Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:85446
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain zend.com designates 209.85.160.178 as permitted sender)
MIME-Version: 1.0
In-Reply-To: <CAF+90c9B7seGdPdn-7=mxinFVHXU_rvdK_EDouW+A01HWjkWFw@mail.gmail.com>
References: <CA+9eiLsAQPTkVuR=D0wXMFXhBNM8DQzGq0DRXzSuL+hjPsUpgA@mail.gmail.com>
	<CAF+90c9Kw0iGxEZkpwbfNV+uZKrnpJ32gz9g257w00G1-rC1JQ@mail.gmail.com>
	<CA+9eiLt2tUVJ40_YTVq5TgUWX0a0URvmYwFQU=33nxManhXsng@mail.gmail.com>
	<CAF+90c9B7seGdPdn-7=mxinFVHXU_rvdK_EDouW+A01HWjkWFw@mail.gmail.com>
Date: Tue, 24 Mar 2015 15:08:12 +0300
Message-ID: <CA+9eiLv0pakhXf9NhpiF+TkPgKd52ATH=dUdrpu1fAM2GAPSbw@mail.gmail.com>
To: Nikita Popov <nikita.ppv@gmail.com>
Cc: Xinchen Hui <xinchen.h@zend.com>, Joe Watkins <pthreads@pthreads.org>, 
	PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a1133f77c0380d6051207a3b4
Subject: Re: Use "ropes" for string concatenation
From: dmitry@zend.com (Dmitry Stogov)

--001a1133f77c0380d6051207a3b4
Content-Type: text/plain; charset=UTF-8

On Tue, Mar 24, 2015 at 2:51 PM, Nikita Popov <nikita.ppv@gmail.com> wrote:

> On Tue, Mar 24, 2015 at 10:28 AM, Dmitry Stogov <dmitry@zend.com> wrote:
>
>> I thought about something like this :)
>> In my opinion UString is really not a proper way to implement Unicoide,
>> but I agree not break anything in current stage.
>> Anyway, please review the first PR (in my opinion it is safe to commit),
>> but you may find some other issues.
>>
>> Thanks. Dmitry.
>>
>
> First PR looks okay to me. One question: Why the separate INIT and ADD
> opcodes? They seem pretty much the same, just one using a hardcoded 0
> instead of ex_val.
>

Oh. It's historical, at first we allocated rope on heap. I'll check if
INIT_ROPE is still necessary.
Most probably we still need it, to know the size of rope vector.


> Regarding exception-safety - is the problem that doing an EG(exception)
> check and releasing the rope is too expensive?
>

No. It's a common problem. Because exception may be thrown in some other
opcode and we don't clean IS_VAR/IS_TMP_VAR zvals.
For example the following script leaks independently from the patch

<?php
function foo() {
  throw new Exception();
}
try {
        $a = "a";
        $a = $a . $a . $a . foo() . $a . "\n";
} catch (Exception $e) {
}
?>

Thanks. Dmitry.


>
> Nikita
>

--001a1133f77c0380d6051207a3b4--