[php] Print PHP Call Stack

I'm looking for a way to print the call stack in PHP.

Bonus points if the function flushes the IO buffer.

debug_backtrace()

If you want a stack trace which looks very similar to how php formats the exception stack trace than use this function I wrote:

function debug_backtrace_string() {
    $stack = '';
    $i = 1;
    $trace = debug_backtrace();
    unset($trace[0]); //Remove call to this function from stack trace
    foreach($trace as $node) {
        $stack .= "#$i ".$node['file'] ."(" .$node['line']."): "; 
        if(isset($node['class'])) {
            $stack .= $node['class'] . "->"; 
        }
        $stack .= $node['function'] . "()" . PHP_EOL;
        $i++;
    }
    return $stack;
} 

This will return a stack trace formatted like this:

#1 C:\Inetpub\sitename.com\modules\sponsors\class.php(306): filePathCombine()
#2 C:\Inetpub\sitename.com\modules\sponsors\class.php(294): Process->_deleteImageFile()
#3 C:\Inetpub\sitename.com\VPanel\modules\sponsors\class.php(70): Process->_deleteImage()
#4 C:\Inetpub\sitename.com\modules\sponsors\process.php(24): Process->_delete() 

More readable than debug_backtrace():

$e = new \Exception;
var_dump($e->getTraceAsString());

#2 /usr/share/php/PHPUnit/Framework/TestCase.php(626): SeriesHelperTest->setUp()
#3 /usr/share/php/PHPUnit/Framework/TestResult.php(666): PHPUnit_Framework_TestCase->runBare()
#4 /usr/share/php/PHPUnit/Framework/TestCase.php(576): PHPUnit_Framework_TestResult->run(Object(SeriesHelperTest))
#5 /usr/share/php/PHPUnit/Framework/TestSuite.php(757): PHPUnit_Framework_TestCase->run(Object(PHPUnit_Framework_TestResult))
#6 /usr/share/php/PHPUnit/Framework/TestSuite.php(733): PHPUnit_Framework_TestSuite->runTest(Object(SeriesHelperTest), Object(PHPUnit_Framework_TestResult))
#7 /usr/share/php/PHPUnit/TextUI/TestRunner.php(305): PHPUnit_Framework_TestSuite->run(Object(PHPUnit_Framework_TestResult), false, Array, Array, false)
#8 /usr/share/php/PHPUnit/TextUI/Command.php(188): PHPUnit_TextUI_TestRunner->doRun(Object(PHPUnit_Framework_TestSuite), Array)
#9 /usr/share/php/PHPUnit/TextUI/Command.php(129): PHPUnit_TextUI_Command->run(Array, true)
#10 /usr/bin/phpunit(53): PHPUnit_TextUI_Command::main()
#11 {main}"

Walltearer's solution is excellent, particularly if enclosed in a 'pre' tag:

<pre>
<?php debug_print_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS); ?>
</pre>

- which sets out the calls on separate lines, neatly numbered

Backtrace dumps a whole lot of garbage that you don't need. It takes is very long, difficult to read. All you usuall ever want is "what called what from where?" Here is a simple static function solution. I usually put it in a class called 'debug', which contains all of my debugging utility functions.

class debugUtils {
    public static function callStack($stacktrace) {
        print str_repeat("=", 50) ."\n";
        $i = 1;
        foreach($stacktrace as $node) {
            print "$i. ".basename($node['file']) .":" .$node['function'] ."(" .$node['line'].")\n";
            $i++;
        }
    } 
}

You call it like this:

debugUtils::callStack(debug_backtrace());

And it produces output like this:

==================================================
 1. DatabaseDriver.php::getSequenceTable(169)
 2. ClassMetadataFactory.php::loadMetadataForClass(284)
 3. ClassMetadataFactory.php::loadMetadata(177)
 4. ClassMetadataFactory.php::getMetadataFor(124)
 5. Import.php::getAllMetadata(188)
 6. Command.php::execute(187)
 7. Application.php::run(194)
 8. Application.php::doRun(118)
 9. doctrine.php::run(99)
 10. doctrine::include(4)
==================================================

phptrace is a great tool to print PHP stack anytime when you want without installing any extensions.

There are two major function of phptrace: first, print call stack of PHP which need not install anything, second, trace php execution flows which needs to install the extension it supplies.

as follows:

$ ./phptrace -p 3130 -s             # phptrace -p <PID> -s
phptrace 0.2.0 release candidate, published by infra webcore team
process id = 3130
script_filename = /home/xxx/opt/nginx/webapp/block.php
[0x7f27b9a99dc8]  sleep /home/xxx/opt/nginx/webapp/block.php:6
[0x7f27b9a99d08]  say /home/xxx/opt/nginx/webapp/block.php:3
[0x7f27b9a99c50]  run /home/xxx/opt/nginx/webapp/block.php:10 

You might want to look into debug_backtrace, or perhaps debug_print_backtrace.

See debug_print_backtrace. I guess you can call flush afterwards if you want.

Use debug_backtrace to get a backtrace of what functions and methods had been called and what files had been included that led to the point where debug_backtrace has been called.

please take a look at this utils class, may be helpful:

Usage:

<?php
/* first caller */
 Who::callme();

/* list the entire list of calls */
Who::followme();

Source class: https://github.com/augustowebd/utils/blob/master/Who.php

Strange that noone posted this way:

debug_print_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);

This actually prints backtrace without the garbage - just what method was called and where.

To log the trace

$e = new Exception;
error_log(var_export($e->getTraceAsString(), true));

Thanks @Tobiasz

var_dump(debug_backtrace());

Does that do what you want?

I have adapted Don Briggs's answer above to use internal error logging instead of public printing, which may be your big concern when working on a live server. Also, added few more modifications like option to include full file path instead of basic name (because, there could be files with same name in different paths), and also (for those who require it) a complete node stack output:

class debugUtils {
    public static function callStack($stacktrace) {
        error_log(str_repeat("=", 100));
        $i = 1;
        foreach($stacktrace as $node) {
            // uncomment next line to debug entire node stack
            // error_log(print_r($node, true));
            error_log( $i . '.' . ' file: ' .$node['file'] . ' | ' . 'function: ' . $node['function'] . '(' . ' line: ' . $node['line'] . ')' );
            $i++;
        }
        error_log(str_repeat("=", 100));
    } 
}

// call debug stack
debugUtils::callStack(debug_backtrace());