* Compact Bytes original capacity representation
In order to avoid unnecessary allocations, a `Bytes` structure remembers
the capacity with which it was first created. When a reserve operation
is issued, this original capacity value is used to as a baseline for
reallocating new storage.
Previously, this original capacity value was stored in its raw form. In
other words, the original capacity `usize` was stored as is. In order to
reclaim some `Bytes` internal storage space for additional features,
this original capacity value is compressed from requiring 16 bits to 3.
To do this, instead of storing the exact original capacity. The original
capacity is rounded down to the nearest power of two. If the original
capacity is less than 1024, then it is rounded down to zero. This
roughly means that the original capacity is now stored as a table:
0 => 0
1 => 1k
2 => 2k
3 => 4k
4 => 8k
5 => 16k
6 => 32k
7 => 64k
For the purposes that the original capacity feature was introduced, this
is sufficient granularity.
* Provide `advance` on Bytes and BytesMut
This is the `advance` function that would be part of a `Buf`
implementation. However, `Bytes` and `BytesMut` cannot impl `Buf` until
the next breaking release.
The implementation uses the additional storage made available by the
previous commit to store the number of bytes that the view was advanced.
The `ptr` pointer will point to the start of the window, avoiding any
pointer arithmetic when dereferencing the `Bytes` handle.
The shared debug_assert is to ensure that the internal Bytes
representation is such that offset views are supported. The only
representation that does not support offset views is vec.
Fixes#97
Limit the number of threads when using qemu to 1. Also, don't bother
running the stress test as this will trigger qemu bugs. Finally, also
make the stress test actually stress test.
The `Source` trait was essentially covering the same case as `IntoBuf`,
so remove it.
While technically a breaking change, this should not have any impact due
to:
1) There are no reverse dependencies that currently depend on `bytes`
2) Source was not supposed to be implemented externally
3) IntoBuf provides the same implementations as `Source`
Given these points, the change should be safe to apply.
This change tracks the original capacity requested when `BytesMut` is
first created. This capacity is used when a `reserve` needs to allocate
due to the current view being too small. The newly allocated buffer will
be sized the same as the original allocation.
The previous implementation didn't factor in a single `Bytes` handle
being stored in an `Arc`. This new implementation correctly impelments
both `Bytes` and `BytesMut` such that both are `Sync`.
The rewrite also increases the number of bytes that can be stored
inline.
This commit is a significant overhaul of the library in an effort to head
towards a stable API. The rope implementation as well as a number of buffer
implementations have been removed from the library and will live at
https://github.com/carllerche/bytes-more while they incubate.
**Bytes / BytesMut**
`Bytes` is now an atomic ref counted byte slice. As it is contigous, it offers
a richer API than before.
`BytesMut` is a mutable variant. It is safe by ensuring that it is the only
handle to a given byte slice.
**AppendBuf -> ByteBuf**
`AppendBuf` has been replaced by `ByteBuf`. The API is not identical, but is
close enough to be considered a suitable replacement.
**Removed types**
The following types have been removed in favor of living in bytes-more
* RingBuf
* BlockBuf
* `Bytes` as a rope implementation
* ReadExt
* WriteExt
Carl Lerche