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jsteemannjsteemann
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add automatic failover to driver
this is not yet ideal, because the driver will still connect to the configured endpoint every time, only to find out that there is a new leader. it could be significantly improved by storing the current leader in some sort of cache
1 parent b2157e7 commit 5a3e2e2

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7 files changed

+175
-20
lines changed

7 files changed

+175
-20
lines changed

‎lib/ArangoDBClient/Connection.php

Lines changed: 67 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -206,9 +206,11 @@ public function getOption($name)
206206
*/
207207
public function get($url, array $customHeaders = [])
208208
{
209-
$response = $this->executeRequest(HttpHelper::METHOD_GET, $url, '', $customHeaders);
209+
return $this->handleFailover(function() use (&$url, &$customHeaders) {
210+
$response = $this->executeRequest(HttpHelper::METHOD_GET, $url, '', $customHeaders);
210211

211-
return $this->parseResponse($response);
212+
return $this->parseResponse($response);
213+
});
212214
}
213215

214216
/**
@@ -224,9 +226,11 @@ public function get($url, array $customHeaders = [])
224226
*/
225227
public function post($url, $data, array $customHeaders = [])
226228
{
227-
$response = $this->executeRequest(HttpHelper::METHOD_POST, $url, $data, $customHeaders);
229+
return $this->handleFailover(function() use (&$url, &$data, &$customHeaders) {
230+
$response = $this->executeRequest(HttpHelper::METHOD_POST, $url, $data, $customHeaders);
228231

229-
return $this->parseResponse($response);
232+
return $this->parseResponse($response);
233+
});
230234
}
231235

232236
/**
@@ -242,9 +246,11 @@ public function post($url, $data, array $customHeaders = [])
242246
*/
243247
public function put($url, $data, array $customHeaders = [])
244248
{
245-
$response = $this->executeRequest(HttpHelper::METHOD_PUT, $url, $data, $customHeaders);
249+
return $this->handleFailover(function() use (&$url, &$data, &$customHeaders) {
250+
$response = $this->executeRequest(HttpHelper::METHOD_PUT, $url, $data, $customHeaders);
246251

247-
return $this->parseResponse($response);
252+
return $this->parseResponse($response);
253+
});
248254
}
249255

250256
/**
@@ -259,9 +265,11 @@ public function put($url, $data, array $customHeaders = [])
259265
*/
260266
public function head($url, array $customHeaders = [])
261267
{
262-
$response = $this->executeRequest(HttpHelper::METHOD_HEAD, $url, '', $customHeaders);
268+
return $this->handleFailover(function() use (&$url, &$data, &$customHeaders) {
269+
$response = $this->executeRequest(HttpHelper::METHOD_HEAD, $url, '', $customHeaders);
263270

264-
return $this->parseResponse($response);
271+
return $this->parseResponse($response);
272+
});
265273
}
266274

267275
/**
@@ -276,10 +284,12 @@ public function head($url, array $customHeaders = [])
276284
* @return HttpResponse
277285
*/
278286
public function patch($url, $data, array $customHeaders = [])
279-
{
280-
$response = $this->executeRequest(HttpHelper::METHOD_PATCH, $url, $data, $customHeaders);
287+
{
288+
return $this->handleFailover(function() use (&$url, &$data, &$customHeaders) {
289+
$response = $this->executeRequest(HttpHelper::METHOD_PATCH, $url, $data, $customHeaders);
281290

282-
return $this->parseResponse($response);
291+
return $this->parseResponse($response);
292+
});
283293
}
284294

285295
/**
@@ -295,9 +305,28 @@ public function patch($url, $data, array $customHeaders = [])
295305
*/
296306
public function delete($url, array $customHeaders = [], $data = '')
297307
{
298-
$response = $this->executeRequest(HttpHelper::METHOD_DELETE, $url, $data, $customHeaders);
308+
return $this->handleFailover(function() use (&$url, &$data) {
309+
$response = $this->executeRequest(HttpHelper::METHOD_DELETE, $url, $data, $customHeaders);
299310

300-
return $this->parseResponse($response);
311+
return $this->parseResponse($response);
312+
});
313+
}
314+
315+
316+
private function handleFailover($cb) {
317+
$tries = 0;
318+
319+
while (true) {
320+
try {
321+
return $cb();
322+
} catch (FailoverException $e) {
323+
// got a failover. now try again...
324+
if ($tries++ >= $this->_options[ConnectionOptions::OPTION_FAILOVER_TRIES]) {
325+
throw $e;
326+
}
327+
}
328+
// let all other exception types escape from here
329+
}
301330
}
302331

303332

@@ -477,7 +506,7 @@ private function executeRequest($method, $url, $data, array $customHeaders = [])
477506
}
478507

479508
$response = new HttpResponse($result, $url, $method, $wasAsync);
480-
509+
481510
if ($traceFunc) {
482511
// call tracer func
483512
if ($this->_options[ConnectionOptions::OPTION_ENHANCED_TRACE]) {
@@ -518,6 +547,30 @@ public function parseResponse(HttpResponse $response)
518547
if ($body !== '') {
519548
// check if we can find details in the response body
520549
$details = json_decode($body, true);
550+
551+
// handle failover
552+
if (is_array($details) && isset($details['errorNum'])) {
553+
if ($details['errorNum'] === 1496) {
554+
// not a leader. now try to find new leader
555+
$leader = $response->getLeaderEndpointHeader();
556+
if ($leader) {
557+
// close existing connection
558+
if ($this->_handle && is_resource($this->_handle)) {
559+
@fclose($this->_handle);
560+
$this->_handle = 0;
561+
}
562+
563+
// have a different leader
564+
$this->_options[ConnectionOptions::OPTION_ENDPOINT] = $leader;
565+
$this->updateHttpHeader();
566+
567+
$exception = new FailoverException($details['errorMessage'], $details['code']);
568+
$exception->setLeader($leader);
569+
throw $exception;
570+
}
571+
}
572+
}
573+
521574
if (is_array($details) && isset($details['errorMessage'])) {
522575
// yes, we got details
523576
$exception = new ServerException($details['errorMessage'], $details['code']);

‎lib/ArangoDBClient/ConnectionOptions.php

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -56,6 +56,11 @@ class ConnectionOptions implements \ArrayAccess
5656
* Timeout value index constant
5757
*/
5858
const OPTION_TIMEOUT = 'timeout';
59+
60+
/**
61+
* Number of tries for failover constant
62+
*/
63+
const OPTION_FAILOVER_TRIES = 'failoverTries';
5964

6065
/**
6166
* Trace function index constant
@@ -304,6 +309,7 @@ private static function getDefaults()
304309
self::OPTION_ENDPOINT => null,
305310
self::OPTION_HOST => null,
306311
self::OPTION_PORT => DefaultValues::DEFAULT_PORT,
312+
self::OPTION_FAILOVER_TRIES => DefaultValues::DEFAULT_FAILOVER_TRIES,
307313
self::OPTION_TIMEOUT => DefaultValues::DEFAULT_TIMEOUT,
308314
self::OPTION_CREATE => DefaultValues::DEFAULT_CREATE,
309315
self::OPTION_UPDATE_POLICY => DefaultValues::DEFAULT_UPDATE_POLICY,

‎lib/ArangoDBClient/DefaultValues.php

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,11 @@ abstract class DefaultValues
3030
*/
3131
const DEFAULT_TIMEOUT = 30;
3232

33+
/**
34+
* Default number of failover tries (used in case there is an automatic failover)
35+
*/
36+
const DEFAULT_FAILOVER_TRIES = 2;
37+
3338
/**
3439
* Default Authorization type (use HTTP basic authentication)
3540
*/

‎lib/ArangoDBClient/Endpoint.php

Lines changed: 18 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -55,12 +55,12 @@ class Endpoint
5555
/**
5656
* Regexp for TCP endpoints
5757
*/
58-
const REGEXP_TCP = '/^tcp:\/\/(.+?):(\d+)\/?$/';
58+
const REGEXP_TCP = '/^(tcp|http):\/\/(.+?):(\d+)\/?$/';
5959

6060
/**
6161
* Regexp for SSL endpoints
6262
*/
63-
const REGEXP_SSL = '/^ssl:\/\/(.+?):(\d+)\/?$/';
63+
const REGEXP_SSL = '/^(ssl|https):\/\/(.+?):(\d+)\/?$/';
6464

6565
/**
6666
* Regexp for UNIX socket endpoints
@@ -130,6 +130,19 @@ public static function getType($value)
130130

131131
return null;
132132
}
133+
134+
135+
/**
136+
* Return normalize an endpoint string - will convert http: into tcp:, and https: into ssl:
137+
*
138+
* @param string $value - endpoint string
139+
*
140+
* @return string - normalized endpoint string
141+
*/
142+
public static function normalize($value)
143+
{
144+
return preg_replace([ "/http:/", "/https:/" ], [ "tcp:", "ssl:" ], $value);
145+
}
133146

134147
/**
135148
* Return the host name of an endpoint
@@ -141,11 +154,11 @@ public static function getType($value)
141154
public static function getHost($value)
142155
{
143156
if (preg_match(self::REGEXP_TCP, $value, $matches)) {
144-
return $matches[1];
157+
return preg_replace("/^http:/", "tcp:", $matches[2]);
145158
}
146159

147160
if (preg_match(self::REGEXP_SSL, $value, $matches)) {
148-
return $matches[1];
161+
return preg_replace("/^https:/", "ssl:", $matches[2]);
149162
}
150163

151164
return null;
@@ -177,7 +190,7 @@ public static function isValid($value)
177190
*
178191
* @param Connection $connection - the connection to be used
179192
*
180-
* @link https://docs.arangodb.com/HTTP/Endpoints/index.html
193+
* @link https://docs.arangodb.com/HTTP/Endpoints/index.html
181194
* @return array $responseArray - The response array.
182195
* @throws \ArangoDBClient\Exception
183196
*/

‎lib/ArangoDBClient/FailoverException.php

Lines changed: 63 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
1+
<?php
2+
3+
/**
4+
* ArangoDB PHP client: failover exception
5+
*
6+
* @package ArangoDBClient
7+
* @author Jan Steemann
8+
* @copyright Copyright 2018, ArangoDB GmbH, Cologne, Germany
9+
*/
10+
11+
namespace ArangoDBClient;
12+
13+
/**
14+
* Failover-Exception
15+
*
16+
* This exception type will be thrown internally when a failover happens
17+
*
18+
* @package ArangoDBClient
19+
* @since 3.3
20+
*/
21+
class FailoverException extends Exception
22+
{
23+
/**
24+
* New leader endpoint
25+
*
26+
* @param string
27+
*/
28+
private $_leader;
29+
30+
/**
31+
* Return a string representation of the exception
32+
*
33+
* @return string - string representation
34+
*/
35+
public function __toString()
36+
{
37+
return __CLASS__ . ': ' . $this->getLeader();
38+
}
39+
40+
/**
41+
* Set the new leader endpoint
42+
*
43+
* @param string - the new leader endpoint
44+
*
45+
* @return void
46+
*/
47+
public function setLeader($leader)
48+
{
49+
$this->_leader = $leader;
50+
}
51+
52+
/**
53+
* Return the new leader endpoint
54+
*
55+
* @return string - new leader endpoint
56+
*/
57+
public function getLeader()
58+
{
59+
return $this->_leader;
60+
}
61+
}
62+
63+
class_alias(FailoverException::class, '\triagens\ArangoDb\Failover');

‎lib/ArangoDBClient/HttpHelper.php

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -97,7 +97,7 @@ public static function createConnection(ConnectionOptions $options)
9797
}
9898

9999
$fp = @stream_socket_client(
100-
$endpoint,
100+
Endpoint::normalize($endpoint),
101101
$errNo,
102102
$message,
103103
$options[ConnectionOptions::OPTION_TIMEOUT],

‎lib/ArangoDBClient/HttpResponse.php

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -73,6 +73,11 @@ class HttpResponse
7373
* HTTP location header
7474
*/
7575
const HEADER_LOCATION = 'location';
76+
77+
/**
78+
* HTTP leader endpoint header, used in failover
79+
*/
80+
const HEADER_LEADER_ENDPOINT = 'x-arango-endpoint';
7681

7782
/**
7883
* Set up the response
@@ -164,6 +169,16 @@ public function getLocationHeader()
164169
{
165170
return $this->getHeader(self::HEADER_LOCATION);
166171
}
172+
173+
/**
174+
* Return the leader location HTTP header of the response
175+
*
176+
* @return string - header value, NULL is header wasn't set in response
177+
*/
178+
public function getLeaderEndpointHeader()
179+
{
180+
return $this->getHeader(self::HEADER_LEADER_ENDPOINT);
181+
}
167182

168183
/**
169184
* Return the body of the response

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