Re: [gentoo-dev] [PATCH] qmail.eclass: simplify is_prime()
Hi,
On Thu, Jun 17, 2021 at 05:42:12PM +, Peter Stuge wrote:
> Rolf Eike Beer wrote:
> > The previous algorithm would scan for all primes for a given number,
> > which takes needlessly long.
>
> Please also mention how this caused a problem for you in the commit
> message, to help us understand why you're proposing to change this.
>
>
> > +++ b/eclass/qmail.eclass
> > -# @FUNCTION: is_prima
> > +# @FUNCTION: is_prime
> > # @USAGE:
> > # @DESCRIPTION:
> > # Checks wether a number is a prime number
>
> Maybe name the algorithm? Looks like an optimization of the sieve of
> Eratosthenes?
>
>
> > is_prime() {
> > local number=${1} i
> > - for i in $(primes ${number} ${number})
> > +
> > + if [[ $[number % 2] == 0 ]]; then
> > + return 1
> > + fi
>
> While 2 itself is prime the above returns 1 for any even number.
There's actually a much simpler solution to this:
$ is_prime() { test $(factor $1 | cut -d: -f2 | wc -w) == 1; }
$ for n in $(seq 0 10); do is_prime $n && echo $n is prime; done
2 is prime
3 is prime
5 is prime
7 is prime
$ time factor 20187319083467888113
20187319083467888113: 20187319083467888113
0.00
Cheers,
-Guilherme
Re: [gentoo-dev] [PATCH] qmail.eclass: simplify is_prime()
Rolf Eike Beer wrote:
> The previous algorithm would scan for all primes for a given number,
> which takes needlessly long.
Please also mention how this caused a problem for you in the commit
message, to help us understand why you're proposing to change this.
> +++ b/eclass/qmail.eclass
> -# @FUNCTION: is_prima
> +# @FUNCTION: is_prime
> # @USAGE:
> # @DESCRIPTION:
> # Checks wether a number is a prime number
Maybe name the algorithm? Looks like an optimization of the sieve of
Eratosthenes?
> is_prime() {
> local number=${1} i
> - for i in $(primes ${number} ${number})
> +
> + if [[ $[number % 2] == 0 ]]; then
> + return 1
> + fi
While 2 itself is prime the above returns 1 for any even number.
> + for ((i = 3; i * i <= number; i += 2))
> do
> - [[ ${i} == ${number} ]] && return 0
> + if [[ $[number % i ] == 0 ]]; then
An inconsistent space after "% i" here. I don't know what style is correct.
//Peter
[gentoo-dev] [PATCH] qmail.eclass: simplify is_prime()
The previous algorithm would scan for all primes for a given number, which
takes needlessly long.
Signed-off-by: Rolf Eike Beer
---
eclass/qmail.eclass | 45 -
1 file changed, 12 insertions(+), 33 deletions(-)
diff --git a/eclass/qmail.eclass b/eclass/qmail.eclass
index f42f0491515..aaec205a6bd 100644
--- a/eclass/qmail.eclass
+++ b/eclass/qmail.eclass
@@ -20,46 +20,25 @@ GENQMAIL_S="${WORKDIR}"/genqmail-${GENQMAIL_PV}
QMAIL_SPP_F=qmail-spp-${QMAIL_SPP_PV}.tar.gz
QMAIL_SPP_S="${WORKDIR}"/qmail-spp-${QMAIL_SPP_PV}
-# @FUNCTION: primes
-# @USAGE:
-# @DESCRIPTION:
-# Prints a list of primes between min and max inclusive
-# Note: this functions gets very slow when used with large numbers.
-primes() {
- local min=${1} max=${2}
- local result= primelist=2 i p
-
- [[ ${min} -le 2 ]] && result="${result} 2"
-
- for ((i = 3; i <= max; i += 2))
- do
- for p in ${primelist}
- do
- [[ $[i % p] == 0 || $[p * p] -gt ${i} ]] && \
- break
- done
- if [[ $[i % p] != 0 ]]
- then
- primelist="${primelist} ${i}"
- [[ ${i} -ge ${min} ]] && \
- result="${result} ${i}"
- fi
- done
-
- echo ${result}
-}
-
-# @FUNCTION: is_prima
+# @FUNCTION: is_prime
# @USAGE:
# @DESCRIPTION:
# Checks wether a number is a prime number
is_prime() {
local number=${1} i
- for i in $(primes ${number} ${number})
+
+ if [[ $[number % 2] == 0 ]]; then
+ return 1
+ fi
+
+ for ((i = 3; i * i <= number; i += 2))
do
- [[ ${i} == ${number} ]] && return 0
+ if [[ $[number % i ] == 0 ]]; then
+ return 1
+ fi
done
- return 1
+
+ return 0
}
dospp() {
--
2.26.2
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Re: [gentoo-dev] [PATCH] fcaps.eclass: support EAPI 8
On Thu, Jun 17, 2021 at 7:02 AM Ulrich Mueller wrote:
> > On Thu, 17 Jun 2021, Michał Górny wrote:
> > On Thu, 2021-06-17 at 12:10 +0200, Ulrich Mueller wrote:
> >> > > > > > On Thu, 17 Jun 2021, David Michael wrote:
> >> > @@ -33,15 +34,12 @@ _FCAPS_ECLASS=1
> >> >
> >> > IUSE="+filecaps"
> >> >
> >> > -# Since it is needed in pkg_postinst() it must be in RDEPEND
> >> > +# Since it is needed in pkg_postinst() it must be in IDEPEND
> >> > case "${EAPI:-0}" in
> >> > - [0-6])
> >> > - RDEPEND="filecaps? ( sys-libs/libcap )"
> >> > - ;;
> >> > - *)
> >> > - BDEPEND="filecaps? ( sys-libs/libcap )"
> >> > - RDEPEND="${BDEPEND}"
> >> > - ;;
> >> > + 7) BDEPEND="filecaps? ( sys-libs/libcap )" ;&
> >>
> >> This is ill-defined in old EAPIs (5 and before), so the case statement
> >> may fail. You cannot use ;& in global scope of an eclass.
> >>
> >> Why not just change * to 7, and add a new case for 8? It's one
> >> additional line, and IMHO would be better readable than having a
> >> fallthrough.
>
> > I've already left a comment on the PR suggesting to split it into two
> > cases: one to check for valid EAPI, the other for deps. It would be
> > cleaner IMO, as the second case would cover all future EAPIs via *,
> > and the first one would prevent the syntax error from applying to old
> > EAPIs (I've tested that).
>
> That would work too. But please add a comment making it clear that there
> is a fallthrough.
I've updated https://github.com/gentoo/gentoo/pull/21239 with this.
Thanks.
David
Re: [gentoo-dev] [PATCH] fcaps.eclass: support EAPI 8
> On Thu, 17 Jun 2021, Michał Górny wrote:
> On Thu, 2021-06-17 at 12:10 +0200, Ulrich Mueller wrote:
>> > > > > > On Thu, 17 Jun 2021, David Michael wrote:
>>
>> > @@ -33,15 +34,12 @@ _FCAPS_ECLASS=1
>> >
>> > IUSE="+filecaps"
>> >
>> > -# Since it is needed in pkg_postinst() it must be in RDEPEND
>> > +# Since it is needed in pkg_postinst() it must be in IDEPEND
>> > case "${EAPI:-0}" in
>> > - [0-6])
>> > - RDEPEND="filecaps? ( sys-libs/libcap )"
>> > - ;;
>> > - *)
>> > - BDEPEND="filecaps? ( sys-libs/libcap )"
>> > - RDEPEND="${BDEPEND}"
>> > - ;;
>> > + 7) BDEPEND="filecaps? ( sys-libs/libcap )" ;&
>>
>> This is ill-defined in old EAPIs (5 and before), so the case statement
>> may fail. You cannot use ;& in global scope of an eclass.
>>
>> Why not just change * to 7, and add a new case for 8? It's one
>> additional line, and IMHO would be better readable than having a
>> fallthrough.
> I've already left a comment on the PR suggesting to split it into two
> cases: one to check for valid EAPI, the other for deps. It would be
> cleaner IMO, as the second case would cover all future EAPIs via *,
> and the first one would prevent the syntax error from applying to old
> EAPIs (I've tested that).
That would work too. But please add a comment making it clear that there
is a fallthrough.
Ulrich
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Re: [gentoo-dev] [PATCH] fcaps.eclass: support EAPI 8
On Thu, 2021-06-17 at 12:10 +0200, Ulrich Mueller wrote:
> > > > > > On Thu, 17 Jun 2021, David Michael wrote:
>
> > @@ -33,15 +34,12 @@ _FCAPS_ECLASS=1
> >
> > IUSE="+filecaps"
> >
> > -# Since it is needed in pkg_postinst() it must be in RDEPEND
> > +# Since it is needed in pkg_postinst() it must be in IDEPEND
> > case "${EAPI:-0}" in
> > - [0-6])
> > - RDEPEND="filecaps? ( sys-libs/libcap )"
> > - ;;
> > - *)
> > - BDEPEND="filecaps? ( sys-libs/libcap )"
> > - RDEPEND="${BDEPEND}"
> > - ;;
> > + 7) BDEPEND="filecaps? ( sys-libs/libcap )" ;&
>
> This is ill-defined in old EAPIs (5 and before), so the case statement
> may fail. You cannot use ;& in global scope of an eclass.
>
> Why not just change * to 7, and add a new case for 8? It's one
> additional line, and IMHO would be better readable than having a
> fallthrough.
I've already left a comment on the PR suggesting to split it into two
cases: one to check for valid EAPI, the other for deps. It would be
cleaner IMO, as the second case would cover all future EAPIs via *,
and the first one would prevent the syntax error from applying to old
EAPIs (I've tested that).
--
Best regards,
Michał Górny
Re: [gentoo-dev] EAPI 8 is here!
> On Thu, 17 Jun 2021, Sam James wrote: > EAPI 8 is here! In fact, it arrived a few days ago on Sunday: > [...] > Things you need to know: > * You can read the full specification in PMS as above. > * It's fully implemented in Portage 3.0.20, pkgcore 0.12.0, and > pkgcheck 0.10.0. IIUC, implementation of EAPI 8 in pkgcore is still incomplete: https://github.com/pkgcore/pkgcore/issues/313 In general, the PMS team tracks EAPI support in package managers on this wiki page: https://wiki.gentoo.org/wiki/Project:PMS#Implementation_in_package_managers Ulrich signature.asc Description: PGP signature
Re: [gentoo-dev] [PATCH] fcaps.eclass: support EAPI 8
> On Thu, 17 Jun 2021, David Michael wrote:
> @@ -33,15 +34,12 @@ _FCAPS_ECLASS=1
>
> IUSE="+filecaps"
>
> -# Since it is needed in pkg_postinst() it must be in RDEPEND
> +# Since it is needed in pkg_postinst() it must be in IDEPEND
> case "${EAPI:-0}" in
> - [0-6])
> - RDEPEND="filecaps? ( sys-libs/libcap )"
> - ;;
> - *)
> - BDEPEND="filecaps? ( sys-libs/libcap )"
> - RDEPEND="${BDEPEND}"
> - ;;
> + 7) BDEPEND="filecaps? ( sys-libs/libcap )" ;&
This is ill-defined in old EAPIs (5 and before), so the case statement
may fail. You cannot use ;& in global scope of an eclass.
Why not just change * to 7, and add a new case for 8? It's one
additional line, and IMHO would be better readable than having a
fallthrough.
> + 6) RDEPEND="filecaps? ( sys-libs/libcap )" ;;
> + 8) IDEPEND="filecaps? ( sys-libs/libcap )" ;;
> + *) die "EAPI ${EAPI:-0} is unsupported" ;;
> esac
>
> # @ECLASS-VARIABLE: FILECAPS
Ulrich
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Re: [gentoo-dev] Up for grabs: various base-system@ packages
On 2021-06-16 19:18, Sam James wrote: - app-editors/hexcurse I'll take this one. -- Marecki OpenPGP_signature Description: OpenPGP digital signature
