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Fixed half open state transition #5

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merged 1 commit into from
May 13, 2019
Merged

Fixed half open state transition #5

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8 changes: 5 additions & 3 deletions src/PartialCircuitBreaker.php
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Original file line number Diff line number Diff line change
Expand Up @@ -85,17 +85,19 @@ public function isClosed(): bool
* @param string $state the Place state
* @param string $service the service URI
*
* @return bool
* @return Transaction
*/
protected function moveStateTo($state, $service): bool
protected function moveStateTo($state, $service): Transaction
{
$this->currentPlace = $this->places[$state];
$transaction = SimpleTransaction::createFromPlace(
$this->currentPlace,
$service
);

return $this->storage->saveTransaction($service, $transaction);
$this->storage->saveTransaction($service, $transaction);

return $transaction;
}

/**
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12 changes: 6 additions & 6 deletions src/SimpleCircuitBreaker.php
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Original file line number Diff line number Diff line change
Expand Up @@ -24,15 +24,15 @@ public function call(string $service, callable $fallback, array $serviceParamete
{
$transaction = $this->initTransaction($service);

try {
if ($this->isOpened()) {
if ($this->canAccessService($transaction)) {
$this->moveStateTo(States::HALF_OPEN_STATE, $service);
}

if ($this->isOpened()) {
if (!$this->canAccessService($transaction)) {
return (string) $fallback();
}

$transaction = $this->moveStateTo(States::HALF_OPEN_STATE, $service);
}

try {
$response = $this->request($service);
$this->moveStateTo(States::CLOSED_STATE, $service);

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22 changes: 11 additions & 11 deletions src/SymfonyCircuitBreaker.php
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Original file line number Diff line number Diff line change
Expand Up @@ -38,20 +38,20 @@ public function call(string $service, callable $fallback, array $serviceParamete
{
$transaction = $this->initTransaction($service);

try {
if ($this->isOpened()) {
if ($this->canAccessService($transaction)) {
$this->moveStateTo(States::HALF_OPEN_STATE, $service);
$this->dispatch(
Transitions::CHECKING_AVAILABILITY_TRANSITION,
$service,
$serviceParameters
);
}

if ($this->isOpened()) {
if (!$this->canAccessService($transaction)) {
return (string) $fallback();
}

$transaction = $this->moveStateTo(States::HALF_OPEN_STATE, $service);
$this->dispatch(
Transitions::CHECKING_AVAILABILITY_TRANSITION,
$service,
$serviceParameters
);
}

try {
$response = $this->request($service, $serviceParameters);
$this->moveStateTo(States::CLOSED_STATE, $service);
$this->dispatch(
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2 changes: 1 addition & 1 deletion tests/CircuitBreakerTestCase.php
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ protected function getSystem(): MainSystem
return MainSystem::createFromArray(
[
'open' => [0, 0.0, 1.0], // threshold 1.0s
'half_open' => [0, 0.2, 0.0], // timeout 0.2s to test the service
'half_open' => [1, 0.4, 0.0], // timeout 0.4s to test the service with a better timeout
'closed' => [2, 0.2, 0.0], // 2 failures allowed, 0.2s timeout
]
);
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80 changes: 24 additions & 56 deletions tests/CircuitBreakerWorkflowTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,11 @@

class CircuitBreakerWorkflowTest extends CircuitBreakerTestCase
{
/**
* @var int the number of seconds to wait before try to reach again the service
*/
private const OPEN_THRESHOLD = 1;

/**
* When we use the circuit breaker on unreachable service
* the fallback response is used.
Expand All @@ -22,7 +27,7 @@ class CircuitBreakerWorkflowTest extends CircuitBreakerTestCase
*/
public function testCircuitBreakerIsInClosedStateAtStart(CircuitBreaker $circuitBreaker): void
{
$this->assertSame('CLOSED', $circuitBreaker->getState());
$this->assertTrue($circuitBreaker->isClosed());

$this->assertSame(
'{}',
Expand All @@ -41,49 +46,22 @@ public function testCircuitBreakerIsInClosedStateAtStart(CircuitBreaker $circuit
* @depends testCircuitBreakerIsInClosedStateAtStart
* @dataProvider getCircuitBreakers
*/
public function testCircuitBreakerWillBeOpenedInCaseOfFailures(CircuitBreaker $circuitBreaker): void
public function testCircuitBreakerWillBeOpenInCaseOfFailures(CircuitBreaker $circuitBreaker): void
{
// CLOSED
$circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());

$this->assertSame('OPEN', $circuitBreaker->getState());
$this->assertSame(
'{}',
$circuitBreaker->call(
'https://httpbin.org/get/foo',
$this->createFallbackResponse()
)
);
}

/**
* Once the threshold is reached, the circuit breaker
* try again to reach the service. This time, the service
* is not reachable.
*
* @param CircuitBreaker $circuitBreaker
* @depends testCircuitBreakerIsInClosedStateAtStart
* @depends testCircuitBreakerWillBeOpenedInCaseOfFailures
* @dataProvider getCircuitBreakers
*/
public function testAfterTheThresholdTheCircuitBreakerMovesInHalfOpenState(CircuitBreaker $circuitBreaker): void
{
// CLOSED
$circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());
// OPEN
$circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());
$this->assertTrue($circuitBreaker->isClosed());
$response = $circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());
$this->assertSame('{}', $response);

$this->waitFor(1);
// NOW HALF OPEN
//After two failed calls switch to OPEN state
$this->assertTrue($circuitBreaker->isOpened());
$this->assertSame(
'{}',
$circuitBreaker->call(
'https://httpbin.org/get/foo',
$this->createFallbackResponse()
)
);
$this->assertSame('HALF OPEN', $circuitBreaker->getState());
$this->assertTrue($circuitBreaker->isHalfOpened());
}

/**
Expand All @@ -92,41 +70,31 @@ public function testAfterTheThresholdTheCircuitBreakerMovesInHalfOpenState(Circu
*
* @param CircuitBreaker $circuitBreaker
* @depends testCircuitBreakerIsInClosedStateAtStart
* @depends testCircuitBreakerWillBeOpenedInCaseOfFailures
* @depends testAfterTheThresholdTheCircuitBreakerMovesInHalfOpenState
* @depends testCircuitBreakerWillBeOpenInCaseOfFailures
* @dataProvider getCircuitBreakers
*/
public function testOnceInHalfOpenModeServiceIsFinallyReachable(CircuitBreaker $circuitBreaker): void
{
// CLOSED
$circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());
// OPEN
$circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());

$this->waitFor(1);
// NOW HALF OPEN
$this->assertSame(
'{}',
$circuitBreaker->call(
'https://httpbin.org/get/foo',
$this->createFallbackResponse()
)
);
$this->assertSame('HALF OPEN', $circuitBreaker->getState());
$this->assertTrue($circuitBreaker->isHalfOpened());
// CLOSED - first call fails (twice)
$this->assertTrue($circuitBreaker->isClosed());
$response = $circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());
$this->assertSame('{}', $response);
$this->assertTrue($circuitBreaker->isOpened());

$this->waitFor(1);
// OPEN - no call to client
$response = $circuitBreaker->call('https://httpbin.org/get/foo', $this->createFallbackResponse());
$this->assertSame('{}', $response);
$this->assertTrue($circuitBreaker->isOpened());
$this->waitFor(2 * self::OPEN_THRESHOLD);

// CLOSED
// SWITCH TO HALF OPEN - retry to call the service
$this->assertSame(
'{"hello": "world"}',
$circuitBreaker->call(
'https://httpbin.org/get/foo',
$this->createFallbackResponse()
)
);

$this->assertSame('CLOSED', $circuitBreaker->getState());
$this->assertTrue($circuitBreaker->isClosed());
}

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