Convert to a class

nasa-gcn · Jan 6, 2023 · 2c13f05 · 2c13f05
1 parent 1f6d8a7
commit 2c13f05
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Showing 2 changed files with 42 additions and 47 deletions.
diff --git a/src/index.ts b/src/index.ts
@@ -6,7 +6,7 @@ import type {
 } from '@aws-sdk/lib-dynamodb'
 import type { NativeAttributeValue } from '@aws-sdk/util-dynamodb'
 
-export interface dynamoDBAutoIncrementProps {
+export interface DynamoDBAutoIncrementProps {
   /** a DynamoDB document client instance */
   doc: DynamoDBDocument
 
@@ -59,78 +59,76 @@ export interface dynamoDBAutoIncrementProps {
  * })
  * ```
  */
-export function dynamoDBAutoIncrement({
-  doc,
-  counterTableName,
-  counterTableKey,
-  counterTableAttributeName,
-  tableName,
-  tableAttributeName,
-  initialValue,
-  dangerously,
-}: dynamoDBAutoIncrementProps) {
-  async function getLast(): Promise<number | undefined> {
+export class DynamoDBAutoIncrement {
+  constructor(readonly props: DynamoDBAutoIncrementProps) {}
+
+  async getLast(): Promise<number | undefined> {
     return (
       (
-        await doc.get({
-          AttributesToGet: [counterTableAttributeName],
-          Key: counterTableKey,
-          TableName: counterTableName,
+        await this.props.doc.get({
+          AttributesToGet: [this.props.counterTableAttributeName],
+          Key: this.props.counterTableKey,
+          TableName: this.props.counterTableName,
         })
-      ).Item?.[counterTableAttributeName] ?? undefined
+      ).Item?.[this.props.counterTableAttributeName] ?? undefined
     )
   }
 
-  async function put(item: Record<string, NativeAttributeValue>) {
+  async put(item: Record<string, NativeAttributeValue>) {
     for (;;) {
-      const counter = await getLast()
+      const counter = await this.getLast()
 
       let nextCounter: number
       let Update: UpdateCommandInput & { UpdateExpression: string }
 
       if (counter === undefined) {
-        nextCounter = initialValue
+        nextCounter = this.props.initialValue
         Update = {
           ConditionExpression: 'attribute_not_exists(#counter)',
           ExpressionAttributeNames: {
-            '#counter': counterTableAttributeName,
+            '#counter': this.props.counterTableAttributeName,
           },
           ExpressionAttributeValues: {
             ':nextCounter': nextCounter,
           },
-          Key: counterTableKey,
-          TableName: counterTableName,
+          Key: this.props.counterTableKey,
+          TableName: this.props.counterTableName,
           UpdateExpression: 'SET #counter = :nextCounter',
         }
       } else {
         nextCounter = counter + 1
         Update = {
           ConditionExpression: '#counter = :counter',
           ExpressionAttributeNames: {
-            '#counter': counterTableAttributeName,
+            '#counter': this.props.counterTableAttributeName,
           },
           ExpressionAttributeValues: {
             ':counter': counter,
             ':nextCounter': nextCounter,
           },
-          Key: counterTableKey,
-          TableName: counterTableName,
+          Key: this.props.counterTableKey,
+          TableName: this.props.counterTableName,
           UpdateExpression: 'SET #counter = :nextCounter',
         }
       }
 
       const Put: PutCommandInput = {
         ConditionExpression: 'attribute_not_exists(#counter)',
-        ExpressionAttributeNames: { '#counter': tableAttributeName },
-        Item: { [tableAttributeName]: nextCounter, ...item },
-        TableName: tableName,
+        ExpressionAttributeNames: { '#counter': this.props.tableAttributeName },
+        Item: { [this.props.tableAttributeName]: nextCounter, ...item },
+        TableName: this.props.tableName,
       }
 
-      if (dangerously) {
-        await Promise.all([doc.update(Update), doc.put(Put)])
+      if (this.props.dangerously) {
+        await Promise.all([
+          this.props.doc.update(Update),
+          this.props.doc.put(Put),
+        ])
       } else {
         try {
-          await doc.transactWrite({ TransactItems: [{ Update }, { Put }] })
+          await this.props.doc.transactWrite({
+            TransactItems: [{ Update }, { Put }],
+          })
         } catch (e) {
           if (e instanceof TransactionCanceledException) {
             continue
@@ -143,8 +141,4 @@ export function dynamoDBAutoIncrement({
       return nextCounter
     }
   }
-
-  put.getLast = getLast
-
-  return put
 }
diff --git a/src/test.ts b/src/test.ts
@@ -3,12 +3,12 @@ import {
   DynamoDB,
 } from '@aws-sdk/client-dynamodb'
 import { DynamoDBDocument } from '@aws-sdk/lib-dynamodb'
-import type { dynamoDBAutoIncrementProps } from '.'
-import { dynamoDBAutoIncrement } from '.'
+import type { DynamoDBAutoIncrementProps } from '.'
+import { DynamoDBAutoIncrement } from '.'
 
 let doc: DynamoDBDocument
-let autoincrement: ReturnType<typeof dynamoDBAutoIncrement>
-let autoincrementDangerously: ReturnType<typeof dynamoDBAutoIncrement>
+let autoincrement: DynamoDBAutoIncrement
+let autoincrementDangerously: DynamoDBAutoIncrement
 const N = 20
 
 beforeAll(async () => {
@@ -19,7 +19,7 @@ beforeAll(async () => {
       region: '-',
     })
   )
-  const options: dynamoDBAutoIncrementProps = {
+  const options: DynamoDBAutoIncrementProps = {
     doc,
     counterTableName: 'autoincrement',
     counterTableKey: { tableName: 'widgets' },
@@ -28,8 +28,8 @@ beforeAll(async () => {
     tableAttributeName: 'widgetID',
     initialValue: 1,
   }
-  autoincrement = dynamoDBAutoIncrement(options)
-  autoincrementDangerously = dynamoDBAutoIncrement({
+  autoincrement = new DynamoDBAutoIncrement(options)
+  autoincrementDangerously = new DynamoDBAutoIncrement({
     ...options,
     dangerously: true,
   })
@@ -71,7 +71,7 @@ describe('dynamoDBAutoIncrement', () => {
         nextID = lastID + 1
       }
 
-      const result = await autoincrement({ widgetName: 'runcible spoon' })
+      const result = await autoincrement.put({ widgetName: 'runcible spoon' })
       expect(result).toEqual(nextID)
 
       expect(await autoincrement.getLast()).toEqual(nextID)
@@ -96,7 +96,7 @@ describe('dynamoDBAutoIncrement', () => {
 
   test('correctly handles a large number of parallel puts', async () => {
     const ids = Array.from(Array(N).keys()).map((i) => i + 1)
-    const result = await Promise.all(ids.map(() => autoincrement({})))
+    const result = await Promise.all(ids.map(() => autoincrement.put({})))
     expect(result.sort()).toEqual(ids.sort())
   })
 })
@@ -106,15 +106,16 @@ describe('dynamoDBAutoIncrement dangerously', () => {
     const ids = Array.from(Array(N).keys()).map((i) => i + 1)
     const result: number[] = []
     for (const item of ids) {
-      result.push(await autoincrementDangerously({ widgetName: item }))
+      result.push(await autoincrementDangerously.put({ widgetName: item }))
     }
     expect(result.sort()).toEqual(ids.sort())
   })
 
   test('fails on a large number of parallel puts', async () => {
     const ids = Array.from(Array(N).keys()).map((i) => i + 1)
     await expect(
-      async () => await Promise.all(ids.map(() => autoincrementDangerously({})))
+      async () =>
+        await Promise.all(ids.map(() => autoincrementDangerously.put({})))
     ).rejects.toThrow(ConditionalCheckFailedException)
   })
 })