philkra · philkra · Feb 21, 2019 · Feb 16, 2019 · Feb 16, 2019 · Feb 21, 2019
diff --git a/src/Agent.php b/src/Agent.php
@@ -129,16 +129,19 @@ public function __construct(array $config, array $sharedContext = [], EventFacto
      *
      * @return Transaction
      */
-    public function startTransaction(string $name, array $context = []): Transaction
+    public function startTransaction(string $name, array $context = [], float $start = null): Transaction
     {
         // Create and Store Transaction
         $this->transactionsStore->register(
-            $this->eventFactory->createTransaction($name, array_replace_recursive($this->sharedContext, $context))
+            $this->eventFactory->createTransaction($name, array_replace_recursive($this->sharedContext, $context), $start)
         );
 
         // Start the Transaction
         $transaction = $this->transactionsStore->fetch($name);
-        $transaction->start();
+
+        if (null === $start) {
+            $transaction->start();
+        }
 
         return $transaction;
     }

diff --git a/src/Events/DefaultEventFactory.php b/src/Events/DefaultEventFactory.php
@@ -15,8 +15,8 @@ public function createError(\Throwable $throwable, array $contexts): Error
     /**
      * {@inheritdoc}
      */
-    public function createTransaction(string $name, array $contexts): Transaction
+    public function createTransaction(string $name, array $contexts, float $start = null): Transaction
     {
-        return new Transaction($name, $contexts);
+        return new Transaction($name, $contexts, $start);
     }
 }
diff --git a/src/Events/EventFactoryInterface.php b/src/Events/EventFactoryInterface.php
@@ -20,5 +20,5 @@ public function createError(\Throwable $throwable, array $contexts): Error;
      * @param string $name
      * @param array  $contexts
      */
-    public function createTransaction(string $name, array $contexts): Transaction;
+    public function createTransaction(string $name, array $contexts, float $start = null): Transaction;
 }
diff --git a/src/Events/Transaction.php b/src/Events/Transaction.php
@@ -51,11 +51,11 @@ class Transaction extends EventBean implements \JsonSerializable
     * @param string $name
     * @param array $contexts
     */
-    public function __construct(string $name, array $contexts)
+    public function __construct(string $name, array $contexts, $start = null)
     {
         parent::__construct($contexts);
         $this->setTransactionName($name);
-        $this->timer = new Timer();
+        $this->timer = new Timer($start);
     }
 
     /**

diff --git a/src/Exception/Timer/AlreadyRunningException.php b/src/Exception/Timer/AlreadyRunningException.php
@@ -0,0 +1,13 @@
+<?php
+namespace PhilKra\Exception\Timer;
+
+/**
+ * Trying to stop a Timer that is already running
+ */
+class AlreadyRunningException extends \Exception {
+
+  public function __construct( string $message = '', int $code = 0, \Throwable $previous = NULL ) {
+    parent::__construct( 'Can\'t start a timer which is already running.', $code, $previous );
+  }
+
+}
diff --git a/src/Helper/Timer.php b/src/Helper/Timer.php
@@ -2,6 +2,7 @@
 
 namespace PhilKra\Helper;
 
+use PhilKra\Exception\Timer\AlreadyRunningException;
 use PhilKra\Exception\Timer\NotStartedException;
 use PhilKra\Exception\Timer\NotStoppedException;
 
@@ -24,13 +25,23 @@ class Timer
      */
     private $stoppedOn = null;
 
+    public function __construct(float $startTime = null)
+    {
+        $this->startedOn = $startTime;
+    }
+
     /**
      * Start the Timer
      *
      * @return void
+     * @throws AlreadyRunningException
      */
     public function start()
     {
+        if (null !== $this->startedOn) {
+            throw new AlreadyRunningException();
+        }
+
         $this->startedOn = microtime(true);
     }
 

diff --git a/tests/AgentTest.php b/tests/AgentTest.php
@@ -35,6 +35,32 @@ public function testStartAndStopATransaction() {
     $this->assertNotEmpty( $summary['backtrace'] );
   }
 
+  /**
+   * @covers \PhilKra\Agent::__construct
+   * @covers \PhilKra\Agent::startTransaction
+   * @covers \PhilKra\Agent::stopTransaction
+   * @covers \PhilKra\Agent::getTransaction
+   */
+  public function testStartAndStopATransactionWithExplicitStart() {
+    $agent = new Agent( [ 'appName' => 'phpunit_1' ] );
+
+    // Create a Transaction, wait and Stop it
+    $name = 'trx';
+    $agent->startTransaction( $name, [], microtime(true) - 1);
+    usleep( 500 * 1000 ); // sleep milliseconds
+    $agent->stopTransaction( $name );
+
+    // Transaction Summary must be populated
+    $summary = $agent->getTransaction( $name )->getSummary();
+
+    $this->assertArrayHasKey( 'duration', $summary );
+    $this->assertArrayHasKey( 'backtrace', $summary );
+
+    // Expect duration in milliseconds
+    $this->assertDurationIsWithinThreshold(1500, $summary['duration'], 150);
+    $this->assertNotEmpty( $summary['backtrace'] );
+  }
+
   /**
    * @depends testStartAndStopATransaction
    *

diff --git a/tests/Helper/TimerTest.php b/tests/Helper/TimerTest.php
@@ -1,6 +1,7 @@
 <?php
 namespace PhilKra\Tests\Helper;
 
+use PhilKra\Exception\Timer\AlreadyRunningException;
 use \PhilKra\Helper\Timer;
 use PhilKra\Tests\TestCase;
 
@@ -92,4 +93,31 @@ public function testCannotBeStoppedWithoutStart() {
     $timer->stop();
   }
 
+    /**
+     * @covers \PhilKra\Helper\Timer::start
+     * @covers \PhilKra\Helper\Timer::getDurationInMilliseconds
+     */
+    public function testCanBeStartedWithExplicitStartTime() {
+        $timer = new Timer(microtime(true) - .5); // Start timer 500 milliseconds ago
+
+        usleep(500 * 1000); // Sleep for 500 milliseconds
+
+        $timer->stop();
+
+        $duration = $timer->getDurationInMilliseconds();
+
+        // Duration should be more than 1000 milliseconds
+        //  sum of initial offset and sleep
+        $this->assertGreaterThanOrEqual(1000, $duration);
+    }
+
+    /**
+     * @covers \PhilKra\Helper\Timer::start
+     */
+    public function testCannotBeStartedIfAlreadyRunning() {
+        $timer = new Timer(microtime(true));
+
+        $this->expectException(AlreadyRunningException::class);
+        $timer->start();
+    }
 }
diff --git a/tests/TestCase.php b/tests/TestCase.php
@@ -12,14 +12,12 @@
 abstract class TestCase extends \PHPUnit\Framework\TestCase
 {
 
-    protected function assertDurationIsWithinThreshold(int $sleptMilliseconds, float $timedDuration)
+    protected function assertDurationIsWithinThreshold(int $expectedMilliseconds, float $timedDuration, float $maxOverhead = 10)
     {
-        $this->assertGreaterThanOrEqual( $sleptMilliseconds, $timedDuration );
+        $this->assertGreaterThanOrEqual( $expectedMilliseconds, $timedDuration );
 
-        // Generally we should expect less than 1ms of overhead, but that is not guaranteed.
-        // 10ms should be enough unless the test system is really unresponsive.
-        $overhead = ($timedDuration - $sleptMilliseconds);
-        $this->assertLessThanOrEqual( 10, $overhead );
+        $overhead = ($timedDuration - $expectedMilliseconds);
+        $this->assertLessThanOrEqual( $maxOverhead, $overhead );
     }
 
 }