Currently if a print happens while a thread is being torn down it may cause a
panic if the LOCAL_STDOUT TLS slot has been destroyed by that point. This adds a
guard to check and prints to the process stdout if that's the case (as we do for
if the slot is already borrowed).
Closes#29488
These two commits do a few things:
1. reformat to 80 cols
2. use the reference-style links where appropriate for improved in-source readability
3. adds a few links, tweaks a couple of words, `3` -> `three`, stuff like that
While the diff is big due to these edits, there's no significant content change.
r? @brson
Before this patch `reserve` function allocated twice as requested
amount elements (not twice as capacity). It leaded to unnecessary
excessive memory usage in scenarios like this:
```
let mut v = Vec::new();
v.push(17);
v.extend(0..10);
println!("{}", v.capacity());
```
`Vec` allocated 22 elements, while it could allocate just 11.
`reserve` function must have a property of keeping `push` operation
cost (which calls `reserve`) `O(1)`. To achieve this `reserve` must
exponentialy grow its capacity when it does reallocation.
There's better strategy to implement `reserve`:
```
let new_capacity = max(current_capacity * 2, requested_capacity);
```
This strategy still guarantees that capacity grows at `O(1)` with
`reserve`, and fixes the issue with `extend`.
Patch imlpements this strategy.
Before this patch `reserve` function allocated twice as requested
amount elements (not twice as capacity). It leaded to unnecessary
excessive memory usage in scenarios like this:
```
let mut v = Vec::new();
v.push(17);
v.extend(0..10);
println!("{}", v.capacity());
```
`Vec` allocated 22 elements, while it could allocate just 11.
`reserve` function must have a property of keeping `push` operation
cost (which calls `reserve`) `O(1)`. To achieve this `reserve` must
exponentialy grow its capacity when it does reallocation.
There's better strategy to implement `reserve`:
```
let new_capacity = max(current_capacity * 2, requested_capacity);
```
This strategy still guarantees that capacity grows at `O(1)` with
`reserve`, and fixes the issue with `extend`.
Patch imlpements this strategy.
This documentation confused me when trying to use truncate on a project. Originally, it was unclear whether truncate removed the last `len` elements, or whether it cut down the vector to be exactly `len` elements long. The example was also ambiguous.
This fixes#29048 (though I think adding better transactional support would be a better fix for that issue, but that is more difficult). It also simplifies region inference and changes the model to a pure data flow one, as discussed in [this internals thread](https://internals.rust-lang.org/t/rough-thoughts-on-the-impl-of-region-inference-mir-etc/2800). I am not 100% sure though if this PR is the right thing to do -- or at least maybe not at this moment, so thoughts on that would be appreciated.
r? @pnkfelix
cc @arielb1
This is two sentences that have been comma spliced, and should
be split with a full stop. (This error made me stop and re-read,
and I submit this as an actual improvement to readability, not
as a grammar weird-o!)
This helps for the case where a match, such as below:
```rust
let foo = match foo {
Some(x) => x,
None => 0
};
```
gets refactored to no longer need the match, but the match keyword has been left accidentally:
```rust
let foo = match foo.unwrap_or(0);
```
This can be hard to spot as the expression grows more complex.
r? @alexcrichton
This documentation confused me when trying to use truncate on a project. Originally, it was unclear whether truncate removed the last `len` elements, or whether it cut down the vector to be exactly `len` elements long. The example was also ambiguous.
This is two sentences that have been comma spliced, and should
be split with a full stop. (This error made me stop and re-read,
and I submit this as an actual improvement to readability, not
as a grammar weird-o!)
I put the reference under the function return operator `->` rather than near the suggested `!` operators as I thought it was more relevant there.
Resolves#29431
…m message
I recently discovered that this is not mentioned in the docs, only in
the examples, and it's not evident for people coming from C++
r? @steveklabnik
Alex Crichton
bors
Ms2ger
Steven Fackler
Vadim Petrochenkov
Steve Klabnik
Stepan Koltsov
Andrew Paseltiner
Alexis Beingessner
pierzchalski
Igor Shuvalov
Tshepang Lekhonkhobe
Brian Anderson
Simon Sapin
Ivan Ivaschenko
Cameron Sun
Ricardo Signes