perf(tenancy): batch list-page summaries

src/govoplan_tenancy/backend/api/v1/routes.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from collections.abc import Mapping, Sequence
 from typing import Any
 
 from fastapi import APIRouter, Body, Depends, HTTPException, Query, status
@@ -33,6 +34,7 @@ from govoplan_core.tenancy.service import (
     assert_tenant_governance_override_allowed,
     effective_tenant_governance,
     tenant_counts,
+    tenant_counts_many,
 )
 from govoplan_tenancy.backend.db.models import Tenant
 from govoplan_tenancy.backend.lifecycle import (
@@ -125,7 +127,12 @@ def _tenant_or_404(session: Session, tenant_id: str) -> Tenant:
     return tenant
 
 
-def _tenant_item(session: Session, tenant: Tenant) -> TenantAdminItem:
+def _tenant_item(
+    session: Session,
+    tenant: Tenant,
+    *,
+    counts: Mapping[str, int] | None = None,
+) -> TenantAdminItem:
     governance = effective_tenant_governance(session, tenant)
     return TenantAdminItem(
         id=tenant.id,
@@ -143,16 +150,36 @@ def _tenant_item(session: Session, tenant: Tenant) -> TenantAdminItem:
             "allow_api_keys": governance.allow_api_keys,
         },
         is_active=tenant.is_active,
-        counts=tenant_counts(
+        counts=(
-            session,
+            dict(counts)
-            tenant.id,
+            if counts is not None
-            module_ids=("campaigns", "files"),
+            else tenant_counts(
+                session,
+                tenant.id,
+                module_ids=("campaigns", "files"),
+            )
         ),
         created_at=tenant.created_at,
         updated_at=tenant.updated_at,
     )
 
 
+def _tenant_items(session: Session, tenants: Sequence[Tenant]) -> list[TenantAdminItem]:
+    counts_by_tenant = tenant_counts_many(
+        session,
+        [tenant.id for tenant in tenants],
+        module_ids=("campaigns", "files"),
+    )
+    return [
+        _tenant_item(
+            session,
+            tenant,
+            counts=counts_by_tenant.get(tenant.id, {}),
+        )
+        for tenant in tenants
+    ]
+
+
 def _tenant_deletion_plan(session: Session, tenant: Tenant, principal: ApiPrincipal, *, mode: str = "retire") -> TenantDeletionPlanResponse:
     issues: list[TenantLifecycleIssue] = []
     counts = tenant_counts(session, tenant.id)
@@ -480,7 +507,7 @@ def list_tenants(
         page_size=page_size,
     )
     return TenantListResponse(
-        tenants=[_tenant_item(session, tenant) for tenant in tenants],
+        tenants=_tenant_items(session, tenants),
         **pagination,
     )
 
@@ -504,7 +531,7 @@ def _full_tenant_list_delta_response(
     )
     has_more = page < pagination["pages"]
     return TenantListDeltaResponse(
-        tenants=[_tenant_item(session, tenant) for tenant in tenants],
+        tenants=_tenant_items(session, tenants),
         deleted=[],
         watermark=(
             _tenant_full_cursor(
@@ -544,7 +571,7 @@ def list_tenants_delta(
         tenants = session.query(Tenant).filter(Tenant.id.in_(changed_ids)).order_by(Tenant.name.asc()).all()
     visible_tenant_ids = {tenant.id for tenant in tenants}
     return TenantListDeltaResponse(
-        tenants=[_tenant_item(session, tenant) for tenant in tenants],
+        tenants=_tenant_items(session, tenants),
         deleted=_tenant_list_deleted_entries(entries, visible_tenant_ids),
         watermark=_tenant_list_response_watermark(session, entries=entries, has_more=has_more),
         has_more=has_more,