Я пишу лямбда-функцию AWS, которая должна обновлять ежедневную статистику игрока каждый раз, когда он выполняет упражнение. Функция запускается один раз с настроенным 0 повторных попыток при новом событии строки DynamoDB.
Я тестирую только эту функцию, уверен, что создаю только одну строку в DynamoDB, которая запускает выполнение лямбда-выражения. Теперь самое интересное. Моя лямбда выполняется один раз целиком, но какая-то ее часть выполняется дважды в одном запросе.
Вот лямбда-код:
const AWS = require('aws-sdk');
var docClient = new AWS.DynamoDB.DocumentClient({region: 'us-west-2'});
const dailyStatsTableName = 'xxx';
const weeklyStatsTableName = 'yyy';
const monthlyStatsPlayerTableName = 'zzz';
const requestsTableName = 'qqq';
exports.handler = async (event, context, callback) => {
//Ensure idempotency of lambda as a whole
let requestID = context.awsRequestId;
let requestAlreadyProcessed = false;
await getRequest(requestsTableName, requestID, (err, data) => {
if (err) {
console.log(err);
} else {
if (data.Item) {
requestAlreadyProcessed = true;
}
}
});
if (requestAlreadyProcessed) {
console.log("This request has already been processed. Aborting.");
return;
}
console.log("Processing new assigned drill performance event. RequestID: " + requestID);
console.log(event);
const record = event.Records[0].dynamodb;
console.log(record);
if (!record || !record.NewImage) {
console.log("New record image undefined");
return;
}
console.log(record.NewImage);
//Get performed touches to count them in statistics
let touches = 0;
try {
touches = parseInt(record.NewImage.touches.N, 10);
} catch (error) {
console.error(error);
}
//Unpack date from record.NewImage.createdAt string
let performanceDate = new Date(Date.parse(record.NewImage.createdAt.S));
console.log("CreatedAt date: " + performanceDate);
//Get daily statistics object from table - I want to update if already exist
let dailyStats = {
drillID: record.NewImage.drillID.S,
targetUserID: record.NewImage.targetUserID.S,
performDay: performanceDate.getDate(),
performMonth: performanceDate.getMonth(),
performYear: performanceDate.getFullYear(),
performDate: performanceDate.toISOString(),
touches: 0,
id: undefined
};
let result = await getDailyStats(dailyStatsTableName, dailyStats.performDay, dailyStats.performMonth, dailyStats.performYear, dailyStats.drillID, dailyStats.targetUserID, (err, data) => {
if (err) {
console.log(err);
} else {
if (data.Items.length !== 0) {
console.log("Found daily stats object"); //this console.log is logged twice. Everything below that line is executed twice.
dailyStats = data.Items[0];
}
}
return "success";
});
//Create or update daily statistics
if (!dailyStats.id) {
console.log("DailyStats ID not found. Creating new with touches " + touches);
dailyStats.touches = touches;
result = await createDailyStats(dailyStatsTableName, dailyStats, requestID, (err, data) => {
if (err) {
console.log(err);
} else {
console.log("Success creating daily stats " + dailyStats.drillID + " " + dailyStats.targetUserID + " " + dailyStats.touches);
}
return "success";
});
} else {
console.log("DailyStats ID found. Updating existing with touches " + touches);
result = await updateDailyStats(dailyStatsTableName, dailyStats.id, touches, requestID, (err, data) => {
if (err) {
console.log(err);
} else {
console.log("Success updating daily stats " + dailyStats.drillID + " " + dailyStats.targetUserID + " " + touches);
}
return "success";
});
}
//Mark this request as processed to ensure idempotency of lambda as a whole
result = await createProcessedRequest(requestsTableName, requestID, (err, data) => {
if (err) {
console.log(err);
} else {
console.log("Success creating processed request " + requestID);
}
return "success";
});
return "success";
};
function createDailyStats(tableName, stats, requestID, callback) {
let now = new Date();
let dateTimeString = now.toISOString();
let params = {
TableName:tableName,
Item:{
"__typename": "PersonalDrillDailyStatistic",
"createdAt": dateTimeString,
"updatedAt": dateTimeString,
"id": stats.id ? stats.id : createUUID(),
"drillID": stats.drillID,
"targetUserID": stats.targetUserID,
"touches": stats.touches,
"performDay": stats.performDay,
"performMonth": stats.performMonth,
"performYear": stats.performYear,
"lastRequestID": requestID
}
};
console.log("Adding a new daily stats (with id) item... " + stats.drillID + " " + stats.targetUserID + " " + stats.touches);
return docClient.put(params, callback).promise();
}
function updateDailyStats(tableName, statsID, touches, requestID, callback) {
var params = {
TableName:tableName,
Key:{
"id": statsID
},
UpdateExpression: "set touches = touches + :val, lastRequestID = :reqID",
ExpressionAttributeValues:{
":val": touches,
":reqID": requestID
},
ConditionExpression: "lastRequestID <> :reqID", //conditional check exception is being thrown during second call, hence Exception in logs output
ReturnValues:"UPDATED_NEW"
};
console.log("Updating daily stats (with id) item... " + statsID + " " + touches);
return docClient.update(params, callback).promise();
}
function getDailyStats(tableName, performDay, performMonth, performYear, drillID, targetUserID, callback) {
console.log("Querying for daily statistics |" + performDay + "." + performMonth + "." + performYear + "| userID: |" + targetUserID + "| drillID: |" + drillID + "| from table " + tableName);
let params = {
TableName: tableName,
FilterExpression: "drillID = :drill_id and targetUserID = :user_id and performDay = :day and performMonth = :month and performYear = :year",
ExpressionAttributeValues: {
":drill_id": drillID,
":user_id": targetUserID,
":day": performDay,
":month": performMonth,
":year": performYear,
}
};
return docClient.scan(params, callback).promise();
}
function createUUID(){
(...)
}
function getRequest(tableName, requestID, callback) {
let params = {
TableName: tableName,
Key: {
"id": requestID
}
};
return docClient.get(params, callback).promise();
}
function createProcessedRequest(tableName, requestID, callback) {
let params = {
TableName:tableName,
Item:{
"id": requestID,
"name": requestID
}
};
return docClient.put(params, callback).promise();
}
Вот выходные данные CloudWatch для этого выполнения лямбда-выражения:
2021-04-16T22:24:49.754+02:00 START RequestId: 8766c005-c1f3-42fb-aee9-9e8352da67ed Version: $LATEST
2021-04-16T22:24:50.464+02:00 2021-04-16T20:24:50.464Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO Processing new assigned drill performance event. RequestID: 8766c005-c1f3-42fb-aee9-9e8352da67ed
2021-04-16T22:24:50.523+02:00 2021-04-16T20:24:50.523Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO { Records: [ { eventID: 'e09a400894c178ef66840f54e71b6c26', eventName: 'INSERT', eventVersion: '1.1', eventSource: 'aws:dynamodb', awsRegion: 'us-west-2', dynamodb: [Object], eventSourceARN: 'arn:aws:dynamodb:us-west-2:900776852541:table/FDrillPerformance-y22t7izqyvb2xiruvbf4zhadvm-fissiondev/stream/2021-04-15T21:48:06.158' } ] }
2021-04-16T22:24:50.541+02:00 2021-04-16T20:24:50.541Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO { ApproximateCreationDateTime: 1618604689, Keys: { id: { S: '7321fcf5-fed2-402a-b1cf-7667e958f73a' } }, NewImage: { createdAt: { S: '2021-04-16T20:24:49.077Z' }, touches: { N: '25' }, __typename: { S: 'FDrillPerformance' }, drillID: { S: '01adc7e6-67be-4bdf-828b-36833cbd7070' }, targetUserID: { S: 'd4a95710-c4fb-4f0f-8355-76082e41c43a' }, id: { S: '7321fcf5-fed2-402a-b1cf-7667e958f73a' }, updatedAt: { S: '2021-04-16T20:24:49.077Z' } }, SequenceNumber: '218143500000000009280556527', SizeBytes: 269, StreamViewType: 'NEW_IMAGE' }
2021-04-16T22:24:50.561+02:00 2021-04-16T20:24:50.561Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO { createdAt: { S: '2021-04-16T20:24:49.077Z' }, touches: { N: '25' }, __typename: { S: 'FDrillPerformance' }, drillID: { S: '01adc7e6-67be-4bdf-828b-36833cbd7070' }, targetUserID: { S: 'd4a95710-c4fb-4f0f-8355-76082e41c43a' }, id: { S: '7321fcf5-fed2-402a-b1cf-7667e958f73a' }, updatedAt: { S: '2021-04-16T20:24:49.077Z' } }
2021-04-16T22:24:50.581+02:00 2021-04-16T20:24:50.581Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO CreatedAt date: Fri Apr 16 2021 20:24:49 GMT+0000 (Coordinated Universal Time)
2021-04-16T22:24:50.581+02:00 2021-04-16T20:24:50.581Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO Querying for daily statistics |16.3.2021| userID: |d4a95710-c4fb-4f0f-8355-76082e41c43a| drillID: |01adc7e6-67be-4bdf-828b-36833cbd7070| from table PersonalDrillDailyStatistic-y22t7izqyvb2xiruvbf4zhadvm-fissiondev
2021-04-16T22:24:50.784+02:00 2021-04-16T20:24:50.783Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO Found daily stats object
2021-04-16T22:24:50.784+02:00 2021-04-16T20:24:50.784Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO DailyStats ID found. Updating existing with touches 25
2021-04-16T22:24:50.784+02:00 2021-04-16T20:24:50.784Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO Updating daily stats (with id) item... ab00afe1-ed4b-4895-b1bb-31ac570fe46d 25
2021-04-16T22:24:50.883+02:00 2021-04-16T20:24:50.883Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO Found daily stats object
2021-04-16T22:24:51.302+02:00 2021-04-16T20:24:51.302Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO Success updating daily stats 01adc7e6-67be-4bdf-828b-36833cbd7070 d4a95710-c4fb-4f0f-8355-76082e41c43a 25
2021-04-16T22:24:51.401+02:00 2021-04-16T20:24:51.384Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO ConditionalCheckFailedException: The conditional request failed at Request.extractError (/var/runtime/node_modules/aws-sdk/lib/protocol/json.js:52:27) at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:106:20) at Request.emit (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:78:10) at Request.emit (/var/runtime/node_modules/aws-sdk/lib/request.js:688:14) at Request.transition (/var/runtime/node_modules/aws-sdk/lib/request.js:22:10) at AcceptorStateMachine.runTo (/var/runtime/node_modules/aws-sdk/lib/state_machine.js:14:12) at /var/runtime/node_modules/aws-sdk/lib/state_machine.js:26:10 at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:38:9) at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:690:12) at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:116:18) { code: 'ConditionalCheckFailedException', time: 2021-04-16T20:24:51.383Z, requestId: 'H8PC553OQABGJKR9KFIJMR1EHJVV4KQNSO5AEMVJF66Q9ASUAAJG', statusCode: 400, retryable: false, retryDelay: 36.82252581429517 }
2021-04-16T22:24:51.462+02:00 2021-04-16T20:24:51.462Z 8766c005-c1f3-42fb-aee9-9e8352da67ed INFO Success creating processed request 8766c005-c1f3-42fb-aee9-9e8352da67ed
2021-04-16T22:24:51.482+02:00 END RequestId: 8766c005-c1f3-42fb-aee9-9e8352da67ed
2021-04-16T22:24:51.482+02:00 REPORT RequestId: 8766c005-c1f3-42fb-aee9-9e8352da67ed Duration: 1728.11 ms Billed Duration: 1729 ms Memory Size: 128 MB Max Memory Used: 91 MB Init Duration: 413.89 ms
Итак, вы можете видеть, что хотя лямбда вызывается один раз, некоторые ее части вызываются дважды, и я не знаю, как с этим бороться. Мне также нужно обновлять еженедельную и ежемесячную статистику, поэтому проблема усложняется. Взлом с ConditionExpression по последнему идентификатору запроса работает, но я бы позаботился о том, чтобы код внутри моей функции не запускался дважды, вместо того, чтобы пытаться использовать такие обходные пути.
