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| 1 | <?php |
| 2 | |
| 3 | namespace CirrusSearch\Assignment; |
| 4 | |
| 5 | use CirrusSearch\SearchConfig; |
| 6 | use Wikimedia\Assert\Assert; |
| 7 | |
| 8 | class MultiClusterAssignment implements ClusterAssignment { |
| 9 | /** @var SearchConfig */ |
| 10 | private $config; |
| 11 | /** @var array[][]|null 2d array mapping (replica, group) to connection configuration */ |
| 12 | private $clusters; |
| 13 | /** @var string */ |
| 14 | private $group; |
| 15 | |
| 16 | public function __construct( SearchConfig $config ) { |
| 17 | $this->config = $config; |
| 18 | $groupConfig = $config->get( 'CirrusSearchReplicaGroup' ); |
| 19 | if ( $groupConfig === null ) { |
| 20 | throw new \RuntimeException( 'CirrusSearchReplicaGroup is null' ); |
| 21 | } |
| 22 | if ( is_string( $groupConfig ) ) { |
| 23 | $groupConfig = [ |
| 24 | 'type' => 'constant', |
| 25 | 'group' => $groupConfig, |
| 26 | ]; |
| 27 | } |
| 28 | $this->group = $this->evalGroupStrategy( $groupConfig ); |
| 29 | } |
| 30 | |
| 31 | /** |
| 32 | * @param array $groupConfig |
| 33 | * @return string |
| 34 | */ |
| 35 | private function evalGroupStrategy( array $groupConfig ) { |
| 36 | // Determine which group this wiki belongs to |
| 37 | switch ( $groupConfig['type'] ) { |
| 38 | case 'constant': |
| 39 | return $groupConfig['group']; |
| 40 | case 'roundrobin': |
| 41 | $wikiId = $this->config->getWikiId(); |
| 42 | $mod = count( $groupConfig['groups'] ); |
| 43 | Assert::precondition( $mod > 0, "At least one replica group must be defined for roundrobin" ); |
| 44 | $idx = crc32( $wikiId ) % $mod; |
| 45 | return $groupConfig['groups'][$idx]; |
| 46 | default: |
| 47 | throw new \RuntimeException( "Unknown replica group type: {$groupConfig['type']}" ); |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | private function initClusters(): array { |
| 52 | $clusters = []; |
| 53 | // We could require the input come in this shape, instead of reshaping |
| 54 | // it when we start, but it seemed awkward to work with. |
| 55 | foreach ( $this->config->get( 'CirrusSearchClusters' ) as $name => $config ) { |
| 56 | $replica = $config['replica'] ?? $name; |
| 57 | // Tempting to skip everything that doesn't match $this->group, but we have |
| 58 | // to also track single group replicas with arbitrary group names. |
| 59 | $group = $config['group'] ?? 'default'; |
| 60 | unset( $config['replica'], $config['group'] ); |
| 61 | if ( isset( $clusters[$replica][$group] ) ) { |
| 62 | throw new \RuntimeException( "Multiple clusters for replica: $replica group: $group" ); |
| 63 | } |
| 64 | $clusters[$replica][$group] = $config; |
| 65 | } |
| 66 | return $clusters; |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * @param string $cluster Name of requested cluster |
| 71 | * @return string Uniquely identifies the connection properties. |
| 72 | */ |
| 73 | public function uniqueId( $cluster ) { |
| 74 | return "{$this->group}:$cluster"; |
| 75 | } |
| 76 | |
| 77 | /** |
| 78 | * @return string[] List of CirrusSearch cluster names to write to. |
| 79 | */ |
| 80 | public function getWritableClusters(): array { |
| 81 | $clusters = $this->config->get( 'CirrusSearchWriteClusters' ); |
| 82 | if ( $clusters !== null ) { |
| 83 | return $clusters; |
| 84 | } |
| 85 | // No explicitly configured set of write clusters. Write to all known replicas. |
| 86 | if ( $this->clusters === null ) { |
| 87 | $this->clusters = $this->initClusters(); |
| 88 | } |
| 89 | return array_keys( $this->clusters ); |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Check if a cluster is configured to accept writes |
| 94 | * |
| 95 | * @param string $cluster |
| 96 | * @return bool |
| 97 | */ |
| 98 | public function canWriteToCluster( $cluster ) { |
| 99 | return in_array( $cluster, $this->getWritableClusters() ); |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * @return string Name of the default search cluster. |
| 104 | */ |
| 105 | public function getSearchCluster() { |
| 106 | return $this->config->get( 'CirrusSearchDefaultCluster' ); |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * @return string Name to prefix indices with when |
| 111 | * using cross-cluster-search. |
| 112 | */ |
| 113 | public function getCrossClusterName() { |
| 114 | return $this->group; |
| 115 | } |
| 116 | |
| 117 | /** |
| 118 | * @param string|null $replica |
| 119 | * @return string[]|array[] |
| 120 | */ |
| 121 | public function getServerList( $replica = null ): array { |
| 122 | if ( $this->clusters === null ) { |
| 123 | $this->clusters = $this->initClusters(); |
| 124 | } |
| 125 | $replica ??= $this->config->get( 'CirrusSearchDefaultCluster' ); |
| 126 | if ( !isset( $this->clusters[$replica] ) ) { |
| 127 | $available = implode( ',', array_keys( $this->clusters ) ); |
| 128 | throw new \RuntimeException( "Missing replica <$replica>, have <$available>" ); |
| 129 | } elseif ( isset( $this->clusters[$replica][$this->group] ) ) { |
| 130 | return $this->clusters[$replica][$this->group]; |
| 131 | } elseif ( count( $this->clusters[$replica] ) === 1 ) { |
| 132 | // If a replica only has a single elasticsearch cluster then by |
| 133 | // definition everything goes there. |
| 134 | return reset( $this->clusters[$replica] ); |
| 135 | } else { |
| 136 | throw new \RuntimeException( "Missing replica: $replica group: {$this->group}" ); |
| 137 | } |
| 138 | } |
| 139 | } |