nodes = array_keys($nodes); $this->weights = $nodes; } else { $this->nodes = $nodes; } $this->generateCircle(); } public function updateWithWeights(array $weights) { if ($weights != $this->weights) { return false; } $this->weights = $weights; $this->nodes = array_keys($weights); $this->generateCircle(); return true; } public function getNode($stringKey) { $pos = $this->getNodePos($stringKey); if ($pos === false) { return ""; } return $this->ring[$this->sortedKeys[$pos]]; } public function getNodePos($stringKey) { if (count($this->ring) == 0) { return false; } $key = $this->genKey($stringKey); $pos = $this->search(count($this->sortedKeys), function ($i) use ($key) { return $this->sortedKeys[$i] > $key; }); if ($pos == count($this->sortedKeys)) { return 0; } else { return $pos; } } /** * Get from golang sort.Search() * @param $n * @param \Closure $operator * @return int */ private function search($n, \Closure $operator) { $i = 0; $j = $n; while ($i < $j) { $h = $i + intval(($j - $i) / 2); if (!$operator($h)) { $i = $h + 1; } else { $j = $h; } } return $i; } public function genKey($stringKey) { $bKey = $this->hashDigest($stringKey); return $this->hashVal(array_slice($bKey, 0, 4)); } public function getNodes($stringKey, $size) { $pos = $this->getNodePos($stringKey); if ($pos === false) { return []; } if ($size > count($this->nodes)) { return []; } $returnedValues = []; $resultSlice = []; for ($i = $pos; $i < $pos + count($this->sortedKeys); $i++) { $key = $this->sortedKeys[$i % count($this->sortedKeys)]; $val = $this->ring[$key]; if (empty($returnedValues[$val])) { $returnedValues[$val] = true; $resultSlice[] = $val; } if (count($returnedValues) == $size) { break; } } return $resultSlice; } public function addNode($node) { return $this->addWeightedNode($node, 1); } public function addWeightedNode($node, $weight) { if ($weight <= 0 OR in_array($node, $this->nodes)) { return false; } $this->nodes[] = $node; $this->weights[$node] = $weight; $this->generateCircle(); return true; } public function updateWeightedNode($node, $weight) { /* node is not need to update for node is not existed or weight is not changed */ if ($weight <= 0 OR empty($this->weights[$node]) OR $this->weights[$node] == $weight) { return false; } $this->weights[$node] = $weight; $this->generateCircle(); return true; } public function removeNode($node) { /* if node isn't exist in hashring, don't refresh hashring */ if (!in_array($node, $this->nodes)) { return false; } if (($key = array_search($node, $this->nodes)) !== false) { unset($this->nodes[$key]); } unset($this->weights[$node]); $this->generateCircle(); return true; } private function getNodeWeight($node) { return empty($this->weights[$node]) ? 1 : intval($this->weights[$node]); } private function generateCircle() { $this->ring = []; $this->sortedKeys = []; $totalWeight = 0; foreach ($this->nodes as $node) { $totalWeight += $this->getNodeWeight($node); } foreach ($this->nodes as $node) { $weight = $this->getNodeWeight($node); $factor = floor(40 * count($this->nodes) * $weight) / $totalWeight; for ($j = 0; $j < $factor; $j++) { $nodeKey = $node . '-' . $j; $bKey = $this->hashDigest($nodeKey); for ($i = 0; $i < 3; $i++) { $key = $this->hashVal(array_slice($bKey, $i * 4, 4)); $this->ring[$key] = $node; $this->sortedKeys[] = $key; } } } sort($this->sortedKeys); } private function hashDigest($key) { return array_map(function ($byte) { return ord($byte); }, str_split(md5($key, TRUE))); } private function hashVal($bKey) { return ($bKey[3] << 24) | ($bKey[2] << 16) | ($bKey[1] << 8) | ($bKey[0]); } }

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