This commit introduces two new buffer wrapper types to `deno_core`. The
main benefit of these new wrappers is that they can wrap a number of
different underlying buffer types. This allows for a more flexible read
and write API on resources that will require less copying of data
between different buffer representations.
- `BufView` is a read-only view onto a buffer. It can be backed by
`ZeroCopyBuf`, `Vec<u8>`, and `bytes::Bytes`.
- `BufViewMut` is a read-write view onto a buffer. It can be cheaply
converted into a `BufView`. It can be backed by `ZeroCopyBuf` or
`Vec<u8>`.
Both new buffer views have a cursor. This means that the start point of
the view can be constrained to write / read from just a slice of the
view. Only the start point of the slice can be adjusted. The end point
is fixed. To adjust the end point, the underlying buffer needs to be
truncated.
Readable resources have been changed to better cater to resources that
do not support BYOB reads. The basic `read` method now returns a
`BufView` instead of taking a `ZeroCopyBuf` to fill. This allows the
operation to return buffers that the resource has already allocated,
instead of forcing the caller to allocate the buffer. BYOB reads are
still very useful for resources that support them, so a new `read_byob`
method has been added that takes a `BufViewMut` to fill. `op_read`
attempts to use `read_byob` if the resource supports it, which falls
back to `read` and performs an additional copy if it does not. For
Rust->JS reads this change should have no impact, but for Rust->Rust
reads, this allows the caller to avoid an additional copy in many
scenarios. This combined with the support for `BufView` to be backed by
`bytes::Bytes` allows us to avoid one data copy when piping from a
`fetch` response into an `ext/http` response.
Writable resources have been changed to take a `BufView` instead of a
`ZeroCopyBuf` as an argument. This allows for less copying of data in
certain scenarios, as described above. Additionally a new
`Resource::write_all` method has been added that takes a `BufView` and
continually attempts to write the resource until the entire buffer has
been written. Certain resources like files can override this method to
provide a more efficient `write_all` implementation.
This is the release commit being forwarded back to main for 1.26.1
Please ensure:
- [x] Everything looks ok in the PR
- [x] The release has been published
To make edits to this PR:
```shell
git fetch upstream forward_v1.26.1 && git checkout -b forward_v1.26.1 upstream/forward_v1.26.1
```
Don't need this PR? Close it.
cc @cjihrig
Co-authored-by: cjihrig <cjihrig@users.noreply.github.com>
This commit adds a fast path to `Request` and `Response` that
make consuming request bodies much faster when using `Body#text`,
`Body#arrayBuffer`, and `Body#blob`, if the body is a FastStream.
Because the response bodies for `fetch` are FastStream, this speeds up
consuming `fetch` response bodies significantly.
Previously if a user specified a content-length header for an POST
request without a body, the request would contain two `content-length`
headers. One added by us, and one added by the user.
This commit ignores all content-length headers coming from the user,
because we need to have the sole authority on the content-length because
we transmit the body.
Welcome to better optimised op calls! Currently opSync is called with parameters of every type and count. This most definitely makes the call megamorphic. Additionally, it seems that spread params leads to V8 not being able to optimise the calls quite as well (apparently Fast Calls cannot be used with spread params).
Monomorphising op calls should lead to some improved performance. Now that unwrapping of sync ops results is done on Rust side, this is pretty simple:
```
opSync("op_foo", param1, param2);
// -> turns to
ops.op_foo(param1, param2);
```
This means sync op calls are now just directly calling the native binding function. When V8 Fast API Calls are enabled, this will enable those to be called on the optimised path.
Monomorphising async ops likely requires using callbacks and is left as an exercise to the reader.
