Move POSIX signal handling to SignalHandler*

Suggested by Helmut Hummel (@helhum).

doc/03-utilities.md

@@ -4,8 +4,9 @@
   can then statically access from anywhere. It is not really a best practice but can
   help in some older codebases or for ease of use.
 - _ErrorHandler_: The `Monolog\ErrorHandler` class allows you to easily register
-  a Logger instance as an exception handler, error handler, fatal error handler or
-  signal handler.
+  a Logger instance as an exception handler, error handler or fatal error handler.
+- _SignalHandler_: The `Monolog\SignalHandler` class allows you to easily register
+  a Logger instance as a POSIX signal handler.
 - _ErrorLevelActivationStrategy_: Activates a FingersCrossedHandler when a certain log
   level is reached.
 - _ChannelLevelActivationStrategy_: Activates a FingersCrossedHandler when a certain

src/Monolog/ErrorHandler.php

@@ -14,12 +14,11 @@ namespace Monolog;
 use Psr\Log\LoggerInterface;
 use Psr\Log\LogLevel;
 use Monolog\Handler\AbstractHandler;
-use ReflectionExtension;
 
 /**
  * Monolog error handler
  *
- * A facility to enable logging of runtime errors, exceptions, fatal errors and signals.
+ * A facility to enable logging of runtime errors, exceptions and fatal errors.
  *
  * Quick setup: <code>ErrorHandler::register($logger);</code>
  *
@@ -42,10 +41,6 @@ class ErrorHandler
     private $lastFatalTrace;
     private static $fatalErrors = array(E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR);
 
-    private $previousSignalHandler = array();
-    private $signalLevelMap = array();
-    private $signalRestartSyscalls = array();
-
     public function __construct(LoggerInterface $logger)
     {
         $this->logger = $logger;
@@ -110,37 +105,6 @@ class ErrorHandler
         $this->hasFatalErrorHandler = true;
     }
 
-    public function registerSignalHandler($signo, $level = LogLevel::CRITICAL, $callPrevious = true, $restartSyscalls = true, $async = true)
-    {
-        if (!extension_loaded('pcntl') || !function_exists('pcntl_signal')) {
-            return $this;
-        }
-
-        if ($callPrevious) {
-            if (function_exists('pcntl_signal_get_handler')) {
-                $handler = pcntl_signal_get_handler($signo);
-                if ($handler === false) {
-                    return $this;
-                }
-                $this->previousSignalHandler[$signo] = $handler;
-            } else {
-                $this->previousSignalHandler[$signo] = true;
-            }
-        } else {
-            unset($this->previousSignalHandler[$signo]);
-        }
-        $this->signalLevelMap[$signo] = $level;
-        $this->signalRestartSyscalls[$signo] = $restartSyscalls;
-
-        if (function_exists('pcntl_async_signals') && $async !== null) {
-            pcntl_async_signals($async);
-        }
-
-        pcntl_signal($signo, array($this, 'handleSignal'), $restartSyscalls);
-
-        return $this;
-    }
-
     protected function defaultErrorLevelMap()
     {
         return array(
@@ -234,55 +198,6 @@ class ErrorHandler
         }
     }
 
-    public function handleSignal($signo, array $siginfo = null)
-    {
-        static $signals = array();
-
-        if (!$signals && extension_loaded('pcntl')) {
-            $pcntl = new ReflectionExtension('pcntl');
-            $constants = $pcntl->getConstants();
-            if (!$constants) {
-                // HHVM 3.24.2 returns an empty array.
-                $constants = get_defined_constants(true);
-                $constants = $constants['Core'];
-            }
-            foreach ($constants as $name => $value) {
-                if (substr($name, 0, 3) === 'SIG' && $name[3] !== '_' && is_int($value)) {
-                    $signals[$value] = $name;
-                }
-            }
-            unset($constants);
-        }
-
-        $level = isset($this->signalLevelMap[$signo]) ? $this->signalLevelMap[$signo] : LogLevel::CRITICAL;
-        $signal = isset($signals[$signo]) ? $signals[$signo] : $signo;
-        $context = isset($siginfo) ? $siginfo : array();
-        $this->logger->log($level, sprintf('Program received signal %s', $signal), $context);
-
-        if (!isset($this->previousSignalHandler[$signo])) {
-            return;
-        }
-
-        if ($this->previousSignalHandler[$signo] === true || $this->previousSignalHandler[$signo] === SIG_DFL) {
-            if (extension_loaded('pcntl') && function_exists('pcntl_signal') && function_exists('pcntl_sigprocmask') && function_exists('pcntl_signal_dispatch')
-                && extension_loaded('posix') && function_exists('posix_getpid') && function_exists('posix_kill')) {
-                $restartSyscalls = isset($this->restartSyscalls[$signo]) ? $this->restartSyscalls[$signo] : true;
-                pcntl_signal($signo, SIG_DFL, $restartSyscalls);
-                pcntl_sigprocmask(SIG_UNBLOCK, array($signo), $oldset);
-                posix_kill(posix_getpid(), $signo);
-                pcntl_signal_dispatch();
-                pcntl_sigprocmask(SIG_SETMASK, $oldset);
-                pcntl_signal($signo, array($this, 'handleSignal'), $restartSyscalls);
-            }
-        } elseif (is_callable($this->previousSignalHandler[$signo])) {
-            if (PHP_VERSION >= 71000) {
-                $this->previousSignalHandler[$signo]($signo, $siginfo);
-            } else {
-                $this->previousSignalHandler[$signo]($signo);
-            }
-        }
-    }
-
     private static function codeToString($code)
     {
         switch ($code) {

src/Monolog/SignalHandler.php

@@ -0,0 +1,115 @@
+<?php
+
+/*
+ * This file is part of the Monolog package.
+ *
+ * (c) Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Monolog;
+
+use Psr\Log\LoggerInterface;
+use Psr\Log\LogLevel;
+use ReflectionExtension;
+
+/**
+ * Monolog POSIX signal handler
+ *
+ * @author Robert Gust-Bardon <robert@gust-bardon.org>
+ */
+class SignalHandler
+{
+    private $logger;
+
+    private $previousSignalHandler = array();
+    private $signalLevelMap = array();
+    private $signalRestartSyscalls = array();
+
+    public function __construct(LoggerInterface $logger)
+    {
+        $this->logger = $logger;
+    }
+
+    public function registerSignalHandler($signo, $level = LogLevel::CRITICAL, $callPrevious = true, $restartSyscalls = true, $async = true)
+    {
+        if (!extension_loaded('pcntl') || !function_exists('pcntl_signal')) {
+            return $this;
+        }
+
+        if ($callPrevious) {
+            if (function_exists('pcntl_signal_get_handler')) {
+                $handler = pcntl_signal_get_handler($signo);
+                if ($handler === false) {
+                    return $this;
+                }
+                $this->previousSignalHandler[$signo] = $handler;
+            } else {
+                $this->previousSignalHandler[$signo] = true;
+            }
+        } else {
+            unset($this->previousSignalHandler[$signo]);
+        }
+        $this->signalLevelMap[$signo] = $level;
+        $this->signalRestartSyscalls[$signo] = $restartSyscalls;
+
+        if (function_exists('pcntl_async_signals') && $async !== null) {
+            pcntl_async_signals($async);
+        }
+
+        pcntl_signal($signo, array($this, 'handleSignal'), $restartSyscalls);
+
+        return $this;
+    }
+
+    public function handleSignal($signo, array $siginfo = null)
+    {
+        static $signals = array();
+
+        if (!$signals && extension_loaded('pcntl')) {
+            $pcntl = new ReflectionExtension('pcntl');
+            $constants = $pcntl->getConstants();
+            if (!$constants) {
+                // HHVM 3.24.2 returns an empty array.
+                $constants = get_defined_constants(true);
+                $constants = $constants['Core'];
+            }
+            foreach ($constants as $name => $value) {
+                if (substr($name, 0, 3) === 'SIG' && $name[3] !== '_' && is_int($value)) {
+                    $signals[$value] = $name;
+                }
+            }
+            unset($constants);
+        }
+
+        $level = isset($this->signalLevelMap[$signo]) ? $this->signalLevelMap[$signo] : LogLevel::CRITICAL;
+        $signal = isset($signals[$signo]) ? $signals[$signo] : $signo;
+        $context = isset($siginfo) ? $siginfo : array();
+        $this->logger->log($level, sprintf('Program received signal %s', $signal), $context);
+
+        if (!isset($this->previousSignalHandler[$signo])) {
+            return;
+        }
+
+        if ($this->previousSignalHandler[$signo] === true || $this->previousSignalHandler[$signo] === SIG_DFL) {
+            if (extension_loaded('pcntl') && function_exists('pcntl_signal') && function_exists('pcntl_sigprocmask') && function_exists('pcntl_signal_dispatch')
+                && extension_loaded('posix') && function_exists('posix_getpid') && function_exists('posix_kill')) {
+                    $restartSyscalls = isset($this->restartSyscalls[$signo]) ? $this->restartSyscalls[$signo] : true;
+                    pcntl_signal($signo, SIG_DFL, $restartSyscalls);
+                    pcntl_sigprocmask(SIG_UNBLOCK, array($signo), $oldset);
+                    posix_kill(posix_getpid(), $signo);
+                    pcntl_signal_dispatch();
+                    pcntl_sigprocmask(SIG_SETMASK, $oldset);
+                    pcntl_signal($signo, array($this, 'handleSignal'), $restartSyscalls);
+                }
+        } elseif (is_callable($this->previousSignalHandler[$signo])) {
+            if (PHP_VERSION_ID >= 70100) {
+                $this->previousSignalHandler[$signo]($signo, $siginfo);
+            } else {
+                $this->previousSignalHandler[$signo]($signo);
+            }
+        }
+    }
+}

tests/Monolog/ErrorHandlerTest.php

@@ -11,55 +11,10 @@
 
 namespace Monolog;
 
-use Monolog\Handler\StreamHandler;
 use Monolog\Handler\TestHandler;
-use Psr\Log\LogLevel;
 
-class ErrorHandlerTest extends TestCase
+class ErrorHandlerTest extends \PHPUnit_Framework_TestCase
 {
-
-    private $asyncSignalHandling;
-    private $blockedSignals;
-    private $signalHandlers;
-
-    protected function setUp()
-    {
-        $this->signalHandlers = array();
-        if (extension_loaded('pcntl')) {
-            if (function_exists('pcntl_async_signals')) {
-                $this->asyncSignalHandling = pcntl_async_signals();
-            }
-            if (function_exists('pcntl_sigprocmask')) {
-                pcntl_sigprocmask(SIG_BLOCK, array(), $this->blockedSignals);
-            }
-        }
-    }
-
-    protected function tearDown()
-    {
-        if ($this->asyncSignalHandling !== null) {
-            pcntl_async_signals($this->asyncSignalHandling);
-        }
-        if ($this->blockedSignals !== null) {
-            pcntl_sigprocmask(SIG_SETMASK, $this->blockedSignals);
-        }
-        if ($this->signalHandlers) {
-            pcntl_signal_dispatch();
-            foreach ($this->signalHandlers as $signo => $handler) {
-                pcntl_signal($signo, $handler);
-            }
-        }
-    }
-
-    private function setSignalHandler($signo, $handler = SIG_DFL) {
-        if (function_exists('pcntl_signal_get_handler')) {
-            $this->signalHandlers[$signo] = pcntl_signal_get_handler($signo);
-        } else {
-            $this->signalHandlers[$signo] = SIG_DFL;
-        }
-        $this->assertTrue(pcntl_signal($signo, $handler));
-    }
-
     public function testHandleError()
     {
         $logger = new Logger('test', array($handler = new TestHandler));
@@ -73,225 +28,4 @@ class ErrorHandlerTest extends TestCase
         $this->assertCount(2, $handler->getRecords());
         $this->assertTrue($handler->hasEmergencyRecords());
     }
-
-    public function testHandleSignal()
-    {
-        $logger = new Logger('test', array($handler = new TestHandler));
-        $errHandler = new ErrorHandler($logger);
-        $signo = 2;  // SIGINT.
-        $siginfo = array('signo' => $signo, 'errno' => 0, 'code' => 0);
-        $errHandler->handleSignal($signo, $siginfo);
-        $this->assertCount(1, $handler->getRecords());
-        $this->assertTrue($handler->hasCriticalRecords());
-        $records = $handler->getRecords();
-        $this->assertSame($siginfo, $records[0]['context']);
-    }
-
-    /**
-     * @depends testHandleSignal
-     * @requires extension pcntl
-     * @requires extension posix
-     * @requires function pcntl_signal
-     * @requires function pcntl_signal_dispatch
-     * @requires function posix_getpid
-     * @requires function posix_kill
-     */
-    public function testRegisterSignalHandler()
-    {
-        // SIGCONT and SIGURG should be ignored by default.
-        if (!defined('SIGCONT') || !defined('SIGURG')) {
-            $this->markTestSkipped('This test requires the SIGCONT and SIGURG pcntl constants.');
-        }
-
-        $this->setSignalHandler(SIGCONT, SIG_IGN);
-        $this->setSignalHandler(SIGURG, SIG_IGN);
-
-        $logger = new Logger('test', array($handler = new TestHandler));
-        $errHandler = new ErrorHandler($logger);
-        $pid = posix_getpid();
-
-        $this->assertTrue(posix_kill($pid, SIGURG));
-        $this->assertTrue(pcntl_signal_dispatch());
-        $this->assertCount(0, $handler->getRecords());
-
-        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, false, false, false);
-
-        $this->assertTrue(posix_kill($pid, SIGCONT));
-        $this->assertTrue(pcntl_signal_dispatch());
-        $this->assertCount(0, $handler->getRecords());
-
-        $this->assertTrue(posix_kill($pid, SIGURG));
-        $this->assertTrue(pcntl_signal_dispatch());
-        $this->assertCount(1, $handler->getRecords());
-        $this->assertTrue($handler->hasInfoThatContains('SIGURG'));
-    }
-
-    /**
-     * @dataProvider defaultPreviousProvider
-     * @depends testRegisterSignalHandler
-     * @requires function pcntl_fork
-     * @requires function pcntl_sigprocmask
-     * @requires function pcntl_waitpid
-     */
-    public function testRegisterDefaultPreviousSignalHandler($signo, $callPrevious, $expected)
-    {
-        $this->setSignalHandler($signo, SIG_DFL);
-
-        $path = tempnam(sys_get_temp_dir(), 'monolog-');
-        $this->assertNotFalse($path);
-
-        $pid = pcntl_fork();
-        if ($pid === 0) {  // Child.
-            $streamHandler = new StreamHandler($path);
-            $streamHandler->setFormatter($this->getIdentityFormatter());
-            $logger = new Logger('test', array($streamHandler));
-            $errHandler = new ErrorHandler($logger);
-            $errHandler->registerSignalHandler($signo, LogLevel::INFO, $callPrevious, false, false);
-            pcntl_sigprocmask(SIG_SETMASK, array(SIGCONT));
-            posix_kill(posix_getpid(), $signo);
-            pcntl_signal_dispatch();
-            // If $callPrevious is true, SIGINT should terminate by this line.
-            pcntl_sigprocmask(SIG_BLOCK, array(), $oldset);
-            file_put_contents($path, implode(' ', $oldset), FILE_APPEND);
-            posix_kill(posix_getpid(), $signo);
-            pcntl_signal_dispatch();
-            exit();
-        }
-
-        $this->assertNotSame(-1, $pid);
-        $this->assertNotSame(-1, pcntl_waitpid($pid, $status));
-        $this->assertNotSame(-1, $status);
-        $this->assertSame($expected, file_get_contents($path));
-    }
-
-    public function defaultPreviousProvider()
-    {
-        if (!defined('SIGCONT') || !defined('SIGINT') || !defined('SIGURG')) {
-            return array();
-        }
-
-        return array(
-            array(SIGINT, false, 'Program received signal SIGINT'.SIGCONT.'Program received signal SIGINT'),
-            array(SIGINT, true, 'Program received signal SIGINT'),
-            array(SIGURG, false, 'Program received signal SIGURG'.SIGCONT.'Program received signal SIGURG'),
-            array(SIGURG, true, 'Program received signal SIGURG'.SIGCONT.'Program received signal SIGURG'),
-        );
-    }
-
-    /**
-     * @dataProvider callablePreviousProvider
-     * @depends testRegisterSignalHandler
-     * @requires function pcntl_signal_get_handler
-     */
-    public function testRegisterCallablePreviousSignalHandler($callPrevious)
-    {
-        $this->setSignalHandler(SIGURG, SIG_IGN);
-
-        $logger = new Logger('test', array($handler = new TestHandler));
-        $errHandler = new ErrorHandler($logger);
-        $previousCalled = 0;
-        pcntl_signal(SIGURG, function ($signo, array $siginfo = null) use (&$previousCalled) {
-            ++$previousCalled;
-        });
-        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, $callPrevious, false, false);
-        $this->assertTrue(posix_kill(posix_getpid(), SIGURG));
-        $this->assertTrue(pcntl_signal_dispatch());
-        $this->assertCount(1, $handler->getRecords());
-        $this->assertTrue($handler->hasInfoThatContains('SIGURG'));
-        $this->assertSame($callPrevious ? 1 : 0, $previousCalled);
-    }
-
-    public function callablePreviousProvider()
-    {
-        return array(
-            array(false),
-            array(true),
-        );
-    }
-
-    /**
-     * @dataProvider restartSyscallsProvider
-     * @depends testRegisterDefaultPreviousSignalHandler
-     * @requires function pcntl_fork
-     * @requires function pcntl_waitpid
-     */
-    public function testRegisterSyscallRestartingSignalHandler($restartSyscalls)
-    {
-        $this->setSignalHandler(SIGURG, SIG_IGN);
-
-        $parentPid = posix_getpid();
-        $microtime = microtime(true);
-
-        $pid = pcntl_fork();
-        if ($pid === 0) {  // Child.
-            usleep(100000);
-            posix_kill($parentPid, SIGURG);
-            usleep(100000);
-            exit();
-        }
-
-        $this->assertNotSame(-1, $pid);
-        $logger = new Logger('test', array($handler = new TestHandler));
-        $errHandler = new ErrorHandler($logger);
-        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, false, $restartSyscalls, false);
-        if ($restartSyscalls) {
-            // pcntl_wait is expected to be restarted after the signal handler.
-            $this->assertNotSame(-1, pcntl_waitpid($pid, $status));
-        } else {
-            // pcntl_wait is expected to be interrupted when the signal handler is invoked.
-            $this->assertSame(-1, pcntl_waitpid($pid, $status));
-        }
-        $this->assertSame($restartSyscalls, microtime(true) - $microtime > 0.15);
-        $this->assertTrue(pcntl_signal_dispatch());
-        $this->assertCount(1, $handler->getRecords());
-        if ($restartSyscalls) {
-            // The child has already exited.
-            $this->assertSame(-1, pcntl_waitpid($pid, $status));
-        } else {
-            // The child has not exited yet.
-            $this->assertNotSame(-1, pcntl_waitpid($pid, $status));
-        }
-    }
-
-    public function restartSyscallsProvider()
-    {
-        return array(
-            array(false),
-            array(true),
-            array(false),
-            array(true),
-        );
-    }
-
-    /**
-     * @dataProvider asyncProvider
-     * @depends testRegisterDefaultPreviousSignalHandler
-     * @requires function pcntl_async_signals
-     */
-    public function testRegisterAsyncSignalHandler($initialAsync, $desiredAsync, $expectedBefore, $expectedAfter)
-    {
-        $this->setSignalHandler(SIGURG, SIG_IGN);
-        pcntl_async_signals($initialAsync);
-
-        $logger = new Logger('test', array($handler = new TestHandler));
-        $errHandler = new ErrorHandler($logger);
-        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, false, false, $desiredAsync);
-        $this->assertTrue(posix_kill(posix_getpid(), SIGURG));
-        $this->assertCount($expectedBefore, $handler->getRecords());
-        $this->assertTrue(pcntl_signal_dispatch());
-        $this->assertCount($expectedAfter, $handler->getRecords());
-    }
-
-    public function asyncProvider()
-    {
-        return array(
-            array(false, false, 0, 1),
-            array(false, null, 0, 1),
-            array(false, true, 1, 1),
-            array(true, false, 0, 1),
-            array(true, null, 1, 1),
-            array(true, true, 1, 1),
-        );
-    }
-
 }

tests/Monolog/SignalHandlerTest.php

@@ -0,0 +1,287 @@
+<?php
+
+/*
+ * This file is part of the Monolog package.
+ *
+ * (c) Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Monolog;
+
+use Monolog\Handler\StreamHandler;
+use Monolog\Handler\TestHandler;
+use Psr\Log\LogLevel;
+
+/**
+ * @author Robert Gust-Bardon <robert@gust-bardon.org>
+ * @covers Monolog\SignalHandler
+ */
+class SignalHandlerTest extends TestCase
+{
+
+    private $asyncSignalHandling;
+    private $blockedSignals;
+    private $signalHandlers;
+
+    protected function setUp()
+    {
+        $this->signalHandlers = array();
+        if (extension_loaded('pcntl')) {
+            if (function_exists('pcntl_async_signals')) {
+                $this->asyncSignalHandling = pcntl_async_signals();
+            }
+            if (function_exists('pcntl_sigprocmask')) {
+                pcntl_sigprocmask(SIG_BLOCK, array(), $this->blockedSignals);
+            }
+        }
+    }
+
+    protected function tearDown()
+    {
+        if ($this->asyncSignalHandling !== null) {
+            pcntl_async_signals($this->asyncSignalHandling);
+        }
+        if ($this->blockedSignals !== null) {
+            pcntl_sigprocmask(SIG_SETMASK, $this->blockedSignals);
+        }
+        if ($this->signalHandlers) {
+            pcntl_signal_dispatch();
+            foreach ($this->signalHandlers as $signo => $handler) {
+                pcntl_signal($signo, $handler);
+            }
+        }
+    }
+
+    private function setSignalHandler($signo, $handler = SIG_DFL) {
+        if (function_exists('pcntl_signal_get_handler')) {
+            $this->signalHandlers[$signo] = pcntl_signal_get_handler($signo);
+        } else {
+            $this->signalHandlers[$signo] = SIG_DFL;
+        }
+        $this->assertTrue(pcntl_signal($signo, $handler));
+    }
+
+    public function testHandleSignal()
+    {
+        $logger = new Logger('test', array($handler = new TestHandler));
+        $errHandler = new SignalHandler($logger);
+        $signo = 2;  // SIGINT.
+        $siginfo = array('signo' => $signo, 'errno' => 0, 'code' => 0);
+        $errHandler->handleSignal($signo, $siginfo);
+        $this->assertCount(1, $handler->getRecords());
+        $this->assertTrue($handler->hasCriticalRecords());
+        $records = $handler->getRecords();
+        $this->assertSame($siginfo, $records[0]['context']);
+    }
+
+    /**
+     * @depends testHandleSignal
+     * @requires extension pcntl
+     * @requires extension posix
+     * @requires function pcntl_signal
+     * @requires function pcntl_signal_dispatch
+     * @requires function posix_getpid
+     * @requires function posix_kill
+     */
+    public function testRegisterSignalHandler()
+    {
+        // SIGCONT and SIGURG should be ignored by default.
+        if (!defined('SIGCONT') || !defined('SIGURG')) {
+            $this->markTestSkipped('This test requires the SIGCONT and SIGURG pcntl constants.');
+        }
+
+        $this->setSignalHandler(SIGCONT, SIG_IGN);
+        $this->setSignalHandler(SIGURG, SIG_IGN);
+
+        $logger = new Logger('test', array($handler = new TestHandler));
+        $errHandler = new SignalHandler($logger);
+        $pid = posix_getpid();
+
+        $this->assertTrue(posix_kill($pid, SIGURG));
+        $this->assertTrue(pcntl_signal_dispatch());
+        $this->assertCount(0, $handler->getRecords());
+
+        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, false, false, false);
+
+        $this->assertTrue(posix_kill($pid, SIGCONT));
+        $this->assertTrue(pcntl_signal_dispatch());
+        $this->assertCount(0, $handler->getRecords());
+
+        $this->assertTrue(posix_kill($pid, SIGURG));
+        $this->assertTrue(pcntl_signal_dispatch());
+        $this->assertCount(1, $handler->getRecords());
+        $this->assertTrue($handler->hasInfoThatContains('SIGURG'));
+    }
+
+    /**
+     * @dataProvider defaultPreviousProvider
+     * @depends testRegisterSignalHandler
+     * @requires function pcntl_fork
+     * @requires function pcntl_sigprocmask
+     * @requires function pcntl_waitpid
+     */
+    public function testRegisterDefaultPreviousSignalHandler($signo, $callPrevious, $expected)
+    {
+        $this->setSignalHandler($signo, SIG_DFL);
+
+        $path = tempnam(sys_get_temp_dir(), 'monolog-');
+        $this->assertNotFalse($path);
+
+        $pid = pcntl_fork();
+        if ($pid === 0) {  // Child.
+            $streamHandler = new StreamHandler($path);
+            $streamHandler->setFormatter($this->getIdentityFormatter());
+            $logger = new Logger('test', array($streamHandler));
+            $errHandler = new SignalHandler($logger);
+            $errHandler->registerSignalHandler($signo, LogLevel::INFO, $callPrevious, false, false);
+            pcntl_sigprocmask(SIG_SETMASK, array(SIGCONT));
+            posix_kill(posix_getpid(), $signo);
+            pcntl_signal_dispatch();
+            // If $callPrevious is true, SIGINT should terminate by this line.
+            pcntl_sigprocmask(SIG_BLOCK, array(), $oldset);
+            file_put_contents($path, implode(' ', $oldset), FILE_APPEND);
+            posix_kill(posix_getpid(), $signo);
+            pcntl_signal_dispatch();
+            exit();
+        }
+
+        $this->assertNotSame(-1, $pid);
+        $this->assertNotSame(-1, pcntl_waitpid($pid, $status));
+        $this->assertNotSame(-1, $status);
+        $this->assertSame($expected, file_get_contents($path));
+    }
+
+    public function defaultPreviousProvider()
+    {
+        if (!defined('SIGCONT') || !defined('SIGINT') || !defined('SIGURG')) {
+            return array();
+        }
+
+        return array(
+            array(SIGINT, false, 'Program received signal SIGINT'.SIGCONT.'Program received signal SIGINT'),
+            array(SIGINT, true, 'Program received signal SIGINT'),
+            array(SIGURG, false, 'Program received signal SIGURG'.SIGCONT.'Program received signal SIGURG'),
+            array(SIGURG, true, 'Program received signal SIGURG'.SIGCONT.'Program received signal SIGURG'),
+        );
+    }
+
+    /**
+     * @dataProvider callablePreviousProvider
+     * @depends testRegisterSignalHandler
+     * @requires function pcntl_signal_get_handler
+     */
+    public function testRegisterCallablePreviousSignalHandler($callPrevious)
+    {
+        $this->setSignalHandler(SIGURG, SIG_IGN);
+
+        $logger = new Logger('test', array($handler = new TestHandler));
+        $errHandler = new SignalHandler($logger);
+        $previousCalled = 0;
+        pcntl_signal(SIGURG, function ($signo, array $siginfo = null) use (&$previousCalled) {
+            ++$previousCalled;
+        });
+        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, $callPrevious, false, false);
+        $this->assertTrue(posix_kill(posix_getpid(), SIGURG));
+        $this->assertTrue(pcntl_signal_dispatch());
+        $this->assertCount(1, $handler->getRecords());
+        $this->assertTrue($handler->hasInfoThatContains('SIGURG'));
+        $this->assertSame($callPrevious ? 1 : 0, $previousCalled);
+    }
+
+    public function callablePreviousProvider()
+    {
+        return array(
+            array(false),
+            array(true),
+        );
+    }
+
+    /**
+     * @dataProvider restartSyscallsProvider
+     * @depends testRegisterDefaultPreviousSignalHandler
+     * @requires function pcntl_fork
+     * @requires function pcntl_waitpid
+     */
+    public function testRegisterSyscallRestartingSignalHandler($restartSyscalls)
+    {
+        $this->setSignalHandler(SIGURG, SIG_IGN);
+
+        $parentPid = posix_getpid();
+        $microtime = microtime(true);
+
+        $pid = pcntl_fork();
+        if ($pid === 0) {  // Child.
+            usleep(100000);
+            posix_kill($parentPid, SIGURG);
+            usleep(100000);
+            exit();
+        }
+
+        $this->assertNotSame(-1, $pid);
+        $logger = new Logger('test', array($handler = new TestHandler));
+        $errHandler = new SignalHandler($logger);
+        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, false, $restartSyscalls, false);
+        if ($restartSyscalls) {
+            // pcntl_wait is expected to be restarted after the signal handler.
+            $this->assertNotSame(-1, pcntl_waitpid($pid, $status));
+        } else {
+            // pcntl_wait is expected to be interrupted when the signal handler is invoked.
+            $this->assertSame(-1, pcntl_waitpid($pid, $status));
+        }
+        $this->assertSame($restartSyscalls, microtime(true) - $microtime > 0.15);
+        $this->assertTrue(pcntl_signal_dispatch());
+        $this->assertCount(1, $handler->getRecords());
+        if ($restartSyscalls) {
+            // The child has already exited.
+            $this->assertSame(-1, pcntl_waitpid($pid, $status));
+        } else {
+            // The child has not exited yet.
+            $this->assertNotSame(-1, pcntl_waitpid($pid, $status));
+        }
+    }
+
+    public function restartSyscallsProvider()
+    {
+        return array(
+            array(false),
+            array(true),
+            array(false),
+            array(true),
+        );
+    }
+
+    /**
+     * @dataProvider asyncProvider
+     * @depends testRegisterDefaultPreviousSignalHandler
+     * @requires function pcntl_async_signals
+     */
+    public function testRegisterAsyncSignalHandler($initialAsync, $desiredAsync, $expectedBefore, $expectedAfter)
+    {
+        $this->setSignalHandler(SIGURG, SIG_IGN);
+        pcntl_async_signals($initialAsync);
+
+        $logger = new Logger('test', array($handler = new TestHandler));
+        $errHandler = new SignalHandler($logger);
+        $errHandler->registerSignalHandler(SIGURG, LogLevel::INFO, false, false, $desiredAsync);
+        $this->assertTrue(posix_kill(posix_getpid(), SIGURG));
+        $this->assertCount($expectedBefore, $handler->getRecords());
+        $this->assertTrue(pcntl_signal_dispatch());
+        $this->assertCount($expectedAfter, $handler->getRecords());
+    }
+
+    public function asyncProvider()
+    {
+        return array(
+            array(false, false, 0, 1),
+            array(false, null, 0, 1),
+            array(false, true, 1, 1),
+            array(true, false, 0, 1),
+            array(true, null, 1, 1),
+            array(true, true, 1, 1),
+        );
+    }
+
+}