@duongtrungnguyen/nestro/dist/esm/discovery/loadbalancing/least-connection.strategy.js

Service registry for Nest JS

class LeastConnectionsStrategy {
  constructor() {
    this.connectionCounters = /* @__PURE__ */ new Map();
  }
  selectInstance(instances) {
    if (!instances || instances.length === 0) {
      return null;
    }
    if (instances.length === 1) {
      return instances[0];
    }
    let minConnections = Number.MAX_SAFE_INTEGER;
    let selectedInstance = instances[0];
    let candidatesWithSameConnections = [];
    for (const instance of instances) {
      const instanceId = this.getInstanceId(instance);
      const connections = this.connectionCounters.get(instanceId) || 0;
      if (connections < minConnections) {
        minConnections = connections;
        selectedInstance = instance;
        candidatesWithSameConnections = [instance];
      } else if (connections === minConnections) {
        candidatesWithSameConnections.push(instance);
      }
    }
    if (candidatesWithSameConnections.length > 1) {
      const randomIndex = Math.floor(Math.random() * candidatesWithSameConnections.length);
      selectedInstance = candidatesWithSameConnections[randomIndex];
    }
    return selectedInstance;
  }
  trackConnectionStart(instanceId) {
    const currentCount = this.connectionCounters.get(instanceId) || 0;
    this.connectionCounters.set(instanceId, currentCount + 1);
  }
  trackConnectionEnd(instanceId) {
    const currentCount = this.connectionCounters.get(instanceId) || 0;
    if (currentCount > 0) {
      this.connectionCounters.set(instanceId, currentCount - 1);
    }
  }
  reset() {
    this.connectionCounters.clear();
  }
  getInstanceId(instance) {
    return `${instance.name}:${instance.host}:${instance.port}`;
  }
}
export {
  LeastConnectionsStrategy
};
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