Introduce visibility timeout

Author: stevebux

infrastructure/terraform/components/api/README.md

@@ -11,7 +11,7 @@ resource "aws_dynamodb_table" "letter_queue" {
   }
 
   local_secondary_index {
-    name            = "queueTimestamp-index"
+    name            = "queueSortOrder-index"
     range_key       = "queueTimestamp"
     projection_type = "ALL"
   }

infrastructure/terraform/components/api/ddb_table_letter_queue.tf

@@ -35,7 +35,7 @@ module "update_letter_queue" {
   log_subscription_role_arn = local.acct.log_subscription_role_arn
 
   lambda_env_vars = merge(local.common_lambda_env_vars, {
-    LETTER_QUEUE_TABLE_NAME = aws_dynamodb_table.letter_queue.name,
+    LETTER_QUEUE_TABLE_NAME = "${local.csi}-letter-queue",
     LETTER_QUEUE_TTL_HOURS  = 168 # 7 days
   })
 }
@@ -51,8 +51,8 @@ data "aws_iam_policy_document" "update_letter_queue_lambda" {
     ]
 
     resources = [
-      aws_dynamodb_table.letter_queue.arn,
-      "${aws_dynamodb_table.letter_queue.arn}/index/*"
+      "arn:aws:dynamodb:${var.region}:${var.aws_account_id}:table/${local.csi}-letter-queue",
+      "arn:aws:dynamodb:${var.region}:${var.aws_account_id}:table/${local.csi}-letter-queue/index/*"
     ]
   }
 

infrastructure/terraform/components/api/module_lambda_update_letter_queue.tf

@@ -129,7 +129,7 @@ const createLetterQueueTableCommand = new CreateTableCommand({
   ],
   LocalSecondaryIndexes: [
     {
-      IndexName: "timestamp-index",
+      IndexName: "queueSortOrder-index",
       KeySchema: [
         { AttributeName: "supplierId", KeyType: "HASH" }, // Partition key for LSI
         { AttributeName: "queueTimestamp", KeyType: "RANGE" }, // Sort key for LSI

internal/datastore/src/__test__/db.ts

@@ -53,32 +53,16 @@ describe("LetterQueueRepository", () => {
     await db.container.stop();
   });
 
-  function assertTtl(ttl: number, before: number, after: number) {
-    const expectedLower = Math.floor(
-      before / 1000 + 60 * 60 * db.config.letterQueueTtlHours,
-    );
-    const expectedUpper = Math.floor(
-      after / 1000 + 60 * 60 * db.config.lettersTtlHours,
-    );
-    expect(ttl).toBeGreaterThanOrEqual(expectedLower);
-    expect(ttl).toBeLessThanOrEqual(expectedUpper);
-  }
-
   describe("putLetter", () => {
     it("adds a letter to the database", async () => {
-      const before = Date.now();
+      jest.useFakeTimers().setSystemTime(new Date("2026-03-04T13:15:45.000Z"));
 
       const pendingLetter =
         await letterQueueRepository.putLetter(createLetter());
 
-      const after = Date.now();
-
-      const timestampInMillis = new Date(
-        pendingLetter.queueTimestamp,
-      ).valueOf();
-      expect(timestampInMillis).toBeGreaterThanOrEqual(before);
-      expect(timestampInMillis).toBeLessThanOrEqual(after);
-      assertTtl(pendingLetter.ttl, before, after);
+      expect(pendingLetter.queueTimestamp).toBe("2026-03-04T13:15:45.000Z");
+      expect(pendingLetter.visibilityTimeout).toBe("2026-03-04T13:15:45.000Z");
+      expect(pendingLetter.ttl).toBe(1_772_633_745);
       expect(await letterExists(db, "supplier1", "letter1")).toBe(true);
     });
 

internal/datastore/src/__test__/letter-queue-repository.test.ts

@@ -27,10 +27,13 @@ export default class LetterQueueRepository {
   async putLetter(
     insertPendingLetter: InsertPendingLetter,
   ): Promise<PendingLetter> {
+    // needs to be an ISO timestamp as Db sorts alphabetically
+    const now = new Date().toISOString();
+
     const pendingLetter: PendingLetter = {
       ...insertPendingLetter,
-      // needs to be an ISO timestamp as Db sorts alphabetically
-      queueTimestamp: new Date().toISOString(),
+      queueTimestamp: now,
+      visibilityTimeout: now,
       ttl: Math.floor(
         Date.now() / 1000 + 60 * 60 * this.config.letterQueueTtlHours,
       ),

internal/datastore/src/letter-queue-repository.ts

@@ -80,14 +80,18 @@ export const PendingLetterSchema = z.object({
   supplierId: idRef(SupplierSchema, "id"),
   letterId: idRef(LetterSchema, "id"),
   queueTimestamp: z.string().describe("Secondary index SK"),
+  visibilityTimeout: z.string(),
   specificationId: z.string(),
   groupId: z.string(),
   ttl: z.int(),
 });
 
 export type PendingLetter = z.infer<typeof PendingLetterSchema>;
 
-export type InsertPendingLetter = Omit<PendingLetter, "ttl" | "queueTimestamp">;
+export type InsertPendingLetter = Omit<
+  PendingLetter,
+  "ttl" | "queueTimestamp" | "visibilityTimeout"
+>;
 
 export const MISchemaBase = z.object({
   id: z.string(),