milestone 32: task-shaped configuration, file mode as a rendering, config status api

src/web/handlers/upstreams.zig

@@ -52,6 +52,10 @@ pub fn applyCreate(
     state.config_lock.unlock(io);
 
     const id = inserted catch |err| return .{ .fail = mutations.dbFailure(err, url_conflict) };
+    // Ruling 12: the pool is built at startup, so the row now stored governs
+    // nothing until the next one. Stored after the insert, never before — a
+    // rejected url or a conflict owes no restart.
+    state.restart_pending.store(true, .monotonic);
     return .{ .id = id };
 }
 
@@ -83,6 +87,7 @@ pub fn applyUpdate(
 
     upstreams_repo.updateUpstream(database, id, item) catch |err|
         return mutations.dbFailure(err, url_conflict);
+    state.restart_pending.store(true, .monotonic);
     return null;
 }
 
@@ -106,6 +111,7 @@ pub fn applyDelete(state: *server.WebState, io: std.Io, arena: Allocator, id: i6
 
     upstreams_repo.deleteUpstream(database, id) catch |err|
         return mutations.dbFailure(err, url_conflict);
+    state.restart_pending.store(true, .monotonic);
     return null;
 }
 
@@ -245,6 +251,26 @@ test "a url the validator refuses never reaches the database" {
     try testing.expectEqual(@as(i64, 0), try bench.queryInt("SELECT count(*) FROM upstreams"));
 }
 
+test "a refused upstream write owes no restart, and an accepted one does" {
+    var bench: mutations.Bench = undefined;
+    try bench.init(testing.allocator);
+    defer bench.deinit(testing.allocator);
+
+    try testing.expect((try applyCreate(&bench.state, bench.io(), bench.arena(), .{
+        .url = "udp://1.1.1.1:53",
+    })).fail == .invalid);
+    try testing.expect(!bench.state.restart_pending.load(.monotonic));
+
+    try testing.expect((try applyUpdate(&bench.state, bench.io(), bench.arena(), 999, doh)).? == .not_found);
+    try testing.expect(!bench.state.restart_pending.load(.monotonic));
+
+    try testing.expect(applyDelete(&bench.state, bench.io(), bench.arena(), 999).? == .not_found);
+    try testing.expect(!bench.state.restart_pending.load(.monotonic));
+
+    _ = try applyCreate(&bench.state, bench.io(), bench.arena(), doh);
+    try testing.expect(bench.state.restart_pending.load(.monotonic));
+}
+
 test "a duplicate url is a conflict" {
     var bench: mutations.Bench = undefined;
     try bench.init(testing.allocator);