feat: implement in-memory caching for dashboard data and background warmup task

src/dashboard_cache.py

@@ -0,0 +1,32 @@
+"""
+In-memory cache for dashboard Overview data.
+
+A background task periodically refreshes this cache so the dashboard
+serves pre-computed data instantly instead of hitting SQLite cold.
+
+Memory footprint is fixed — each key is overwritten on every refresh.
+"""
+
+import threading
+from typing import Any, Dict, Optional
+
+_lock = threading.Lock()
+_cache: Dict[str, Any] = {}
+
+
+def get_cached(key: str) -> Optional[Any]:
+    """Get a value from the dashboard cache."""
+    with _lock:
+        return _cache.get(key)
+
+
+def set_cached(key: str, value: Any) -> None:
+    """Set a value in the dashboard cache."""
+    with _lock:
+        _cache[key] = value
+
+
+def is_warm() -> bool:
+    """Check if the cache has been populated at least once."""
+    with _lock:
+        return "stats" in _cache

src/routes/api.py

@@ -18,6 +18,7 @@ from pydantic import BaseModel
 
 from dependencies import get_db, get_client_ip
 from logger import get_app_logger
+from dashboard_cache import get_cached, is_warm
 
 # Server-side session token store (valid tokens for authenticated sessions)
 _auth_tokens: set = set()
@@ -249,10 +250,16 @@ async def all_ips(
     sort_by: str = Query("total_requests"),
     sort_order: str = Query("desc"),
 ):
-    db = get_db()
     page = max(1, page)
     page_size = min(max(1, page_size), 10000)
 
+    # Serve from cache on default map request (top 100 IPs)
+    if page == 1 and page_size == 100 and sort_by == "total_requests" and sort_order == "desc" and is_warm():
+        cached = get_cached("map_ips")
+        if cached:
+            return JSONResponse(content=cached, headers=_no_cache_headers())
+
+    db = get_db()
     try:
         result = db.get_all_ips_paginated(
             page=page, page_size=page_size, sort_by=sort_by, sort_order=sort_order

src/routes/dashboard.py

@@ -10,6 +10,7 @@ from fastapi.responses import JSONResponse
 from logger import get_app_logger
 
 from dependencies import get_db, get_templates
+from dashboard_cache import get_cached, is_warm
 
 router = APIRouter()
 
@@ -17,17 +18,19 @@ router = APIRouter()
 @router.get("")
 @router.get("/")
 async def dashboard_page(request: Request):
-    db = get_db()
     config = request.app.state.config
     dashboard_path = "/" + config.dashboard_secret_path.lstrip("/")
 
-    # Get initial data for server-rendered sections
-    stats = db.get_dashboard_counts()
-    suspicious = db.get_recent_suspicious(limit=10)
-
-    # Get credential count for the stats card
-    cred_result = db.get_credentials_paginated(page=1, page_size=1)
-    stats["credential_count"] = cred_result["pagination"]["total"]
+    # Serve from pre-computed cache when available, fall back to live queries
+    if is_warm():
+        stats = get_cached("stats")
+        suspicious = get_cached("suspicious")
+    else:
+        db = get_db()
+        stats = db.get_dashboard_counts()
+        suspicious = db.get_recent_suspicious(limit=10)
+        cred_result = db.get_credentials_paginated(page=1, page_size=1)
+        stats["credential_count"] = cred_result["pagination"]["total"]
 
     templates = get_templates()
     return templates.TemplateResponse(

src/routes/htmx.py

@@ -10,6 +10,7 @@ from fastapi.responses import HTMLResponse
 
 from dependencies import get_db, get_templates
 from routes.api import verify_auth
+from dashboard_cache import get_cached, is_warm
 
 router = APIRouter()
 
@@ -58,10 +59,15 @@ async def htmx_top_ips(
     sort_by: str = Query("count"),
     sort_order: str = Query("desc"),
 ):
-    db = get_db()
-    result = db.get_top_ips_paginated(
-        page=max(1, page), page_size=8, sort_by=sort_by, sort_order=sort_order
-    )
+    # Serve from cache on default first-page request
+    cached = get_cached("top_ips") if (page == 1 and sort_by == "count" and sort_order == "desc" and is_warm()) else None
+    if cached:
+        result = cached
+    else:
+        db = get_db()
+        result = db.get_top_ips_paginated(
+            page=max(1, page), page_size=8, sort_by=sort_by, sort_order=sort_order
+        )
 
     templates = get_templates()
     return templates.TemplateResponse(
@@ -87,10 +93,14 @@ async def htmx_top_paths(
     sort_by: str = Query("count"),
     sort_order: str = Query("desc"),
 ):
-    db = get_db()
-    result = db.get_top_paths_paginated(
-        page=max(1, page), page_size=5, sort_by=sort_by, sort_order=sort_order
-    )
+    cached = get_cached("top_paths") if (page == 1 and sort_by == "count" and sort_order == "desc" and is_warm()) else None
+    if cached:
+        result = cached
+    else:
+        db = get_db()
+        result = db.get_top_paths_paginated(
+            page=max(1, page), page_size=5, sort_by=sort_by, sort_order=sort_order
+        )
 
     templates = get_templates()
     return templates.TemplateResponse(
@@ -116,10 +126,14 @@ async def htmx_top_ua(
     sort_by: str = Query("count"),
     sort_order: str = Query("desc"),
 ):
-    db = get_db()
-    result = db.get_top_user_agents_paginated(
-        page=max(1, page), page_size=5, sort_by=sort_by, sort_order=sort_order
-    )
+    cached = get_cached("top_ua") if (page == 1 and sort_by == "count" and sort_order == "desc" and is_warm()) else None
+    if cached:
+        result = cached
+    else:
+        db = get_db()
+        result = db.get_top_user_agents_paginated(
+            page=max(1, page), page_size=5, sort_by=sort_by, sort_order=sort_order
+        )
 
     templates = get_templates()
     return templates.TemplateResponse(

src/tasks/dashboard_warmup.py

@@ -0,0 +1,68 @@
+# tasks/dashboard_warmup.py
+
+"""
+Pre-computes all Overview tab data and stores it in the in-memory cache.
+This keeps SQLite page buffers warm and lets the dashboard respond instantly.
+"""
+
+from logger import get_app_logger
+from database import get_database
+from dashboard_cache import set_cached
+
+app_logger = get_app_logger()
+
+# ----------------------
+# TASK CONFIG
+# ----------------------
+TASK_CONFIG = {
+    "name": "dashboard-warmup",
+    "cron": "*/1 * * * *",
+    "enabled": True,
+    "run_when_loaded": True,
+}
+
+
+# ----------------------
+# TASK LOGIC
+# ----------------------
+def main():
+    """
+    Refresh the in-memory dashboard cache with current Overview data.
+    TasksMaster will call this function based on the cron schedule.
+    """
+    task_name = TASK_CONFIG.get("name")
+    app_logger.info(f"[Background Task] {task_name} starting...")
+
+    try:
+        db = get_database()
+
+        # --- Server-rendered data (stats cards + suspicious table) ---
+        stats = db.get_dashboard_counts()
+
+        cred_result = db.get_credentials_paginated(page=1, page_size=1)
+        stats["credential_count"] = cred_result["pagination"]["total"]
+
+        suspicious = db.get_recent_suspicious(limit=10)
+
+        # --- HTMX Overview tables (first page, default sort) ---
+        top_ips = db.get_top_ips_paginated(page=1, page_size=8)
+        top_ua = db.get_top_user_agents_paginated(page=1, page_size=5)
+        top_paths = db.get_top_paths_paginated(page=1, page_size=5)
+
+        # --- Map data (default: top 100 IPs by total_requests) ---
+        map_ips = db.get_all_ips_paginated(
+            page=1, page_size=100, sort_by="total_requests", sort_order="desc"
+        )
+
+        # Store everything in the cache (overwrites previous values)
+        set_cached("stats", stats)
+        set_cached("suspicious", suspicious)
+        set_cached("top_ips", top_ips)
+        set_cached("top_ua", top_ua)
+        set_cached("top_paths", top_paths)
+        set_cached("map_ips", map_ips)
+
+        app_logger.info(f"[Background Task] {task_name} cache refreshed successfully.")
+
+    except Exception as e:
+        app_logger.error(f"[Background Task] {task_name} failed: {e}")