Whenever a failure happens, if a program is run with
`RUST_LOG=std::rt::backtrace` a backtrace will be printed to the task's stderr
handle. Stack traces are uncondtionally printed on double-failure and
rtabort!().
This ended up having a nontrivial implementation, and here's some highlights of
it:
* We're bundling libbacktrace for everything but OSX and Windows
* We use libgcc_s and its libunwind apis to get a backtrace of instruction
pointers
* On OSX we use dladdr() to go from an instruction pointer to a symbol
* On unix that isn't OSX, we use libbacktrace to get symbols
* Windows, as usual, has an entirely separate implementation
Lots more fun details and comments can be found in the source itself.
Closes#10128
* All I/O now returns IoResult<T> = Result<T, IoError>
* All formatting traits now return fmt::Result = IoResult<()>
* The if_ok!() macro was added to libstd
* vec::raw::to_ptr is gone
* Pausible => Pausable
* Removing @
* Calling the main task "<main>"
* Removing unused imports
* Removing unused mut
* Bringing some libextra tests up to date
* Allowing compiletest to work at stage0
* Fixing the bootstrap-from-c rmake tests
* assert => rtassert in a few cases
* printing to stderr instead of stdout in fail!()
This extracts everything related to green scheduling from libstd and introduces
a new libgreen crate. This mostly involves deleting most of std::rt and moving
it to libgreen.
Along with the movement of code, this commit rearchitects many functions in the
scheduler in order to adapt to the fact that Local::take now *only* works on a
Task, not a scheduler. This mostly just involved threading the current green
task through in a few locations, but there were one or two spots where things
got hairy.
There are a few repercussions of this commit:
* tube/rc have been removed (the runtime implementation of rc)
* There is no longer a "single threaded" spawning mode for tasks. This is now
encompassed by 1:1 scheduling + communication. Convenience methods have been
introduced that are specific to libgreen to assist in the spawning of pools of
schedulers.
Printing is an incredibly useful debugging utility, and it's not much help if
your debugging prints just trigger an obscure abort when you need them most. In
order to handle this case, forcibly fall back to a libc::write implementation of
printing whenever a local task is not available.
Note that this is *not* a 1:1 fallback. All 1:1 rust tasks will still have a
local Task that it can go through (and stdio will be created through the local
IO factory), this is only a fallback for "no context" rust code (such as that
setting up the context).
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!)
These two attributes are no longer useful now that Rust has decided to leave
segmented stacks behind. It is assumed that the rust task's stack is always
large enough to make an FFI call (due to the stack being very large).
There's always the case of stack overflow, however, to consider. This does not
change the behavior of stack overflow in Rust. This is still normally triggered
by the __morestack function and aborts the whole process.
C stack overflow will continue to corrupt the stack, however (as it did before
this commit as well). The future improvement of a guard page at the end of every
rust stack is still unimplemented and is intended to be the mechanism through
which we attempt to detect C stack overflow.
Closes#8822Closes#10155
The isn't an ideal patch, and the comment why is in the code. Basically uvio
uses task::unkillable which touches the kill flag for a task, and if the task is
failing due to mismangement of the kill flag, then there will be serious
problems when the task tries to print that it's failing.
When uv's TTY I/O is used for the stdio streams, the file descriptors are put
into a non-blocking mode. This means that other concurrent writes to the same
stream can fail with EAGAIN or EWOULDBLOCK. By all I/O to event-loop I/O, we
avoid this error.
There is one location which cannot move, which is the runtime's dumb_println
function. This was implemented to handle the EAGAIN and EWOULDBLOCK errors and
simply retry again and again.
Naturally, and sadly, turning off sanity checks in the runtime is
a noticable performance win. The particular test I'm running goes from
~1.5 s to ~1.3s.
Sanity checks are turned *on* when not optimizing, or when cfg
includes `rtdebug` or `rtassert`.
Instead of a furious storm of idle callbacks we just have one. This is a major performance gain - around 40% on my machine for the ping pong bench.
Also in this PR is a cleanup commit for the scheduler code. Was previously up as a separate PR, but bors load + imminent merge hell led me to roll them together. Was #8549.
- Made naming schemes consistent between Option, Result and Either
- Changed Options Add implementation to work like the maybe monad (return None if any of the inputs is None)
- Removed duplicate Option::get and renamed all related functions to use the term `unwrap` instead
