From d192d6cf91669f0638048e4d708712f39c345f8e Mon Sep 17 00:00:00 2001
From: falsycat <me@falsy.cat>
Date: Fri, 10 Jun 2022 18:23:03 +0900
Subject: [PATCH] add nf7::GenericWatcher

---
 CMakeLists.txt            |  1 +
 common/generic_watcher.hh | 30 ++++++++++++++++
 file/luajit_obj.cc        | 76 +++++++++++++++++----------------------
 3 files changed, 63 insertions(+), 44 deletions(-)
 create mode 100644 common/generic_watcher.hh

diff --git a/CMakeLists.txt b/CMakeLists.txt
index fab7e09..b41a57b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -56,6 +56,7 @@ target_sources(nf7
     common/generic_history.hh
     common/generic_memento.hh
     common/generic_type_info.hh
+    common/generic_watcher.hh
     common/gui_file.hh
     common/gui_node.hh
     common/gui_window.hh
diff --git a/common/generic_watcher.hh b/common/generic_watcher.hh
new file mode 100644
index 0000000..311b3fa
--- /dev/null
+++ b/common/generic_watcher.hh
@@ -0,0 +1,30 @@
+#pragma once
+
+#include <unordered_map>
+
+#include "nf7.hh"
+
+
+namespace nf7 {
+
+class GenericWatcher final : public Env::Watcher {
+ public:
+  using Handler = std::function<void(const File::Event&)>;
+
+  GenericWatcher(Env& env) noexcept : Watcher(env) {
+  }
+
+  void AddHandler(File::Event::Type type, Handler&& h) noexcept {
+    handlers_[type] = std::move(h);
+  }
+  void Handle(const File::Event& ev) noexcept override {
+    auto handler = handlers_.find(ev.type);
+    if (handler == handlers_.end()) return;
+    handler->second(ev);
+  }
+
+ private:
+  std::unordered_map<File::Event::Type, Handler> handlers_;
+};
+
+}  // namespace nf7
diff --git a/file/luajit_obj.cc b/file/luajit_obj.cc
index f10953e..d93b137 100644
--- a/file/luajit_obj.cc
+++ b/file/luajit_obj.cc
@@ -17,6 +17,7 @@
 #include "common/future.hh"
 #include "common/generic_context.hh"
 #include "common/generic_type_info.hh"
+#include "common/generic_watcher.hh"
 #include "common/lock.hh"
 #include "common/luajit.hh"
 #include "common/luajit_obj.hh"
@@ -42,7 +43,6 @@ class Obj final : public nf7::File,
 
   static constexpr size_t kMaxSize = 1024*1024*16;  /* = 16 MiB */
 
-  class SrcWatcher;
   class ExecTask;
 
   Obj(Env& env, Path&& path = {}) noexcept :
@@ -75,8 +75,8 @@ class Obj final : public nf7::File,
  private:
   std::shared_ptr<nf7::LoggerRef> log_;
 
-  std::unique_ptr<SrcWatcher> srcwatcher_;
-  std::shared_ptr<nf7::luajit::Ref> cache_;
+  std::optional<nf7::GenericWatcher> watcher_;
+  std::shared_ptr<nf7::luajit::Ref>  cache_;
 
   nf7::Task<std::shared_ptr<nf7::luajit::Ref>>::Holder exec_;
 
@@ -94,27 +94,6 @@ class Obj final : public nf7::File,
   void Reset() noexcept;
 };
 
-class Obj::SrcWatcher final : public nf7::Env::Watcher {
- public:
-  SrcWatcher(Obj& owner, File::Id id) :
-      Watcher(owner.env()), owner_(&owner) {
-    if (owner.id() == id) throw Exception("self watch");
-    if (id == 0) throw Exception("invalid id");
-    Watch(id);
-  }
-
-  void Handle(const File::Event& ev) noexcept override {
-    if (ev.type == File::Event::kUpdate) {
-      owner_->log_->Info("detected update of source file, drops cache automatically");
-      owner_->cache_ = nullptr;
-      owner_->Touch();
-    }
-  }
-
- private:
-  Obj* const owner_;
-};
-
 class Obj::ExecTask final : public nf7::Task<std::shared_ptr<nf7::luajit::Ref>> {
  public:
   ExecTask(Obj& target) noexcept :
@@ -175,9 +154,28 @@ class Obj::ExecTask final : public nf7::Task<std::shared_ptr<nf7::luajit::Ref>>
         return luaL_ref(L, LUA_REGISTRYINDEX);
       });
 
-      // context for luajit script running
-      auto lua_ctx = std::make_shared<nf7::GenericContext>(env(), initiator());
-      lua_ctx->description() = "luajit object build script runner";
+      // setup watcher
+      try {
+        *target_->src_;  // check if the src is alive
+
+        auto& w = target_->watcher_;
+        w.emplace(env());
+        w->Watch(srcf.id());
+
+        std::weak_ptr<Task> wself = self();
+        w->AddHandler(Event::kUpdate, [t = target_, wself](auto&) {
+          if (auto self = wself.lock()) {
+            t->log_->Info("detected update of source file, aborts building");
+            t->exec_ = {};
+          } else if (t->cache_) {
+            t->log_->Info("detected update of source file, drops cache automatically");
+            t->cache_ = nullptr;
+            t->Touch();
+          }
+        });
+      } catch (Exception& e) {
+        log_->Warn("watcher setup error: "+e.msg());
+      }
 
       // queue task to trigger the thread
       auto ljq = target_->
@@ -242,18 +240,12 @@ nf7::Future<std::shared_ptr<nf7::luajit::Ref>> Obj::Build() noexcept {
 void Obj::Handle(const Event& ev) noexcept {
   switch (ev.type) {
   case Event::kAdd:
-    try {
-      log_->SetUp(*this);
-      auto ctx = std::make_shared<nf7::GenericContext>(env(), id());
-      ctx->description() = "resetting state";
-      env().ExecMain(ctx, [this]() { Reset(); });
-    } catch (Exception&) {
-    }
+    log_->SetUp(*this);
     break;
   case Event::kRemove:
-    exec_       = {};
-    cache_      = nullptr;
-    srcwatcher_ = nullptr;
+    exec_    = {};
+    cache_   = nullptr;
+    watcher_ = std::nullopt;
     log_->TearDown();
     break;
  
@@ -262,13 +254,9 @@ void Obj::Handle(const Event& ev) noexcept {
   }
 }
 void Obj::Reset() noexcept {
-  exec_  = {};
-  cache_ = nullptr;
-  try {
-    srcwatcher_ = std::make_unique<SrcWatcher>(*this, src_.id());
-  } catch (Exception&) {
-    srcwatcher_ = nullptr;
-  }
+  exec_    = {};
+  cache_   = nullptr;
+  watcher_ = std::nullopt;
 }
 
 void Obj::Update() noexcept {