[v11.x] src: allocate Buffer memory using ArrayBuffer allocator by addaleax · Pull Request #26302

[v11.x] src: allocate Buffer memory using ArrayBuffer allocator by addaleax · Pull Request #26302 · nodejs/node

added c++

Issues and PRs that require attention from people who are familiar with C++.

Issues and PRs related to general changes in the lib or src directory.

Feb 25, 2019

This enables us to identify whether we are using an
allocator that we know more about than what the generic
`ArrayBuffer::Allocator` API provides, in particular
whether it is `malloc()`-compatible.

PR-URL: nodejs#26207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

If the `ArrayBuffer::Allocator` used to create `ArrayBuffer`s
in the current `Isolate` is not a Node.js `ArrayBufferAllocator`,
we cannot know that it is `malloc()`-based, an in particular it might
not be compatible with the `ArrayBuffer::Allocator` on the receiving
end of the connection.

PR-URL: nodejs#26207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

Add a subclass of `ArrayBufferAllocator` that performs additional
debug checking, which in particular verifies that:

- All `ArrayBuffer` backing stores have been allocated with this
  allocator, or have been explicitly marked as coming from a
  compatible source.
- All memory allocated by the allocator has been freed once it is
  destroyed.

PR-URL: nodejs#26207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

Add a RAII utility for managing blocks of memory that have
been allocated with the `ArrayBuffer::Allocator` for a given
`Isolate`.

PR-URL: nodejs#26207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

Always use the right allocator for memory that is turned into
an `ArrayBuffer` at a later point.

This enables embedders to use their own `ArrayBuffer::Allocator`s,
and is inspired by Electron’s electron/node@f61bae3440e. It should
render their downstream patch unnecessary.

Refs: electron/node@f61bae3

PR-URL: nodejs#26207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>