PHP／Laravel中的“异常链”

之前知道，Python 3 中终于实现了对异常链的支持。 最近，在代码中，有一处写着：

try {
// some code
} catch (\Exception $e) {
\Log::error(‘xxx_id’ . $xxx->id);
}

问了之后才发现，这是需要知道是哪个id触发的错误，如果不捕获异常的话，在backtrace信息中可能不会出现此id。 但是，这样做虽然可以达到他的目的，但是掩盖了底层的错误，对后续的追查不利。 然后，作为（伪）Python开发者的我就想起了Python3中的异常链技术，所以找了下PHP中有没有类似的东西，结果发现：自PHP 5.3开始，支持了类似的技术。 解决方案：可以自己扩展Excepiton类，默认的构造方法里面，第三个参数是前一个异常，经过测试，在Laravel框架中，同一条链中的Exception都会展示出来（无论是在Console输出，还是日志输出中）。

---

好，让我们来自己试一试。 首先写一个Command：

class NestExceptionTest extends Command
{
protected $name = ‘NestExceptionTest’;

public function fire()
{
    try {
        $this->testOneLevel();
    } catch (\\Exception $e) {
        throw new \\Exception("top level", 0, $e);
    }
}

private function testOneLevel()
{
    try {
        $this->testTwoLeve();
    } catch (\\Exception $e) {
        throw new \\Exception('one level', 0, $e);
    }
}

private function testTwoLeve()
{
    throw new \\Exception('two level');
}

}

为了偷懒，就没有自己定义自己的Exception，仅仅是不同的错误信息来区分。 执行此命令，输出如下： 同时，日志输出如下：

[2015-12-12 13:54:06] production.ERROR: exception ‘Exception’ with message ‘two level’ in /Users/robberphex/projects/xxx/app/Console/Commands/NestExceptionTest.job:31
Stack trace:
#0 /Users/robberphex/projects/xxx/app/Console/Commands/NestExceptionTest.job(23): App\Console\Commands\SiteMap\SiteMapBuild->testTwoLeve()
#1 /Users/robberphex/projects/xxx/app/Console/Commands/NestExceptionTest.job(14): App\Console\Commands\SiteMap\SiteMapBuild->testOneLevel()
#2 [internal function]: App\Console\Commands\SiteMap\SiteMapBuild->fire()
#3 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Container/Container.php(503): call_user_func_array(Array, Array)
#4 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Console/Command.php(150): Illuminate\Container\Container->call(Array)
#5 /Users/robberphex/projects/xxx/vendor/symfony/console/Command/Command.php(256): Illuminate\Console\Command->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#6 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Console/Command.php(136): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#7 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(838): Illuminate\Console\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#8 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(189): Symfony\Component\Console\Application->doRunCommand(Object(App\Console\Commands\SiteMap\SiteMapBuild), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#9 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(120): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#10 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Foundation/Console/Kernel.php(107): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#11 /Users/robberphex/projects/xxx/artisan(36): Illuminate\Foundation\Console\Kernel->handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#12 {main}

Next exception ‘Exception’ with message ‘one level’ in /Users/robberphex/projects/xxx/app/Console/Commands/NestExceptionTest.job:25
Stack trace:
#0 /Users/robberphex/projects/xxx/app/Console/Commands/NestExceptionTest.job(14): App\Console\Commands\SiteMap\SiteMapBuild->testOneLevel()
#1 [internal function]: App\Console\Commands\SiteMap\SiteMapBuild->fire()
#2 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Container/Container.php(503): call_user_func_array(Array, Array)
#3 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Console/Command.php(150): Illuminate\Container\Container->call(Array)
#4 /Users/robberphex/projects/xxx/vendor/symfony/console/Command/Command.php(256): Illuminate\Console\Command->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#5 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Console/Command.php(136): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#6 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(838): Illuminate\Console\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#7 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(189): Symfony\Component\Console\Application->doRunCommand(Object(App\Console\Commands\SiteMap\SiteMapBuild), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#8 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(120): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#9 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Foundation/Console/Kernel.php(107): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#10 /Users/robberphex/projects/xxx/artisan(36): Illuminate\Foundation\Console\Kernel->handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#11 {main}

Next exception ‘Exception’ with message ‘top level’ in /Users/robberphex/projects/xxx/app/Console/Commands/NestExceptionTest.job:16
Stack trace:
#0 [internal function]: App\Console\Commands\SiteMap\SiteMapBuild->fire()
#1 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Container/Container.php(503): call_user_func_array(Array, Array)
#2 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Console/Command.php(150): Illuminate\Container\Container->call(Array)
#3 /Users/robberphex/projects/xxx/vendor/symfony/console/Command/Command.php(256): Illuminate\Console\Command->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#4 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Console/Command.php(136): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#5 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(838): Illuminate\Console\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#6 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(189): Symfony\Component\Console\Application->doRunCommand(Object(App\Console\Commands\SiteMap\SiteMapBuild), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#7 /Users/robberphex/projects/xxx/vendor/symfony/console/Application.php(120): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#8 /Users/robberphex/projects/xxx/vendor/laravel/framework/src/Illuminate/Foundation/Console/Kernel.php(107): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#9 /Users/robberphex/projects/xxx/artisan(36): Illuminate\Foundation\Console\Kernel->handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#10 {main} {“request”:[],}

可以看到，Exception都输出在同一个错误信息中了，方便排查错误，了解错误之间的关联。