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https://github.com/PerpetualSoftware/pad.git
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xarmian
7ef4506cfa
When the browser tab lost focus and regained it, 5 independent onTabResume callbacks all fired simultaneously, flooding the server with redundant requests. This replaces that pattern with a 4-layer sync architecture: 1. Replay buffer — per-workspace ring buffer stores recent events with monotonic IDs. On SSE reconnect, missed events are replayed via Last-Event-ID so the client is already caught up. 2. Last-Event-ID support — SSE handler reads the header, replays from buffer, or sends sync_required if the gap is too large. 3. Incremental sync — new /changes?since=<ms> endpoint returns only modified/deleted items since a timestamp, including archived items for view consistency. 4. Centralized sync coordinator — single decision tree replaces 5 scattered callbacks. Short absences skip sync entirely, SSE-covered gaps need no API calls, and full refresh is a last resort. Key robustness details: - Global event IDs via Redis INCR for multi-instance safety - Server-time cursors to avoid client clock skew - Safe cursor management (only advances on confirmed sync) - 9 new tests for replay buffer and event ID behavior Fixes BUG-26.
78 lines
2.3 KiB
Go
78 lines
2.3 KiB
Go
package server
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import (
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"net/http"
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"strconv"
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"time"
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)
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// ChangesResponse is the response for GET /workspaces/{ws}/changes?since=<unix_ms>.
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type ChangesResponse struct {
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// Updated items (with full item data).
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Updated []interface{} `json:"updated"`
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// IDs of items that were deleted since the requested timestamp.
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Deleted []string `json:"deleted"`
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// Server timestamp at the time of this response (unix ms).
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// Clients should use this as the `since` value for the next sync.
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ServerTime int64 `json:"server_time"`
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// Whether the collection metadata (counts, schemas) may have changed.
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// True if any items were updated/deleted, signaling the client should
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// also refresh collection metadata.
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CollectionsChanged bool `json:"collections_changed"`
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}
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// handleGetChanges returns items modified since a given timestamp.
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// GET /api/v1/workspaces/{ws}/changes?since=<unix_milliseconds>
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//
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// This is the incremental sync endpoint used by the frontend when the
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// tab regains focus. Instead of re-fetching everything, the client sends
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// the timestamp of its last successful sync and gets back only the delta.
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func (s *Server) handleGetChanges(w http.ResponseWriter, r *http.Request) {
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workspaceID, ok := s.getWorkspaceID(w, r)
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if !ok {
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return
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}
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sinceStr := r.URL.Query().Get("since")
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if sinceStr == "" {
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writeError(w, http.StatusBadRequest, "bad_request", "since query parameter is required (unix milliseconds)")
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return
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}
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sinceMs, err := strconv.ParseInt(sinceStr, 10, 64)
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if err != nil || sinceMs < 0 {
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writeError(w, http.StatusBadRequest, "bad_request", "since must be a valid unix timestamp in milliseconds")
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return
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}
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since := time.UnixMilli(sinceMs)
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serverTime := time.Now().UnixMilli()
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updated, deletedIDs, err := s.store.ItemsModifiedSince(workspaceID, since)
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if err != nil {
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writeInternalError(w, err)
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return
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}
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// Convert to interface slice for JSON marshaling.
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updatedItems := make([]interface{}, len(updated))
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for i, item := range updated {
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updatedItems[i] = item
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}
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if updatedItems == nil {
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updatedItems = []interface{}{}
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}
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if deletedIDs == nil {
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deletedIDs = []string{}
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}
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resp := ChangesResponse{
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Updated: updatedItems,
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Deleted: deletedIDs,
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ServerTime: serverTime,
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CollectionsChanged: len(updated) > 0 || len(deletedIDs) > 0,
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}
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writeJSON(w, http.StatusOK, resp)
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}
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