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Feature/support feature flags #12

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Feature/support feature flags #12

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692e8ba
Upgrade phplint
imhmdb Jun 9, 2021
706baa3
Feature/support feature flags decide API
imhmdb Jun 9, 2021
ceae2ac
Change default host to app.posthog.com
imhmdb Jun 9, 2021
8c3d022
Remove extra line
imhmdb Jun 9, 2021
dbc3357
Extract http client functionalities
imhmdb Jun 9, 2021
2a35f87
(WIP) Rework feature flags based on spec `https://github.com/PostHog/…
imhmdb Jun 9, 2021
25aefc7
Don't set payload on get requests
imhmdb Jun 10, 2021
3b4bf56
Implement isSimpleFlagEnabled
imhmdb Jun 10, 2021
bfc6cd7
Use LONG_SCALE const
imhmdb Jun 10, 2021
dcff4fa
Fix is_simple_flag tests by mocking response
imhmdb Jun 12, 2021
09c443d
Merge remote-tracking branch 'upstream/master'
imhmdb Jun 12, 2021
587a1c6
Fix: make rolloutPercentage nullable in isSimpleFlagEnabled
imhmdb Jun 12, 2021
5ddb701
Add test case for isFeatureEnabled with the simple flag in the mocked…
imhmdb Jun 12, 2021
bf461fe
Fix user agent undefined array key
imhmdb Jun 14, 2021
86ef9fb
Cleanup isFeatureEnabled docblock
imhmdb Jun 14, 2021
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5 changes: 3 additions & 2 deletions composer.json
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Expand Up @@ -18,7 +18,7 @@
"php": ">=7.1"
},
"require-dev": {
"overtrue/phplint": "^2.3",
"overtrue/phplint": "^3.0",
"phpunit/phpunit": "^9.0",
"squizlabs/php_codesniffer": "^3.6"
},
Expand All @@ -29,7 +29,8 @@
},
"autoload-dev": {
"psr-4": {
"PostHog\\Test\\": "test/"
"PostHog\\Test\\": "test/",
"PostHog\\Test\\Assets\\": "test/assests"
}
},
"bin": [
Expand Down
166 changes: 153 additions & 13 deletions lib/Client.php
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Expand Up @@ -2,6 +2,7 @@

namespace PostHog;

use Exception;
use PostHog\Consumer\File;
use PostHog\Consumer\ForkCurl;
use PostHog\Consumer\LibCurl;
Expand All @@ -10,35 +11,61 @@
class Client
{

private const CONSUMERS = [
"socket" => Socket::class,
"file" => File::class,
"fork_curl" => ForkCurl::class,
"lib_curl" => LibCurl::class,
];

private const LONG_SCALE = 0xFFFFFFFFFFFFFFF;

/**
* @var string
*/
private $apiKey;

/**
* Consumer object handles queueing and bundling requests to PostHog.
*
* @var Consumer
*/
protected $consumer;

protected $featureFlags = null;

/**
* @var string|null
*/
private $personalApiKey;

/**
* @var HttpClient
*/
private $httpClient;


/**
* Create a new posthog object with your app's API key
* key
*
* @param string $apiKey
* @param array $options array of consumer options [optional]
* @param string Consumer constructor to use, libcurl by default.
*
* @param HttpClient|null $httpClient
*/
public function __construct($apiKey, $options = array())
public function __construct(string $apiKey, array $options = [], ?HttpClient $httpClient = null)
{
$consumers = array(
"socket" => Socket::class,
"file" => File::class,
"fork_curl" => ForkCurl::class,
"lib_curl" => LibCurl::class,
);

// Use our socket libcurl by default
$consumer_type = $options["consumer"] ?? "lib_curl";
$Consumer = $consumers[$consumer_type];
$this->apiKey = $apiKey;
$Consumer = self::CONSUMERS[$options["consumer"] ?? "lib_curl"];
$this->consumer = new $Consumer($apiKey, $options);
$this->personalApiKey = $options["personal_api_key"] ?? null;
$this->httpClient = $httpClient !== null ? $httpClient : new HttpClient(
$options['host'] ?? "app.posthog.com",
$options['ssl'] ?? true,
10000,
false,
$options["debug"] ?? false
);
}

public function __destruct()
Expand Down Expand Up @@ -79,6 +106,81 @@ public function identify(array $message)
return $this->consumer->identify($message);
}

/**
* decide if the feature flag is enabled for this distinct id.
*
* @param string $key
* @param string $distinctId
* @param mixed $defaultValue
* @return bool
* @throws Exception
*/
public function isFeatureEnabled(string $key, string $distinctId, $defaultValue = false): bool
{
if (null === $this->personalApiKey) {
throw new Exception(
"To use feature flags, please set a personal_api_key.
For More information: https://posthog.com/docs/api/overview"
);
}

if (null === $this->featureFlags) {
$this->loadFeatureFlags();
}

if (null === $this->featureFlags) { // if loading failed.
return $defaultValue;
}

$selectedFlag = null;
foreach ($this->featureFlags as $flag) {
if ($flag['key'] === $key) {
$selectedFlag = $flag;
}
}
if (null === $selectedFlag) {
return $defaultValue;
}

if ((bool) $selectedFlag['is_simple_flag']) {
$result = $this->isSimpleFlagEnabled($key, $distinctId, $flag['rollout_percentage']);
} else {
$result = in_array($key, $this->fetchEnabledFeatureFlags($distinctId));
}

$this->capture([
"properties" => [
'$feature_flag' => $key,
'$feature_flag_response' => $result,
],
"distinct_id" => $distinctId,
"event" => '$feature_flag_called',
]);

return $result ?? $defaultValue;
}


/**
* @param string $distinctId
* @return array
* @throws Exception
*/
public function fetchEnabledFeatureFlags(string $distinctId): array
{
return json_decode($this->decide($distinctId), true)['featureFlags'] ?? [];
}

public function decide(string $distinctId)
{
$payload = json_encode([
'api_key' => $this->apiKey,
'distinct_id' => $distinctId,
]);

return $this->httpClient->sendRequest('/decide/', $payload)->getResponse();
}

/**
* Aliases from one user id to another
*
Expand Down Expand Up @@ -203,4 +305,42 @@ private function message($msg)

return $msg;
}

private function loadFeatureFlags(): void
{
$response = $this->httpClient->sendRequest(
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Ok so I tried this locally and it didn't work. I suspect this is a potential problem. We're sending a POST request here, when it should actually be a GET request.

'/api/feature_flag',
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We've made a change since you last edited this, so this should now be /api/feature_flag?token=project_api_key_here.

No way you could have known though!

null,
[
"Authorization: Bearer $this->personalApiKey",
]
);
if (401 === $response->getResponseCode()) {
throw new Exception(
"Your personalApiKey is invalid. Are you sure you're not using your Project API key?
More information: https://posthog.com/docs/api/overview"
);
}

$responseBody = json_decode($response->getResponse(), true);
if (null === $responseBody) {
return;
}

if (empty($responseBody)) {
$this->featureFlags = [];
}

$this->featureFlags = $responseBody['results'];
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Another change we made is that this should filter by active flags.

The active property is in $responseBody['results'][i]['active']

}

private function isSimpleFlagEnabled(string $key, string $distinctId, ?int $rolloutPercentage): bool
{
if (! (bool) $rolloutPercentage) {
return true;
}
$hexValueOfHash = sha1("$key.$distinctId", false);
$integerRepresentationOfHashSubset = intval(substr($hexValueOfHash, 0, 15), 16);
return ($integerRepresentationOfHashSubset / self::LONG_SCALE) <= ($rolloutPercentage / 100);
}
}
8 changes: 2 additions & 6 deletions lib/Consumer/ForkCurl.php
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Expand Up @@ -47,13 +47,9 @@ public function flushBatch($messages)
$payload = escapeshellarg($payload);

$protocol = $this->ssl() ? "https://" : "http://";
if ($this->host) {
$host = $this->host;
} else {
$host = "t.posthog.com";
}

$path = "/batch/";
$url = $protocol . $host . $path;
$url = $protocol . $this->host . $path;

$cmd = "curl -X POST -H 'Content-Type: application/json'";

Expand Down
98 changes: 22 additions & 76 deletions lib/Consumer/LibCurl.php
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Expand Up @@ -2,11 +2,16 @@

namespace PostHog\Consumer;

use PostHog\HttpClient;
use PostHog\QueueConsumer;

class LibCurl extends QueueConsumer
{
protected $type = "LibCurl";
/**
* @var HttpClient
*/
private $httpClient;

/**
* Creates a new queued libcurl consumer
Expand All @@ -16,9 +21,17 @@ class LibCurl extends QueueConsumer
* number "max_queue_size" - the max size of messages to enqueue
* number "batch_size" - how many messages to send in a single request
*/
public function __construct($apiKey, $options = array())
public function __construct($apiKey, $options = [])
{
parent::__construct($apiKey, $options);
$this->httpClient = new HttpClient(
$this->host,
$this->ssl(),
$this->maximum_backoff_duration,
$this->compress_request,
$this->debug(),
$this->options['error_handler'] ?? null
);
}

/**
Expand All @@ -42,7 +55,6 @@ public function flushBatch($messages)
{
$body = $this->payload($messages);
$payload = json_encode($body);
$apiKey = $this->apiKey;

// Verify message size is below than 32KB
if (strlen($payload) >= 32 * 1024) {
Expand All @@ -58,79 +70,13 @@ public function flushBatch($messages)
$payload = gzencode($payload);
}

$protocol = $this->ssl() ? "https://" : "http://";
if ($this->host) {
$host = $this->host;
} else {
$host = "t.posthog.com";
}
$path = "/batch/";
$url = $protocol . $host . $path;

$backoff = 100; // Set initial waiting time to 100ms

while ($backoff < $this->maximum_backoff_duration) {
$start_time = microtime(true);

// open connection
$ch = curl_init();

// set the url, number of POST vars, POST data
curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);

// set variables for headers
$header = array();
$header[] = 'Content-Type: application/json';

if ($this->compress_request) {
$header[] = 'Content-Encoding: gzip';
}

// Send user agent in the form of {library_name}/{library_version} as per RFC 7231.
$libName = $messages[0]['library'];
$libVersion = $messages[0]['library_version'];
$header[] = "User-Agent: ${libName}/${libVersion}";

curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// retry failed requests just once to diminish impact on performance
$httpResponse = $this->executePost($ch);

//close connection
curl_close($ch);

$elapsed_time = microtime(true) - $start_time;

if (200 != $httpResponse) {
// log error
$this->handleError($ch, $httpResponse);

if (($httpResponse >= 500 && $httpResponse <= 600) || 429 == $httpResponse) {
// If status code is greater than 500 and less than 600, it indicates server error
// Error code 429 indicates rate limited.
// Retry uploading in these cases.
usleep($backoff * 1000);
$backoff *= 2;
} elseif ($httpResponse >= 400) {
break;
} elseif ($httpResponse == 0) {
break;
}
} else {
break; // no error
}
}

return $httpResponse;
}

public function executePost($ch)
{
curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);

return $httpCode;
return $this->httpClient->sendRequest(
'/batch/',
$payload,
[
// Send user agent in the form of {library_name}/{library_version} as per RFC 7231.
"User-Agent: {$messages[0]['library']}/{$messages[0]['library_version']}",
]
)->getResponse();
}
}