override `VecDeque`'s `Iter::try_fold` #57974

llogiq · 2019-01-29T15:21:05Z

This should improve performance (wherever it is used), but I haven't found the time to benchmark it yet.

rust-highfive · 2019-01-29T15:21:18Z

r? @alexcrichton

(rust_highfive has picked a reviewer for you, use r? to override)

alexcrichton · 2019-01-29T22:07:12Z

Thanks! Can you be sure to add some tests to exercise this overriddent implementation in a few possible edge cases?

llogiq · 2019-01-29T23:11:17Z

Sure thing.

alexcrichton · 2019-01-29T23:44:03Z

@bors: r+

Thanks!

bors · 2019-01-29T23:44:04Z

📌 Commit 7e22cb2 has been approved by alexcrichton

…ichton override `VecDeque`'s `Iter::try_fold` This should improve performance (wherever it is used), but I haven't found the time to benchmark it yet.

rust-highfive · 2019-01-30T00:40:40Z

The job x86_64-gnu-llvm-6.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

travis_time:end:0f450735:start=1548803812323085264,finish=1548803885287012601,duration=72963927337
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
Setting environment variables from .travis.yml
$ export IMAGE=x86_64-gnu-llvm-6.0
---
travis_time:start:test_debuginfo
Check compiletest suite=debuginfo mode=debuginfo-both (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[01:14:33] 
[01:14:33] running 119 tests
[01:14:58] .iiiii...i.....i..i...i..i.i..i.ii...i.....i..i....i..........iiii..........i...ii...i.......ii.i.i. 100/119
[01:15:03] i......iii.i.....ii
[01:15:03] 
[01:15:03]  finished in 29.242
[01:15:03] travis_fold:end:test_debuginfo

---
[01:22:06]    Compiling alloc v0.0.0 (/checkout/src/liballoc)
[01:22:15] error[E0382]: use of moved value: `v`
[01:22:15]     --> src/liballoc/../liballoc/tests/vec_deque.rs:1466:21
[01:22:15]      |
[01:22:15] 1466 |             let r = v[n];
[01:22:15]      |                     ^ value used here after move
[01:22:15] ...
[01:22:15] 1471 |         assert_eq!(Ok::<_, ()>(66), v.into_iter().try_fold(0, |a, b| Ok(a + b)));
[01:22:15]      |                                     - value moved here
[01:22:15]      |
[01:22:15]      = note: move occurs because `v` has type `std::collections::VecDeque<usize>`, which does not implement the `Copy` trait
[01:22:15] error[E0382]: use of moved value: `v`
[01:22:15]     --> src/liballoc/../liballoc/tests/vec_deque.rs:1467:13
[01:22:15]      |
[01:22:15]      |
[01:22:15] 1467 |             v.rotate_left(n ^ r);
[01:22:15]      |             ^ value used here after move
[01:22:15] ...
[01:22:15] 1471 |         assert_eq!(Ok::<_, ()>(66), v.into_iter().try_fold(0, |a, b| Ok(a + b)));
[01:22:15]      |                                     - value moved here
[01:22:15]      |
[01:22:15]      = note: move occurs because `v` has type `std::collections::VecDeque<usize>`, which does not implement the `Copy` trait
[01:22:15] error[E0382]: use of moved value: `v`
[01:22:15]     --> src/liballoc/../liballoc/tests/vec_deque.rs:1469:13
[01:22:15]      |
[01:22:15]      |
[01:22:15] 1469 |             v.rotate_right(n % 11);
[01:22:15]      |             ^ value used here after move
[01:22:15] 1470 |         }
[01:22:15] 1471 |         assert_eq!(Ok::<_, ()>(66), v.into_iter().try_fold(0, |a, b| Ok(a + b)));
[01:22:15]      |                                     - value moved here
[01:22:15]      |
[01:22:15]      = note: move occurs because `v` has type `std::collections::VecDeque<usize>`, which does not implement the `Copy` trait
[01:22:15] error[E0382]: use of moved value: `v`
[01:22:15]     --> src/liballoc/../liballoc/tests/vec_deque.rs:1471:37
[01:22:15]      |
[01:22:15]      |
[01:22:15] 1471 |         assert_eq!(Ok::<_, ()>(66), v.into_iter().try_fold(0, |a, b| Ok(a + b)));
[01:22:15]      |                                     ^ value moved here in previous iteration of loop
[01:22:15]      |
[01:22:15]      = note: move occurs because `v` has type `std::collections::VecDeque<usize>`, which does not implement the `Copy` trait
[01:22:15] error: aborting due to 4 previous errors
[01:22:15] 
[01:22:15] For more information about this error, try `rustc --explain E0382`.
[01:22:15] error: Could not compile `alloc`.
[01:22:15] error: Could not compile `alloc`.
[01:22:15] warning: build failed, waiting for other jobs to finish...
[01:22:20] error: build failed
[01:22:20] 
[01:22:20] 
[01:22:20] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "test" "--target" "x86_64-unknown-linux-gnu" "-j" "4" "--release" "--locked" "--color" "always" "--features" "panic-unwind backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "-p" "alloc" "--" "--quiet"
[01:22:20] 
[01:22:20] 
[01:22:20] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:22:20] Build completed unsuccessfully in 0:19:20
[01:22:20] Build completed unsuccessfully in 0:19:20
[01:22:20] make: *** [check] Error 1
[01:22:20] Makefile:48: recipe for target 'check' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:02ef8918
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Wed Jan 30 00:40:34 UTC 2019
---
travis_time:end:043f888a:start=1548808835951465266,finish=1548808835956618014,duration=5152748
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:159505c8
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:03caaf58
travis_time:start:03caaf58
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:196aa5c0
$ dmesg | grep -i kill

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

Centril · 2019-01-30T05:41:49Z

Failed in rollup, #57982 (comment).

@bors r-

llogiq · 2019-01-30T05:58:39Z

Oops, sorry about that. It was very late here when I added the tests.

alexcrichton · 2019-01-30T15:25:59Z

@bors: r+

bors · 2019-01-30T15:26:02Z

📌 Commit b062b75 has been approved by alexcrichton

bors · 2019-01-30T21:04:14Z

⌛ Testing commit b062b75 with merge 147311c...

override `VecDeque`'s `Iter::try_fold` This should improve performance (wherever it is used), but I haven't found the time to benchmark it yet.

bors · 2019-01-30T23:47:26Z

☀️ Test successful - checks-travis, status-appveyor
Approved by: alexcrichton
Pushing 147311c to master...

scottmcm

Thanks for picking this up, @llogiq!

scottmcm · 2019-01-30T23:48:39Z

src/liballoc/collections/vec_deque.rs

+    {
+        let (front, back) = RingSlices::ring_slices(self.ring, self.head, self.tail);
+        let accum = front.iter().try_fold(init, &mut f)?;
+        back.iter().try_fold(accum, &mut f)


I'm concerned about this -- if it short-circuits it's not going to resume from the correct place, since it's try_folding on slice iterators and not updating the state of the self iterator.

I'd like to see a test like this one:

rust/src/libcore/tests/iter.rs

Lines 1990 to 1993 in 7164a9f

let a = [10, 20, 30, 40, 100, 60, 70, 80, 90];

let mut iter = a.iter().rev();

assert_eq!(iter.try_fold(0_i8, |acc, &x| acc.checked_add(x)), None);

assert_eq!(iter.next(), Some(&70));

scottmcm · 2019-01-30T23:50:29Z

Oh, oops, apparently I'm late to this :/

Centril · 2019-01-30T23:55:20Z

Oh, oops, apparently I'm late to this :/

There's plenty of time to revert if that's necessary. :)

llogiq · 2019-01-31T05:25:55Z

You're right, @scottmcm. I'll do a follow-up PR to rectify this.

scottmcm · 2019-01-31T05:33:37Z

Thanks, @llogiq!

(As an aside, while you're at it, consider overriding try_rfold too.)

llogiq · 2019-01-31T06:57:57Z

I'm a bit unsure how to best proceed: Should I try to reinstate the pointer from the slice after the iteration? Or better change the iterator wholesale to a Chain-Wrapper?

rust-highfive assigned alexcrichton Jan 29, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 29, 2019

llogiq force-pushed the vec-deque-try-fold branch from c86e77b to 7e22cb2 Compare January 29, 2019 23:10

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 29, 2019

Centril mentioned this pull request Jan 30, 2019

Rollup of 4 pull requests #57982

Closed

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jan 30, 2019

llogiq force-pushed the vec-deque-try-fold branch from 7e22cb2 to b472a1a Compare January 30, 2019 08:08

override VecDeque's Iter::try_fold

b062b75

llogiq force-pushed the vec-deque-try-fold branch from b472a1a to b062b75 Compare January 30, 2019 08:11

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 30, 2019

bors added a commit that referenced this pull request Jan 30, 2019

Auto merge of #57974 - llogiq:vec-deque-try-fold, r=alexcrichton

147311c

override `VecDeque`'s `Iter::try_fold` This should improve performance (wherever it is used), but I haven't found the time to benchmark it yet.

bors merged commit b062b75 into rust-lang:master Jan 30, 2019

bors mentioned this pull request Jan 30, 2019

[WIP] Calculate capacity when collecting into Option and Result #52910

Closed

scottmcm reviewed Jan 30, 2019

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llogiq deleted the vec-deque-try-fold branch January 31, 2019 05:44

scottmcm mentioned this pull request Feb 3, 2019

RangeInclusive internal iteration performance improvement. #58122

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override `VecDeque`'s `Iter::try_fold` #57974

override `VecDeque`'s `Iter::try_fold` #57974

llogiq commented Jan 29, 2019 •

edited by killercup

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llogiq commented Jan 31, 2019

	let a = [10, 20, 30, 40, 100, 60, 70, 80, 90];
	let mut iter = a.iter().rev();
	assert_eq!(iter.try_fold(0_i8, \|acc, &x\| acc.checked_add(x)), None);
	assert_eq!(iter.next(), Some(&70));

override VecDeque's Iter::try_fold #57974

override VecDeque's Iter::try_fold #57974

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override `VecDeque`'s `Iter::try_fold` #57974

override `VecDeque`'s `Iter::try_fold` #57974

llogiq commented Jan 29, 2019 •

edited by killercup

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