Go SDK - Advanced Topics

Concurrency and Goroutines

Leveraging Go's built-in concurrency primitives is crucial for building scalable and responsive applications with the SDK. This section explores how to effectively manage goroutines, channels, and wait groups.

Goroutines for Parallel Operations

When performing multiple independent operations with the SDK, such as fetching data from different endpoints or processing multiple records, launching them as goroutines can significantly improve performance.

import (
	"fmt"
	"sync"
	"your_sdk_package" // Replace with your actual SDK package
)

func main() {
	var wg sync.WaitGroup
	client := your_sdk_package.NewClient("your_api_key")

	// Example: Fetching data from multiple sources concurrently
	dataSources := []string{"source1", "source2", "source3"}

	for _, source := range dataSources {
		wg.Add(1)
		go func(s string) {
			defer wg.Done()
			data, err := client.FetchData(s)
			if err != nil {
				fmt.Printf("Error fetching from %s: %v\n", s, err)
				return
			}
			fmt.Printf("Data from %s: %v\n", s, data)
		}(source)
	}

	wg.Wait()
	fmt.Println("All data fetched.")
}
            

Channels for Communication

Channels provide a safe and elegant way for goroutines to communicate with each other. Use channels to pass results, synchronize operations, or signal completion.

func processData(data <-chan string, results chan<- string, wg *sync.WaitGroup) {
	defer wg.Done()
	for item := range data {
		// Simulate processing
		processedItem := fmt.Sprintf("PROCESSED: %s", item)
		results <- processedItem
	}
}

func main() {
	var wg sync.WaitGroup
	inputData := []string{"itemA", "itemB", "itemC"}
	
	dataCh := make(chan string, len(inputData))
	resultsCh := make(chan string, len(inputData))

	// Populate data channel
	for _, item := range inputData {
		dataCh <- item
	}
	close(dataCh) // Close channel to signal no more data

	// Start worker goroutines
	numWorkers := 3
	wg.Add(numWorkers)
	for i := 0; i < numWorkers; i++ {
		go processData(dataCh, resultsCh, &wg)
	}

	// Wait for all workers to finish and close results channel
	go func() {
		wg.Wait()
		close(resultsCh)
	}()

	// Collect results
	fmt.Println("Processing complete:")
	for result := range resultsCh {
		fmt.Println(result)
	}
}
            

Error Handling and Resilience

Robust error handling is paramount. Learn how to handle API errors gracefully, implement retry mechanisms, and utilize context for request cancellation.

Custom Error Types

Define custom error types to provide more specific information about failures.

import (
	"errors"
	"fmt"
	"your_sdk_package"
)

type APIError struct {
	StatusCode int
	Message    string
}

func (e *APIError) Error() string {
	return fmt.Sprintf("API Error %d: %s", e.StatusCode, e.Message)
}

func (c *your_sdk_package.Client) CallAPI(endpoint string) (string, error) {
	// ... API call logic ...
	if apiFailed {
		return "", &APIError{StatusCode: 500, Message: "Internal Server Error"}
	}
	return "Success", nil
}

func main() {
	client := your_sdk_package.NewClient("api_key")
	_, err := client.CallAPI("/resource")
	if err != nil {
		var apiErr *APIError
		if errors.As(err, &apiErr) {
			fmt.Printf("Caught specific API error: Status %d, %s\n", apiErr.StatusCode, apiErr.Message)
		} else {
			fmt.Printf("Caught general error: %v\n", err)
		}
	}
}
            

Context for Cancellation and Timeouts

The context.Context is indispensable for managing request lifecycles, including cancellation and deadlines.

import (
	"context"
	"fmt"
	"time"
	"your_sdk_package"
)

func main() {
	client := your_sdk_package.NewClient("api_key")

	// Create a context with a 5-second timeout
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel() // Always call cancel to release resources

	go func() {
		// Simulate a long-running operation that might be cancelled
		result, err := client.LongRunningOperation(ctx)
		if err != nil {
			if err == context.DeadlineExceeded {
				fmt.Println("Operation timed out.")
			} else {
				fmt.Printf("Operation failed: %v\n", err)
			}
			return
		}
		fmt.Printf("Operation successful: %s\n", result)
	}()

	// Allow operation to run, or be cancelled by timeout
	time.Sleep(6 * time.Second) // Exceeds timeout
}
            

Performance Optimizations

Discover techniques to maximize the efficiency of your SDK usage.

Testing Your Integration

Writing effective tests is key to ensuring your application behaves as expected when interacting with the SDK.

Mocking SDK Clients

Use mocking libraries to isolate your application logic from actual API calls during unit tests.

import (
	"testing"
	"github.com/stretchr/testify/mock"
	"your_sdk_package"
)

// Define a mock for the SDK client
type MockSDKClient struct {
	mock.Mock
}

func (m *MockSDKClient) FetchData(source string) (string, error) {
	args := m.Called(source)
	return args.String(0), args.Error(1)
}

func TestMyApplicationLogic(t *testing.T) {
	mockClient := new(MockSDKClient)
	
	// Set up expectations for the mock
	mockClient.On("FetchData", "source1").Return("mocked_data_1", nil)
	
	// Call your function that uses the SDK client
	result, err := yourFunctionThatUsesSDK(mockClient, "source1") 

	// Assertions
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	if result != "processed_mocked_data_1" { // Assuming your function processes it
		t.Errorf("Expected result 'processed_mocked_data_1', got '%s'", result)
	}

	mockClient.AssertExpectations(t) // Verify that all expectations were met
}