return connections.count {
      it.withLock { it.calls.isEmpty() }
    }
  }

  fun connectionCount(): Int {
    return connections.size
  }

  /**
   * Attempts to acquire a recycled connection to [address] for [connectionUser]. Returns the connection if it
   * was acquired, or null if no connection was acquired. The acquired connection will also be

import java.net.InetSocketAddress
import java.net.Proxy

/**
 * Listener for metrics events. Extend this class to monitor the quantity, size, and duration of
 * your application's HTTP calls.
 *
 * All start/connect/acquire events will eventually receive a matching end/release event, either
 * successful (non-null parameters), or failed (non-null throwable). The first common parameters of