perf: websocket grid connectivity for all internode communication (#18461)

This PR adds a WebSocket grid feature that allows servers to communicate via 
a single two-way connection.

There are two request types:

* Single requests, which are `[]byte => ([]byte, error)`. This is for efficient small
  roundtrips with small payloads.

* Streaming requests which are `[]byte, chan []byte => chan []byte (and error)`,
  which allows for different combinations of full two-way streams with an initial payload.

Only a single stream is created between two machines - and there is, as such, no
server/client relation since both sides can initiate and handle requests. Which server
initiates the request is decided deterministically on the server names.

Requests are made through a mux client and server, which handles message
passing, congestion, cancelation, timeouts, etc.

If a connection is lost, all requests are canceled, and the calling server will try
to reconnect. Registered handlers can operate directly on byte 
slices or use a higher-level generics abstraction.

There is no versioning of handlers/clients, and incompatible changes should
be handled by adding new handlers.

The request path can be changed to a new one for any protocol changes.

First, all servers create a "Manager." The manager must know its address 
as well as all remote addresses. This will manage all connections.
To get a connection to any remote, ask the manager to provide it given
the remote address using.

```
func (m *Manager) Connection(host string) *Connection
```

All serverside handlers must also be registered on the manager. This will
make sure that all incoming requests are served. The number of in-flight 
requests and responses must also be given for streaming requests.

The "Connection" returned manages the mux-clients. Requests issued
to the connection will be sent to the remote.

* `func (c *Connection) Request(ctx context.Context, h HandlerID, req []byte) ([]byte, error)`
   performs a single request and returns the result. Any deadline provided on the request is
   forwarded to the server, and canceling the context will make the function return at once.

* `func (c *Connection) NewStream(ctx context.Context, h HandlerID, payload []byte) (st *Stream, err error)`
   will initiate a remote call and send the initial payload.

```Go
// A Stream is a two-way stream.
// All responses *must* be read by the caller.
// If the call is canceled through the context,
//The appropriate error will be returned.
type Stream struct {
	// Responses from the remote server.
	// Channel will be closed after an error or when the remote closes.
	// All responses *must* be read by the caller until either an error is returned or the channel is closed.
	// Canceling the context will cause the context cancellation error to be returned.
	Responses <-chan Response

	// Requests sent to the server.
	// If the handler is defined with 0 incoming capacity this will be nil.
	// Channel *must* be closed to signal the end of the stream.
	// If the request context is canceled, the stream will no longer process requests.
	Requests chan<- []byte
}

type Response struct {
	Msg []byte
	Err error
}
```

There are generic versions of the server/client handlers that allow the use of type
safe implementations for data types that support msgpack marshal/unmarshal.

cmd/lock-rest-client.go

@@ -18,121 +18,86 @@
 package cmd
 
 import (
-	"bytes"
 	"context"
-	"io"
-	"net/url"
+	"errors"
 
 	"github.com/minio/minio/internal/dsync"
-	xhttp "github.com/minio/minio/internal/http"
-	"github.com/minio/minio/internal/rest"
+	"github.com/minio/minio/internal/grid"
+	"github.com/minio/minio/internal/logger"
 )
 
 // lockRESTClient is authenticable lock REST client
 type lockRESTClient struct {
-	restClient *rest.Client
-	u          *url.URL
-}
-
-func toLockError(err error) error {
-	if err == nil {
-		return nil
-	}
-
-	switch err.Error() {
-	case errLockConflict.Error():
-		return errLockConflict
-	case errLockNotFound.Error():
-		return errLockNotFound
-	}
-	return err
-}
-
-// String stringer *dsync.NetLocker* interface compatible method.
-func (client *lockRESTClient) String() string {
-	return client.u.String()
-}
-
-// Wrapper to restClient.Call to handle network errors, in case of network error the connection is marked disconnected
-// permanently. The only way to restore the connection is at the xl-sets layer by xlsets.monitorAndConnectEndpoints()
-// after verifying format.json
-func (client *lockRESTClient) callWithContext(ctx context.Context, method string, values url.Values, body io.Reader, length int64) (respBody io.ReadCloser, err error) {
-	if values == nil {
-		values = make(url.Values)
-	}
-
-	respBody, err = client.restClient.Call(ctx, method, values, body, length)
-	if err == nil {
-		return respBody, nil
-	}
-
-	return nil, toLockError(err)
+	connection *grid.Connection
 }
 
 // IsOnline - returns whether REST client failed to connect or not.
-func (client *lockRESTClient) IsOnline() bool {
-	return client.restClient.IsOnline()
+func (c *lockRESTClient) IsOnline() bool {
+	return c.connection.State() == grid.StateConnected
 }
 
 // Not a local locker
-func (client *lockRESTClient) IsLocal() bool {
+func (c *lockRESTClient) IsLocal() bool {
 	return false
 }
 
 // Close - marks the client as closed.
-func (client *lockRESTClient) Close() error {
-	client.restClient.Close()
+func (c *lockRESTClient) Close() error {
 	return nil
 }
 
-// restCall makes a call to the lock REST server.
-func (client *lockRESTClient) restCall(ctx context.Context, call string, args dsync.LockArgs) (reply bool, err error) {
-	argsBytes, err := args.MarshalMsg(metaDataPoolGet()[:0])
+// String - returns the remote host of the connection.
+func (c *lockRESTClient) String() string {
+	return c.connection.Remote
+}
+
+func (c *lockRESTClient) call(ctx context.Context, h *grid.SingleHandler[*dsync.LockArgs, *dsync.LockResp], args *dsync.LockArgs) (ok bool, err error) {
+	r, err := h.Call(ctx, c.connection, args)
 	if err != nil {
+		logger.LogIfNot(ctx, err, grid.ErrDisconnected)
 		return false, err
 	}
-	defer metaDataPoolPut(argsBytes)
-	body := bytes.NewReader(argsBytes)
-	respBody, err := client.callWithContext(ctx, call, nil, body, body.Size())
-	defer xhttp.DrainBody(respBody)
-	switch err {
-	case nil:
-		return true, nil
-	case errLockConflict, errLockNotFound:
-		return false, nil
+	defer h.PutResponse(r)
+	ok = r.Code == dsync.RespOK
+	switch r.Code {
+	case dsync.RespLockConflict, dsync.RespLockNotFound, dsync.RespOK:
+	// no error
+	case dsync.RespLockNotInitialized:
+		err = errLockNotInitialized
 	default:
-		return false, err
+		err = errors.New(r.Err)
 	}
+	return ok, err
 }
 
 // RLock calls read lock REST API.
-func (client *lockRESTClient) RLock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	return client.restCall(ctx, lockRESTMethodRLock, args)
+func (c *lockRESTClient) RLock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
+	return c.call(ctx, lockRPCRLock, &args)
 }
 
 // Lock calls lock REST API.
-func (client *lockRESTClient) Lock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	return client.restCall(ctx, lockRESTMethodLock, args)
+func (c *lockRESTClient) Lock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
+	return c.call(ctx, lockRPCLock, &args)
 }
 
 // RUnlock calls read unlock REST API.
-func (client *lockRESTClient) RUnlock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	return client.restCall(ctx, lockRESTMethodRUnlock, args)
+func (c *lockRESTClient) RUnlock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
+	return c.call(ctx, lockRPCRUnlock, &args)
 }
 
-// RUnlock calls read unlock REST API.
-func (client *lockRESTClient) Refresh(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	return client.restCall(ctx, lockRESTMethodRefresh, args)
+// Refresh calls Refresh REST API.
+func (c *lockRESTClient) Refresh(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
+	return c.call(ctx, lockRPCRefresh, &args)
 }
 
 // Unlock calls write unlock RPC.
-func (client *lockRESTClient) Unlock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	return client.restCall(ctx, lockRESTMethodUnlock, args)
+func (c *lockRESTClient) Unlock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
+	return c.call(ctx, lockRPCUnlock, &args)
 }
 
 // ForceUnlock calls force unlock handler to forcibly unlock an active lock.
-func (client *lockRESTClient) ForceUnlock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	return client.restCall(ctx, lockRESTMethodForceUnlock, args)
+func (c *lockRESTClient) ForceUnlock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
+	return c.call(ctx, lockRPCForceUnlock, &args)
 }
 
 func newLockAPI(endpoint Endpoint) dsync.NetLocker {
@@ -143,27 +108,6 @@ func newLockAPI(endpoint Endpoint) dsync.NetLocker {
 }
 
 // Returns a lock rest client.
-func newlockRESTClient(endpoint Endpoint) *lockRESTClient {
-	serverURL := &url.URL{
-		Scheme: endpoint.Scheme,
-		Host:   endpoint.Host,
-		Path:   pathJoin(lockRESTPrefix, lockRESTVersion),
-	}
-
-	restClient := rest.NewClient(serverURL, globalInternodeTransport, newCachedAuthToken())
-	// Use a separate client to avoid recursive calls.
-	healthClient := rest.NewClient(serverURL, globalInternodeTransport, newCachedAuthToken())
-	healthClient.NoMetrics = true
-	restClient.HealthCheckFn = func() bool {
-		ctx, cancel := context.WithTimeout(context.Background(), restClient.HealthCheckTimeout)
-		defer cancel()
-		respBody, err := healthClient.Call(ctx, lockRESTMethodHealth, nil, nil, -1)
-		xhttp.DrainBody(respBody)
-		return !isNetworkError(err)
-	}
-
-	return &lockRESTClient{u: &url.URL{
-		Scheme: endpoint.Scheme,
-		Host:   endpoint.Host,
-	}, restClient: restClient}
+func newlockRESTClient(ep Endpoint) *lockRESTClient {
+	return &lockRESTClient{globalGrid.Load().Connection(ep.GridHost())}
 }