src: expose node::AddPromiseHook

Expose `node::AddPromiseHook`, which wraps V8’s `SetPromiseHook` in
a way that allows multiple hooks to be set up.

PR-URL: #12489
Reviewed-By: Matthew Loring <mattloring@google.com>
Reviewed-By: Julien Gilli <jgilli@nodejs.org>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: addaleax

src/env.cc

@@ -188,4 +188,20 @@ void Environment::AtExit(void (*cb)(void* arg), void* arg) {
   at_exit_functions_.push_back(AtExitCallback{cb, arg});
 }
 
+void Environment::AddPromiseHook(promise_hook_func fn, void* arg) {
+  promise_hooks_.push_back(PromiseHookCallback{fn, arg});
+  if (promise_hooks_.size() == 1) {
+    isolate_->SetPromiseHook(EnvPromiseHook);
+  }
+}
+
+void Environment::EnvPromiseHook(v8::PromiseHookType type,
+                                 v8::Local<v8::Promise> promise,
+                                 v8::Local<v8::Value> parent) {
+  Environment* env = Environment::GetCurrent(promise->CreationContext());
+  for (const PromiseHookCallback& hook : env->promise_hooks_) {
+    hook.cb_(type, promise, parent, hook.arg_);
+  }
+}
+
 }  // namespace node

src/env.h

@@ -35,6 +35,7 @@
 #include "util.h"
 #include "uv.h"
 #include "v8.h"
+#include "node.h"
 
 #include <list>
 #include <stdint.h>
@@ -572,6 +573,8 @@ class Environment {
 
   static const int kContextEmbedderDataIndex = NODE_CONTEXT_EMBEDDER_DATA_INDEX;
 
+  void AddPromiseHook(promise_hook_func fn, void* arg);
+
  private:
   inline void ThrowError(v8::Local<v8::Value> (*fun)(v8::Local<v8::String>),
                          const char* errmsg);
@@ -620,6 +623,16 @@ class Environment {
   };
   std::list<AtExitCallback> at_exit_functions_;
 
+  struct PromiseHookCallback {
+    promise_hook_func cb_;
+    void* arg_;
+  };
+  std::vector<PromiseHookCallback> promise_hooks_;
+
+  static void EnvPromiseHook(v8::PromiseHookType type,
+                             v8::Local<v8::Promise> promise,
+                             v8::Local<v8::Value> parent);
+
 #define V(PropertyName, TypeName)                                             \
   v8::Persistent<TypeName> PropertyName ## _;
   ENVIRONMENT_STRONG_PERSISTENT_PROPERTIES(V)

src/node.cc

@@ -1233,6 +1233,12 @@ void SetupPromises(const FunctionCallbackInfo<Value>& args) {
 }  // anonymous namespace
 
 
+void AddPromiseHook(v8::Isolate* isolate, promise_hook_func fn, void* arg) {
+  Environment* env = Environment::GetCurrent(isolate);
+  env->AddPromiseHook(fn, arg);
+}
+
+
 Local<Value> MakeCallback(Environment* env,
                           Local<Value> recv,
                           const Local<Function> callback,

src/node.h

@@ -516,6 +516,17 @@ NODE_EXTERN void AtExit(void (*cb)(void* arg), void* arg = 0);
  */
 NODE_EXTERN void AtExit(Environment* env, void (*cb)(void* arg), void* arg = 0);
 
+typedef void (*promise_hook_func) (v8::PromiseHookType type,
+                                   v8::Local<v8::Promise> promise,
+                                   v8::Local<v8::Value> parent,
+                                   void* arg);
+
+/* Registers an additional v8::PromiseHook wrapper. This API exists because V8
+ * itself supports only a single PromiseHook. */
+NODE_EXTERN void AddPromiseHook(v8::Isolate* isolate,
+                                promise_hook_func fn,
+                                void* arg);
+
 }  // namespace node
 
 #endif  // SRC_NODE_H_