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feat: implement strongly typed HandlerContext interface

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Convert HandlerContext from struct to interface with strongly typed getters
for different client types. This provides better type safety and a cleaner
API for push notification handlers while maintaining flexibility.

Key Changes:

1. HandlerContext Interface Design:
   - Converted HandlerContext from struct to interface
   - Added strongly typed getters for different client types
   - GetClusterClient() returns ClusterClientInterface
   - GetSentinelClient() returns SentinelClientInterface
   - GetFailoverClient() returns FailoverClientInterface
   - GetRegularClient() returns RegularClientInterface
   - GetPubSub() returns PubSubInterface

2. Client Type Interfaces:
   - Defined ClusterClientInterface for cluster client access
   - Defined SentinelClientInterface for sentinel client access
   - Defined FailoverClientInterface for failover client access
   - Defined RegularClientInterface for regular client access
   - Defined PubSubInterface for pub/sub access
   - Each interface provides String() method for basic operations

3. Concrete Implementation:
   - Created handlerContext struct implementing HandlerContext interface
   - Added NewHandlerContext constructor function
   - Implemented type-safe getters with interface casting
   - Returns nil for incorrect client types (type safety)

4. Updated All Usage:
   - Updated Handler interface to use HandlerContext interface
   - Updated ProcessorInterface to use HandlerContext interface
   - Updated all processor implementations (Processor, VoidProcessor)
   - Updated all handler context creation sites
   - Updated test handlers and test context creation

5. Helper Methods:
   - Updated pushNotificationHandlerContext() in baseClient
   - Updated pushNotificationHandlerContext() in PubSub
   - Consistent context creation across all client types
   - Proper parameter passing for different connection types

6. Type Safety Benefits:
   - Handlers can safely cast to specific client types
   - Compile-time checking for client type access
   - Clear API for accessing different client capabilities
   - No runtime panics from incorrect type assertions

7. API Usage Example:
   ```go
   func (h *MyHandler) HandlePushNotification(
       ctx context.Context,
       handlerCtx HandlerContext,
       notification []interface{},
   ) bool {
       // Strongly typed access
       if clusterClient := handlerCtx.GetClusterClient(); clusterClient != nil {
           // Handle cluster-specific logic
       }
       if sentinelClient := handlerCtx.GetSentinelClient(); sentinelClient != nil {
           // Handle sentinel-specific logic
       }
       return true
   }
   ```

8. Backward Compatibility:
   - Interface maintains same functionality as original struct
   - All existing handler patterns continue to work
   - No breaking changes to handler implementations
   - Smooth migration path for existing code

Benefits:
- Strong type safety for client access in handlers
- Clear API with explicit client type getters
- Compile-time checking prevents runtime errors
- Flexible interface allows future extensions
- Better separation of concerns between client types
- Enhanced developer experience with IntelliSense support

This enhancement provides handlers with strongly typed access to different
Redis client types while maintaining the flexibility and context information
needed for sophisticated push notification handling, particularly important
for hitless upgrades and cluster management operations.
This commit is contained in:
Nedyalko Dyakov
2025-07-04 19:53:19 +03:00
parent 47dd490a8a
commit 1606de8b73
11 changed files with 197 additions and 107 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
internal/pool/conn.go
View File

@ -8,7 +8,6 @@ import (
"time"
"github.com/redis/go-redis/v9/internal/proto"
"github.com/redis/go-redis/v9/internal/pushnotif"
)
var noDeadline = time.Time{}
@ -26,10 +25,6 @@ type Conn struct {
createdAt time.Time
onClose func() error
// Push notification processor for handling push notifications on this connection
// This is set when the connection is created and is a reference to the processor
PushNotificationProcessor pushnotif.ProcessorInterface
}
func NewConn(netConn net.Conn) *Conn {
@ -77,9 +72,6 @@ func (cn *Conn) RemoteAddr() net.Addr {
func (cn *Conn) WithReader(
ctx context.Context, timeout time.Duration, fn func(rd *proto.Reader) error,
) error {
// Push notification processing is now handled by the client before calling WithReader
// This ensures proper context (client, connection pool, connection) is available to handlers
if timeout >= 0 {
if err := cn.netConn.SetReadDeadline(cn.deadline(ctx, timeout)); err != nil {
return err

5
internal/pool/pool.go
View File

@ -10,7 +10,6 @@ import (
"github.com/redis/go-redis/v9/internal"
"github.com/redis/go-redis/v9/internal/proto"
"github.com/redis/go-redis/v9/internal/pushnotif"
)
var (
@ -74,10 +73,6 @@ type Options struct {
ConnMaxIdleTime time.Duration
ConnMaxLifetime time.Duration
// Push notification processor for connections
// This is an interface to avoid circular imports
PushNotificationProcessor pushnotif.ProcessorInterface
// Protocol version for optimization (3 = RESP3 with push notifications, 2 = RESP2 without)
Protocol int
}

4
internal/pushnotif/processor.go
View File

@ -40,7 +40,7 @@ func (p *Processor) UnregisterHandler(pushNotificationName string) error {
// ProcessPendingNotifications checks for and processes any pending push notifications.
// The handlerCtx provides context about the client, connection pool, and connection.
func (p *Processor) ProcessPendingNotifications(ctx context.Context, handlerCtx *HandlerContext, rd *proto.Reader) error {
func (p *Processor) ProcessPendingNotifications(ctx context.Context, handlerCtx HandlerContext, rd *proto.Reader) error {
// Check for nil reader
if rd == nil {
return nil
@ -179,7 +179,7 @@ func (v *VoidProcessor) UnregisterHandler(pushNotificationName string) error {
// ProcessPendingNotifications for VoidProcessor does nothing since push notifications
// are only available in RESP3 and this processor is used for RESP2 connections.
// This avoids unnecessary buffer scanning overhead.
func (v *VoidProcessor) ProcessPendingNotifications(ctx context.Context, handlerCtx *HandlerContext, rd *proto.Reader) error {
func (v *VoidProcessor) ProcessPendingNotifications(ctx context.Context, handlerCtx HandlerContext, rd *proto.Reader) error {
// VoidProcessor is used for RESP2 connections where push notifications are not available.
// Since push notifications only exist in RESP3, we can safely skip all processing
// to avoid unnecessary buffer scanning overhead.

8
internal/pushnotif/pushnotif.go Normal file
View File

@ -0,0 +1,8 @@
package pushnotif
// This is an EXPERIMENTAL API for push notifications.
// It is subject to change without notice.
// The handler interface may change in the future to include more or less context information.
// The handler context has fields that are currently empty interfaces.
// This is to allow for future expansion without breaking compatibility.
// The context information will be filled in with concrete types or more specific interfaces in the future.

20
internal/pushnotif/pushnotif_test.go
View File

@ -25,7 +25,7 @@ func NewTestHandler(name string, returnValue bool) *TestHandler {
}
}
func (h *TestHandler) HandlePushNotification(ctx context.Context, handlerCtx *HandlerContext, notification []interface{}) bool {
func (h *TestHandler) HandlePushNotification(ctx context.Context, handlerCtx HandlerContext, notification []interface{}) bool {
h.handled = append(h.handled, notification)
// Store the handler context for testing if needed
_ = handlerCtx
@ -134,11 +134,7 @@ func testProcessPendingNotifications(processor *Processor, ctx context.Context,
}
// Create a test handler context
handlerCtx := &HandlerContext{
Client: nil,
ConnPool: nil,
Conn: nil,
}
handlerCtx := NewHandlerContext(nil, nil, nil, nil, false)
for {
// Check if there are push notifications available
@ -429,11 +425,7 @@ func TestProcessor(t *testing.T) {
ctx := context.Background()
// Test with nil reader
handlerCtx := &HandlerContext{
Client: nil,
ConnPool: nil,
Conn: nil,
}
handlerCtx := NewHandlerContext(nil, nil, nil, nil, false)
err := processor.ProcessPendingNotifications(ctx, handlerCtx, nil)
if err != nil {
t.Errorf("ProcessPendingNotifications with nil reader should not error, got: %v", err)
@ -651,11 +643,7 @@ func TestVoidProcessor(t *testing.T) {
t.Run("ProcessPendingNotifications", func(t *testing.T) {
processor := NewVoidProcessor()
ctx := context.Background()
handlerCtx := &HandlerContext{
Client: nil,
ConnPool: nil,
Conn: nil,
}
handlerCtx := NewHandlerContext(nil, nil, nil, nil, false)
// VoidProcessor should always succeed and do nothing
err := processor.ProcessPendingNotifications(ctx, handlerCtx, nil)

154
internal/pushnotif/types.go
View File

@ -3,20 +3,154 @@ package pushnotif
import (
"context"
"github.com/redis/go-redis/v9/internal/pool"
"github.com/redis/go-redis/v9/internal/proto"
)
// HandlerContext provides context information about where a push notification was received.
// This allows handlers to make informed decisions based on the source of the notification.
type HandlerContext struct {
// Client is the Redis client instance that received the notification
Client interface{}
// This interface allows handlers to make informed decisions based on the source of the notification
// with strongly typed access to different client types.
type HandlerContext interface {
// GetClient returns the Redis client instance that received the notification.
// Returns nil if no client context is available.
GetClient() interface{}
// ConnPool is the connection pool from which the connection was obtained
ConnPool interface{}
// GetClusterClient returns the client as a ClusterClient if it is one.
// Returns nil if the client is not a ClusterClient or no client context is available.
GetClusterClient() ClusterClientInterface
// Conn is the specific connection on which the notification was received
Conn interface{}
// GetSentinelClient returns the client as a SentinelClient if it is one.
// Returns nil if the client is not a SentinelClient or no client context is available.
GetSentinelClient() SentinelClientInterface
// GetFailoverClient returns the client as a FailoverClient if it is one.
// Returns nil if the client is not a FailoverClient or no client context is available.
GetFailoverClient() FailoverClientInterface
// GetRegularClient returns the client as a regular Client if it is one.
// Returns nil if the client is not a regular Client or no client context is available.
GetRegularClient() RegularClientInterface
// GetConnPool returns the connection pool from which the connection was obtained.
// Returns nil if no connection pool context is available.
GetConnPool() interface{}
// GetPubSub returns the PubSub instance that received the notification.
// Returns nil if this is not a PubSub connection.
GetPubSub() PubSubInterface
// GetConn returns the specific connection on which the notification was received.
// Returns nil if no connection context is available.
GetConn() *pool.Conn
// IsBlocking returns true if the notification was received on a blocking connection.
IsBlocking() bool
}
// Client interfaces for strongly typed access
type ClusterClientInterface interface {
// Add methods that handlers might need from ClusterClient
String() string
}
type SentinelClientInterface interface {
// Add methods that handlers might need from SentinelClient
String() string
}
type FailoverClientInterface interface {
// Add methods that handlers might need from FailoverClient
String() string
}
type RegularClientInterface interface {
// Add methods that handlers might need from regular Client
String() string
}
type PubSubInterface interface {
// Add methods that handlers might need from PubSub
String() string
}
// handlerContext is the concrete implementation of HandlerContext interface
type handlerContext struct {
client interface{}
connPool interface{}
pubSub interface{}
conn *pool.Conn
isBlocking bool
}
// NewHandlerContext creates a new HandlerContext implementation
func NewHandlerContext(client, connPool, pubSub interface{}, conn *pool.Conn, isBlocking bool) HandlerContext {
return &handlerContext{
client: client,
connPool: connPool,
pubSub: pubSub,
conn: conn,
isBlocking: isBlocking,
}
}
// GetClient returns the Redis client instance that received the notification
func (h *handlerContext) GetClient() interface{} {
return h.client
}
// GetClusterClient returns the client as a ClusterClient if it is one
func (h *handlerContext) GetClusterClient() ClusterClientInterface {
if client, ok := h.client.(ClusterClientInterface); ok {
return client
}
return nil
}
// GetSentinelClient returns the client as a SentinelClient if it is one
func (h *handlerContext) GetSentinelClient() SentinelClientInterface {
if client, ok := h.client.(SentinelClientInterface); ok {
return client
}
return nil
}
// GetFailoverClient returns the client as a FailoverClient if it is one
func (h *handlerContext) GetFailoverClient() FailoverClientInterface {
if client, ok := h.client.(FailoverClientInterface); ok {
return client
}
return nil
}
// GetRegularClient returns the client as a regular Client if it is one
func (h *handlerContext) GetRegularClient() RegularClientInterface {
if client, ok := h.client.(RegularClientInterface); ok {
return client
}
return nil
}
// GetConnPool returns the connection pool from which the connection was obtained
func (h *handlerContext) GetConnPool() interface{} {
return h.connPool
}
// GetPubSub returns the PubSub instance that received the notification
func (h *handlerContext) GetPubSub() PubSubInterface {
if pubSub, ok := h.pubSub.(PubSubInterface); ok {
return pubSub
}
return nil
}
// GetConn returns the specific connection on which the notification was received
func (h *handlerContext) GetConn() *pool.Conn {
return h.conn
}
// IsBlocking returns true if the notification was received on a blocking connection
func (h *handlerContext) IsBlocking() bool {
return h.isBlocking
}
// Handler defines the interface for push notification handlers.
@ -25,13 +159,13 @@ type Handler interface {
// The handlerCtx provides information about the client, connection pool, and connection
// on which the notification was received, allowing handlers to make informed decisions.
// Returns true if the notification was handled, false otherwise.
HandlePushNotification(ctx context.Context, handlerCtx *HandlerContext, notification []interface{}) bool
HandlePushNotification(ctx context.Context, handlerCtx HandlerContext, notification []interface{}) bool
}
// ProcessorInterface defines the interface for push notification processors.
type ProcessorInterface interface {
GetHandler(pushNotificationName string) Handler
ProcessPendingNotifications(ctx context.Context, handlerCtx *HandlerContext, rd *proto.Reader) error
ProcessPendingNotifications(ctx context.Context, handlerCtx HandlerContext, rd *proto.Reader) error
RegisterHandler(pushNotificationName string, handler Handler, protected bool) error
}

2
options.go
View File

@ -599,8 +599,6 @@ func newConnPool(
MaxActiveConns: opt.MaxActiveConns,
ConnMaxIdleTime: opt.ConnMaxIdleTime,
ConnMaxLifetime: opt.ConnMaxLifetime,
// Pass push notification processor for connection initialization
PushNotificationProcessor: opt.PushNotificationProcessor,
// Pass protocol version for push notification optimization
Protocol: opt.Protocol,
})

64
pubsub.go
View File

@ -48,12 +48,6 @@ func (c *PubSub) init() {
c.exit = make(chan struct{})
}
// SetPushNotificationProcessor sets the push notification processor for handling
// generic push notifications received on this PubSub connection.
func (c *PubSub) SetPushNotificationProcessor(processor PushNotificationProcessorInterface) {
c.pushProcessor = processor
}
func (c *PubSub) String() string {
c.mu.Lock()
defer c.mu.Unlock()
@ -377,18 +371,6 @@ func (p *Pong) String() string {
return "Pong"
}
// PushNotificationMessage represents a generic push notification received on a PubSub connection.
type PushNotificationMessage struct {
// Command is the push notification command (e.g., "MOVING", "CUSTOM_EVENT").
Command string
// Args are the arguments following the command.
Args []interface{}
}
func (m *PushNotificationMessage) String() string {
return fmt.Sprintf("push: %s", m.Command)
}
func (c *PubSub) newMessage(reply interface{}) (interface{}, error) {
switch reply := reply.(type) {
case string:
@ -435,25 +417,6 @@ func (c *PubSub) newMessage(reply interface{}) (interface{}, error) {
Payload: reply[1].(string),
}, nil
default:
// Try to handle as generic push notification
ctx := c.getContext()
handler := c.pushProcessor.GetHandler(kind)
if handler != nil {
// Create handler context for pubsub
handlerCtx := &pushnotif.HandlerContext{
Client: c,
ConnPool: nil, // Not available in pubsub context
Conn: nil, // Not available in pubsub context
}
handled := handler.HandlePushNotification(ctx, handlerCtx, reply)
if handled {
// Return a special message type to indicate it was handled
return &PushNotificationMessage{
Command: kind,
Args: reply[1:],
}, nil
}
}
return nil, fmt.Errorf("redis: unsupported pubsub message: %q", kind)
}
default:
@ -477,6 +440,12 @@ func (c *PubSub) ReceiveTimeout(ctx context.Context, timeout time.Duration) (int
}
err = cn.WithReader(ctx, timeout, func(rd *proto.Reader) error {
// To be sure there are no buffered push notifications, we process them before reading the reply
if err := c.processPendingPushNotificationWithReader(ctx, cn, rd); err != nil {
// Log the error but don't fail the command execution
// Push notification processing errors shouldn't break normal Redis operations
internal.Logger.Printf(ctx, "push: error processing pending notifications before reading reply: %v", err)
}
return c.cmd.readReply(rd)
})
@ -573,6 +542,22 @@ func (c *PubSub) ChannelWithSubscriptions(opts ...ChannelOption) <-chan interfac
return c.allCh.allCh
}
func (c *PubSub) processPendingPushNotificationWithReader(ctx context.Context, cn *pool.Conn, rd *proto.Reader) error {
if c.pushProcessor == nil {
return nil
}
// Create handler context with client, connection pool, and connection information
handlerCtx := c.pushNotificationHandlerContext(cn)
return c.pushProcessor.ProcessPendingNotifications(ctx, handlerCtx, rd)
}
func (c *PubSub) pushNotificationHandlerContext(cn *pool.Conn) pushnotif.HandlerContext {
// PubSub doesn't have a client or connection pool, so we pass nil for those
// PubSub connections are blocking
return pushnotif.NewHandlerContext(nil, nil, c, cn, true)
}
type ChannelOption func(c *channel)
// WithChannelSize specifies the Go chan size that is used to buffer incoming messages.
@ -699,9 +684,6 @@ func (c *channel) initMsgChan() {
// Ignore.
case *Pong:
// Ignore.
case *PushNotificationMessage:
// Ignore push notifications in message-only channel
// They are already handled by the push notification processor
case *Message:
timer.Reset(c.chanSendTimeout)
select {
@ -756,7 +738,7 @@ func (c *channel) initAllChan() {
switch msg := msg.(type) {
case *Pong:
// Ignore.
case *Subscription, *Message, *PushNotificationMessage:
case *Subscription, *Message:
timer.Reset(c.chanSendTimeout)
select {
case c.allCh <- msg:

6
push_notifications.go
View File

@ -7,6 +7,8 @@ import (
"github.com/redis/go-redis/v9/internal/pushnotif"
)
type PushNotificationHandlerContext = pushnotif.HandlerContext
// PushNotificationHandler defines the interface for push notification handlers.
// This is an alias to the internal push notification handler interface.
type PushNotificationHandler = pushnotif.Handler
@ -76,7 +78,7 @@ func (p *PushNotificationProcessor) UnregisterHandler(pushNotificationName strin
// ProcessPendingNotifications checks for and processes any pending push notifications.
// The handlerCtx provides context about the client, connection pool, and connection.
func (p *PushNotificationProcessor) ProcessPendingNotifications(ctx context.Context, handlerCtx *pushnotif.HandlerContext, rd *proto.Reader) error {
func (p *PushNotificationProcessor) ProcessPendingNotifications(ctx context.Context, handlerCtx PushNotificationHandlerContext, rd *proto.Reader) error {
return p.processor.ProcessPendingNotifications(ctx, handlerCtx, rd)
}
@ -103,7 +105,7 @@ func (v *VoidPushNotificationProcessor) RegisterHandler(pushNotificationName str
}
// ProcessPendingNotifications reads and discards any pending push notifications.
func (v *VoidPushNotificationProcessor) ProcessPendingNotifications(ctx context.Context, handlerCtx *pushnotif.HandlerContext, rd *proto.Reader) error {
func (v *VoidPushNotificationProcessor) ProcessPendingNotifications(ctx context.Context, handlerCtx PushNotificationHandlerContext, rd *proto.Reader) error {
return v.processor.ProcessPendingNotifications(ctx, handlerCtx, rd)
}

24
redis.go
View File

@ -835,8 +835,9 @@ func NewClient(opt *Options) *Client {
}
c.init()
// Initialize push notification processor
c.initializePushProcessor()
// Initialize push notification processor using shared helper
// Use void processor for RESP2 connections (push notifications not available)
c.pushProcessor = initializePushProcessor(opt)
// Update options with the initialized push processor for connection pool
opt.PushNotificationProcessor = c.pushProcessor
@ -896,11 +897,6 @@ func initializePushProcessor(opt *Options) PushNotificationProcessorInterface {
return NewVoidPushNotificationProcessor()
}
// initializePushProcessor initializes the push notification processor for this client.
func (c *Client) initializePushProcessor() {
c.pushProcessor = initializePushProcessor(c.opt)
}
// RegisterPushNotificationHandler registers a handler for a specific push notification name.
// Returns an error if a handler is already registered for this push notification name.
// If protected is true, the handler cannot be unregistered.
@ -963,12 +959,10 @@ func (c *Client) pubSub() *PubSub {
return c.newConn(ctx)
},
closeConn: c.connPool.CloseConn,
pushProcessor: c.pushProcessor,
}
pubsub.init()
// Set the push notification processor
pubsub.SetPushNotificationProcessor(c.pushProcessor)
return pubsub
}
@ -1053,7 +1047,7 @@ func newConn(opt *Options, connPool pool.Pooler, parentHooks *hooksMixin) *Conn
}
// Initialize push notification processor using shared helper
// Use void processor by default for connections (typically don't need push notifications)
// Use void processor for RESP2 connections (push notifications not available)
c.pushProcessor = initializePushProcessor(opt)
c.cmdable = c.Process
@ -1145,10 +1139,6 @@ func (c *baseClient) processPendingPushNotificationWithReader(ctx context.Contex
}
// pushNotificationHandlerContext creates a handler context for push notification processing
func (c *baseClient) pushNotificationHandlerContext(cn *pool.Conn) *pushnotif.HandlerContext {
return &pushnotif.HandlerContext{
Client: c,
ConnPool: c.connPool,
Conn: cn,
}
func (c *baseClient) pushNotificationHandlerContext(cn *pool.Conn) pushnotif.HandlerContext {
return pushnotif.NewHandlerContext(c, c.connPool, nil, cn, false)
}

7
sentinel.go
View File

@ -15,6 +15,7 @@ import (
"github.com/redis/go-redis/v9/auth"
"github.com/redis/go-redis/v9/internal"
"github.com/redis/go-redis/v9/internal/pool"
"github.com/redis/go-redis/v9/internal/pushnotif"
"github.com/redis/go-redis/v9/internal/rand"
)
@ -429,7 +430,7 @@ func NewFailoverClient(failoverOpt *FailoverOptions) *Client {
rdb.init()
// Initialize push notification processor using shared helper
// Use void processor by default for failover clients (typically don't need push notifications)
// Use void processor by default for RESP2 connections
rdb.pushProcessor = initializePushProcessor(opt)
connPool = newConnPool(opt, rdb.dialHook)
@ -499,8 +500,8 @@ func NewSentinelClient(opt *Options) *SentinelClient {
}
// Initialize push notification processor using shared helper
// Use void processor by default for sentinel clients (typically don't need push notifications)
c.pushProcessor = initializePushProcessor(opt)
// Use void processor for Sentinel clients
c.pushProcessor = pushnotif.NewVoidProcessor()
c.initHooks(hooks{
dial: c.baseClient.dial,