sharding-jdbc中RootInvokeHook的用法

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序

本文主要研究一下sharding-jdbc的RootInvokeHook

RootInvokeHook

incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-execute/src/main/java/org/apache/shardingsphere/core/execute/hook/RootInvokeHook.java

public interface RootInvokeHook {          /**      * Handle when root invoke started.      */     void start();          /**      * Handle when root invoke finished.      *       * @param connectionCount connection count      */     void finish(int connectionCount); }

• RootInvokeHook定义了start、finish接口

SPIRootInvokeHook

incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-execute/src/main/java/org/apache/shardingsphere/core/execute/hook/SPIRootInvokeHook.java

public final class SPIRootInvokeHook implements RootInvokeHook {          private final Collection<RootInvokeHook> rootInvokeHooks = NewInstanceServiceLoader.newServiceInstances(RootInvokeHook.class);          static {         NewInstanceServiceLoader.register(RootInvokeHook.class);     }          @Override     public void start() {         for (RootInvokeHook each : rootInvokeHooks) {             each.start();         }     }          @Override     public void finish(final int connectionCount) {         for (RootInvokeHook each : rootInvokeHooks) {             each.finish(connectionCount);         }     } }

• SPIRootInvokeHook实现了RootInvokeHook接口，它使用NewInstanceServiceLoader注册了RootInvokeHook；rootInvokeHooks集合由NewInstanceServiceLoader.newServiceInstances创建；start方法遍历rootInvokeHooks，执行其start方法；finish方法则遍历rootInvokeHooks，执行器finish方法

NewInstanceServiceLoader

incubator-shardingsphere-4.0.0-RC1/sharding-core/sharding-core-common/src/main/java/org/apache/shardingsphere/core/spi/NewInstanceServiceLoader.java

@NoArgsConstructor(access = AccessLevel.PRIVATE) public final class NewInstanceServiceLoader {          private static final Map<Class, Collection<Class<?>>> SERVICE_MAP = new HashMap<>();          /**      * Register SPI service into map for new instance.      *      * @param service service type      * @param <T> type of service      */     public static <T> void register(final Class<T> service) {         for (T each : ServiceLoader.load(service)) {             registerServiceClass(service, each);         }     }          @SuppressWarnings("unchecked")     private static <T> void registerServiceClass(final Class<T> service, final T instance) {         Collection<Class<?>> serviceClasses = SERVICE_MAP.get(service);         if (null == serviceClasses) {             serviceClasses = new LinkedHashSet<>();         }         serviceClasses.add(instance.getClass());         SERVICE_MAP.put(service, serviceClasses);     }          /**      * New service instances.      *      * @param service service class      * @param <T> type of service      * @return service instances      */     @SneakyThrows     @SuppressWarnings("unchecked")     public static <T> Collection<T> newServiceInstances(final Class<T> service) {         Collection<T> result = new LinkedList<>();         if (null == SERVICE_MAP.get(service)) {             return result;         }         for (Class<?> each : SERVICE_MAP.get(service)) {             result.add((T) each.newInstance());         }         return result;     } }

• NewInstanceServiceLoader的register方法会使用ServiceLoader.load加载指定service的实现类，然后调用registerServiceClass注册到SERVICE_MAP；newServiceInstances则找到指定service的实现类，然后挨个创建实例

OpenTracingRootInvokeHook

incubator-shardingsphere-4.0.0-RC1/sharding-opentracing/src/main/java/org/apache/shardingsphere/opentracing/hook/OpenTracingRootInvokeHook.java

public final class OpenTracingRootInvokeHook implements RootInvokeHook {          public static final String ACTIVE_SPAN_CONTINUATION = "ACTIVE_SPAN_CONTINUATION";          private static final String OPERATION_NAME = "/" + ShardingTags.COMPONENT_NAME + "/rootInvoke/";          private ActiveSpan activeSpan;          @Override     public void start() {         activeSpan = ShardingTracer.get().buildSpan(OPERATION_NAME).withTag(Tags.COMPONENT.getKey(), ShardingTags.COMPONENT_NAME).startActive();         ShardingExecuteDataMap.getDataMap().put(ACTIVE_SPAN_CONTINUATION, activeSpan.capture());     }          @Override     public void finish(final int connectionCount) {         activeSpan.setTag(ShardingTags.CONNECTION_COUNT.getKey(), connectionCount).deactivate();     } }

• OpenTracingRootInvokeHook实现了RootInvokeHook接口，其start方法创建并启动activeSpan；finish方法则设置CONNECTION_COUNT，然后标记activeSpan为deactivate

AbstractConnectionAdapter

incubator-shardingsphere-4.0.0-RC1/sharding-jdbc/sharding-jdbc-core/src/main/java/org/apache/shardingsphere/shardingjdbc/jdbc/adapter/AbstractConnectionAdapter.java

@Getter public abstract class AbstractConnectionAdapter extends AbstractUnsupportedOperationConnection {          private final Multimap<String, Connection> cachedConnections = LinkedHashMultimap.create();          private boolean autoCommit = true;          private boolean readOnly = true;          private volatile boolean closed;          private int transactionIsolation = TRANSACTION_READ_UNCOMMITTED;          private final ForceExecuteTemplate<Connection> forceExecuteTemplate = new ForceExecuteTemplate<>();          private final ForceExecuteTemplate<Entry<String, Connection>> forceExecuteTemplateForClose = new ForceExecuteTemplate<>();          private final RootInvokeHook rootInvokeHook = new SPIRootInvokeHook();          private final ShardingTransactionManager shardingTransactionManager;          private ShardingTransactionManagerEngine shardingTransactionManagerEngine;          private TransactionType transactionType;          protected AbstractConnectionAdapter(final ShardingTransactionManagerEngine shardingTransactionManagerEngine, final TransactionType transactionType) {         rootInvokeHook.start();         this.transactionType = transactionType;         this.shardingTransactionManagerEngine = shardingTransactionManagerEngine;         shardingTransactionManager = shardingTransactionManagerEngine.getTransactionManager(transactionType);     }     //......     public final void close() throws SQLException {         closed = true;         MasterVisitedManager.clear();         TransactionTypeHolder.clear();         int connectionSize = cachedConnections.size();         try {             forceExecuteTemplateForClose.execute(cachedConnections.entries(), new ForceExecuteCallback<Entry<String, Connection>>() {                          @Override                 public void execute(final Entry<String, Connection> cachedConnections) throws SQLException {                     cachedConnections.getValue().close();                 }             });         } finally {             cachedConnections.clear();             rootInvokeHook.finish(connectionSize);         }     }     //...... }

• AbstractConnectionAdapter的构造器会执行rootInvokeHook.start()；其close方法会执行rootInvokeHook.finish(connectionSize)

小结

RootInvokeHook定义了start、finish接口；SPIRootInvokeHook实现了RootInvokeHook接口，它使用NewInstanceServiceLoader注册了RootInvokeHook；rootInvokeHooks集合由NewInstanceServiceLoader.newServiceInstances创建；start方法遍历rootInvokeHooks，执行其start方法；finish方法则遍历rootInvokeHooks，执行器finish方法

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