blob, &opts);
     errdefer handles.deinit(allocator);
 
-    var blocking = try Handle.init(client, ca_blob, &opts);
-    errdefer blocking.deinit();
-
     client.* = .{
         .queue = .{},
         .active = 0,
         .intercepted = 0,
         .multi = multi,
         .handles = handles,
-        .blocking = blocking,
         .allocator = allocator,
         .http_proxy = opts.http_proxy,
         .user_agent = opts.user_agent,
@@ -142,7 +135,6 @@ pub fn init(allocator: Allocator, ca_blob: ?c.curl_blob, opts: Http.Opts) !*Clie
 
 pub fn deinit(self: *Client) void {
     self.abort();
-    self.blocking.deinit();
     self.handles.deinit(self.allocator);
 
     _ = c.curl_multi_cleanup(self.multi);
@@ -263,12 +255,6 @@ pub fn fulfillTransfer(self: *Client, transfer: *Transfer, status: u16, headers:
     return transfer.fulfill(status, headers, body);
 }
 
-// See ScriptManager.blockingGet
-pub fn blockingRequest(self: *Client, req: Request) !void {
-    const transfer = try self.makeTransfer(req);
-    return self.makeRequest(&self.blocking, transfer);
-}
-
 fn makeTransfer(self: *Client, req: Request) !*Transfer {
     errdefer req.headers.deinit();
 
@@ -329,7 +315,6 @@ pub fn changeProxy(self: *Client, proxy: [:0]const u8) !void {
     for (self.handles.handles) |*h| {
         try errorCheck(c.curl_easy_setopt(h.conn.easy, c.CURLOPT_PROXY, proxy.ptr));
     }
-    try errorCheck(c.curl_easy_setopt(self.blocking.conn.easy, c.CURLOPT_PROXY, proxy.ptr));
 }
 
 // Same restriction as changeProxy. Should be ok since this is only called on
@@ -341,7 +326,6 @@ pub fn restoreOriginalProxy(self: *Client) !void {
     for (self.handles.handles) |*h| {
         try errorCheck(c.curl_easy_setopt(h.conn.easy, c.CURLOPT_PROXY, proxy));
     }
-    try errorCheck(c.curl_easy_setopt(self.blocking.conn.easy, c.CURLOPT_PROXY, proxy));
 }
 
 fn makeRequest(self: *Client, handle: *Handle, transfer: *Transfer) !void {
@@ -504,7 +488,7 @@ fn endTransfer(self: *Client, transfer: *Transfer) void {
         log.fatal(.http, "Failed to remove handle", .{ .err = err });
     };
 
-    self.handles.release(self, handle);
+    self.handles.release(handle);
     transfer._handle = null;
     self.active -= 1;
 }
@@ -563,13 +547,7 @@ const Handles = struct {
         return null;
     }
 
-    fn release(self: *Handles, client: *Client, handle: *Handle) void {
-        if (handle == &client.blocking) {
-            // the handle we've reserved for blocking request doesn't participate
-            // int he in_use/available pools
-            return;
-        }
-
+    fn release(self: *Handles, handle: *Handle) void {
         var node = &handle.node;
         self.in_use.remove(node);
         node.prev = null;
@@ -747,7 +725,7 @@ pub const Transfer = struct {
     fn deinit(self: *Transfer) void {
         self.req.headers.deinit();
         if (self._handle) |handle| {
-            self.client.handles.release(self.client, handle);
+            self.client.handles.release(handle);
         }
         self.arena.deinit();
         self.client.transfer_pool.destroy(self);

src/runtime/js.zig

@@ -410,19 +410,9 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             // when the handle_scope is freed.
             // We also maintain our own "context_arena" which allows us to have
             // all page related memory easily managed.
-            pub fn createJsContext(self: *ExecutionWorld, global: anytype, state: State, module_loader: anytype, enter: bool, global_callback: ?GlobalMissingCallback) !*JsContext {
+            pub fn createJsContext(self: *ExecutionWorld, global: anytype, state: State, script_manager: ?*ScriptManager, enter: bool, global_callback: ?GlobalMissingCallback) !*JsContext {
                 std.debug.assert(self.js_context == null);
 
-                const ModuleLoader = switch (@typeInfo(@TypeOf(module_loader))) {
-                    .@"struct" => @TypeOf(module_loader),
-                    .pointer => |ptr| ptr.child,
-                    .void => ErrorModuleLoader,
-                    else => @compileError("invalid module_loader"),
-                };
-
-                // If necessary, turn a void context into something we can safely ptrCast
-                const safe_module_loader: *anyopaque = if (ModuleLoader == ErrorModuleLoader) @ptrCast(@constCast(&{})) else module_loader;
-
                 const env = self.env;
                 const isolate = env.isolate;
                 const Global = @TypeOf(global.*);
@@ -542,13 +532,9 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     .templates = &env.templates,
                     .meta_lookup = &env.meta_lookup,
                     .handle_scope = handle_scope,
+                    .script_manager = script_manager,
                     .call_arena = self.call_arena.allocator(),
                     .context_arena = self.context_arena.allocator(),
-                    .module_loader = .{
-                        .ptr = safe_module_loader,
-                        .func = ModuleLoader.fetchModuleSource,
-                        .async = ModuleLoader.fetchAsyncModuleSource,
-                    },
                     .global_callback = global_callback,
                 };
 
@@ -692,12 +678,6 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             // the function that resolves/rejects them.
             persisted_promise_resolvers: std.ArrayListUnmanaged(v8.Persistent(v8.PromiseResolver)) = .empty,
 
-            // When we need to load a resource (i.e. an external script), we call
-            // this function to get the source. This is always a reference to the
-            // Page's fetchModuleSource, but we use a function pointer
-            // since this js module is decoupled from the browser implementation.
-            module_loader: ModuleLoader,
-
             // Some Zig types have code to execute to cleanup
             destructor_callbacks: std.ArrayListUnmanaged(DestructorCallback) = .empty,
 
@@ -711,15 +691,12 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             // necessary to lookup/store the dependent module in the module_cache.
             module_identifier: std.AutoHashMapUnmanaged(u32, []const u8) = .empty,
 
+            // the page's script manager
+            script_manager: ?*ScriptManager,
+
             // Global callback is called on missing property.
             global_callback: ?GlobalMissingCallback = null,
 
-            const ModuleLoader = struct {
-                ptr: *anyopaque,
-                func: *const fn (ptr: *anyopaque, url: [:0]const u8) anyerror!ScriptManager.GetResult,
-                async: *const fn (ptr: *anyopaque, url: [:0]const u8, cb: ScriptManager.AsyncModule.Callback, cb_state: *anyopaque) anyerror!void,
-            };
-
             const ModuleEntry = struct {
                 // Can be null if we're asynchrously loading the module, in
                 // which case resolver_promise cannot be null.
@@ -861,8 +838,33 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                 try self.module_identifier.putNoClobber(arena, m.getIdentityHash(), owned_url);
                 errdefer _ = self.module_identifier.remove(m.getIdentityHash());
 
-                // resolveModuleCallback loads module's dependencies.
                 const v8_context = self.v8_context;
+                {
+                    // Non-async modules are blocking. We can download them in
+                    // parallel, but they need to be processed serially. So we
+                    // want to get the list of dependent modules this module has
+                    // and start downloading them asap.
+                    const requests = m.getModuleRequests();
+                    const isolate = self.isolate;
+                    for (0..requests.length()) |i| {
+                        const req = requests.get(v8_context, @intCast(i)).castTo(v8.ModuleRequest);
+                        const specifier = try jsStringToZig(self.call_arena, req.getSpecifier(), isolate);
+                        const normalized_specifier = try @import("../url.zig").stitch(
+                            self.call_arena,
+                            specifier,
+                            owned_url,
+                            .{ .alloc = .if_needed, .null_terminated = true },
+                        );
+                        const gop = try self.module_cache.getOrPut(self.context_arena, normalized_specifier);
+                        if (!gop.found_existing) {
+                            const owned_specifier = try self.context_arena.dupeZ(u8, normalized_specifier);
+                            gop.key_ptr.* = owned_specifier;
+                            gop.value_ptr.* = .{};
+                            try self.script_manager.?.getModule(owned_specifier);
+                        }
+                    }
+                }
+
                 if (try m.instantiate(v8_context, resolveModuleCallback) == false) {
                     return error.ModuleInstantiationError;
                 }
@@ -891,14 +893,13 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
 
                 var gop = try self.module_cache.getOrPut(arena, owned_url);
                 if (gop.found_existing) {
-                    // only way for us to have found an existing entry, is if
-                    // we're asynchronously loading this module
+                    // If we're here, it's because we had a cache entry, but no
+                    // module. This happens because both our synch and async
+                    // module loaders create the entry to prevent concurrent
+                    // loads of the same resource (like Go's Singleflight).
                     std.debug.assert(gop.value_ptr.module == null);
                     std.debug.assert(gop.value_ptr.module_promise == null);
-                    std.debug.assert(gop.value_ptr.resolver_promise != null);
 
-                    // keep the resolver promise, it's doing the heavy lifting
-                    // and any other async loads will be chained to it.
                     gop.value_ptr.module = persisted_module;
                     gop.value_ptr.module_promise = persisted_promise;
                 } else {
@@ -1639,8 +1640,29 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     .{ .alloc = .if_needed, .null_terminated = true },
                 );
 
-                const module_loader = self.module_loader;
-                var fetch_result = try module_loader.func(module_loader.ptr, normalized_specifier);
+                const gop = try self.module_cache.getOrPut(self.context_arena, normalized_specifier);
+                if (gop.found_existing) {
+                    if (gop.value_ptr.module) |m| {
+                        return m.handle;
+                    }
+                    // We don't have a module, but we do have a cache entry for it
+                    // That means we're already trying to load it. We just have
+                    // to wait for it to be done.
+                } else {
+                    // I don't think it's possible for us to be here. This is
+                    // only ever called by v8 when we evaluate a module. But
+                    // before evaluating, we should have already started
+                    // downloading all of the module's nested modules. So it
+                    // should be impossible that this is the first time we've
+                    // heard about this module.
+                    // But, I'm not confident enough in that, and ther's little
+                    // harm in handling this case.
+                    @branchHint(.unlikely);
+                    gop.value_ptr.* = .{};
+                    try self.script_manager.?.getModule(normalized_specifier);
+                }
+
+                var fetch_result = try self.script_manager.?.waitForModule(normalized_specifier);
                 defer fetch_result.deinit();
 
                 var try_catch: TryCatch = undefined;
@@ -1756,8 +1778,7 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     };
 
                     // Next, we need to actually load it.
-                    const module_loader = self.module_loader;
-                    module_loader.async(module_loader.ptr, specifier, dynamicModuleSourceCallback, state) catch |err| {
+                    self.script_manager.?.getAsyncModule(specifier, dynamicModuleSourceCallback, state) catch |err| {
                         const error_msg = v8.String.initUtf8(isolate, @errorName(err));
                         _ = resolver.reject(self.v8_context, error_msg.toValue());
                     };
@@ -4185,16 +4206,6 @@ const NoopInspector = struct {
     pub fn onInspectorEvent(_: *anyopaque, _: []const u8) void {}
 };
 
-const ErrorModuleLoader = struct {
-    pub fn fetchModuleSource(_: *anyopaque, _: [:0]const u8) !ScriptManager.GetResult {
-        return error.NoModuleLoadConfigured;
-    }
-
-    pub fn fetchAsyncModuleSource(_: *anyopaque, _: [:0]const u8, _: ScriptManager.AsyncModule.Callback, _: *anyopaque) !void {
-        return error.NoModuleLoadConfigured;
-    }
-};
-
 // If we have a struct:
 // const Cat = struct {
 //    pub fn meow(self: *Cat) void { ... }

src/runtime/testing.zig

@@ -52,7 +52,7 @@ pub fn Runner(comptime State: type, comptime Global: type, comptime types: anyty
             self.js_context = try self.executor.createJsContext(
                 if (Global == void) &default_global else global,
                 state,
-                {},
+                null,
                 true,
                 null,
             );