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2023-02-10math/rand: fix typo in Seed deprecation commentValentin Deleplace
Change-Id: I37a9e4362953a711840087e1b7b8d7a25f1a83b7 Reviewed-on: https://go-review.googlesource.com/c/go/+/467275 Reviewed-by: Russ Cox <rsc@golang.org> TryBot-Bypass: Russ Cox <rsc@golang.org> Auto-Submit: Russ Cox <rsc@golang.org>
2023-02-09math/rand: rewrite the math/rand package comment to say what it's good forRob Pike
It currently says only what it wasn't good for, which is not helpful. Change-Id: I468c7f385c14eaca99788a94d53c30b729ed0944 Reviewed-on: https://go-review.googlesource.com/c/go/+/466276 Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@google.com> Run-TryBot: Ian Lance Taylor <iant@google.com>
2023-02-07math/rand: use fastrand64 if possibleIan Lance Taylor
Now that the top-level math/rand functions are auto-seeded by default (issue #54880), use the runtime fastrand64 function when 1) Seed has not been called; 2) the GODEBUG randautoseed=0 is not used. The benchmarks run quickly and are relatively noisy, but they show significant improvements for parallel calls to the top-level functions. goos: linux goarch: amd64 pkg: math/rand cpu: 11th Gen Intel(R) Core(TM) i7-11850H @ 2.50GHz │ /tmp/foo.1 │ /tmp/foo.2 │ │ sec/op │ sec/op vs base │ Int63Threadsafe-16 11.605n ± 1% 3.094n ± 1% -73.34% (p=0.000 n=10) Int63ThreadsafeParallel-16 67.8350n ± 2% 0.4000n ± 1% -99.41% (p=0.000 n=10) Int63Unthreadsafe-16 1.947n ± 3% 1.924n ± 2% ~ (p=0.189 n=10) Intn1000-16 4.295n ± 2% 4.287n ± 3% ~ (p=0.517 n=10) Int63n1000-16 4.379n ± 0% 4.192n ± 2% -4.27% (p=0.000 n=10) Int31n1000-16 3.641n ± 3% 3.506n ± 0% -3.69% (p=0.000 n=10) Float32-16 3.330n ± 7% 3.250n ± 2% -2.40% (p=0.017 n=10) Float64-16 2.194n ± 6% 2.056n ± 4% -6.31% (p=0.004 n=10) Perm3-16 43.39n ± 9% 38.28n ± 12% -11.77% (p=0.015 n=10) Perm30-16 324.4n ± 6% 315.9n ± 19% ~ (p=0.315 n=10) Perm30ViaShuffle-16 175.4n ± 1% 143.6n ± 2% -18.15% (p=0.000 n=10) ShuffleOverhead-16 223.4n ± 2% 215.8n ± 1% -3.38% (p=0.000 n=10) Read3-16 5.428n ± 3% 5.406n ± 2% ~ (p=0.780 n=10) Read64-16 41.55n ± 5% 40.14n ± 3% -3.38% (p=0.000 n=10) Read1000-16 622.9n ± 4% 594.9n ± 2% -4.50% (p=0.000 n=10) Concurrent-16 136.300n ± 2% 4.647n ± 26% -96.59% (p=0.000 n=10) geomean 23.40n 12.15n -48.08% Fixes #49892 Change-Id: Iba75b326145512ab0b7ece233b98ac3d4e1fb504 Reviewed-on: https://go-review.googlesource.com/c/go/+/465037 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Russ Cox <rsc@golang.org> Auto-Submit: Ian Lance Taylor <iant@google.com>
2023-01-19internal/godebug: export non-default-behavior counters in runtime/metricsRuss Cox
Allow GODEBUG users to report how many times a setting resulted in non-default behavior. Record non-default-behaviors for all existing GODEBUGs. Also rework tests to ensure that runtime is in sync with runtime/metrics.All, and generate docs mechanically from metrics.All. For #56986. Change-Id: Iefa1213e2a5c3f19ea16cd53298c487952ef05a4 Reviewed-on: https://go-review.googlesource.com/c/go/+/453618 TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com>
2022-11-16math/rand: deprecate SeedRuss Cox
Programs that call Seed and then expect a specific sequence of results from the global random source (using functions such as Int) can be broken when a dependency changes how much it consumes from the global random source. To avoid such breakages, programs that need a specific result sequence should use NewRand(NewSource(seed)) to obtain a random generator that other packages cannot access. Fixes #56319. Change-Id: Idac33991b719d2c71f109f51dacb3467a649e01e Reviewed-on: https://go-review.googlesource.com/c/go/+/451375 Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Russ Cox <rsc@golang.org>
2022-11-14internal/godebug: define more efficient APIRuss Cox
We have been expanding our use of GODEBUG for compatibility, and the current implementation forces a tradeoff between freshness and efficiency. It parses the environment variable in full each time it is called, which is expensive. But if clients cache the result, they won't respond to run-time GODEBUG changes, as happened with x509sha1 (#56436). This CL changes the GODEBUG API to provide efficient, up-to-date results. Instead of a single Get function, New returns a *godebug.Setting that itself has a Get method. Clients can save the result of New, which is no more expensive than errors.New, in a global variable, and then call that variable's Get method to get the value. Get costs only two atomic loads in the case where the variable hasn't changed since the last call. Unfortunately, these changes do require importing sync from godebug, which will mean that sync itself will never be able to use a GODEBUG setting. That doesn't seem like such a hardship. If it was really necessary, the runtime could pass a setting to package sync itself at startup, with the caveat that that setting, like the ones used by runtime itself, would not respond to run-time GODEBUG changes. Change-Id: I99a3acfa24fb2a692610af26a5d14bbc62c966ac Reviewed-on: https://go-review.googlesource.com/c/go/+/449504 Run-TryBot: Russ Cox <rsc@golang.org> Auto-Submit: Russ Cox <rsc@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
2022-10-27math/rand: deprecate Readhopehook
For #20661. Change-Id: I1e638cb619e643eadc210d71f92bd1af7bafc912 Reviewed-on: https://go-review.googlesource.com/c/go/+/436955 Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: hopehook <hopehook@golangcn.org> Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Robert Griesemer <gri@google.com> Run-TryBot: Ian Lance Taylor <iant@google.com>
2022-10-26all: remove uses of rand.SeedRuss Cox
As of CL 443058, rand.Seed is not necessary to call, nor is it a particular good idea. For #54880. Change-Id: If9d70763622c09008599db8c97a90fcbe285c6f8 Reviewed-on: https://go-review.googlesource.com/c/go/+/445395 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Russ Cox <rsc@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com>
2022-10-25math/rand: auto-seed global sourceRuss Cox
Implement proposal #54880, to automatically seed the global source. The justification for this not being a breaking change is that any use of the global source in a package's init function or exported API clearly must be valid - that is, if a package changes how much randomness it consumes at init time or in an exported API, that clearly isn't the kind of breaking change that requires issuing a v2 of that package. That kind of per-package change in the position of the global source is indistinguishable from seeding the global source differently. So if the per-package change is valid, so is auto-seeding. And then, of course, auto-seeding means that packages will be far less likely to depend on the specific results of the global source and therefore not break when those kinds of per-package changes happen in the future. Seed(1) can be called in programs that need the old sequence from the global source and want to restore the old behavior. Of course, those programs will still be broken by the per-package changes just described, and it would be better for them to allocate local sources rather than continue to use the global one. Fixes #54880. Change-Id: Ib9dc3307b97f7a45587a9cc50d81f919d3edc7ae Reviewed-on: https://go-review.googlesource.com/c/go/+/443058 Reviewed-by: Austin Clements <austin@google.com> Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Russ Cox <rsc@golang.org>
2022-10-18math/rand: refactor to delay allocation of global sourceRuss Cox
This sets up for delaying the decision of which seed to use, but this CL still keeps the original global Seed(1) semantics. Preparation for #54880. Change-Id: Ibfa9d50ec9023aa755a83852e55168fa7d24b115 Reviewed-on: https://go-review.googlesource.com/c/go/+/443057 Auto-Submit: Russ Cox <rsc@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Russ Cox <rsc@golang.org>
2022-09-02math/rand: document that Source returned by NewSource implements Source64Jonathan FOng
Fixes #44488 Change-Id: I570950799788678b9dc6e9ddad894973b4611e09 Reviewed-on: https://go-review.googlesource.com/c/go/+/425974 Reviewed-by: Daniel Martí <mvdan@mvdan.cc> Reviewed-by: Joseph Tsai <joetsai@digital-static.net> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Joseph Tsai <joetsai@digital-static.net> Reviewed-by: Heschi Kreinick <heschi@google.com> Reviewed-by: David Chase <drchase@google.com>
2022-04-11all: gofmt main repoRuss Cox
[This CL is part of a sequence implementing the proposal #51082. The design doc is at https://go.dev/s/godocfmt-design.] Run the updated gofmt, which reformats doc comments, on the main repository. Vendored files are excluded. For #51082. Change-Id: I7332f099b60f716295fb34719c98c04eb1a85407 Reviewed-on: https://go-review.googlesource.com/c/go/+/384268 Reviewed-by: Jonathan Amsterdam <jba@google.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2022-04-01all: remove trailing blank doc comment linesRuss Cox
A future change to gofmt will rewrite // Doc comment. // func f() to // Doc comment. func f() Apply that change preemptively to all doc comments. For #51082. Change-Id: I4023e16cfb0729b64a8590f071cd92f17343081d Reviewed-on: https://go-review.googlesource.com/c/go/+/384259 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org>
2021-12-13all: gofmt -w -r 'interface{} -> any' srcRuss Cox
And then revert the bootstrap cmd directories and certain testdata. And adjust tests as needed. Not reverting the changes in std that are bootstrapped, because some of those changes would appear in API docs, and we want to use any consistently. Instead, rewrite 'any' to 'interface{}' in cmd/dist for those directories when preparing the bootstrap copy. A few files changed as a result of running gofmt -w not because of interface{} -> any but because they hadn't been updated for the new //go:build lines. Fixes #49884. Change-Id: Ie8045cba995f65bd79c694ec77a1b3d1fe01bb09 Reviewed-on: https://go-review.googlesource.com/c/go/+/368254 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org>
2021-10-28all: go fix -fix=buildtag std cmd (except for bootstrap deps, vendor)Russ Cox
When these packages are released as part of Go 1.18, Go 1.16 will no longer be supported, so we can remove the +build tags in these files. Ran go fix -fix=buildtag std cmd and then reverted the bootstrapDirs as defined in src/cmd/dist/buildtool.go, which need to continue to build with Go 1.4 for now. Also reverted src/vendor and src/cmd/vendor, which will need to be updated in their own repos first. Manual changes in runtime/pprof/mprof_test.go to adjust line numbers. For #41184. Change-Id: Ic0f93f7091295b6abc76ed5cd6e6746e1280861e Reviewed-on: https://go-review.googlesource.com/c/go/+/344955 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Bryan C. Mills <bcmills@google.com>
2021-06-16math/rand: mention half-open intervals explicitlyRuss Cox
If someone sees "in [0,n)" it might look like a typo. Saying "in the half-open interval [0,n)" will give people something to search the web for (half-open interval). Change-Id: I3c343f0a7171891e106e709ca77ab9db5daa5c84 Reviewed-on: https://go-review.googlesource.com/c/go/+/328210 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> TryBot-Result: Go Bot <gobot@golang.org>
2021-04-28testing: add -shuffle=off|on|N to alter the execution order of tests and ↵Paschalis Tsilias
benchmarks This CL adds a new flag to the testing package and the go test command which randomizes the execution order for tests and benchmarks. This can be useful for identifying unwanted dependencies between test or benchmark functions. The flag is off by default. If `-shuffle` is set to `on` then the system clock will be used as the seed value. If `-shuffle` is set to an integer N, then N will be used as the seed value. In both cases, the seed will be reported for failed runs so that they can reproduced later on. Fixes #28592 Change-Id: I62e7dfae5f63f97a0cbd7830ea844d9f7beac335 Reviewed-on: https://go-review.googlesource.com/c/go/+/310033 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com> Trust: Bryan C. Mills <bcmills@google.com>
2021-04-23math/rand: make the security warning clearer and more prominentFilippo Valsorda
It is still a common misconception that math/rand can be used for security-sensitive work if seeded with crypto/rand (lazyledger/lazyledger-core#270). It can not. Change-Id: I8598c352d1750eabeada50be9976ab68cbb42cc0 Reviewed-on: https://go-review.googlesource.com/c/go/+/310350 Trust: Filippo Valsorda <filippo@golang.org> Reviewed-by: Katie Hockman <katie@golang.org> Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
2021-02-20all: go fmt std cmd (but revert vendor)Russ Cox
Make all our package sources use Go 1.17 gofmt format (adding //go:build lines). Part of //go:build change (#41184). See https://golang.org/design/draft-gobuild Change-Id: Ia0534360e4957e58cd9a18429c39d0e32a6addb4 Reviewed-on: https://go-review.googlesource.com/c/go/+/294430 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2021-01-04math/rand: fix typo in commentToasa
Change-Id: I57fbabf272bdfd61918db155ee6f7091f18e5979 GitHub-Last-Rev: e138804b1ab8086b3742861873b077d6cca8108a GitHub-Pull-Request: golang/go#43495 Reviewed-on: https://go-review.googlesource.com/c/go/+/281373 Reviewed-by: Ian Lance Taylor <iant@golang.org> Trust: Alberto Donizetti <alb.donizetti@gmail.com>
2019-12-04math/rand: update comment to avoid use of ^ for exponentiationBrad Fitzpatrick
Fixes #35920 Change-Id: I1a4d26c5f7f3fbd4de13fc337de482667d83c47f Reviewed-on: https://go-review.googlesource.com/c/go/+/209758 Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>
2019-09-30math/rand: devirtualize interface call in ReadCarlo Alberto Ferraris
This allows to inline the common case in which the Source is a rngSource. On linux/amd64 in a VM: name old time/op new time/op delta Read3-4 33.8ns ± 8% 18.5ns ± 8% -45.38% (p=0.000 n=10+10) Read64-4 371ns ± 8% 70ns ± 7% -81.00% (p=0.000 n=10+10) Read1000-4 5.33µs ± 5% 0.86µs ± 3% -83.85% (p=0.000 n=9+9) Change-Id: Ibf47b0e9ecdfe62ffcb66d6a92f191800bdc740e Reviewed-on: https://go-review.googlesource.com/c/go/+/191539 Reviewed-by: Daniel Martí <mvdan@mvdan.cc> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-09-29math/rand: devirtualize interface in lockedSourceCarlo Alberto Ferraris
Avoid interface calls, enable inlining, and store the rngSource close to the Mutex to exploit better memory locality. Also add a benchmark to properly measure the threadsafe nature of globalRand. On a linux/amd64 VM: name old time/op new time/op delta Int63Threadsafe-4 36.4ns ±12% 20.6ns ±11% -43.52% (p=0.000 n=30+30) Int63ThreadsafeParallel-4 79.3ns ± 5% 56.5ns ± 5% -28.69% (p=0.000 n=29+30) Change-Id: I6ab912c1a1e9afc7bacd8e72c82d4d50d546a510 Reviewed-on: https://go-review.googlesource.com/c/go/+/191538 Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com> Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-05-22all: shorten some testsRuss Cox
Shorten some of the longest tests that run during all.bash. Removes 7r 50u 21s from all.bash. After this change, all.bash is under 5 minutes again on my laptop. For #26473. Change-Id: Ie0460aa935808d65460408feaed210fbaa1d5d79 Reviewed-on: https://go-review.googlesource.com/c/go/+/177559 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2019-03-25math/rand: add example for Intn funcVladimir Kovpak
Change-Id: I831ffb5c3fa2872d71def8d8461f0adbd4ae2c1a GitHub-Last-Rev: 2adfcd2d5a592ef4c63da781240a391da89b5d9e GitHub-Pull-Request: golang/go#30706 Reviewed-on: https://go-review.googlesource.com/c/go/+/166426 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2018-08-03math/rand: improve package documentationBenjamin Cable
Notify readers that interval notation is used. Fixes: #26765 Change-Id: Id02a7fcffbf41699e85631badeee083f5d4b2201 Reviewed-on: https://go-review.googlesource.com/127549 Reviewed-by: Rob Pike <r@golang.org>
2018-06-01all: update comment URLs from HTTP to HTTPS, where possibleTim Cooper
Each URL was manually verified to ensure it did not serve up incorrect content. Change-Id: I4dc846227af95a73ee9a3074d0c379ff0fa955df Reviewed-on: https://go-review.googlesource.com/115798 Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org>
2018-05-12math/rand: clarify documentation for Seed exampleAgniva De Sarker
Fixes #25325 Change-Id: I101641be99a820722edb7272918e04e8d2e1646c Reviewed-on: https://go-review.googlesource.com/112775 Reviewed-by: Rob Pike <r@golang.org>
2018-04-16math/rand: refactor rng.goweeellz
Made constant names more idiomatic, moved some constants to function seedrand, and found better name for _M. Change-Id: I192172f398378bef486a5bbceb6ba86af48ebcc9 Reviewed-on: https://go-review.googlesource.com/107135 Reviewed-by: Daniel Martí <mvdan@mvdan.cc> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gobot Gobot <gobot@golang.org>
2018-04-04go/printer, gofmt: tuned table alignment for better resultsRobert Griesemer
The go/printer (and thus gofmt) uses a heuristic to determine whether to break alignment between elements of an expression list which is spread across multiple lines. The heuristic only kicked in if the entry sizes (character length) was above a certain threshold (20) and the ratio between the previous and current entry size was above a certain value (4). This heuristic worked reasonably most of the time, but also led to unfortunate breaks in many cases where a single entry was suddenly much smaller (or larger) then the previous one. The behavior of gofmt was sufficiently mysterious in some of these situations that many issues were filed against it. The simplest solution to address this problem is to remove the heuristic altogether and have a programmer introduce empty lines to force different alignments if it improves readability. The problem with that approach is that the places where it really matters, very long tables with many (hundreds, or more) entries, may be machine-generated and not "post-processed" by a human (e.g., unicode/utf8/tables.go). If a single one of those entries is overlong, the result would be that the alignment would force all comments or values in key:value pairs to be adjusted to that overlong value, making the table hard to read (e.g., that entry may not even be visible on screen and all other entries seem spaced out too wide). Instead, we opted for a slightly improved heuristic that behaves much better for "normal", human-written code. 1) The threshold is increased from 20 to 40. This disables the heuristic for many common cases yet even if the alignment is not "ideal", 40 is not that many characters per line with todays screens, making it very likely that the entire line remains "visible" in an editor. 2) Changed the heuristic to not simply look at the size ratio between current and previous line, but instead considering the geometric mean of the sizes of the previous (aligned) lines. This emphasizes the "overall picture" of the previous lines, rather than a single one (which might be an outlier). 3) Changed the ratio from 4 to 2.5. Now that we ignore sizes below 40, a ratio of 4 would mean that a new entry would have to be 4 times bigger (160) or smaller (10) before alignment would be broken. A ratio of 2.5 seems more sensible. Applied updated gofmt to all of src and misc. Also tested against several former issues that complained about this and verified that the output for the given examples is satisfactory (added respective test cases). Some of the files changed because they were not gofmt-ed in the first place. For #644. For #7335. For #10392. (and probably more related issues) Fixes #22852. Change-Id: I5e48b3d3b157a5cf2d649833b7297b33f43a6f6e
2018-01-04math/rand: typo fixed in documentation of seedPosPaul PISCUC
In the comment of seedPost, the word: condiiton was changed to: condition Change-Id: I8967cc0e9f5d37776bada96cc1443c8bf46e1117 Reviewed-on: https://go-review.googlesource.com/86156 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-11-16Revert "math/rand: make Perm match Shuffle"Russ Cox
This reverts CL 55972. Reason for revert: this changes Perm's behavior unnecessarily. I asked for this change originally but I now regret it. Reverting so that I don't have to justify it in Go 1.10 release notes. Edited to keep the change to rand_test.go, which seems to have been mostly unrelated. Fixes #22744. Change-Id: If8bb1bcde3ced0db2fdcd0aa65ab128613686c66 Reviewed-on: https://go-review.googlesource.com/78195 Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com> Reviewed-by: Rob Pike <r@golang.org> Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-09-14math/rand: fix comment for ShuffleBurak Guven
Shuffle panics if n < 0, not n <= 0. The comment for the (*Rand).Shuffle function is already accurate. Change-Id: I073049310bca9632e50e9ca3ff79eec402122793 Reviewed-on: https://go-review.googlesource.com/63750 Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-09-08math/rand: change http to https in commentIan Lance Taylor
Change-Id: I19c1b0e1b238dda82e69bd47459528ed06b55840 Reviewed-on: https://go-review.googlesource.com/62310 Reviewed-by: David Crawshaw <crawshaw@golang.org>
2017-09-08math/rand: make Perm match ShuffleJosh Bleecher Snyder
Perm and Shuffle are fundamentally doing the same work. This change makes Perm's algorithm match Shuffle's. In addition to allowing developers to switch more easily between the two methods, it affords a nice speed-up: name old time/op new time/op delta Perm3-8 75.7ns ± 1% 51.8ns ± 1% -31.59% (p=0.000 n=9+8) Perm30-8 610ns ± 1% 405ns ± 1% -33.67% (p=0.000 n=9+9) This change alters the output from Perm, given the same Source and seed. This is a change from Go 1.0 behavior. This necessitates updating the regression test. This also changes the number of calls made to the Source during Perm, which changes the output of the math/rand examples. This also slightly perturbs the output of Perm, nudging it out of the range currently accepted by TestUniformFactorial. However, it is complete unclear that the helpers relied on by TestUniformFactorial are correct. That is #21211. This change updates checkSimilarDistribution to respect closeEnough for standard deviations, which makes the test pass. The whole situation is muddy; see #21211 for details. There is an alternative implementation of Perm that avoids initializing m, which is more similar to the existing implementation, plus some optimizations: func (r *Rand) Perm(n int) []int { m := make([]int, n) max31 := n if n > 1<<31-1-1 { max31 = 1<<31 - 1 - 1 } i := 1 for ; i < max31; i++ { j := r.int31n(int32(i + 1)) m[i] = m[j] m[j] = i } for ; i < n; i++ { j := r.Int63n(int64(i + 1)) m[i] = m[j] m[j] = i } return m } This is a tiny bit faster than the implementation actually used in this change: name old time/op new time/op delta Perm3-8 51.8ns ± 1% 50.3ns ± 1% -2.83% (p=0.000 n=8+9) Perm30-8 405ns ± 1% 394ns ± 1% -2.66% (p=0.000 n=9+8) However, 3% in performance doesn't seem worth having the two algorithms diverge, nor the reduced readability of this alternative. Updates #16213. Change-Id: I11a7441ff8837ee9c241b4c88f7aa905348be781 Reviewed-on: https://go-review.googlesource.com/55972 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Rob Pike <r@golang.org>
2017-09-08math/rand: add ShuffleJosh Bleecher Snyder
Shuffle uses the Fisher-Yates algorithm. Since this is new API, it affords us the opportunity to use a much faster Int31n implementation that mostly avoids division. As a result, BenchmarkPerm30ViaShuffle is about 30% faster than BenchmarkPerm30, despite requiring a separate initialization loop and using function calls to swap elements. Fixes #20480 Updates #16213 Updates #21211 Change-Id: Ib8956c4bebed9d84f193eb98282ec16ee7c2b2d5 Reviewed-on: https://go-review.googlesource.com/51891 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-08-08math/rand: use t.Helper in testsJosh Bleecher Snyder
Change-Id: Iece39e6412c0f6c63f563eed1621b8cca02de835 Reviewed-on: https://go-review.googlesource.com/51890 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Avelino <t@avelino.xxx> TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-08-08math/rand: fix uniform distribution stddev in testsJosh Bleecher Snyder
The standard deviation of a uniform distribution is size / √12. The size of the interval [0, 255] is 256, not 255. While we're here, simplify the expression. The tests previously passed only because the error margin was large enough. Sample observed standard deviations while running tests: 73.7893634666819 73.9221651548294 73.8077961697150 73.9084236069471 73.8968446814785 73.8684209136244 73.9774618960282 73.9523483202549 255 / √12 == 73.6121593216772 256 / √12 == 73.9008344562721 Change-Id: I7bc6cdc11e5d098951f2f2133036f62489275979 Reviewed-on: https://go-review.googlesource.com/51310 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-07-15math/rand: add concurrency warning to overview commentAditya Mukerjee
Change-Id: I52efa7aa72a23256e5ca56470ffeba975ed8f739 Reviewed-on: https://go-review.googlesource.com/48760 Reviewed-by: Bryan Mills <bcmills@google.com>
2016-11-23math/rand: export Source64, mainly for documentation valueRuss Cox
There is some code value too: types intending to implement Source64 can write a conversion confirming that. For #4254 and the Go 1.8 release notes. Change-Id: I7fc350a84f3a963e4dab317ad228fa340dda5c66 Reviewed-on: https://go-review.googlesource.com/33456 Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-11-16math/rand: make floating point tests shorter on mips and mipsleBrad Fitzpatrick
Like GOARM=5 does. Fixes #17944 Change-Id: Ica2a54a90fbd4a29471d1c6009ace2fcc5e82a73 Reviewed-on: https://go-review.googlesource.com/33326 Reviewed-by: Cherry Zhang <cherryyz@google.com>
2016-10-03math/rand: add Rand.Uint64Florian Uekermann
This adds Uint64 methods to Rand and rngSource. Rand.Uint64 uses Source.Uint64 directly if it is present. rngSource.Uint64 provides access to all 64 bits generated by the underlying ALFG. To ensure high seed quality a 64th bit has been added to all elements of the array of "cooked" random numbers that are used for seeding. gen_cooked.go generates both the 63 bit and 64 bit array. Fixes #4254 Change-Id: I22855618ac69abae3d2799b3e7e59996d4c5a4b1 Reviewed-on: https://go-review.googlesource.com/27253 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-09-02math/rand: document that NewSource sources raceDavid Glasser
While it was previously explicitly documented that "the default Source" is safe for concurrent use, a careless reader can interpret that as meaning "the implementation of the Source interface created by functions in this package" rather than "the default shared Source used by top-level functions". Be explicit that the Source returned by NewSource is not safe for use by multiple goroutines. Fixes #3611. Change-Id: Iae4bc04c3887ad6e2491e36e38feda40324022c5 Reviewed-on: https://go-review.googlesource.com/25501 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-08-17math/rand: Document origin of cooked pseudo-random numbersFlorian Uekermann
The Source provided by math/rand relies on an array of cooked pseudo-random 63bit integers for seeding. The origin of these numbers is undocumented. Add a standalone program in math/rand folder that generates the 63bit integer array as well as a 64bit version supporting extension of the Source to 64bit pseudo-random number generation while maintaining the current sequence in the lower 63bit. The code is largely based on the initial implementation of the random number generator in the go repository by Ken Thompson (revision 399). Change-Id: Ib4192aea8127595027116a0f5a7be53f11dc110b Reviewed-on: https://go-review.googlesource.com/22230 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-07-11math/rand: fix raciness in Rand.ReadIan Lance Taylor
There are no synchronization points protecting the readVal and readPos variables. This leads to a race when Read is called concurrently. Fix this by adding methods to lockedSource, which is the case where a race matters. Fixes #16308. Change-Id: Ic028909955700906b2d71e5c37c02da21b0f4ad9 Reviewed-on: https://go-review.googlesource.com/24852 Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2016-06-27math/rand: fix io.Reader implementationDmitri Popov
Do not throw away the rest of Int63 value used for generation random bytes. Save it in Rand struct and re-use during the next Read call. Fixes #16124 Change-Id: Ic70bd80c3c3a6590e60ac615e8b3c2324589bea3 Reviewed-on: https://go-review.googlesource.com/24251 Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com> Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-06-26math/rand: fix comment about bits of seed used by the default SourceKonstantin Shaposhnikov
Fixes #15788 Change-Id: I5a1fd1e5992f1c16cf8d8437d742bf02e1653b9c Reviewed-on: https://go-review.googlesource.com/23461 Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-05-24math/rand: Doc fix for how many bits Seed usesJeff R. Allen
Document the fact that the default Source uses only the bottom 31 bits of the given seed. Fixes #15788 Change-Id: If20d1ec44a55c793a4a0a388f84b9392c2102bd1 Reviewed-on: https://go-review.googlesource.com/23352 Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-03-09testing: implement 'Unordered Output' in Examples.Brady Catherman
Adds a type of output to Examples that allows tests to have unordered output. This is intended to help clarify when the output of a command will produce a fixed return, but that return might not be in an constant order. Examples where this is useful would be documenting the rand.Perm() call, or perhaps the (os.File).Readdir(), both of which can not guarantee order, but can guarantee the elements of the output. Fixes #10149 Change-Id: Iaf0cf1580b686afebd79718ed67ea744f5ed9fc5 Reviewed-on: https://go-review.googlesource.com/19280 Reviewed-by: Andrew Gerrand <adg@golang.org>
2016-03-01all: make copyright headers consistent with one space after periodBrad Fitzpatrick
This is a subset of https://golang.org/cl/20022 with only the copyright header lines, so the next CL will be smaller and more reviewable. Go policy has been single space after periods in comments for some time. The copyright header template at: https://golang.org/doc/contribute.html#copyright also uses a single space. Make them all consistent. Change-Id: Icc26c6b8495c3820da6b171ca96a74701b4a01b0 Reviewed-on: https://go-review.googlesource.com/20111 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
generated by cgit v1.3 (git 2.53.0) at 2026-04-15 12:36:50 +0000