Before, if we couldn't read enough data out of the buffer, we would re-
fill the buffer and recursively call read(), which in turn reads data
from the buffer into the resliced target span. This incurs very
intensive superflous memmove's when large chunks of data are read from
a buffered stream.
This commit changes the behavior so that when we exhaust the buffer, we
first read any necessary additional data directly into the target, then
fill up the buffer again. Effectively, this results in drastically
reduced overhead from Buffered when reading large contiguous chunks.
Of course, Buffered is designed to speed up data access patterns with
small frequent reads, but it's nice to be able to combine both access
patterns on one stream without penalties either way.
The final performance gain is about an additional 80% of abench decoding
speed.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
This commit makes the user-facing StdLibExtras templates and utilities
arguably more nice-looking by removing the need to reach into the
wrapper structs generated by them to get the value/type needed.
The C++ standard library had to invent `_v` and `_t` variants (likely
because of backwards compat), but we don't need to cater to any codebase
except our own, so might as well have good things for free. :^)
Problem:
- Several files have missing includes. This results in complaints from
`clang-tidy`.
- `#ifdef` is followed by `#elif <value>` which evaluates to `0`.
Solution:
- Add missing includes.
- Change to `#elif defined(<value>)`.
Consider the following snippet:
void foo(InputStream& stream) {
if(!stream.eof()) {
u8 byte;
stream >> byte;
}
}
There is a very subtle bug in this snippet, for some input streams eof()
might return false even if no more data can be read. In this case an
error flag would be set on the stream.
Until now I've always ensured that this is not the case, but this made
the implementation of eof() unnecessarily complicated.
InputFileStream::eof had to keep a ByteBuffer around just to make this
possible. That meant a ton of unnecessary copies just to get a reliable
eof().
In most cases it isn't actually necessary to have a reliable eof()
implementation.
In most other cases a reliable eof() is avaliable anyways because in
some cases like InputMemoryStream it is very easy to implement.
The streaming operator doesn't short-circuit, consider the following
snippet:
void foo(InputStream& stream) {
int a, b;
stream >> a >> b;
}
If the first read fails, the second is called regardless. It should be
well defined what happens in this case: nothing.
