X-Recipient: archive-cygwin AT delorie DOT com
DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:message-id:date:from:mime-version:to:subject
	:references:in-reply-to:content-type:content-transfer-encoding;
	 q=dns; s=default; b=JTScjd1FiHhx3mTivd0hvlvirsI3+xbDJEU7ogXbBw6
	SYeOkbXPj1GbJ5Ky9oMA+5T1C+dsi4gg+eheMlkFv+9ZzL6Wd31ZImMHsswQWJ3S
	Hzbia4kw+NaXNxQTj1VxXTCgdq3iQ+3pzkdNZvNMlJFW9yS7hepI+jv2OquE/0D0
	=
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:message-id:date:from:mime-version:to:subject
	:references:in-reply-to:content-type:content-transfer-encoding;
	 s=default; bh=CGyIatX2x+Mc54acWxD0g08khC4=; b=EDfGNNZe4qJOJD5Kr
	SnYCxO9PgvotNolIlhkTvIrmcfE8PFRNA9lwUMKGMFNV86QpTge0RnBSDM2TTG6B
	hZY7osviH3+4DD5N2G5cDPLp5EzSAXeFidNh3wVNTf/GTo4N5CbL3XcgnAQ9r94Z
	1Z/WRyla6ZdAjbAA0BX0tcWP1s=
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id: <cygwin.cygwin.com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Authentication-Results: sourceware.org; auth=none
X-Virus-Found: No
X-Spam-SWARE-Status: No, score=1.0 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,KAM_COUK,RCVD_IN_BL_SPAMCOP_NET,SPF_PASS autolearn=no version=3.3.2
X-HELO: out.ipsmtp2nec.opaltelecom.net
X-SMTPAUTH: drstacey AT tiscali DOT co DOT uk
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: ApMBAHRh9VJPRtO6/2dsb2JhbAANTMAFgwmBIYMZAQEBBCcRQBELGAkWDwkDAgECAUUTCAEBsnehYxePBBaEIgEDrDuBPg
X-IPAS-Result: ApMBAHRh9VJPRtO6/2dsb2JhbAANTMAFgwmBIYMZAQEBBCcRQBELGAkWDwkDAgECAUUTCAEBsnehYxePBBaEIgEDrDuBPg
Message-ID: <52F561EE.8090806@tiscali.co.uk>
Date: Fri, 07 Feb 2014 22:45:02 +0000
From: David Stacey <drstacey AT tiscali DOT co DOT uk>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
MIME-Version: 1.0
To: cygwin AT cygwin DOT com
Subject: Re: get rid of getpwent? (Was: cygwin-1.7.28 getpwent header declaration changes ?)
References: <52F339CA DOT 5070305 AT gmail DOT com> <20140206090117 DOT GD2821 AT calimero DOT vinschen DOT de> <52F361C5 DOT 3000807 AT gmail DOT com> <20140206141321 DOT GI2821 AT calimero DOT vinschen DOT de> <52F40208 DOT 5030901 AT etr-usa DOT com> <20140207094917 DOT GN2821 AT calimero DOT vinschen DOT de> <52F53D7C DOT 5050201 AT etr-usa DOT com> <52F553AA DOT 9090500 AT cygwin DOT com>
In-Reply-To: <52F553AA.9090500@cygwin.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-IsSubscribed: yes

On 07/02/14 21:44, Larry Hall (Cygwin) wrote:
> On 2/7/2014 3:09 PM, Warren Young wrote:
>> This takes 7.1 seconds on my system, with a 12-line /etc/passwd file:
>>
>>       #include <pwd.h>
>>       #include <stdio.h>
>>       #include <stdlib.h>
>>
>>       int main(int argc, const char* argv[])
>>       {
>>           int i;
>>           const char* user = argv[1];
>>
>>           if (!user) {
>>               printf("usage: %s username\n", argv[0]);
>>               exit(1);
>>           }
>>
>>           for (i = 0; i < 1000000; ++i) {
>>               struct passwd* pw = getpwnam(user);
>>               if (!pw) {
>>                   printf("User %s doesn't exist!\n", user);
>>                   exit(2);
>>               }
>>               else if (i == 0) {
>>                   printf("User %s is UID %d\n", user, pw->pw_uid);
>>               }
>>           }
>>       }
>>
>> So, each getpwnam() call takes 7.1 microseconds on average.
>
> I think you forgot to put an "exit(0);" after the last printf(). Without
> it, you're checking for the same user a million times, which is certainly
> going to take a little time. ;-)
>

I thought the point of the programme /was/ to call getpwnam() a million 
times. Time this as accurately as you can. Then, with a quick division, 
you get the time for one call.

Dave.


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple