text: "use strict";
  /*
   * Copyright 2019 gRPC authors.
   *
   * 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.
   *
   */
  Object.defineProperty(exports, "__esModule", { value: true });
  const load_balancer_1 = require("./load-balancer");
  const channel_1 = require("./channel");
  const picker_1 = require("./picker");
  const subchannel_1 = require("./subchannel");
  const logging = require("./logging");
  const constants_1 = require("./constants");
  const TRACER_NAME = 'round_robin';
  function trace(text) {
      logging.trace(constants_1.LogVerbosity.DEBUG, TRACER_NAME, text);
  }
  const TYPE_NAME = 'round_robin';
  class RoundRobinPicker {
      constructor(subchannelList, nextIndex = 0) {
          this.subchannelList = subchannelList;
          this.nextIndex = nextIndex;
      }
      pick(pickArgs) {
          const pickedSubchannel = this.subchannelList[this.nextIndex];
          this.nextIndex = (this.nextIndex + 1) % this.subchannelList.length;
          return {
              pickResultType: picker_1.PickResultType.COMPLETE,
              subchannel: pickedSubchannel,
              status: null,
          };
      }
      /**
       * Check what the next subchannel returned would be. Used by the load
       * balancer implementation to preserve this part of the picker state if
       * possible when a subchannel connects or disconnects.
       */
      peekNextSubchannel() {
          return this.subchannelList[this.nextIndex];
      }
  }
  class RoundRobinLoadBalancer {
      constructor(channelControlHelper) {
          this.channelControlHelper = channelControlHelper;
          this.subchannels = [];
          this.currentState = channel_1.ConnectivityState.IDLE;
          this.currentReadyPicker = null;
          this.updateState(channel_1.ConnectivityState.IDLE, new picker_1.QueuePicker(this));
          this.subchannelStateCounts = {
              [channel_1.ConnectivityState.CONNECTING]: 0,
              [channel_1.ConnectivityState.IDLE]: 0,
              [channel_1.ConnectivityState.READY]: 0,
              [channel_1.ConnectivityState.SHUTDOWN]: 0,
              [channel_1.ConnectivityState.TRANSIENT_FAILURE]: 0,
          };
          this.subchannelStateListener = (subchannel, previousState, newState) => {
              this.subchannelStateCounts[previousState] -= 1;
              this.subchannelStateCounts[newState] += 1;
              this.calculateAndUpdateState();
              if (newState === channel_1.ConnectivityState.TRANSIENT_FAILURE) {
                  this.channelControlHelper.requestReresolution();
              }
              if (newState === channel_1.ConnectivityState.TRANSIENT_FAILURE ||
                  newState === channel_1.ConnectivityState.IDLE) {
                  subchannel.startConnecting();
              }
          };
      }
      calculateAndUpdateState() {
          if (this.subchannelStateCounts[channel_1.ConnectivityState.READY] > 0) {
              const readySubchannels = this.subchannels.filter(subchannel => subchannel.getConnectivityState() === channel_1.ConnectivityState.READY);
              let index = 0;
              if (this.currentReadyPicker !== null) {
                  index = readySubchannels.indexOf(this.currentReadyPicker.peekNextSubchannel());
                  if (index < 0) {
                      index = 0;
                  }
              }
              this.updateState(channel_1.ConnectivityState.READY, new RoundRobinPicker(readySubchannels, index));
          }
          else if (this.subchannelStateCounts[channel_1.ConnectivityState.CONNECTING] > 0) {
              this.updateState(channel_1.ConnectivityState.CONNECTING, new picker_1.QueuePicker(this));
          }
          else if (this.subchannelStateCounts[channel_1.ConnectivityState.TRANSIENT_FAILURE] > 0) {
              this.updateState(channel_1.ConnectivityState.TRANSIENT_FAILURE, new picker_1.UnavailablePicker());
          }
          else {
              this.updateState(channel_1.ConnectivityState.IDLE, new picker_1.QueuePicker(this));
          }
      }
      updateState(newState, picker) {
          trace(channel_1.ConnectivityState[this.currentState] +
              ' -> ' +
              channel_1.ConnectivityState[newState]);
          if (newState === channel_1.ConnectivityState.READY) {
              this.currentReadyPicker = picker;
          }
          else {
              this.currentReadyPicker = null;
          }
          this.currentState = newState;
          this.channelControlHelper.updateState(newState, picker);
      }
      resetSubchannelList() {
          for (const subchannel of this.subchannels) {
              subchannel.removeConnectivityStateListener(this.subchannelStateListener);
              subchannel.unref();
          }
          this.subchannelStateCounts = {
              [channel_1.ConnectivityState.CONNECTING]: 0,
              [channel_1.ConnectivityState.IDLE]: 0,
              [channel_1.ConnectivityState.READY]: 0,
              [channel_1.ConnectivityState.SHUTDOWN]: 0,
              [channel_1.ConnectivityState.TRANSIENT_FAILURE]: 0,
          };
          this.subchannels = [];
      }
      updateAddressList(addressList, lbConfig) {
          this.resetSubchannelList();
          trace('Connect to address list ' +
              addressList.map(address => subchannel_1.subchannelAddressToString(address)));
          this.subchannels = addressList.map(address => this.channelControlHelper.createSubchannel(address, {}));
          for (const subchannel of this.subchannels) {
              subchannel.ref();
              subchannel.addConnectivityStateListener(this.subchannelStateListener);
              const subchannelState = subchannel.getConnectivityState();
              this.subchannelStateCounts[subchannelState] += 1;
              if (subchannelState === channel_1.ConnectivityState.IDLE ||
                  subchannelState === channel_1.ConnectivityState.TRANSIENT_FAILURE) {
                  subchannel.startConnecting();
              }
          }
          this.calculateAndUpdateState();
      }
      exitIdle() {
          for (const subchannel of this.subchannels) {
              subchannel.startConnecting();
          }
      }
      resetBackoff() {
          /* The pick first load balancer does not have a connection backoff, so this
           * does nothing */
      }
      destroy() {
          this.resetSubchannelList();
      }
      getTypeName() {
          return TYPE_NAME;
      }
      replaceChannelControlHelper(channelControlHelper) {
          this.channelControlHelper = channelControlHelper;
      }
  }
  exports.RoundRobinLoadBalancer = RoundRobinLoadBalancer;
  function setup() {
      load_balancer_1.registerLoadBalancerType(TYPE_NAME, RoundRobinLoadBalancer);
  }
  exports.setup = setup;
  //# sourceMappingURL=load-balancer-round-robin.js.map