Profiling could be more informative

[SDKiller]

As of now:

   ...
     * @param string $token token for the code block
     * @param string $category the category of this log message
     * @see endProfile()
     */
    public static function beginProfile($token, $category = 'application')
    {
        static::getLogger()->log($token, Logger::LEVEL_PROFILE_BEGIN, $category);
    }

The same is for endProfile.
Here $token is just a key to match the corresponding beginProfile and endProfile records.

But for logger $token is message, which can be

 * @param string|array $message the message to be logged. This can be a simple string or a more
 * complex data structure that will be handled by a [[Target|log target]].

When profiling you could wish (and usually it is nesessary) to save additional information related to it - for example object state (often - both for begin and end of profiling).

Of course you can immediately log this info as separate record using log(), but:

1. later you'll have to seek for log records corresponding to this profiling record to retrieve this info;
2. its additional overhead which will affect profile timing
3. object which properties you want to pass as additional info may change between profile and log records, so you need to introduce additional variables to save it state at the moment of profiling to be sure that proper values will be logged;
4. its additional code.

Could be useful if beginProfile and endProfile could accept the same format as log() (finally - they are just proxy functions for log()).

Formally passing array to beginProfile and endProfile is possible, but is actually restricted by \yii\log\Logger::calculateTimings - as it treats $token only as string for comparison.

For logging there is no problem as \yii\log\Target::formatMessage processes non-string messages by VarDumper::export

IMO - \yii\log\Logger::calculateTimings could be modified.

If $token was passed as string - left as is.
If as array - their could be a constant, a naming convention or configuration parameter for token array key, and the rest of the message could be processed by VarDumper::export

[SDKiller]

Something like this:

...
    public $tokenKey = 'token';

...
    public function calculateTimings($messages)
    {
...
        foreach ($messages as $i => $log) {
            list($message, $level, $category, $timestamp, $traces) = $log;
            $token = $this->resolveToken($message);
            if ($token === null) {
                continue;
            }
...
            } elseif ($level == Logger::LEVEL_PROFILE_END) {
                if (($last = array_pop($stack)) !== null) {
                    $lastToken = $this->resolveToken($last[0]);
                    if ($lastToken === $token) {
...
    }

    /**
     * @param array|string $message
     * @return string|null
     */
    protected function resolveToken($message)
    {
        $token = is_string($message) ? $message : ArrayHelper::getValue($message, $this->tokenKey, null);

        return $token;
    }

UPD: updated example

[yii-bot]

Issue moved to yiisoft/yii2-debug#81