content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.alibaba.csp.sentinel;
  
  import java.lang.reflect.Method;
  import java.util.List;
  
  import com.alibaba.csp.sentinel.context.ContextUtil;
  import com.alibaba.csp.sentinel.log.RecordLog;
  import com.alibaba.csp.sentinel.slots.block.BlockException;
  import com.alibaba.csp.sentinel.slots.block.Rule;
  import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager;
  import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
  import com.alibaba.csp.sentinel.slots.system.SystemRule;
  import com.alibaba.csp.sentinel.slots.system.SystemRuleManager;
  
  /**
   * Conceptually, physical or logical resource that need protection should be
   * surrounded by an entry. The requests to this resource will be blocked if any
   * criteria is met, eg. when any {@link Rule}'s threshold is exceeded. Once blocked,
   * {@link SphO}#entry() will return false.
   *
   * <p>
   * To configure the criteria, we can use <code>XXXRuleManager.loadRules()</code> to add rules. eg.
   * {@link FlowRuleManager#loadRules(List)}, {@link DegradeRuleManager#loadRules(List)},
   * {@link SystemRuleManager#loadRules(List)}.
   * </p>
   *
   * <p>
   * Following code is an example. {@code "abc"} represent a unique name for the
   * protected resource:
   * </p>
   *
   * <pre>
   * public void foo() {
   *    if (SphO.entry("abc")) {
   *        try {
   *            // business logic
   *        } finally {
   *            SphO.exit(); // must exit()
   *        }
   *    } else {
   *        // failed to enter the protected resource.
   *    }
   * }
   * </pre>
   *
   * Make sure {@code SphO.entry()} and {@link SphO#exit()} be paired in the same thread,
   * otherwise {@link ErrorEntryFreeException} will be thrown.
   *
   * @author jialiang.linjl
   * @author leyou
   * @author Eric Zhao
   * @see SphU
   */
  public class SphO {
  
      private static final Object[] OBJECTS0 = new Object[0];
  
      /**
       * Record statistics and perform rule checking for the given resource.
       *
       * @param name the unique name of the protected resource
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(String name) {
          return entry(name, EntryType.OUT, 1, OBJECTS0);
      }
  
      /**
       * Checking all {@link Rule}s about the protected method.
       *
       * @param method the protected method
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(Method method) {
          return entry(method, EntryType.OUT, 1, OBJECTS0);
      }
  
      /**
       * Checking all {@link Rule}s about the protected method.
       *
       * @param method     the protected method
       * @param batchCount the amount of calls within the invocation (e.g. batchCount=2 means request for 2 tokens)
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(Method method, int batchCount) {
          return entry(method, EntryType.OUT, batchCount, OBJECTS0);
      }
  
      /**
       * Record statistics and perform rule checking for the given resource.
       *
       * @param name       the unique string for the resource
       * @param batchCount the amount of calls within the invocation (e.g. batchCount=2 means request for 2 tokens)
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(String name, int batchCount) {
          return entry(name, EntryType.OUT, batchCount, OBJECTS0);
      }
  
      /**
       * Checking all {@link Rule}s about the protected method.
       *
       * @param method the protected method
       * @param type   the resource is an inbound or an outbound method. This is used
       *               to mark whether it can be blocked when the system is unstable,
       *               only inbound traffic could be blocked by {@link SystemRule}
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(Method method, EntryType type) {
          return entry(method, type, 1, OBJECTS0);
      }
  
      /**
       * Record statistics and perform rule checking for the given resource.
       *
       * @param name the unique name for the protected resource
       * @param type the resource is an inbound or an outbound method. This is used
       *             to mark whether it can be blocked when the system is unstable,
       *             only inbound traffic could be blocked by {@link SystemRule}
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(String name, EntryType type) {
          return entry(name, type, 1, OBJECTS0);
      }
  
      /**
       * Checking all {@link Rule}s about the protected method.
       *
       * @param method the protected method
       * @param type   the resource is an inbound or an outbound method. This is used
       *               to mark whether it can be blocked when the system is unstable,
       *               only inbound traffic could be blocked by {@link SystemRule}
       * @param count  the amount of calls within the invocation (e.g. batchCount=2 means request for 2 tokens)
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(Method method, EntryType type, int count) {
          return entry(method, type, count, OBJECTS0);
      }
  
      /**
       * Record statistics and perform rule checking for the given resource.
       *
       * @param name  the unique name for the protected resource
       * @param type  the resource is an inbound or an outbound method. This is used
       *              to mark whether it can be blocked when the system is unstable,
       *              only inbound traffic could be blocked by {@link SystemRule}
       * @param count the amount of calls within the invocation (e.g. batchCount=2 means request for 2 tokens)
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(String name, EntryType type, int count) {
          return entry(name, type, count, OBJECTS0);
      }
  
      /**
       * Record statistics and perform rule checking for the given resource.
       *
       * @param name        the unique name for the protected resource
       * @param trafficType the traffic type (inbound, outbound or internal). This is used
       *                    to mark whether it can be blocked when the system is unstable,
       *                    only inbound traffic could be blocked by {@link SystemRule}
       * @param batchCount  the amount of calls within the invocation (e.g. batchCount=2 means request for 2 tokens)
       * @param args        args for parameter flow control or customized slots
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(String name, EntryType trafficType, int batchCount, Object... args) {
          try {
              Env.sph.entry(name, trafficType, batchCount, args);
          } catch (BlockException e) {
              return false;
          } catch (Throwable e) {
              RecordLog.warn("SphO fatal error", e);
              return true;
          }
          return true;
      }
  
      /**
       * Record statistics and perform rule checking for the given method resource.
       *
       * @param method      the protected method
       * @param trafficType the traffic type (inbound, outbound or internal). This is used
       *                    to mark whether it can be blocked when the system is unstable,
       *                    only inbound traffic could be blocked by {@link SystemRule}
       * @param batchCount  the amount of calls within the invocation (e.g. batchCount=2 means request for 2 tokens)
       * @param args        args for parameter flow control or customized slots
       * @return true if no rule's threshold is exceeded, otherwise return false.
       */
      public static boolean entry(Method method, EntryType trafficType, int batchCount, Object... args) {
          try {
              Env.sph.entry(method, trafficType, batchCount, args);
          } catch (BlockException e) {
              return false;
          } catch (Throwable e) {
              RecordLog.warn("SphO fatal error", e);
              return true;
          }
          return true;
      }
  
      public static void exit(int count, Object... args) {
          ContextUtil.getContext().getCurEntry().exit(count, args);
      }
  
      public static void exit(int count) {
          ContextUtil.getContext().getCurEntry().exit(count, OBJECTS0);
      }
  
      public static void exit() {
          ContextUtil.getContext().getCurEntry().exit();
      }
  }
  