Kiro/docs/task-3.1-implementation.md

Task 3.1 Implementation: DynamoDB Storage Service Wrapper

Overview

Enhanced the existing DynamoDB client from Task 2.1 with retry logic, connection pooling, transaction support, and batch operations.

Implementation Details

1. Enhanced Client Configuration

• Retry Strategy: Configured with exponential backoff and jitter
  • Max attempts: 5
  • Max backoff: 20 seconds
  • Prevents thundering herd with jitter
• Connection Pooling: Uses AWS SDK's default HTTP client with built-in connection pooling

2. Transaction Support

Implemented TransactWriteItems method for ACID transactions:

• Supports multiple write operations in a single atomic transaction
• Automatic retry on transient failures
• Proper error handling and wrapping

3. Batch Operations

Implemented two batch operation methods:

BatchGetItems

• Retrieves multiple items in a single request
• Automatically retries unprocessed keys with exponential backoff
• Merges results from retry attempts
• Max 5 retry attempts with increasing backoff (100ms → 20s)

BatchWriteItems

• Writes multiple items in a single request
• Automatically retries unprocessed items with exponential backoff
• Max 5 retry attempts with increasing backoff (100ms → 20s)

4. Standard Operations

Wrapped standard DynamoDB operations with automatic retry:

• PutItem - Put a single item
• GetItem - Get a single item
• UpdateItem - Update a single item
• DeleteItem - Delete a single item
• Query - Query items

All operations include proper error handling and wrapping.

5. Comprehensive Testing

Created dynamodb_test.go with tests for:

• Client initialization
• Transaction operations
• Batch get operations
• Batch write operations
• Put and get operations
• Update operations
• Delete operations
• Query operations

Tests include:

• Automatic skip when DynamoDB is not available
• Helper function for test setup with dummy AWS credentials
• Table creation and cleanup helpers
• Verification of all operations

Files Modified/Created

Modified

• internal/storage/dynamodb.go - Enhanced with retry logic, transactions, and batch operations

Created

• internal/storage/dynamodb_test.go - Comprehensive test suite
• internal/storage/README.md - Documentation for the storage service
• docs/task-3.1-implementation.md - This implementation document

Requirements Addressed

✅ Requirement 8.1: Immediate persistence with reliable operations ✅ Requirement 8.8: Efficient scaling through batch operations and connection pooling ✅ Design: Retry logic with exponential backoff ✅ Design: Transaction support (TransactWrite) ✅ Design: Batch operations (BatchGet, BatchWrite) ✅ Design: Connection pooling

Testing

Running Tests

# Start DynamoDB Local
docker-compose up -d

# Run all storage tests
go test -v ./internal/storage

# Run specific tests
go test -v ./internal/storage -run TestTransactWriteItems

Test Coverage

• ✅ Client initialization with retry configuration
• ✅ Transaction writes with multiple items
• ✅ Batch get with multiple items
• ✅ Batch write with multiple items
• ✅ Single item operations (Put, Get, Update, Delete)
• ✅ Query operations
• ✅ Graceful skip when DynamoDB unavailable

Usage Example

// Create client
ctx := context.Background()
client, err := storage.NewDynamoDBClient(ctx, "http://localhost:8000")
if err != nil {
    log.Fatal(err)
}

// Transaction example
err = client.TransactWriteItems(ctx, &dynamodb.TransactWriteItemsInput{
    TransactItems: []types.TransactWriteItem{
        {
            Put: &types.Put{
                TableName: aws.String("MyTable"),
                Item: map[string]types.AttributeValue{
                    "id": &types.AttributeValueMemberS{Value: "item1"},
                },
            },
        },
    },
})

// Batch write example
err = client.BatchWriteItems(ctx, &dynamodb.BatchWriteItemInput{
    RequestItems: map[string][]types.WriteRequest{
        "MyTable": {
            {
                PutRequest: &types.PutRequest{
                    Item: map[string]types.AttributeValue{
                        "id": &types.AttributeValueMemberS{Value: "item1"},
                    },
                },
            },
        },
    },
})

// Batch get example
output, err := client.BatchGetItems(ctx, &dynamodb.BatchGetItemInput{
    RequestItems: map[string]types.KeysAndAttributes{
        "MyTable": {
            Keys: []map[string]types.AttributeValue{
                {"id": &types.AttributeValueMemberS{Value: "item1"}},
            },
        },
    },
})

Next Steps

This enhanced storage service is now ready to be used by:

• Task 3.2: Data model implementations
• Task 3.3: Table schema creation
• All future tasks requiring DynamoDB operations

The retry logic, transaction support, and batch operations provide a solid foundation for building scalable, reliable data access patterns.