// ErrConnDone is returned by any operation that is performed on a connection
// that has already been returned to the connection pool.
var ErrConnDone = errors.New("sql: connection is already closed")

// Conn returns a single connection by either opening a new connection
// or returning an existing connection from the connection pool. Conn will
// block until either a connection is returned or ctx is canceled.

// an HTTP handler to take over the connection.
//
// The default [ResponseWriter] for HTTP/1.x connections supports
// Hijacker, but HTTP/2 connections intentionally do not.
// ResponseWriter wrappers may also not support Hijacker. Handlers
// should always test for this ability at runtime.
type Hijacker interface {
	// Hijack lets the caller take over the connection.
	// After a call to Hijack the HTTP server library

	// Wait until the goroutine we've just created has started waiting.
	<-drv.waitingCh
	// Now close the busy connections. This provides a connection for
	// the blocked goroutine and then fills up the idle queue.
	for _, v := range rows {
		v.Close()
	}
	// At this point we give the new connection to DB. This connection is
	// now useless, since the idle queue is full and there are no pending

		ConnectStart:         func(network, addr string) { logf("ConnectStart: Connecting to %s %s ...", network, addr) },
		ConnectDone: func(network, addr string, err error) {
			if err != nil {
				t.Errorf("ConnectDone: %v", err)
			}
			logf("ConnectDone: connected to %s %s = %v", network, addr, err)
		},
		WroteHeaderField: func(key string, value []string) {

			c.Write([]byte("HTTP/1.0 200 OK\r\nConnection: close\r\n\r\nHello."))
			c.Close()
			panic("intentional panic")
		},
	}

	// A stateLog is a log of states over the lifetime of a connection.
	type stateLog struct {
		active   net.Conn // The connection for which the log is recorded; set to the first connection seen in StateNew.
		got      []ConnState
		want     []ConnState

,"targets":[{"datasource":{"type":"prometheus","uid":"$datasource"},"expr":"sum(envoy_cluster_upstream_cx_active{cluster_name=\"xds-grpc\"})","legendFormat":"Connections (client reported)"},{"datasource":{"type":"prometheus","uid":"$datasource"},"expr":"sum(pilot_xds{})","legendFormat":"Connections (server reported)"}],"title":"Connections","type":"timeseries"},{"datasource":{"type":"datasource","uid":"-- Mixed --"},"description":"Number of push errors. Many of these are at least potentional fatal...

          // This request will share a connection with 'A' cause it's all done.
          client.newCall(Request.Builder().url(server.url("/b")).build()).enqueue(callback)
        }
      },
    )
    callback.await(server.url("/b")).assertCode(200).assertBody("def")
    // New connection.
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)
    // Connection reuse!

	failureCallbacks := int64(0)

	// set up a listener that hangs connections
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	assert.NoError(t, err)
	defer ln.Close()
	go func() {
		// accept connections and just let them hang
		for {
			_, err := ln.Accept()
			if err != nil {
				t.Log(err)
				return
			}
			t.Log("accepted connection")
			atomic.AddInt64(&attempts, 1)
		}
	}()

      </description>
      <fields>
        <field>
          <name>connection</name>
          <version>4.0.0+</version>
          <description>
            <![CDATA[
            The source control management system URL
            that describes the repository and how to connect to the
            repository.
            This connection is read-only.

			valid: true,
		},

		{name: "invalid connection pool, empty", in: &networking.ConnectionPoolSettings{}, valid: false},

		{
			name: "invalid connection pool, bad max connections", in: &networking.ConnectionPoolSettings{
				Tcp: &networking.ConnectionPoolSettings_TCPSettings{MaxConnections: -1},
			},
			valid: false,
		},

		{