Integrate circuit break state switch with proxy

shardingsphere-proxy/shardingsphere-proxy-frontend/shardingsphere-proxy-frontend-core/src/main/java/org/apache/shardingsphere/proxy/frontend/state/impl/CircuitBreakProxyState.java

@@ -17,12 +17,17 @@
 
 package org.apache.shardingsphere.proxy.frontend.state.impl;
 
+import com.google.common.eventbus.Subscribe;
 import io.netty.channel.ChannelHandlerContext;
 import org.apache.shardingsphere.db.protocol.packet.DatabasePacket;
+import org.apache.shardingsphere.governance.core.event.GovernanceEventBus;
+import org.apache.shardingsphere.governance.core.registry.event.CircuitStateChangedEvent;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
 import org.apache.shardingsphere.proxy.backend.exception.CircuitBreakException;
 import org.apache.shardingsphere.proxy.frontend.spi.DatabaseProtocolFrontendEngine;
 import org.apache.shardingsphere.proxy.frontend.state.ProxyState;
+import org.apache.shardingsphere.proxy.frontend.state.ProxyStateMachine;
+import org.apache.shardingsphere.proxy.frontend.state.ProxyStateType;
 
 import java.util.Optional;
 
@@ -31,10 +36,29 @@ import java.util.Optional;
  */
 public final class CircuitBreakProxyState implements ProxyState {
     
+    public CircuitBreakProxyState() {
+        GovernanceEventBus.getInstance().register(this);
+    }
+    
     @Override
     public void execute(final ChannelHandlerContext context, final Object message, final DatabaseProtocolFrontendEngine databaseProtocolFrontendEngine, final BackendConnection backendConnection) {
         context.writeAndFlush(databaseProtocolFrontendEngine.getCommandExecuteEngine().getErrorPacket(new CircuitBreakException()));
         Optional<DatabasePacket<?>> databasePacket = databaseProtocolFrontendEngine.getCommandExecuteEngine().getOtherPacket();
         databasePacket.ifPresent(context::writeAndFlush);
     }
+    
+    /**
+     * Renew circuit breaker state.
+     *
+     * @param event circuit state changed event
+     */
+    @Subscribe
+    public synchronized void renew(final CircuitStateChangedEvent event) {
+        if (event.isCircuitBreak()) {
+            ProxyStateMachine.switchState(ProxyStateType.CIRCUIT_BREAK);
+        } else {
+            // TODO check previous state, maybe lock
+            ProxyStateMachine.switchState(ProxyStateType.OK);
+        }
+    }
 }