Commit Graph

18 Commits

Author SHA1 Message Date
Tim Schumacher
60ac254df6 AK: Use hashing to accelerate searching a CircularBuffer 2023-07-06 15:06:20 +01:00
Tim Schumacher
4a10cf1506 AK: Make CircularBuffer::read_with_seekback const
Compared to the other read and write functions, this doesn't modify the
internal state of the circular buffer.
2023-07-06 15:06:20 +01:00
Tim Schumacher
42d01b21d8 AK: Rewrite the hint-based CircularBuffer::find_copy_in_seekback
This now searches the memory in blocks, which should be slightly more
efficient. However, it doesn't make much difference (e.g. ~1% in LZMA
compression) in most real-world applications, as the non-hint function
is more expensive by orders of magnitude.
2023-07-06 15:06:20 +01:00
Tim Schumacher
2109f61b0d AK: Add search-related helpers to CircularBuffer
This factors out a lot of complicated math into somewhat understandable
functions.

While at it, rename `next_read_span_with_seekback` to
`next_seekback_span` to keep the naming consistent and to avoid making
function names any longer.
2023-07-06 15:06:20 +01:00
Tim Schumacher
d12036132e AK: Allow passing an offset to CircularBuffer::next_read_span() 2023-07-06 15:06:20 +01:00
Tim Schumacher
046a9faeb3 AK: Split up CircularBuffer::find_copy_in_seekback
The "operation modes" of this function have very different focuses, and
trying to combine both in a way where we share the most amount of code
probably results in the worst performance.

Instead, split up the function into "existing distances" and "no
existing distances" so that we can optimize either case separately.
2023-07-06 15:06:20 +01:00
Tim Schumacher
9e82ad758e AK: Move parts for searching CircularBuffer into a new class
We will be adding extra logic to the CircularBuffer to optimize
searching, but this would negatively impact the performance of
CircularBuffer users that don't need that functionality.
2023-07-06 15:06:20 +01:00
Ben Wiederhake
041f5e931d AK: Use AK_MAKE_DEFAULT_MOVABLE to avoid mistakes in default impls 2023-06-18 08:47:51 +01:00
Tim Schumacher
221b91ff61 AK: Add CircularBuffer::find_copy_in_seekback()
This is useful for compressors, which quite frequently need to find a
matching span of data within the seekback.
2023-05-17 09:08:53 +02:00
Lucas CHOLLET
48b000a36c AK: Add CircularBuffer::flush_to_stream
In a similar fashion to what have been done with `fill_from_stream`,
this new method allows to write CircularBuffer's data to a Stream
without additional copies.
2023-05-09 11:18:46 +02:00
Tim Schumacher
767fb01a8c AK: Report copied bytes when seekback copying from CircularBuffer
Otherwise, we have no way of determining whether our copy was truncated
by accident.
2023-04-05 07:30:38 -04:00
Timothy Flynn
8b56d82865 AK+LibCompress: Remove the Deflate back-reference intermediate buffer
Instead of reading bytes from the output stream into a buffer, just to
immediately write them back out, we can skip the middle-man and copy the
bytes directly into the output buffer.
2023-03-31 06:56:11 +02:00
Timothy Flynn
5c38b14045 AK: Remove arbitrary 1 KB limit when filling a BufferedStream's buffer
When reading, we currently only fill a BufferedStream's buffer when it
is empty, and only with 1 KB of data. This means that while the buffer
defaults to a size of 16 KB, at least 15 KB is always unused.
2023-03-30 08:47:22 +02:00
Tim Schumacher
52d9fc92f1 AK: Expose the seekback limit of CircularBuffer 2023-03-21 10:25:13 +01:00
Lucas CHOLLET
9a7accddb7 AK: Add an optional starting offset to CircularBuffer::offset_of
This parameter allows to start searching after an offset. For example,
to resume a search.

It is unfortunately a breaking change in API so this patch also modifies
one user and one test.
2023-01-14 16:20:30 -07:00
Lucas CHOLLET
34922c0cc0 AK: Default move operators for CircularBuffer
The previously defined operator was swap-based. With the defaulted
implementation, both integers are now copied, but it doesn't matter as
only the `ByteBuffer` allocates memory (i.e. non-null integers values
won't affect the destruction).
2023-01-14 16:15:31 -07:00
Tim Schumacher
d717a08003 AK: Add CircularBuffer::read_with_seekback 2023-01-13 17:34:45 -07:00
Lucas CHOLLET
f12e81b74a AK: Add CircularBuffer
The class is very similar to `CircularDuplexStream` in its behavior.
Main differences are that `CircularBuffer`:
 - does not inherit from `AK::Stream`
 - uses `ErrorOr` for its API
 - is heap allocated (and OOM-Safe)

 This patch also add some tests.
2022-12-31 04:44:17 -07:00