add one minute chart + refactor rpc

- add one minute charts
- update disk io to use bytes
- update hub and agent connection interfaces / handlers to be more
flexible
- change agent cache to use cache time instead of session id
- refactor collection of metrics which require deltas to track
separately per cache time

internal/hub/ws/request_manager.go

@@ -0,0 +1,186 @@
+package ws
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/fxamacker/cbor/v2"
+	"github.com/henrygd/beszel/internal/common"
+	"github.com/lxzan/gws"
+)
+
+// RequestID uniquely identifies a request
+type RequestID uint32
+
+// PendingRequest tracks an in-flight request
+type PendingRequest struct {
+	ID         RequestID
+	ResponseCh chan *gws.Message
+	Context    context.Context
+	Cancel     context.CancelFunc
+	CreatedAt  time.Time
+}
+
+// RequestManager handles concurrent requests to an agent
+type RequestManager struct {
+	sync.RWMutex
+	conn        *gws.Conn
+	pendingReqs map[RequestID]*PendingRequest
+	nextID      atomic.Uint32
+}
+
+// NewRequestManager creates a new request manager for a WebSocket connection
+func NewRequestManager(conn *gws.Conn) *RequestManager {
+	rm := &RequestManager{
+		conn:        conn,
+		pendingReqs: make(map[RequestID]*PendingRequest),
+	}
+	return rm
+}
+
+// SendRequest sends a request and returns a channel for the response
+func (rm *RequestManager) SendRequest(ctx context.Context, action common.WebSocketAction, data any) (*PendingRequest, error) {
+	reqID := RequestID(rm.nextID.Add(1))
+
+	reqCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+
+	req := &PendingRequest{
+		ID:         reqID,
+		ResponseCh: make(chan *gws.Message, 1),
+		Context:    reqCtx,
+		Cancel:     cancel,
+		CreatedAt:  time.Now(),
+	}
+
+	rm.Lock()
+	rm.pendingReqs[reqID] = req
+	rm.Unlock()
+
+	hubReq := common.HubRequest[any]{
+		Id:     (*uint32)(&reqID),
+		Action: action,
+		Data:   data,
+	}
+
+	// Send the request
+	if err := rm.sendMessage(hubReq); err != nil {
+		rm.cancelRequest(reqID)
+		return nil, fmt.Errorf("failed to send request: %w", err)
+	}
+
+	// Start cleanup watcher for timeout/cancellation
+	go rm.cleanupRequest(req)
+
+	return req, nil
+}
+
+// sendMessage encodes and sends a message over WebSocket
+func (rm *RequestManager) sendMessage(data any) error {
+	if rm.conn == nil {
+		return gws.ErrConnClosed
+	}
+
+	bytes, err := cbor.Marshal(data)
+	if err != nil {
+		return fmt.Errorf("failed to marshal request: %w", err)
+	}
+
+	return rm.conn.WriteMessage(gws.OpcodeBinary, bytes)
+}
+
+// handleResponse processes a single response message
+func (rm *RequestManager) handleResponse(message *gws.Message) {
+	var response common.AgentResponse
+	if err := cbor.Unmarshal(message.Data.Bytes(), &response); err != nil {
+		// Legacy response without ID - route to first pending request of any type
+		rm.routeLegacyResponse(message)
+		return
+	}
+
+	reqID := RequestID(*response.Id)
+
+	rm.RLock()
+	req, exists := rm.pendingReqs[reqID]
+	rm.RUnlock()
+
+	if !exists {
+		// Request not found (might have timed out) - close the message
+		message.Close()
+		return
+	}
+
+	select {
+	case req.ResponseCh <- message:
+		// Message successfully delivered - the receiver will close it
+		rm.deleteRequest(reqID)
+	case <-req.Context.Done():
+		// Request was cancelled/timed out - close the message
+		message.Close()
+	}
+}
+
+// routeLegacyResponse handles responses that don't have request IDs (backwards compatibility)
+func (rm *RequestManager) routeLegacyResponse(message *gws.Message) {
+	// Snapshot the oldest pending request without holding the lock during send
+	rm.RLock()
+	var oldestReq *PendingRequest
+	for _, req := range rm.pendingReqs {
+		if oldestReq == nil || req.CreatedAt.Before(oldestReq.CreatedAt) {
+			oldestReq = req
+		}
+	}
+	rm.RUnlock()
+
+	if oldestReq != nil {
+		select {
+		case oldestReq.ResponseCh <- message:
+			// Message successfully delivered - the receiver will close it
+			rm.deleteRequest(oldestReq.ID)
+		case <-oldestReq.Context.Done():
+			// Request was cancelled - close the message
+			message.Close()
+		}
+	} else {
+		// No pending requests - close the message
+		message.Close()
+	}
+}
+
+// cleanupRequest handles request timeout and cleanup
+func (rm *RequestManager) cleanupRequest(req *PendingRequest) {
+	<-req.Context.Done()
+	rm.cancelRequest(req.ID)
+}
+
+// cancelRequest removes a request and cancels its context
+func (rm *RequestManager) cancelRequest(reqID RequestID) {
+	rm.Lock()
+	defer rm.Unlock()
+
+	if req, exists := rm.pendingReqs[reqID]; exists {
+		req.Cancel()
+		delete(rm.pendingReqs, reqID)
+	}
+}
+
+// deleteRequest removes a request from the pending map without cancelling its context.
+func (rm *RequestManager) deleteRequest(reqID RequestID) {
+	rm.Lock()
+	defer rm.Unlock()
+	delete(rm.pendingReqs, reqID)
+}
+
+// Close shuts down the request manager
+func (rm *RequestManager) Close() {
+	rm.Lock()
+	defer rm.Unlock()
+
+	// Cancel all pending requests
+	for _, req := range rm.pendingReqs {
+		req.Cancel()
+	}
+	rm.pendingReqs = make(map[RequestID]*PendingRequest)
+}