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117 lines
4.3 KiB
Markdown
117 lines
4.3 KiB
Markdown
Logging
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=======
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> Note: This section is under development.
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Yii provides flexible and extensible logger that is able to handle messages according to severity level or their type.
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You may filter messages by multiple criteria and forward them to files, email, debugger etc.
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Logging basics
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--------------
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Basic logging is as simple as calling one method:
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```php
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\Yii::info('Hello, I am a test log message');
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```
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You can log simple strings as well as more complex data structures such as arrays or objects.
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When logging data that is not a string the defaulf yii log targets will serialize the value using [[yii\helpers\Vardumper::export()]].
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### Message category
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Additionally to the message itself message category could be specified in order to allow filtering such messages and
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handing these differently. Message category is passed as a second argument of logging methods and is `application` by
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default.
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### Severity levels
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There are multiple severity levels and corresponding methods available:
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- [[Yii::trace]] used maily for development purpose to indicate workflow of some code. Note that it only works in
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development mode when `YII_DEBUG` is set to `true`.
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- [[Yii::error]] used when there's unrecoverable error.
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- [[Yii::warning]] used when an error occurred but execution can be continued.
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- [[Yii::info]] used to keep record of important events such as administrator logins.
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Log targets
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-----------
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When one of the logging methods is called, message is passed to [[yii\log\Logger]] component accessible as
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`Yii::getLogger()`. Logger accumulates messages in memory and then when there are enough messages
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or when the current request finishes, sends them to different log targets, such as file or email.
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You may configure the targets in application configuration, like the following:
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```php
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[
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'bootstrap' => ['log'], // ensure logger gets loaded before application starts
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'components' => [
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'log' => [
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'targets' => [
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'file' => [
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'class' => 'yii\log\FileTarget',
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'levels' => ['trace', 'info'],
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'categories' => ['yii\*'],
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],
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'email' => [
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'class' => 'yii\log\EmailTarget',
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'levels' => ['error', 'warning'],
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'message' => [
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'to' => ['admin@example.com', 'developer@example.com'],
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'subject' => 'New example.com log message',
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],
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],
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],
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],
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],
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]
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```
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In the config above we are defining two log targets: [[yii\log\FileTarget|file]] and [[yii\log\EmailTarget|email]].
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In both cases we are filtering messages handles by these targets by severity. In case of file target we're
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additionally filter by category. `yii\*` means all categories starting with `yii\`.
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Each log target can have a name and can be referenced via the [[yii\log\Logger::targets|targets]] property as follows:
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```php
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Yii::$app->log->targets['file']->enabled = false;
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```
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When the application ends or [[yii\log\Logger::flushInterval|flushInterval]] is reached, Logger will call
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[[yii\log\Logger::flush()|flush()]] to send logged messages to different log targets, such as file, email, web.
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> Note: In the above configuration we added the log component to the list of [bootstrap](runtime-bootstrapping.md) components that
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get initialized when the application is initialized to ensure logging is enabled from the start.
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Profiling
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---------
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Performance profiling is a special type of message logging that can be used to measure the time needed for the
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specified code blocks to execute and find out what the performance bottleneck is.
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To use it we need to identify which code blocks need to be profiled. Then we mark the beginning and the end of each code
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block by inserting the following methods:
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```php
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\Yii::beginProfile('myBenchmark');
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...code block being profiled...
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\Yii::endProfile('myBenchmark');
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```
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where `myBenchmark` uniquely identifies the code block.
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Note, code blocks need to be nested properly such as
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```php
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\Yii::beginProfile('block1');
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// some code to be profiled
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\Yii::beginProfile('block2');
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// some other code to be profiled
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\Yii::endProfile('block2');
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\Yii::endProfile('block1');
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```
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Profiling results [could be displayed in debugger](module-debug.md).
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