Add solution for Challenge 30 by nzamulov

challenge-30/submissions/nzamulov/solution-template.go

@@ -0,0 +1,146 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+)
+
+// ContextManager defines a simplified interface for basic context operations
+type ContextManager interface {
+	// Create a cancellable context from a parent context
+	CreateCancellableContext(parent context.Context) (context.Context, context.CancelFunc)
+
+	// Create a context with timeout
+	CreateTimeoutContext(parent context.Context, timeout time.Duration) (context.Context, context.CancelFunc)
+
+	// Add a value to context
+	AddValue(parent context.Context, key, value interface{}) context.Context
+
+	// Get a value from context
+	GetValue(ctx context.Context, key interface{}) (interface{}, bool)
+
+	// Execute a task with context cancellation support
+	ExecuteWithContext(ctx context.Context, task func() error) error
+
+	// Wait for context cancellation or completion
+	WaitForCompletion(ctx context.Context, duration time.Duration) error
+}
+
+// Simple context manager implementation
+type simpleContextManager struct{}
+
+// NewContextManager creates a new context manager
+func NewContextManager() ContextManager {
+	return &simpleContextManager{}
+}
+
+// CreateCancellableContext creates a cancellable context
+func (cm *simpleContextManager) CreateCancellableContext(parent context.Context) (context.Context, context.CancelFunc) {
+	return context.WithCancel(parent)
+}
+
+// CreateTimeoutContext creates a context with timeout
+func (cm *simpleContextManager) CreateTimeoutContext(parent context.Context, timeout time.Duration) (context.Context, context.CancelFunc) {
+	return context.WithTimeout(parent, timeout)
+}
+
+// AddValue adds a key-value pair to the context
+func (cm *simpleContextManager) AddValue(parent context.Context, key, value interface{}) context.Context {
+	return context.WithValue(parent, key, value)
+}
+
+// GetValue retrieves a value from the context
+func (cm *simpleContextManager) GetValue(ctx context.Context, key interface{}) (interface{}, bool) {
+	val := ctx.Value(key)
+	return val, val != nil
+}
+
+// ExecuteWithContext executes a task that can be cancelled via context
+func (cm *simpleContextManager) ExecuteWithContext(ctx context.Context, task func() error) error {
+	ch := make(chan error, 1)
+
+	go func() {
+		ch <- task()
+	}()
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case err := <-ch:
+		return err
+	}
+}
+
+// WaitForCompletion waits for a duration or until context is cancelled
+func (cm *simpleContextManager) WaitForCompletion(ctx context.Context, duration time.Duration) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-time.After(duration):
+		return nil
+	}
+}
+
+// Helper function - simulate work that can be cancelled
+func SimulateWork(ctx context.Context, workDuration time.Duration, _ string) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-time.After(workDuration):
+		return nil
+	}
+}
+
+// Helper function - process multiple items with context
+func ProcessItems(ctx context.Context, items []string) ([]string, error) {
+	var result []string
+
+	ch := make(chan string, 1)
+
+	go func() {
+		defer close(ch)
+
+		for _, item := range items {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+			}
+			ch <- fmt.Sprintf("processed_%s", item)
+			time.Sleep(50 * time.Millisecond)
+		}
+	}()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return result, ctx.Err()
+		case item, ok := <-ch:
+			if !ok {
+				return result, nil
+			}
+			result = append(result, item)
+		}
+	}
+}
+
+// Example usage
+func main() {
+	fmt.Println("Context Management Challenge")
+	fmt.Println("Implement the context manager methods!")
+
+	// Example of how the context manager should work:
+	cm := NewContextManager()
+
+	// Create a cancellable context
+	ctx, cancel := cm.CreateCancellableContext(context.Background())
+	defer cancel()
+
+	// Add some values
+	ctx = cm.AddValue(ctx, "user", "alice")
+	ctx = cm.AddValue(ctx, "requestID", "12345")
+
+	// Use the context
+	fmt.Println("Context created with values!")
+}