Similar to internal/lazyregexp, this will allow removing unnecessary
work from init functions with trivial refactors, thanks to sync.Once.
Copy the structure. The only major difference is that a template also
carries a name.
For #29382.
Change-Id: I65d096dc2e2072b310bf59a814cd62669856b5b5
Reviewed-on: https://go-review.googlesource.com/c/164337
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
These regexes are all related to commands like get and build, so they're
unnecessary for simpler commands like env. In particular, we need env to
be fast, since libraries like go/packages call it early and often. Some
external Go tools are interactive, so milliseconds matter.
lazyregexp eagerly compiles the patterns when running from within a test
binary, so there's no longer any need to do that as part of non-test
binaries.
Picking up the low-hanging fruit spotted by 'perf record' shaves off
well over a full millisecond off the benchmark on my laptop:
name old time/op new time/op delta
ExecGoEnv-8 4.92ms ± 1% 3.81ms ± 0% -22.52% (p=0.004 n=6+5)
This CL required adding a few more methods to the lazy regexp wrapper.
Updates #29382.
Change-Id: I22417ab6258f7437a2feea0d25ceb2bb4d735a15
Reviewed-on: https://go-review.googlesource.com/c/155540
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This was implemented as part of go/doc, but it's going to be useful in
other packages. In particular, many packages under cmd/go like web and
vcs make somewhat heavy use of global regexes, which add a non-trivial
amount of init work to the cmd/go program.
A lazy wrapper around regexp.Regexp will make it trivial to get rid of
the extra cost with a trivial refactor, so make it possible for other
packages in the repository to make use of it. While naming the package,
give the members better names, such as lazyregexp.New and
lazyregexp.Regexp.
We're also considering adding some form of a lazy API to the public
regexp package, so this internal package will allow us to get some
initial experience across std and cmd.
For #29382.
Change-Id: I30b0e72871d5267c309786f95f4cb15c68b2393d
Reviewed-on: https://go-review.googlesource.com/c/164040
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
