content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  
  package com.actiontech.dble.singleton;
  
  import com.actiontech.dble.config.FlowControllerConfig;
  import com.actiontech.dble.config.model.SystemConfig;
  import com.actiontech.dble.services.mysqlsharding.MySQLResponseService;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.locks.LockSupport;
  
  public final class FlowController {
      private static final Logger LOGGER = LoggerFactory.getLogger(FlowController.class);
      private static final FlowController INSTANCE = new FlowController();
      private volatile FlowControllerConfig config = null;
  
      private FlowController() {
      }
  
      public static void init() throws Exception {
          boolean enableFlowControl = SystemConfig.getInstance().isEnableFlowControl();
          if (enableFlowControl && SystemConfig.getInstance().getUsingAIO() == 1) {
              enableFlowControl = false;
              LOGGER.warn("flow control is not support AIO, please check property [usingAIO] of your bootstrap.cnf");
          }
          INSTANCE.config = new FlowControllerConfig(enableFlowControl,
                  SystemConfig.getInstance().getFlowControlHighLevel(),
                  SystemConfig.getInstance().getFlowControlLowLevel());
  
          if (INSTANCE.config.getLowWaterLevel() <= 0 || INSTANCE.config.getHighWaterLevel() <= 0) {
              throw new Exception("The flowControlHighLevel & flowControlLowLevel must be positive integer");
          } else if (INSTANCE.config.getLowWaterLevel() >= INSTANCE.config.getHighWaterLevel()) {
              throw new Exception("The flowControlHighLevel must bigger than flowControlLowLevel");
          }
      }
  
      // load data
      public static void checkFlowControl(final MySQLResponseService backendService) {
          while (backendService.getConnection().isBackendWriteFlowControlled()) {
              LOGGER.info("wait 1s before read from file because of flow control");
              LockSupport.parkNanos(TimeUnit.SECONDS.toNanos(1));
          }
      }
  
      public static FlowControllerConfig getFlowControllerConfig() {
          return INSTANCE.config;
      }
  
      public static void configChange(FlowControllerConfig newConfig) {
          INSTANCE.config = newConfig;
      }
  
      public static boolean isEnableFlowControl() {
          return INSTANCE.config.isEnableFlowControl();
      }
  
      public static int getFlowHighLevel() {
          return INSTANCE.config.getHighWaterLevel();
      }
  
      public static int getFlowLowLevel() {
          return INSTANCE.config.getLowWaterLevel();
      }
  }
  
  
  