src: add AddCodeEventHook API for code events

Introduces a new API to register code event hooks in nsolid. This
includes new handler classes, queueing, and infrastructure to allow
extensible code event observation and callbacks.

Author: santigimeno

node.gyp

@@ -514,6 +514,7 @@
       'src/nsolid.cc',
       'src/nsolid/continuous_profiler.cc',
       'src/nsolid/nsolid_api.cc',
+      'src/nsolid/nsolid_code_event_handler.cc',
       'src/nsolid/nsolid_trace.cc',
       'src/nsolid/nsolid_cpu_profiler.cc',
       'src/nsolid/nsolid_heap_snapshot.cc',

src/nsolid.cc

@@ -597,6 +597,42 @@ int Snapshot::get_snapshot_(SharedEnvInst envinst,
     GetHeapSnapshot(envinst, redacted, data, proxy, deleter);
 }
 
+class CodeEventHook::Impl {
+ public:
+  Impl() = default;
+  ~Impl() {
+    // Remove the hook from the TSList in EnvList
+    EnvList::Inst()->RemoveCodeEventHook(hook_);
+  }
+
+ private:
+  friend class CodeEventHook;
+  void Setup(internal::code_event_hook_proxy_sig cb,
+             void(*deleter)(void*),
+             void* data) {
+    // Add hook to the TSList in EnvList
+    hook_ = EnvList::Inst()->AddCodeEventHook(data, cb, deleter);
+  }
+
+  TSList<EnvList::CodeEventHookStor>::iterator hook_;
+};
+
+CodeEventHook::CodeEventHook(): impl_(std::make_unique<Impl>()) {
+}
+
+CodeEventHook::~CodeEventHook() = default;
+
+void CodeEventHook::Dispose() {
+  // This method transfers ownership to the callee and deletes the object.
+  // The caller must not use this object after calling Dispose().
+  delete this;
+}
+
+void CodeEventHook::DoSetup(internal::code_event_hook_proxy_sig cb,
+                            internal::deleter_sig deleter,
+                            void* data) {
+  impl_->Setup(cb, deleter, data);
+}
 
 namespace internal {
 
@@ -637,6 +673,17 @@ void thread_removed_hook_(void* data,
   EnvList::Inst()->EnvironmentDeletionHook(data, proxy, deleter);
 }
 
+CodeEventHook* add_code_event_hook_(void* data,
+                                    code_event_hook_proxy_sig proxy,
+                                    deleter_sig deleter) {
+  CodeEventHook* hook = new (std::nothrow) CodeEventHook();
+  if (hook == nullptr) {
+    return nullptr;
+  }
+  hook->DoSetup(proxy, deleter, data);
+  return hook;
+}
+
 
 int queue_callback_(void* data, queue_callback_proxy_sig proxy) {
   return EnvList::Inst()->QueueCallback(proxy, data);

src/nsolid.h

@@ -27,6 +27,8 @@ namespace nsolid {
 
 class EnvInst;
 struct LogWriteInfo;
+class CodeEventHook;
+struct CodeEventInfo;
 
 #define kNSByte "byte"
 #define kNSMhz "MHz"
@@ -285,6 +287,7 @@ using on_log_write_hook_proxy_sig = void(*)(SharedEnvInst, LogWriteInfo, void*);
 using at_exit_hook_proxy_sig = void(*)(bool, bool, void*);
 using thread_added_hook_proxy_sig = void(*)(SharedEnvInst, void*);
 using thread_removed_hook_proxy_sig = thread_added_hook_proxy_sig;
+using code_event_hook_proxy_sig = void(*)(SharedEnvInst, CodeEventInfo, void*);
 using deleter_sig = void(*)(void*);
 using user_data = std::unique_ptr<void, deleter_sig>;
 
@@ -314,6 +317,8 @@ void thread_added_hook_proxy_(SharedEnvInst, void* data);
 template <typename G>
 void thread_removed_hook_proxy_(SharedEnvInst, void* data);
 template <typename G>
+void code_event_hook_proxy_(SharedEnvInst, CodeEventInfo, void*);
+template <typename G>
 void delete_proxy_(void* g);
 
 
@@ -348,7 +353,9 @@ NODE_EXTERN void thread_added_hook_(void*,
 NODE_EXTERN void thread_removed_hook_(void*,
                                       thread_removed_hook_proxy_sig,
                                       deleter_sig);
-
+NODE_EXTERN CodeEventHook* add_code_event_hook_(void*,
+                                                code_event_hook_proxy_sig,
+                                                deleter_sig);
 }  // namespace internal
 
 /** @endcond */
@@ -647,6 +654,52 @@ NODE_EXTERN int ThreadAddedHook(Cb&& cb, Data&&... data);
 template <typename Cb, typename... Data>
 NODE_EXTERN int ThreadRemovedHook(Cb&& cb, Data&&... data);
 
+template <typename Cb, typename... Data>
+NODE_EXTERN CodeEventHook* AddCodeEventHook(Cb&& cb, Data&&... data);
+
+struct CodeEventInfo {
+  uint64_t thread_id;
+  uint64_t timestamp;
+  v8::CodeEventType type;
+  uintptr_t code_start;
+  uintptr_t new_code_start;
+  size_t code_len;
+  std::string fn_name;
+  std::string script_name;
+  int script_line;
+  int script_column;
+  std::string comment;
+};
+
+/**
+ * @brief Opaque handle for a code event hook registered with AddCodeEventHook.
+ *
+ * Only Dispose() should be used to remove the hook and release resources.
+ */
+class NODE_EXTERN CodeEventHook {
+ public:
+  /**
+  * @brief Dispose and remove the registered code event hook.
+  *
+  * After calling Dispose(), this object must not be used again.
+  */
+  void Dispose();
+
+ private:
+  CodeEventHook();
+  ~CodeEventHook();
+  friend CodeEventHook* internal::add_code_event_hook_(
+    void*, internal::code_event_hook_proxy_sig, internal::deleter_sig);
+  CodeEventHook(const CodeEventHook&) = delete;
+  CodeEventHook& operator=(const CodeEventHook&) = delete;
+
+  void DoSetup(internal::code_event_hook_proxy_sig cb,
+               internal::deleter_sig deleter,
+               void* data);
+
+  class Impl;
+  std::unique_ptr<Impl> impl_;
+};
 
 /**
  * @brief Defines the types of metrics supported
@@ -1776,6 +1829,38 @@ int ThreadRemovedHook(Cb&& cb, Data&&... data) {
 }
 
 
+/**
+ * @brief Register a hook (function) to be called on code events.
+ *
+ * @tparam Cb Callback type. The callback will be invoked with (...Data) arguments.
+ * @tparam Data Variable argument types to be propagated to the callback.
+ * @param cb Hook function with signature: cb(...Data)
+ * @param data Variable number of arguments to be propagated to the callback.
+ * @return Pointer to CodeEventHook if successful, nullptr otherwise.
+ */
+template <typename Cb, typename... Data>
+inline CodeEventHook* AddCodeEventHook(Cb&& cb, Data&&... data) {
+  // NOLINTNEXTLINE(build/namespaces)
+  using namespace std::placeholders;
+  using UserData = decltype(std::bind(
+        std::forward<Cb>(cb), _1, _2, std::forward<Data>(data)...));
+
+  // _1 - SharedEnvInst
+  // _2 - CodeEventInfo
+  UserData* user_data = new (std::nothrow) UserData(std::bind(
+        std::forward<Cb>(cb), _1, _2, std::forward<Data>(data)...));
+  if (user_data == nullptr) {
+    return nullptr;
+  }
+
+  return internal::add_code_event_hook_(
+    user_data,
+    internal::code_event_hook_proxy_<UserData>,
+    internal::delete_proxy_<UserData>);
+}
+
+
+
 namespace internal {
 
 template <typename G>
@@ -1842,6 +1927,13 @@ void thread_removed_hook_proxy_(SharedEnvInst envinst, void* data) {
   (*static_cast<G*>(data))(envinst);
 }
 
+template <typename G>
+void code_event_hook_proxy_(SharedEnvInst envinst,
+                            CodeEventInfo info,
+                            void* data) {
+  (*static_cast<G*>(data))(envinst, std::move(info));
+}
+
 template <typename G>
 void delete_proxy_(void* g) {
   delete static_cast<G*>(g);

src/nsolid/nsolid_api.cc

@@ -1,4 +1,5 @@
 #include "nsolid_api.h"
+#include "nsolid/nsolid_code_event_handler.h"
 #include "nsolid/nsolid_heap_snapshot.h"
 #include "nsolid_bindings.h"
 #include "node_buffer.h"
@@ -840,6 +841,19 @@ void EnvInst::StoreSourceCode(int script_id,
 }
 
 
+void EnvInst::setup_code_event_handler() {
+  if (!code_event_handler_) {
+    code_event_handler_ =
+      std::make_unique<NSolidCodeEventHandler>(isolate_, thread_id_);
+    code_event_handler_->Enable();
+  }
+}
+
+void EnvInst::disable_code_event_handler() {
+  code_event_handler_.reset();
+}
+
+
 EnvList::EnvList(): info_(nlohmann::json()) {
   int er;
   // Create event loop and new thread to run EnvList commands.
@@ -869,6 +883,13 @@ EnvList::EnvList(): info_(nlohmann::json()) {
   er = thread_.create(env_list_routine_, this);
   CHECK_EQ(er, 0);
   continuous_profiler_ = std::make_shared<ContinuousProfiler>(&thread_loop_);
+  on_code_event_q_ =
+    AsyncTSQueue<CodeEventInfo>::create(
+      &thread_loop_,
+      +[](CodeEventInfo&& info, EnvList* envlist) {
+        envlist->got_code_event(std::move(info));
+      },
+      this);
 }
 
 
@@ -978,6 +999,58 @@ void EnvList::OnUnblockedLoopHook(
     { 0, proxy, nsolid::internal::user_data(data, deleter) });
 }
 
+TSList<EnvList::CodeEventHookStor>::iterator EnvList::AddCodeEventHook(
+    void* data,
+    internal::code_event_hook_proxy_sig proxy,
+    internal::deleter_sig deleter) {
+
+  auto it = code_event_hook_list_.push_back(
+    { proxy, nsolid::internal::user_data(data, deleter) });
+
+  decltype(env_map_) env_map;
+  {
+    // Copy the envinst map so we don't need to keep it locked the entire time.
+    ns_mutex::scoped_lock lock(map_lock_);
+    env_map = env_map_;
+  }
+
+  for (auto& entry : env_map) {
+    SharedEnvInst envinst = entry.second;
+    int er = RunCommand(envinst,
+                        CommandType::InterruptOnly,
+                        setup_code_event_handler);
+    if (er) {
+      // Nothing to do here, really.
+    }
+  }
+
+  return it;
+}
+
+void EnvList::RemoveCodeEventHook(
+    TSList<EnvList::CodeEventHookStor>::iterator it) {
+  size_t size = code_event_hook_list_.erase(it);
+  if (size == 0) {
+    // No hooks left, disable the code event handler.
+    decltype(env_map_) env_map;
+    {
+      // Copy the envinst map so we don't need to keep it locked the entire
+      // time.
+      ns_mutex::scoped_lock lock(map_lock_);
+      env_map = env_map_;
+    }
+
+    for (auto& entry : env_map) {
+      SharedEnvInst envinst = entry.second;
+      int er = RunCommand(envinst,
+                          CommandType::InterruptOnly,
+                          disable_code_event_handler);
+      if (er) {
+        // Nothing to do here, really.
+      }
+    }
+  }
+}
 
 int EnvList::QueueCallback(q_cb_sig cb, uint64_t timeout, void* data) {
   QCbTimeoutStor* stor = new (std::nothrow) QCbTimeoutStor({
@@ -1041,6 +1114,10 @@ NODE_PERFORMANCE_MILESTONES(V)
   env->isolate()->AddGCEpilogueCallback(EnvInst::v8_gc_epilogue_cb_,
                                         envinst_sp.get());
 
+  if (code_event_hook_list_.size() > 0) {
+    envinst_sp->setup_code_event_handler();
+  }
+
   // Run EnvironmentCreationHook callbacks.
   env_creation_list_.for_each([envinst_sp](auto& stor) {
     stor.cb(envinst_sp, stor.data.get());
@@ -1415,6 +1492,18 @@ void EnvList::datapoint_cb_(std::queue<MetricsStream::Datapoint>&& q) {
   });
 }
 
+void EnvList::setup_code_event_handler(SharedEnvInst envinst_sp) {
+  DCHECK_EQ(envinst_sp->isolate(), v8::Isolate::TryGetCurrent());
+
+  envinst_sp->setup_code_event_handler();
+}
+
+void EnvList::disable_code_event_handler(SharedEnvInst envinst_sp) {
+  DCHECK_EQ(envinst_sp->isolate(), v8::Isolate::TryGetCurrent());
+
+  envinst_sp->disable_code_event_handler();
+}
+
 
 void EnvInst::send_datapoint(MetricsStream::Type type,
                              double value) {
@@ -1617,9 +1706,11 @@ void EnvList::log_written_cb_(ns_async*, EnvList* envlist) {
 // registered users will need to receive their last set of metrics and a
 // notification that it'll be their last.
 void EnvList::removed_env_cb_(ns_async*, EnvList* envlist) {
+  envlist->on_code_event_q_.reset();
   if (envlist->continuous_profiler_) {
     envlist->continuous_profiler_.reset();
   }
+
   envlist->removed_env_msg_.close();
   envlist->process_callbacks_msg_.close();
   envlist->log_written_msg_.close();
@@ -1885,6 +1976,20 @@ void EnvList::fill_trace_id_q() {
   }
 }
 
+void EnvList::got_code_event(CodeEventInfo&& info) {
+  auto envinst_sp = EnvInst::GetInst(info.thread_id);
+  if (envinst_sp == nullptr) {
+    return;
+  }
+
+  code_event_hook_list_.for_each([&info, &envinst_sp](auto& stor, size_t size) {
+    if (size == 1) {
+      stor.cb(envinst_sp, std::move(info), stor.data.get());
+    } else {
+      stor.cb(envinst_sp, info, stor.data.get());
+    }
+  });
+}
 
 void EnvInst::custom_command_(SharedEnvInst envinst_sp,
                               const std::string req_id) {