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.util.LinkedList;
  
  import com.alibaba.csp.sentinel.context.Context;
  import com.alibaba.csp.sentinel.context.ContextUtil;
  import com.alibaba.csp.sentinel.context.NullContext;
  import com.alibaba.csp.sentinel.log.RecordLog;
  import com.alibaba.csp.sentinel.node.Node;
  import com.alibaba.csp.sentinel.slotchain.ProcessorSlot;
  import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
  import com.alibaba.csp.sentinel.util.function.BiConsumer;
  
  /**
   * Linked entry within current context.
   *
   * @author jialiang.linjl
   * @author Eric Zhao
   */
  class CtEntry extends Entry {
  
      protected Entry parent = null;
      protected Entry child = null;
  
      protected ProcessorSlot<Object> chain;
      protected Context context;
      protected LinkedList<BiConsumer<Context, Entry>> exitHandlers;
  
      CtEntry(ResourceWrapper resourceWrapper, ProcessorSlot<Object> chain, Context context) {
          this(resourceWrapper, chain, context, 1, OBJECTS0);
      }
  
      CtEntry(ResourceWrapper resourceWrapper, ProcessorSlot<Object> chain, Context context, int count, Object[] args) {
          super(resourceWrapper, count, args);
          this.chain = chain;
          this.context = context;
  
          setUpEntryFor(context);
      }
  
      private void setUpEntryFor(Context context) {
          // The entry should not be associated to NullContext.
          if (context instanceof NullContext) {
              return;
          }
          this.parent = context.getCurEntry();
          if (parent != null) {
              ((CtEntry) parent).child = this;
          }
          context.setCurEntry(this);
      }
  
      @Override
      public void exit(int count, Object... args) throws ErrorEntryFreeException {
          trueExit(count, args);
      }
  
      /**
       * Note: the exit handlers will be called AFTER onExit of slot chain.
       */
      private void callExitHandlersAndCleanUp(Context ctx) {
          if (exitHandlers != null && !exitHandlers.isEmpty()) {
              for (BiConsumer<Context, Entry> handler : this.exitHandlers) {
                  try {
                      handler.accept(ctx, this);
                  } catch (Exception e) {
                      RecordLog.warn("Error occurred when invoking entry exit handler, current entry: "
                          + resourceWrapper.getName(), e);
                  }
              }
              exitHandlers = null;
          }
      }
  
      protected void exitForContext(Context context, int count, Object... args) throws ErrorEntryFreeException {
          if (context != null) {
              // Null context should exit without clean-up.
              if (context instanceof NullContext) {
                  return;
              }
  
              if (context.getCurEntry() != this) {
                  String curEntryNameInContext = context.getCurEntry() == null ? null
                      : context.getCurEntry().getResourceWrapper().getName();
                  // Clean previous call stack.
                  CtEntry e = (CtEntry) context.getCurEntry();
                  while (e != null) {
                      e.exit(count, args);
                      e = (CtEntry) e.parent;
                  }
                  String errorMessage = String.format("The order of entry exit can't be paired with the order of entry"
                          + ", current entry in context: <%s>, but expected: <%s>", curEntryNameInContext,
                      resourceWrapper.getName());
                  throw new ErrorEntryFreeException(errorMessage);
              } else {
                  // Go through the onExit hook of all slots.
                  if (chain != null) {
                      chain.exit(context, resourceWrapper, count, args);
                  }
                  // Go through the existing terminate handlers (associated to this invocation).
                  callExitHandlersAndCleanUp(context);
  
                  // Restore the call stack.
                  context.setCurEntry(parent);
                  if (parent != null) {
                      ((CtEntry) parent).child = null;
                  }
                  if (parent == null) {
                      // Default context (auto entered) will be exited automatically.
                      if (ContextUtil.isDefaultContext(context)) {
                          ContextUtil.exit();
                      }
                  }
                  // Clean the reference of context in current entry to avoid duplicate exit.
                  clearEntryContext();
              }
          }
      }
  
      protected void clearEntryContext() {
          this.context = null;
      }
  
      @Override
      public void whenTerminate(BiConsumer<Context, Entry> handler) {
          if (this.exitHandlers == null) {
              this.exitHandlers = new LinkedList<>();
          }
          this.exitHandlers.add(handler);
      }
  
      @Override
      protected Entry trueExit(int count, Object... args) throws ErrorEntryFreeException {
          exitForContext(context, count, args);
  
          return parent;
      }
  
      @Override
      public Node getLastNode() {
          return parent == null ? null : parent.getCurNode();
      }
  }