Re: concatenation operator

Hello, Sorry for the late reply, I was away for a while...... I don't think I have dtrace because I'm on fedora.....but i'll research. If i would want to set a breakpoint after php's initialization process, but right before the scripts execution, so that after that I can set breakpoints to emalloc and efree which are executed only during my scripts execution where should i set it? Hope the question was clear enough..... dtrace related: Why have you used 'execute:return' and not concat_function:return? What's with the execute function? Thanks, A. ________________________________ From: Johannes Schlüter <johannes@schlueters.de> To: Adi Mutu <adi_mutu06@yahoo.com> Cc: Felipe Pena <felipensp@gmail.com>; PHP Developers Mailing List <internals@lists.php.net> Sent: Thursday, June 7, 2012 11:18 PM Subject: Re: [PHP-DEV] concatenation operator On Thu, 2012-06-07 at 12:53 -0700, Adi Mutu wrote: > Ok Johannes, thanks for the answer. I'll try to look deeper. > I basically just wanted to know what happens when you concatenate two > strings? what emalloc/efree happens. This depends. As always. As said what has to be done is one allocation for the result value ... and then the zval magic, which depends on refcount, references, ... > Also can you tell me if possible how to put a breakpoint to > emalloc/efree which are executed only after all core functions are > registered? because it takes like a million years like this and a > million F8 presses... Depends on your debugger.. Most allow conditional breakpoints or have a breakpoint and while holding at some place add a few more ... For such a question my preference is using DTrace (on Solaris, Mac or BSD), something like this session:         $ cat test.d         #!/sbin/dtrace                 pid$target::concat_function:entry {             self->in_concat = 1;         }                 pid$target::execute:return {             self->in_concat = 0;         }                 pid$target::_emalloc:entry         / self->in_concat /         {             trace(arg0);             ustack();         }                 pid$target::_erealloc:entry         / self->in_concat /         {             trace(arg0);             trace(arg1);             ustack();         }                 $ cat test1.php         <?php         $a = "foo"; $b = "bar"; $a.$b;                 $ dtrace -s test.d -c 'php test1.php'         dtrace: script 'test.d' matched 4 probes         dtrace: pid 16406 has exited         CPU    ID                    FUNCTION:NAME           3 100372                  _emalloc:entry                7                       php`_emalloc                       php`concat_function+0x270                       php`ZEND_CONCAT_SPEC_CV_CV_HANDLER+0xcd                       php`execute+0x3d9                       php`dtrace_execute+0xe7                       php`zend_execute_scripts+0xf5                       php`php_execute_script+0x2e8                       php`do_cli+0x864                       php`main+0x6e2                       php`_start+0x83                 $ cat test2.php         <?php         $a = 23; $b = "bar"; $a.$b;                 $ dtrace -s test.d -c 'php test2.php'         dtrace: script 'test.d' matched 4 probes         dtrace: pid 16425 has exited         CPU    ID                    FUNCTION:NAME           1 100373                  _erealloc:entry                0              79                       php`_erealloc                       php`xbuf_format_converter+0x11ee                       php`vspprintf+0x34                       php`zend_spprintf+0x2f                       php`_convert_to_string+0x174                       php`zend_make_printable_zval+0x5ec                       php`concat_function+0x3c                       php`ZEND_CONCAT_SPEC_CV_CV_HANDLER+0xcd                       php`execute+0x3d9                       php`dtrace_execute+0xe7                       php`zend_execute_scripts+0xf5                       php`php_execute_script+0x2e8                       php`do_cli+0x864                       php`main+0x6e2                       php`_start+0x83                   1 100372                  _emalloc:entry                6                       php`_emalloc                       php`concat_function+0x270                       php`ZEND_CONCAT_SPEC_CV_CV_HANDLER+0xcd                       php`execute+0x3d9                       php`dtrace_execute+0xe7                       php`zend_execute_scripts+0xf5                       php`php_execute_script+0x2e8                       php`do_cli+0x864                       php`main+0x6e2                       php`_start+0x83         So, when having two constant strings there's a single malloc, in this case allocating 7 bytes (strlen("foo")+strlen("bar")+1), if you have a different type it has to be converted first ... johannes