From bf4ebda92bd34127d496d9edc0d33c6c6beb1ca5 Mon Sep 17 00:00:00 2001
From: John French <johnfrench093@gmail.com>
Date: Tue, 4 Jun 2019 12:21:51 -0700
Subject: [PATCH] AsyncWorker: introduce Destroy() method

`AsyncWorker` contained the assumption that instances of its subclasses
were allocated using `new`, because it unconditionally destroyed
instances using `delete`.

This change replaces the call to `delete` with a call to a protected
instance method `Destroy()`, which can be overridden by subclasses.
This ensures that users can employ their own allocators when
creating `AsyncWorker` subclass instances because they can override
the `Destroy()` method to use their deallocator of choice.

Re: https://github.com/nodejs/node-addon-api/issues/231#issuecomment-480928142
PR-URL: https://github.com/nodejs/node-addon-api/pull/488
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
---
 doc/async_worker.md | 13 +++++++++++++
 napi-inl.h          |  6 +++++-
 napi.h              |  1 +
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/doc/async_worker.md b/doc/async_worker.md
index 43e11d5..da12cba 100644
--- a/doc/async_worker.md
+++ b/doc/async_worker.md
@@ -125,6 +125,19 @@ class was created, passing in the error as the first parameter.
 virtual void Napi::AsyncWorker::OnError(const Napi::Error& e);
 ```
 
+### Destroy
+
+This method is invoked when the instance must be deallocated. If
+`SuppressDestruct()` was not called then this method will be called after either
+`OnError()` or `OnOK()` complete. The default implementation of this method
+causes the instance to delete itself using the `delete` operator. The method is
+provided so as to ensure that instances allocated by means other than the `new`
+operator can be deallocated upon work completion.
+
+```cpp
+virtual void Napi::AsyncWorker::Destroy();
+```
+
 ### Constructor
 
 Creates a new `Napi::AsyncWorker`.
diff --git a/napi-inl.h b/napi-inl.h
index 2b91b12..9f03f3a 100644
--- a/napi-inl.h
+++ b/napi-inl.h
@@ -3529,6 +3529,10 @@ inline AsyncWorker::~AsyncWorker() {
   }
 }
 
+inline void AsyncWorker::Destroy() {
+  delete this;
+}
+
 inline AsyncWorker::AsyncWorker(AsyncWorker&& other) {
   _env = other._env;
   other._env = nullptr;
@@ -3623,7 +3627,7 @@ inline void AsyncWorker::OnWorkComplete(
     });
   }
   if (!self->_suppress_destruct) {
-    delete self;
+    self->Destroy();
   }
 }
 
diff --git a/napi.h b/napi.h
index 7a83d79..bf565fb 100644
--- a/napi.h
+++ b/napi.h
@@ -1803,6 +1803,7 @@ namespace Napi {
     virtual void Execute() = 0;
     virtual void OnOK();
     virtual void OnError(const Error& e);
+    virtual void Destroy();
 
     void SetError(const std::string& error);