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This article shows you what the role of MasterSlaveRouter in sharding-jdbc is, the content is concise and easy to understand, it can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

MasterSlaveRouter

Incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-route/src/main/java/org/apache/shardingsphere/core/route/router/masterslave/MasterSlaveRouter.java

@ RequiredArgsConstructorpublic final class MasterSlaveRouter {private final MasterSlaveRule masterSlaveRule; private final boolean showSQL; / * Route Master slave. * * @ param sql SQL * @ return data source names * / / TODO for multiple masters may return more than one data source public Collection route (final String sql) {Collection result = route (new SQLJudgeEngine (sql). Judge (). GetType ()); if (showSQL) {SQLLogger.logSQL (sql, result);} return result } private Collection route (final SQLType sqlType) {if (isMasterRoute (sqlType)) {MasterVisitedManager.setMasterVisited (); return Collections.singletonList (masterSlaveRule.getMasterDataSourceName ());} return Collections.singletonList (masterSlaveRule.getLoadBalanceAlgorithm () .getDataSource (masterSlaveRule.getName (), masterSlaveRule.getMasterDataSourceName (), new ArrayList (masterSlaveRule.getSlaveDataSourceNames () } private boolean isMasterRoute (final SQLType sqlType) {return SQLType.DQL! = sqlType | | MasterVisitedManager.isMasterVisited () | | HintManager.isMasterRouteOnly ();}}

The route method of MasterSlaveRouter uses masterSlaveRule for routing

MasterSlaveRule

Incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-common/src/main/java/org/apache/shardingsphere/core/rule/MasterSlaveRule.java

Getterpublic class MasterSlaveRule {private final String name; private final String masterDataSourceName; private final Collection slaveDataSourceNames; private final MasterSlaveLoadBalanceAlgorithm loadBalanceAlgorithm; private final MasterSlaveRuleConfiguration masterSlaveRuleConfiguration; public MasterSlaveRule (final String name, final String masterDataSourceName, final Collection slaveDataSourceNames, final MasterSlaveLoadBalanceAlgorithm loadBalanceAlgorithm) {this.name = name; this.masterDataSourceName = masterDataSourceName; this.slaveDataSourceNames = slaveDataSourceNames; this.loadBalanceAlgorithm = null = loadBalanceAlgorithm? New MasterSlaveLoadBalanceAlgorithmServiceLoader () .newService (): loadBalanceAlgorithm; masterSlaveRuleConfiguration = new MasterSlaveRuleConfiguration (name, masterDataSourceName, slaveDataSourceNames, new LoadBalanceStrategyConfiguration (this.loadBalanceAlgorithm.getType (), this.loadBalanceAlgorithm.getProperties ());} public MasterSlaveRule (final MasterSlaveRuleConfiguration config) {name = config.getName (); masterDataSourceName = config.getMasterDataSourceName (); slaveDataSourceNames = config.getSlaveDataSourceNames (); loadBalanceAlgorithm = createMasterSlaveLoadBalanceAlgorithm (config.getLoadBalanceStrategyConfiguration ()); masterSlaveRuleConfiguration = config } private MasterSlaveLoadBalanceAlgorithm createMasterSlaveLoadBalanceAlgorithm (final LoadBalanceStrategyConfiguration loadBalanceStrategyConfiguration) {MasterSlaveLoadBalanceAlgorithmServiceLoader serviceLoader = new MasterSlaveLoadBalanceAlgorithmServiceLoader (); return null = = loadBalanceStrategyConfiguration? ServiceLoader.newService (): serviceLoader.newService (loadBalanceStrategyConfiguration.getType (), loadBalanceStrategyConfiguration.getProperties ());} / * * Judge whether contain data source name. * * @ param dataSourceName data source name * @ return contain or not. * / public boolean containDataSourceName (final String dataSourceName) {return masterDataSourceName.equals (dataSourceName) | | slaveDataSourceNames.contains (dataSourceName);}}

MasterSlaveRule has built-in loadBalanceAlgorithm and masterSlaveRuleConfiguration

MasterSlaveLoadBalanceAlgorithm

Incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-api/src/main/java/org/apache/shardingsphere/spi/masterslave/MasterSlaveLoadBalanceAlgorithm.java

Public interface MasterSlaveLoadBalanceAlgorithm extends TypeBasedSPI {/ * * Get data source. * * @ param name master-slave logic data source name * @ param masterDataSourceName name of master data sources * @ param slaveDataSourceNames names of slave data sources * @ return name of selected data source * / String getDataSource (String name, String masterDataSourceName, List slaveDataSourceNames);}

The MasterSlaveLoadBalanceAlgorithm interface inherits the TypeBasedSPI interface, which defines the getDataSource method; it has two implementation classes: RandomMasterSlaveLoadBalanceAlgorithm and RoundRobinMasterSlaveLoadBalanceAlgorithm

RandomMasterSlaveLoadBalanceAlgorithm

Incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-common/src/main/java/org/apache/shardingsphere/core/strategy/masterslave/RandomMasterSlaveLoadBalanceAlgorithm.java

@ Getter@Setterpublic final class RandomMasterSlaveLoadBalanceAlgorithm implements MasterSlaveLoadBalanceAlgorithm {private Properties properties = new Properties (); @ Override public String getType () {return "RANDOM";} @ Override public String getDataSource (final String name, final String masterDataSourceName, final List slaveDataSourceNames) {return slaveDataSourceNames.get (new Random (). NextInt (slaveDataSourceNames.size ();}}

RandomMasterSlaveLoadBalanceAlgorithm uses Random (). NextInt to do random

RoundRobinMasterSlaveLoadBalanceAlgorithm

Incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-common/src/main/java/org/apache/shardingsphere/core/strategy/masterslave/RoundRobinMasterSlaveLoadBalanceAlgorithm.java

@ Getter@Setterpublic final class RoundRobinMasterSlaveLoadBalanceAlgorithm implements MasterSlaveLoadBalanceAlgorithm {private static final ConcurrentHashMap COUNTS = new ConcurrentHashMap (); private Properties properties = new Properties (); @ Override public String getType () {return "ROUND_ROBIN";} @ Override public String getDataSource (final String name, final String masterDataSourceName, final List slaveDataSourceNames) {AtomicInteger count = COUNTS.containsKey (name)? COUNTS.get (name): new AtomicInteger (0); COUNTS.putIfAbsent (name, count); count.compareAndSet (slaveDataSourceNames.size (), 0); return slaveDataSourceNames.get (Math.abs (count.getAndIncrement ())% slaveDataSourceNames.size ());}}

RoundRobinMasterSlaveLoadBalanceAlgorithm uses Math.abs (count.getAndIncrement ())% slaveDataSourceNames.size () for round robin

MasterSlaveRuleConfiguration

Incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-api/src/main/java/org/apache/shardingsphere/api/config/masterslave/MasterSlaveRuleConfiguration.java

@ Getterpublic class MasterSlaveRuleConfiguration implements RuleConfiguration {private final String name; private final String masterDataSourceName; private final Collection slaveDataSourceNames; private final LoadBalanceStrategyConfiguration loadBalanceStrategyConfiguration; public MasterSlaveRuleConfiguration (final String name, final String masterDataSourceName, final Collection slaveDataSourceNames) {this (name, masterDataSourceName, slaveDataSourceNames, null) } public MasterSlaveRuleConfiguration (final String name, final String masterDataSourceName, final Collection slaveDataSourceNames, final LoadBalanceStrategyConfiguration loadBalanceStrategyConfiguration) {Preconditions.checkArgument (! Strings.isNullOrEmpty (name), "Name is required."); Preconditions.checkArgument (! Strings.isNullOrEmpty (masterDataSourceName), "MasterDataSourceName is required."); Preconditions.checkArgument (null! = slaveDataSourceNames & &! slaveDataSourceNames.isEmpty (), "SlaveDataSourceNames is required.") This.name = name; this.masterDataSourceName = masterDataSourceName; this.slaveDataSourceNames = slaveDataSourceNames; this.loadBalanceStrategyConfiguration = loadBalanceStrategyConfiguration;}}

MasterSlaveRuleConfiguration defines name, masterDataSourceName, slaveDataSourceNames, loadBalanceStrategyConfiguration attributes

Summary

MasterSlaveRouter's route method uses masterSlaveRule for routing; MasterSlaveRule has built-in loadBalanceAlgorithm, and the masterSlaveRuleConfiguration;MasterSlaveLoadBalanceAlgorithm interface inherits the TypeBasedSPI interface, which defines the getDataSource method; it has two implementation classes: RandomMasterSlaveLoadBalanceAlgorithm and RoundRobinMasterSlaveLoadBalanceAlgorithm

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