I cannot tell whether the original comment was unsure about the
arithmetic calculations, or if it was unsure about the assumptions
being made about the alignment of the current allocation pointer.
The arithmetic calculation looks fine to me, though. This technique
is documented e.g. in Henry Warren's "Hacker's Delight" (section 3-1).
(I am sure one can find it elsewhere too, its not an obscure
property.)
I cannot tell whether the original comment was unsure about the
arithmetic calculations, or if it was unsure about the assumptions
being made about the alignment of the current allocation pointer.
The arithmetic calculation looks fine to me, though. This technique
is documented e.g. in Henry Warren's "Hacker's Delight" (section 3-1).
(I am sure one can find it elsewhere too, its not an obscure
property.)
New benchmark tests in vec.rs:
`push`, `starts_with_same_vector`, `starts_with_single_element`,
`starts_with_diff_one_element_end`, `ends_with_same_vector`,
`ends_with_single_element`, `ends_with_diff_one_element_beginning` and
`contains_last_element`
This isn't very useful yet, but it does replace most functionality of `@T`. The `Mut<T>` type will make it unnecessary to have a `GcMut<T>` so I haven't included one. Obviously it doesn't work for trait objects but that needs to be figured out for `Rc<T>` too.
This implements a fair amount of the unimpl() functionality in io::native
relating to filesystem operations. I've also modified all io::fs tests to run in
both a native and uv environment (so everything is actually tested).
There are a few bits of remaining functionality which I was unable to get
working:
* truncate on windows
* change_file_times on windows
* lstat on windows
I think that change_file_times may just need a better interface, but the other
two have large implementations in libuv which I didn't want to tackle trying to
copy. I found a `chsize` function to work for truncate on windows, but it
doesn't quite seem to be working out.
This implements a fair amount of the unimpl() functionality in io::native
relating to filesystem operations. I've also modified all io::fs tests to run in
both a native and uv environment (so everything is actually tested).
There are a two bits of remaining functionality which I was unable to get
working:
* change_file_times on windows
* lstat on windows
I think that change_file_times may just need a better interface, but lstat has a
large implementation in libuv which I didn't want to tackle trying to copy.
There are issues with reading stdin when it is actually attached to a pipe, but
I have run into no problems in writing to stdout/stderr when they are attached
to pipes.
Provide `Closed01` and `Open01` that generate directly from the
closed/open intervals from 0 to 1, in contrast to the plain impls for
f32 and f64 which generate the half-open [0,1).
Fixes#7755.
Explicitly have the only C++ portion of the runtime be one file with exception
handling. All other runtime files must now live in C and be fully defined in C.
This mutex is built on top of pthreads for unix and the related windows apis on
windows. This is a straight port of the lock_and_signal type from C++ to rust.
Almost all operations on the type are unsafe, and it's definitely not
recommended for general use.
Closes#9105
There are issues with reading stdin when it is actually attached to a pipe, but
I have run into no problems in writing to stdout/stderr when they are attached
to pipes.
Provide `Closed01` and `Open01` that generate directly from the
closed/open intervals from 0 to 1, in contrast to the plain impls for
f32 and f64 which generate the half-open [0,1).
Fixes#7755.
These commits create a `Buffer` trait in the `io` module which represents an I/O reader which is internally buffered. This abstraction is used to reasonably implement `read_line` and `read_until` along with at least an ok implementation of `read_char` (although I certainly haven't benchmarked `read_char`).
This commit re-organizes the io::native module slightly in order to have a
working implementation of rtio::IoFactory which uses native implementations. The
goal is to seamlessly multiplex among libuv/native implementations wherever
necessary.
Right now most of the native I/O is unimplemented, but we have existing bindings
for file descriptors and processes which have been hooked up. What this means is
that you can now invoke println!() from libstd with no local task, no local
scheduler, and even without libuv.
There's still plenty of work to do on the native I/O factory, but this is the
first steps into making it an official portion of the standard library. I don't
expect anyone to reach into io::native directly, but rather only std::io
primitives will be used. Each std::io interface seamlessly falls back onto the
native I/O implementation if the local scheduler doesn't have a libuv one
(hurray trait ojects!)
This commit re-organizes the io::native module slightly in order to have a
working implementation of rtio::IoFactory which uses native implementations. The
goal is to seamlessly multiplex among libuv/native implementations wherever
necessary.
Right now most of the native I/O is unimplemented, but we have existing bindings
for file descriptors and processes which have been hooked up. What this means is
that you can now invoke println!() from libstd with no local task, no local
scheduler, and even without libuv.
There's still plenty of work to do on the native I/O factory, but this is the
first steps into making it an official portion of the standard library. I don't
expect anyone to reach into io::native directly, but rather only std::io
primitives will be used. Each std::io interface seamlessly falls back onto the
native I/O implementation if the local scheduler doesn't have a libuv one
(hurray trait ojects!)
I implemented BufWriter. I realize the use of conditions are on their way out for IO, but it does raise a condition if a write will not fit in the buffer for now.
I also replaced the seek code for MemWriter. It was adding the offset as a uint, which is unsound for negative offsets. It only happened to work because unsigned addition performs the same operation with two's complement, and sizeof(uint) <= sizeof(i64) so there was no (lack of) sign extension. I replaced this with computing an offset as an i64 and clamping to zero. I don't expect anyone will have use BufWriter with a byte buffer greater than 2^63 bytes any time soon.
@alexcrichton
Closes#10433
This trait is meant to abstract whether a reader is actually implemented with an
underlying buffer. For all readers which are implemented as such, we can
efficiently implement things like read_char, read_line, read_until, etc. There
are two required methods for managing the internal buffer, and otherwise
read_line and friends can all become default methods.
Closes#10334
Filled in the implementations of Writer and Seek for BufWriter. It
raises the io_error condition if a write cannot fit in the buffer.
The Seek implementation for MemWriter, which was incorrectly using
unsigned arithmatic to add signed offsets, has also been replaced.
This fills in some missing docs in the nums package. Let me know if this is on the right track for what's wanted for docs. I can probably fill in more in the future. Thanks.
(As a side note the precedence of the unary negative operator '-' tripped me up for a bit. Essentially I would expect `-25.0f32.sqrt()` to result in NaN instead of `-5.0`.)
I was benchmarking rust-http recently, and I saw that 50% of its time was spent
creating buffered readers/writers. Albeit rust-http wasn't using
std::rt::io::buffered, but the same idea applies here. It's much cheaper to
malloc a large region and not initialize it than to set it all to 0. Buffered
readers/writers never use uninitialized data, and their internal buffers are
encapsulated, so any usage of uninitialized slots are an implementation bug in
the readers/writers.
