[nfc] Disentangle and Modularize JSG

- Factor several files out of the main JSG target
- Significantly reduce header interdependencies

build/kj_test.bzl

@@ -3,7 +3,8 @@ def kj_test(
         data = [],
         deps = [],
         tags = [],
-        size = "medium"):
+        size = "medium",
+        **kwargs):
     test_name = src.removesuffix(".c++")
     native.cc_test(
         name = test_name,
@@ -18,4 +19,5 @@ def kj_test(
         data = data,
         tags = tags,
         size = size,
+        **kwargs
     )

src/rust/gen-compile-cache/BUILD.bazel

@@ -23,6 +23,7 @@ wd_cc_library(
     deps = [
         "//src/rust/cxx-integration",
         "//src/workerd/jsg",
+        "//src/workerd/jsg:compile-cache",
         "@capnp-cpp//src/kj",
     ],
 )

src/rust/gen-compile-cache/cxx-bridge.c++

@@ -1,7 +1,7 @@
 #include "cxx-bridge.h"
 
 #include <workerd/jsg/compile-cache.h>
-#include <workerd/jsg/setup.h>
+#include <workerd/jsg/type-wrapper.h>
 
 #include <workerd/rust/cxx-integration/lib.rs.h>
 

src/workerd/io/BUILD.bazel

@@ -124,6 +124,8 @@ wd_cc_library(
         "//src/workerd/api:url",
         "//src/workerd/api:urlpattern",
         "//src/workerd/jsg",
+        "//src/workerd/jsg:inspector",
+        "//src/workerd/jsg:script",
         "//src/workerd/util:autogate",
         "//src/workerd/util:completion-membrane",
         "//src/workerd/util:exception",

src/workerd/jsg/BUILD.bazel

@@ -8,21 +8,86 @@ exports_files(["modules.capnp"])
 
 wd_cc_library(
     name = "jsg",
+    srcs = [
+        "modules-new.c++",
+    ],
+    hdrs = [
+        "jsg-test.h",
+        "modules-new.h",
+        "type-wrapper.h",
+    ],
+    local_defines = ["JSG_IMPLEMENTATION"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":exception",
+        ":iterator",
+        ":jsg-core",
+        ":memory-tracker",
+        ":url",
+        "//src/workerd/util",
+        "//src/workerd/util:sentry",
+        "//src/workerd/util:thread-scopes",
+        "@capnp-cpp//src/kj",
+        "@workerd-v8//:v8",
+    ],
+)
+
+wd_cc_library(
+    name = "iterator",
+    srcs = [
+        "iterator.c++",
+    ],
+    hdrs = [
+        "iterator.h",
+        "struct.h",
+        "value.h",
+        "web-idl.h",
+    ],
+    local_defines = ["JSG_IMPLEMENTATION"],
+    deps = [
+        ":exception",
+        ":jsg-core",
+        ":memory-tracker",
+        "//src/workerd/util",
+        "//src/workerd/util:sentry",
+        "//src/workerd/util:thread-scopes",
+        "@capnp-cpp//src/kj",
+        "@simdutf",
+        "@workerd-v8//:v8",
+    ],
+)
+
+wd_cc_library(
+    name = "script",
+    srcs = ["script.c++"],
+    hdrs = ["script.h"],
+    local_defines = ["JSG_IMPLEMENTATION"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":jsg-core",
+        "@capnp-cpp//src/kj",
+        "@workerd-v8//:v8",
+    ],
+)
+
+# Subset of JSG that includes core JSG interfaces, but does not depend on type-wrapper API.
+# Factoring this out reduces the need for circular includes and will make future refactoring of JSG
+# much easier.
+# This is only visible in this package for now – to avoid extensive include changes in code using
+# the JSG type wrapper, the main JSG target should be used instead for now.
+# Avoid adding dependencies or new files to this when possible.
+wd_cc_library(
+    name = "jsg-core",
     srcs = [
         "async-context.c++",
         "buffersource.c++",
         "commonjs.c++",
-        "compile-cache.c++",
         "dom-exception.c++",
-        "inspector.c++",
-        "iterator.c++",
         "jsg.c++",
         "jsvalue.c++",
         "modules.c++",
-        "modules-new.c++",
         "promise.c++",
         "resource.c++",
-        "script.c++",
         "ser.c++",
         "setup.c++",
         "util.c++",
@@ -33,52 +98,75 @@ wd_cc_library(
         "async-context.h",
         "buffersource.h",
         "commonjs.h",
-        "compile-cache.h",
         "dom-exception.h",
         "function.h",
-        "inspector.h",
-        "iterator.h",
         "jsg.h",
-        "jsg-test.h",
         "jsvalue.h",
-        "macro-meta.h",
-        "meta.h",
         "modules.h",
-        "modules-new.h",
         "promise.h",
         "resource.h",
-        "script.h",
         "ser.h",
         "setup.h",
-        "struct.h",
-        "type-wrapper.h",
         "util.h",
         "v8-platform-wrapper.h",
-        "value.h",
-        "web-idl.h",
         "wrappable.h",
     ],
     # Some JSG headers can't be compiled on their own
     features = ["-parse_headers"],
-    visibility = ["//visibility:public"],
+    local_defines = ["JSG_IMPLEMENTATION"],
     deps = [
         ":exception",
+        ":macro-meta",
         ":memory-tracker",
+        ":meta",
         ":modules_capnp",
         ":observer",
-        ":url",
         "//src/workerd/util",
         "//src/workerd/util:autogate",
         "//src/workerd/util:sentry",
         "//src/workerd/util:thread-scopes",
         "//src/workerd/util:uuid",
         "@capnp-cpp//src/kj",
-        "@simdutf",
         "@ssl",
         "@workerd-v8//:v8",
     ],
 )
 
+wd_cc_library(
+    name = "compile-cache",
+    srcs = [
+        "compile-cache.c++",
+    ],
+    hdrs = [
+        "compile-cache.h",
+    ],
+    local_defines = ["JSG_IMPLEMENTATION"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "@capnp-cpp//src/kj",
+        "@workerd-v8//:v8",
+    ],
+)
+
+wd_cc_library(
+    name = "inspector",
+    srcs = [
+        "inspector.c++",
+    ],
+    hdrs = [
+        "inspector.h",
+    ],
+    local_defines = ["JSG_IMPLEMENTATION"],
+    # Some JSG headers can't be compiled on their own
+    visibility = ["//visibility:public"],
+    deps = [
+        ":jsg-core",
+        "@capnp-cpp//src/kj",
+        "@simdutf",
+        "@workerd-v8//:v8",
+    ],
+)
+
 wd_cc_library(
     name = "memory-tracker",
     srcs = ["memory.c++"],
@@ -90,6 +178,16 @@ wd_cc_library(
     ],
 )
 
+wd_cc_library(
+    name = "meta",
+    hdrs = ["meta.h"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "@capnp-cpp//src/kj",
+        "@workerd-v8//:v8",
+    ],
+)
+
 wd_cc_library(
     name = "url",
     srcs = ["url.c++"],
@@ -176,6 +274,7 @@ wd_cc_library(
 
 [kj_test(
     src = f,
+    local_defines = ["JSG_IMPLEMENTATION"],
     deps = [
         ":jsg",
         "//src/workerd/util:autogate",
@@ -243,7 +342,7 @@ kj_test(
 kj_test(
     src = "multiple-typewrappers-test.c++",
     deps = [
-        "//src/workerd/io",
+        "//src/workerd/io:compatibility-date_capnp",
         "//src/workerd/jsg",
     ],
 )

src/workerd/jsg/buffersource.h

@@ -6,6 +6,8 @@
 
 #include "jsg.h"
 
+#include <v8-typed-array.h>
+
 namespace workerd::jsg {
 
 #define JSG_ARRAY_BUFFER_VIEW_TYPES(V)                                                             \

src/workerd/jsg/commonjs.c++

@@ -1,6 +1,8 @@
 #include "commonjs.h"
 
+#include "jsvalue.h"
 #include "modules.h"
+#include "resource.h"
 
 namespace workerd::jsg {
 

src/workerd/jsg/compile-cache.h

@@ -3,11 +3,10 @@
 //     https://opensource.org/licenses/Apache-2.0
 #pragma once
 
-#include "jsg.h"
-#include "setup.h"
-
-#include <v8.h>
+#include <v8-script.h>
 
+#include <kj/map.h>
+#include <kj/mutex.h>
 #include <kj/string.h>
 
 namespace workerd::jsg {

src/workerd/jsg/dom-exception.c++

@@ -4,6 +4,7 @@
 
 #include "dom-exception.h"
 
+#include "jsvalue.h"
 #include "ser.h"
 
 #include <workerd/jsg/memory.h>

src/workerd/jsg/dom-exception.h

@@ -5,7 +5,6 @@
 #pragma once
 
 #include "jsg.h"
-#include "ser.h"
 
 #define JSG_DOM_EXCEPTION_FOR_EACH_ERROR_NAME(f)                                                   \
   f(INDEX_SIZE_ERR, 1, "IndexSizeError") f(DOMSTRING_SIZE_ERR, 2, "DOMStringSizeError")            \
@@ -28,6 +27,8 @@
                                                   f(DATA_CLONE_ERR, 25, "DataCloneError")
 
 namespace workerd::jsg {
+class Serializer;
+class Deserializer;
 
 // JSG allows DOMExceptions to be tunneled through kj::Exceptions (see makeInternalError() for
 // details). While this feature is activated conditionally at run-time, and thus does not depend

src/workerd/jsg/function.h

@@ -8,9 +8,13 @@
 // Handles wrapping a C++ function so that it can be called from JavaScript, and vice versa.
 
 #include "jsg.h"
-#include "meta.h"
 #include "wrappable.h"
 
+#include <workerd/jsg/meta.h>
+
+#include <v8-context.h>
+#include <v8-function.h>
+
 #include <kj/function.h>
 
 namespace workerd::jsg {

src/workerd/jsg/inspector.c++

@@ -1,6 +1,7 @@
 #include "inspector.h"
 
 #include "jsg.h"
+#include "jsvalue.h"
 #include "simdutf.h"
 #include "util.h"
 

src/workerd/jsg/iterator.h

@@ -4,10 +4,9 @@
 
 #pragma once
 
-#include "jsg.h"
-#include "struct.h"
-
+#include <workerd/jsg/jsg.h>
 #include <workerd/jsg/memory.h>
+#include <workerd/jsg/struct.h>
 
 #include <concepts>
 #include <deque>

src/workerd/jsg/jsg-test.h

@@ -5,8 +5,10 @@
 #pragma once
 // Common JSG testing infrastructure
 
-#include "jsg.h"
-#include "setup.h"
+#include <workerd/jsg/jsg.h>
+#include <workerd/jsg/resource.h>
+#include <workerd/jsg/setup.h>
+#include <workerd/jsg/type-wrapper.h>
 
 #include <kj/test.h>