process: start coverage collection before bootstrap

This patch moves the dispatch of `Profiler.takePreciseCoverage`
to a point before the bootstrap scripts are run to ensure that
we can collect coverage data for all the scripts run after
the inspector agent is ready.

Before this patch `lib/internal/bootstrap/primordials.js` was not
covered by `make coverage`, after this patch it is.

PR-URL: https://github.com/nodejs/node/pull/26006
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Coe <bencoe@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

6 files changed, 199 insertions, 5 deletions

diff --git a/src/env.h b/src/env.h
index 5cf2ee2c8b..b892eac26b 100644
--- a/src/env.h
+++ b/src/env.h
@@ -331,6 +331,7 @@ constexpr size_t kFsStatsBufferLength = kFsStatsFieldsNumber * 2;
   V(async_wrap_ctor_template, v8::FunctionTemplate)                            \
   V(async_wrap_object_ctor_template, v8::FunctionTemplate)                     \
   V(buffer_prototype_object, v8::Object)                                       \
+  V(coverage_connection, v8::Object)                                           \
   V(context, v8::Context)                                                      \
   V(crypto_key_object_constructor, v8::Function)                               \
   V(domain_callback, v8::Function)                                             \
@@ -366,6 +367,7 @@ constexpr size_t kFsStatsBufferLength = kFsStatsFieldsNumber * 2;
   V(message_event_object_template, v8::ObjectTemplate)                         \
   V(message_port_constructor_template, v8::FunctionTemplate)                   \
   V(native_module_require, v8::Function)                                       \
+  V(on_coverage_message_function, v8::Function)                                \
   V(performance_entry_callback, v8::Function)                                  \
   V(performance_entry_template, v8::Function)                                  \
   V(pipe_constructor_template, v8::FunctionTemplate)                           \
@@ -450,9 +452,10 @@ struct ContextInfo {
 
 // Listing the AsyncWrap provider types first enables us to cast directly
 // from a provider type to a debug category.
-#define DEBUG_CATEGORY_NAMES(V) \
-    NODE_ASYNC_PROVIDER_TYPES(V) \
-    V(INSPECTOR_SERVER)
+#define DEBUG_CATEGORY_NAMES(V)                                                \
+  NODE_ASYNC_PROVIDER_TYPES(V)                                                 \
+  V(INSPECTOR_SERVER)                                                          \
+  V(COVERAGE)
 
 enum class DebugCategory {
 #define V(name) name,
diff --git a/src/inspector/node_inspector.gypi b/src/inspector/node_inspector.gypi
index 21f98cd900..9483a0712e 100644
--- a/src/inspector/node_inspector.gypi
+++ b/src/inspector/node_inspector.gypi
@@ -45,6 +45,7 @@
     '../../src/inspector_io.cc',
     '../../src/inspector_agent.h',
     '../../src/inspector_io.h',
+    '../../src/inspector_coverage.cc',
     '../../src/inspector_js_api.cc',
     '../../src/inspector_socket.cc',
     '../../src/inspector_socket.h',
diff --git a/src/inspector_coverage.cc b/src/inspector_coverage.cc
new file mode 100644
index 0000000000..8cbec586fb
--- /dev/null
+++ b/src/inspector_coverage.cc
@@ -0,0 +1,168 @@
+#include "base_object-inl.h"
+#include "debug_utils.h"
+#include "inspector_agent.h"
+#include "node_internals.h"
+#include "v8-inspector.h"
+
+namespace node {
+namespace coverage {
+
+using v8::Context;
+using v8::Function;
+using v8::FunctionCallbackInfo;
+using v8::HandleScope;
+using v8::Isolate;
+using v8::Local;
+using v8::MaybeLocal;
+using v8::NewStringType;
+using v8::Object;
+using v8::ObjectTemplate;
+using v8::String;
+using v8::Value;
+
+using v8_inspector::StringBuffer;
+using v8_inspector::StringView;
+
+std::unique_ptr<StringBuffer> ToProtocolString(Isolate* isolate,
+                                               Local<Value> value) {
+  TwoByteValue buffer(isolate, value);
+  return StringBuffer::create(StringView(*buffer, buffer.length()));
+}
+
+class V8CoverageConnection : public BaseObject {
+ public:
+  class V8CoverageSessionDelegate : public inspector::InspectorSessionDelegate {
+   public:
+    explicit V8CoverageSessionDelegate(V8CoverageConnection* connection)
+        : connection_(connection) {}
+
+    void SendMessageToFrontend(
+        const v8_inspector::StringView& message) override {
+      Environment* env = connection_->env();
+      Local<Function> fn = connection_->env()->on_coverage_message_function();
+      bool ending = !fn.IsEmpty();
+      Debug(env,
+            DebugCategory::COVERAGE,
+            "Sending message to frontend, ending = %s\n",
+            ending ? "true" : "false");
+      if (!ending) {
+        return;
+      }
+      Isolate* isolate = env->isolate();
+
+      HandleScope handle_scope(isolate);
+      Context::Scope context_scope(env->context());
+      MaybeLocal<String> v8string =
+          String::NewFromTwoByte(isolate,
+                                 message.characters16(),
+                                 NewStringType::kNormal,
+                                 message.length());
+      Local<Value> args[] = {v8string.ToLocalChecked().As<Value>()};
+      USE(MakeCallback(isolate,
+                       connection_->object(),
+                       fn,
+                       arraysize(args),
+                       args,
+                       async_context{0, 0}));
+    }
+
+   private:
+    V8CoverageConnection* connection_;
+  };
+
+  SET_MEMORY_INFO_NAME(V8CoverageConnection)
+  SET_SELF_SIZE(V8CoverageConnection)
+
+  void MemoryInfo(MemoryTracker* tracker) const override {
+    tracker->TrackFieldWithSize(
+        "session", sizeof(*session_), "InspectorSession");
+  }
+
+  explicit V8CoverageConnection(Environment* env)
+      : BaseObject(env, env->coverage_connection()), session_(nullptr) {
+    inspector::Agent* inspector = env->inspector_agent();
+    std::unique_ptr<inspector::InspectorSession> session = inspector->Connect(
+        std::make_unique<V8CoverageSessionDelegate>(this), false);
+    session_ = std::move(session);
+    MakeWeak();
+  }
+
+  void Start() {
+    Debug(this->env(),
+          DebugCategory::COVERAGE,
+          "Sending Profiler.startPreciseCoverage\n");
+    Isolate* isolate = this->env()->isolate();
+    Local<Value> enable = FIXED_ONE_BYTE_STRING(
+        isolate, "{\"id\": 1, \"method\": \"Profiler.enable\"}");
+    Local<Value> start = FIXED_ONE_BYTE_STRING(
+        isolate,
+        "{"
+        "\"id\": 2,"
+        "\"method\": \"Profiler.startPreciseCoverage\","
+        "\"params\": {\"callCount\": true, \"detailed\": true}"
+        "}");
+    session_->Dispatch(ToProtocolString(isolate, enable)->string());
+    session_->Dispatch(ToProtocolString(isolate, start)->string());
+  }
+
+  void End() {
+    Debug(this->env(),
+          DebugCategory::COVERAGE,
+          "Sending Profiler.takePreciseCoverage\n");
+    Isolate* isolate = this->env()->isolate();
+    Local<Value> end =
+        FIXED_ONE_BYTE_STRING(isolate,
+                              "{"
+                              "\"id\": 3,"
+                              "\"method\": \"Profiler.takePreciseCoverage\""
+                              "}");
+    session_->Dispatch(ToProtocolString(isolate, end)->string());
+  }
+
+  friend class V8CoverageSessionDelegate;
+
+ private:
+  std::unique_ptr<inspector::InspectorSession> session_;
+};
+
+bool StartCoverageCollection(Environment* env) {
+  HandleScope scope(env->isolate());
+
+  Local<ObjectTemplate> t = ObjectTemplate::New(env->isolate());
+  t->SetInternalFieldCount(1);
+  Local<Object> obj;
+  if (!t->NewInstance(env->context()).ToLocal(&obj)) {
+    return false;
+  }
+
+  obj->SetAlignedPointerInInternalField(0, nullptr);
+
+  CHECK(env->coverage_connection().IsEmpty());
+  env->set_coverage_connection(obj);
+  V8CoverageConnection* connection = new V8CoverageConnection(env);
+  connection->Start();
+  return true;
+}
+
+static void EndCoverageCollection(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  CHECK(args[0]->IsFunction());
+  Debug(env, DebugCategory::COVERAGE, "Ending coverage collection\n");
+  env->set_on_coverage_message_function(args[0].As<Function>());
+  V8CoverageConnection* connection =
+      Unwrap<V8CoverageConnection>(env->coverage_connection());
+  CHECK_NOT_NULL(connection);
+  connection->End();
+}
+
+static void Initialize(Local<Object> target,
+                       Local<Value> unused,
+                       Local<Context> context,
+                       void* priv) {
+  Environment* env = Environment::GetCurrent(context);
+  env->SetMethod(target, "end", EndCoverageCollection);
+}
+}  // namespace coverage
+}  // namespace node
+
+NODE_MODULE_CONTEXT_AWARE_INTERNAL(coverage, node::coverage::Initialize)
diff --git a/src/node.cc b/src/node.cc
index f257495a13..82282e202b 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -19,6 +19,7 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+#include "debug_utils.h"
 #include "node_binding.h"
 #include "node_buffer.h"
 #include "node_constants.h"
@@ -230,6 +231,18 @@ MaybeLocal<Value> RunBootstrapping(Environment* env) {
   Isolate* isolate = env->isolate();
   Local<Context> context = env->context();
 
+  std::string coverage;
+  bool rc = credentials::SafeGetenv("NODE_V8_COVERAGE", &coverage);
+  if (rc && !coverage.empty()) {
+#if HAVE_INSPECTOR
+    if (!coverage::StartCoverageCollection(env)) {
+      return MaybeLocal<Value>();
+    }
+#else
+    fprintf(stderr, "NODE_V8_COVERAGE cannot be used without inspector");
+#endif  // HAVE_INSPECTOR
+  }
+
   // Add a reference to the global object
   Local<Object> global = context->Global();
 
diff --git a/src/node_binding.cc b/src/node_binding.cc
index 08d55567d4..c9ff7be46f 100644
--- a/src/node_binding.cc
+++ b/src/node_binding.cc
@@ -21,6 +21,12 @@
 #define NODE_BUILTIN_REPORT_MODULES(V)
 #endif
 
+#if HAVE_INSPECTOR
+#define NODE_BUILTIN_COVERAGE_MODULES(V) V(coverage)
+#else
+#define NODE_BUILTIN_COVERAGE_MODULES(V)
+#endif
+
 // A list of built-in modules. In order to do module registration
 // in node::Init(), need to add built-in modules in the following list.
 // Then in binding::RegisterBuiltinModules(), it calls modules' registration
@@ -77,7 +83,8 @@
   NODE_BUILTIN_STANDARD_MODULES(V)                                             \
   NODE_BUILTIN_OPENSSL_MODULES(V)                                              \
   NODE_BUILTIN_ICU_MODULES(V)                                                  \
-  NODE_BUILTIN_REPORT_MODULES(V)
+  NODE_BUILTIN_REPORT_MODULES(V)                                               \
+  NODE_BUILTIN_COVERAGE_MODULES(V)
 
 // This is used to load built-in modules. Instead of using
 // __attribute__((constructor)), we call the _register_<modname>
diff --git a/src/node_internals.h b/src/node_internals.h
index 6cbad89594..01ebd8b40a 100644
--- a/src/node_internals.h
+++ b/src/node_internals.h
@@ -269,7 +269,9 @@ void DefineZlibConstants(v8::Local<v8::Object> target);
 v8::MaybeLocal<v8::Value> RunBootstrapping(Environment* env);
 v8::MaybeLocal<v8::Value> StartExecution(Environment* env,
                                          const char* main_script_id);
-
+namespace coverage {
+bool StartCoverageCollection(Environment* env);
+}
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS