Struct Conn

internal/pool/conn.go:69–138

}

type Conn struct {
	// Connection identifier for unique tracking
	id uint64

	usedAt      atomic.Int64
	lastPutAt   atomic.Int64
	dialStartNs atomic.Int64 // Time when dial started (for connection create time metric)

	// Lock-free netConn access using atomic.Value
	// Contains *atomicNetConn wrapper, accessed atomically for better performance
	netConnAtomic atomic.Value // stores *atomicNetConn

	rd *proto.Reader
	bw *bufio.Writer
	wr *proto.Writer

	// Lightweight mutex to protect reader operations during handoff and health checks
	// Used during:
	// - SetNetConn (write lock for resetting reader state)
	// - HasBufferedData/PeekReplyTypeSafe (read lock for safe concurrent peek operations)
	readerMu sync.RWMutex

	// State machine for connection state management
	// Replaces: usable, Inited, used
	// Provides thread-safe state transitions with FIFO waiting queue
	// States: CREATED → INITIALIZING → IDLE ⇄ IN_USE
	//                                    ↓
	//                                UNUSABLE (handoff/reauth)
	//                                    ↓
	//                                IDLE/CLOSED
	stateMachine *ConnStateMachine

	// Handoff metadata - managed separately from state machine
	// These are atomic for lock-free access during handoff operations
	handoffStateAtomic   atomic.Value  // stores *HandoffState
	handoffRetriesAtomic atomic.Uint32 // retry counter

	pooled    bool
	pubsub    bool
	createdAt time.Time
	expiresAt time.Time
	poolName  string // Name of the pool this connection belongs to (for metrics)

	// When a goroutine closes a connection, it usually knows the reason, so closeReason is not needed.
	// closeReason is only used when an in-use connection is closed by another goroutine,
	// to inform the goroutine using the connection why the connection was closed.
	closeReason uberatomic.String

	// closeOnPutReason marks an in-use connection for removal when it is returned
	// to the pool. The socket is left open for the in-flight command and closed
	// by ConnPool.Put.
	closeOnPutReason uberatomic.String

	// maintenanceNotifications upgrade support: relaxed timeouts during migrations/failovers

	// Using atomic operations for lock-free access to avoid mutex contention
	relaxedReadTimeoutNs  atomic.Int64 // time.Duration as nanoseconds
	relaxedWriteTimeoutNs atomic.Int64 // time.Duration as nanoseconds