added sharded client and client interface

Author: matthi4s

README.md

@@ -42,4 +42,19 @@ $client->get("key");
 $client->delete("key");
 $client->putIf("key", "newValue", "expectedPreviousValue");
 $client->deleteIf("key", "expectedPreviousValue");
-```
+```
+
+#### Sharded client
+```php
+<?php
+
+$clients = [
+    new Aternos\Etcd\Client("hostA:2379"),
+    new Aternos\Etcd\Client("hostB:2379"),
+    new Aternos\Etcd\Client("hostC:2379")
+];
+$shardedClient = new Aternos\Etcd\ShardedClient($clients);
+
+$shardedClient->put("key", "value");
+$shardedClient->get("key");
+```

composer.json

@@ -5,7 +5,8 @@
   "require": {
     "google/protobuf": "v3.6.1.3",
     "grpc/grpc": "^1.15",
-    "ext-grpc": "*"
+    "ext-grpc": "*",
+    "flexihash/flexihash": "^2.0"
   },
   "license": "MIT",
   "authors": [

composer.lock

@@ -28,7 +28,7 @@
  *
  * @author Matthias Neid
  */
-class Client
+class Client implements ClientInterface
 {
     /**
      * @var string
@@ -72,6 +72,11 @@ public function __construct($hostname = "localhost:2379", $username = false, $pa
         $this->password = $password;
     }
 
+    public function getHostname(): string
+    {
+        return $this->hostname;
+    }
+
     /**
      * Put a value into the key store
      *

src/Client.php

@@ -0,0 +1,70 @@
+<?php
+
+namespace Aternos\Etcd;
+
+use Aternos\Etcd\Exception\Status\InvalidResponseStatusCodeException;
+
+/**
+ * Interface ClientInterface
+ *
+ * @package Aternos\Etcd
+ */
+interface ClientInterface
+{
+    public function getHostname(): string;
+
+    /**
+     * Put a value into the key store
+     *
+     * @param string $key
+     * @param mixed $value
+     * @param bool $prevKv Get the previous key value in the response
+     * @param int $lease
+     * @param bool $ignoreLease Ignore the current lease
+     * @param bool $ignoreValue Updates the key using its current value
+     * @return string|null Returns previous value if $prevKv is set to true
+     * @throws InvalidResponseStatusCodeException
+     */
+    public function put(string $key, $value, bool $prevKv = false, int $lease = 0, bool $ignoreLease = false, bool $ignoreValue = false);
+
+    /**
+     * Get a key value
+     *
+     * @param string $key
+     * @return bool|string
+     * @throws InvalidResponseStatusCodeException
+     */
+    public function get(string $key);
+
+    /**
+     * Delete a key
+     *
+     * @param string $key
+     * @return bool
+     * @throws InvalidResponseStatusCodeException
+     */
+    public function delete(string $key);
+
+    /**
+     * Put $value if $key value matches $previousValue otherwise $returnNewValueOnFail
+     *
+     * @param string $key
+     * @param mixed $value The new value to set
+     * @param mixed $previousValue The previous value to compare against
+     * @param bool $returnNewValueOnFail
+     * @return bool|string
+     * @throws InvalidResponseStatusCodeException
+     */
+    public function putIf(string $key, $value, $previousValue, bool $returnNewValueOnFail = false);
+
+    /**
+     * Delete if $key value matches $previous value otherwise $returnNewValueOnFail
+     *
+     * @param string $key
+     * @param $previousValue
+     * @param bool $returnNewValueOnFail
+     * @return bool|string
+     * @throws InvalidResponseStatusCodeException
+     */
+    public function deleteIf(string $key, $previousValue, bool $returnNewValueOnFail = false);
+}

src/ClientInterface.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace Aternos\Etcd\Exception;
+
+/**
+ * Class InvalidClientException
+ *
+ * @package Aternos\Etcd\Exception
+ */
+class InvalidClientException extends \Exception
+{
+
+}

src/Exception/InvalidClientException.php

@@ -0,0 +1,122 @@
+<?php
+
+namespace Aternos\Etcd;
+
+use Aternos\Etcd\Exception\InvalidClientException;
+use Flexihash\Flexihash;
+
+/**
+ * Class ShardedClient
+ *
+ * @package Aternos\Etcd
+ */
+class ShardedClient implements ClientInterface
+{
+    /**
+     * @var ClientInterface[]
+     */
+    protected $clients = [];
+
+    /**
+     * @var ClientInterface[]
+     */
+    protected $keyCache = [];
+
+    /**
+     * @var Flexihash
+     */
+    protected $hash = null;
+
+    /**
+     * ShardedClient constructor.
+     *
+     * @param ClientInterface[] $clients
+     * @throws InvalidClientException
+     */
+    public function __construct(array $clients)
+    {
+        foreach ($clients as $client) {
+            if (!$client instanceof ClientInterface) {
+                throw new InvalidClientException("Invalid client in client list.");
+            }
+
+            $this->clients[$client->getHostname()] = $client;
+        }
+    }
+
+    /**
+     * Get the correct client object for that key through consistent hashing
+     *
+     * @param string $key
+     * @return ClientInterface
+     * @throws \Flexihash\Exception
+     */
+    protected function getClientFromKey(string $key): ClientInterface
+    {
+        if (isset($this->keyCache[$key])) {
+            return $this->keyCache[$key];
+        }
+
+        if ($this->hash === null) {
+            $this->hash = new Flexihash();
+            foreach ($this->clients as $client) {
+                $this->hash->addTarget($client->getHostname());
+            }
+        }
+
+        $clientHostname = $this->hash->lookup($key);
+        $this->keyCache[$key] = $this->clients[$clientHostname];
+        return $this->keyCache[$key];
+    }
+
+
+    public function getHostname(): string
+    {
+        return implode("-", array_keys($this->clients));
+    }
+
+    /**
+     * @inheritDoc
+     * @throws \Flexihash\Exception
+     */
+    public function put(string $key, $value, bool $prevKv = false, int $lease = 0, bool $ignoreLease = false, bool $ignoreValue = false)
+    {
+        return $this->getClientFromKey($key)->put($key, $value, $prevKv, $lease, $ignoreLease, $ignoreValue);
+    }
+
+    /**
+     * @inheritDoc
+     * @throws \Flexihash\Exception
+     */
+    public function get(string $key)
+    {
+        return $this->getClientFromKey($key)->get($key);
+    }
+
+    /**
+     * @inheritDoc
+     * @throws \Flexihash\Exception
+     */
+    public function delete(string $key)
+    {
+        return $this->getClientFromKey($key)->delete($key);
+    }
+
+    /**
+     * @inheritDoc
+     * @throws \Flexihash\Exception
+     */
+    public function putIf(string $key, $value, $previousValue, bool $returnNewValueOnFail = false)
+    {
+        return $this->getClientFromKey($key)->putIf($key, $value, $previousValue, $returnNewValueOnFail);
+    }
+
+    /**
+     * @inheritDoc
+     * @throws \Flexihash\Exception
+     */
+    public function deleteIf(string $key, $previousValue, bool $returnNewValueOnFail = false)
+    {
+        return $this->getClientFromKey($key)->deleteIf($key, $previousValue, $returnNewValueOnFail);
+    }
+}