Updates circuit breaker documentation and adds test cases for circuit…

… breaker logic

middleware/request/circuit_breaker.go

@@ -20,17 +20,16 @@ const (
 	Open
 )
 
-// NewCircuitBreakerMiddleware creates a new circuit breaker middleware with the specified threshold and period.
-// The circuit breaker middleware wraps a given `wasabi.RequestHandler` and provides circuit breaking functionality.
-// The circuit breaker tracks the number of consecutive errors and opens the circuit when the error count exceeds the threshold.
-// During the open state, all requests are rejected with an `ErrCircuitBreakerOpen` error.
-// After a specified period of time, the circuit breaker transitions to the semi-open state, allowing a single request to be processed.
-// If the request succeeds, the circuit breaker resets the error count and transitions back to the closed state.
-// If the request fails, the circuit breaker remains in the open state.
-// The circuit breaker uses synchronization primitives to ensure thread safety.
-// The `treshold` parameter specifies the maximum number of consecutive errors allowed before opening the circuit.
-// The `period` parameter specifies the duration of time after which the circuit breaker transitions to the semi-open state.
-// The returned function is a middleware that can be used with the `wasabi` framework.
+// NewCircuitBreakerMiddleware creates a new circuit breaker middleware with the specified parameters.
+// It returns a function that wraps the provided `wasabi.RequestHandler` and implements the circuit breaker logic.
+// The circuit breaker monitors the number of errors and successful requests within a given time period.
+// If the number of errors exceeds the threshold, the circuit breaker switches to the "Open" state and rejects subsequent requests.
+// After a specified number of successful requests, the circuit breaker switches back to the "Closed" state.
+// The circuit breaker uses a lock to ensure thread safety.
+// The `treshold` parameter specifies the maximum number of errors allowed within the time period.
+// The `period` parameter specifies the duration of the time period.
+// The `recoverAfter` parameter specifies the number of successful requests required to recover from the "Open" state.
+// The returned function can be used as middleware in a Wasabi server.
 func NewCircuitBreakerMiddleware(treshold uint, period time.Duration, recoverAfter uint) func(next wasabi.RequestHandler) wasabi.RequestHandler {
 	var errorCounter, successCounter uint
 

middleware/request/circuit_breaker_test.go

@@ -0,0 +1,278 @@
+package request
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/ksysoev/wasabi"
+	"github.com/ksysoev/wasabi/dispatch"
+	"github.com/ksysoev/wasabi/mocks"
+)
+
+func TestNewCircuitBreakerMiddleware_ClosedState(t *testing.T) {
+	treshold := uint(3)
+	period := time.Second
+	recoverAfter := uint(1)
+
+	// Create a mock request handler
+	mockHandler := dispatch.RequestHandlerFunc(func(conn wasabi.Connection, req wasabi.Request) error { return nil })
+	mockRequest := mocks.NewMockRequest(t)
+	mockConn := mocks.NewMockConnection(t)
+
+	// Create the circuit breaker middleware
+	middleware := NewCircuitBreakerMiddleware(treshold, period, recoverAfter)(mockHandler)
+
+	// Test the Closed state
+	for i := uint(0); i < treshold+1; i++ {
+		err := middleware.Handle(mockConn, mockRequest)
+		if err != nil {
+			t.Errorf("Expected no error, but got %v", err)
+		}
+	}
+}
+
+func TestNewCircuitBreakerMiddleware_OpenState(t *testing.T) {
+	treshold := uint(1)
+	period := time.Second
+	recoverAfter := uint(1)
+
+	testError := fmt.Errorf("test error")
+
+	// Create a mock request handler
+	mockHandler := dispatch.RequestHandlerFunc(func(conn wasabi.Connection, req wasabi.Request) error {
+		time.Sleep(5 * time.Millisecond)
+		return testError
+	})
+
+	mockRequest := mocks.NewMockRequest(t)
+	mockConn := mocks.NewMockConnection(t)
+
+	// Create the circuit breaker middleware
+	middleware := NewCircuitBreakerMiddleware(treshold, period, recoverAfter)(mockHandler)
+
+	// Bring the circuit breaker to the Open state
+	err := middleware.Handle(mockConn, mockRequest)
+	if err != testError {
+		t.Errorf("Expected error %v, but got %v", testError, err)
+	}
+
+	// Test the Open state
+	results := make(chan error)
+
+	for i := 0; i < 2; i++ {
+		go func() {
+			results <- middleware.Handle(mockConn, mockRequest)
+		}()
+	}
+
+	OpenErrorCount := 0
+	TestErrorCount := 0
+
+	for i := 0; i < 2; i++ {
+		select {
+		case err := <-results:
+			if err != ErrCircuitBreakerOpen && err != testError {
+				t.Errorf("Expected error %v, but got %v", ErrCircuitBreakerOpen, err)
+				continue
+			}
+
+			if err == ErrCircuitBreakerOpen {
+				OpenErrorCount++
+			} else if err == testError {
+				TestErrorCount++
+			}
+
+		case <-time.After(100 * time.Millisecond):
+			t.Fatal("Expected error, but got none")
+		}
+	}
+
+	if OpenErrorCount != 1 {
+		t.Errorf("Expected 1 ErrCircuitBreakerOpen error, but got %d", OpenErrorCount)
+	}
+
+	if TestErrorCount != 1 {
+		t.Errorf("Expected 1 test error, but got %d", TestErrorCount)
+	}
+}
+
+func TestNewCircuitBreakerMiddleware_SemiOpenState(t *testing.T) {
+	treshold := uint(1)
+	period := time.Second
+	recoverAfter := uint(1)
+
+	testError := fmt.Errorf("test error")
+
+	errorToReturn := testError
+
+	// Create a mock request handler
+	mockHandler := dispatch.RequestHandlerFunc(func(conn wasabi.Connection, req wasabi.Request) error {
+		time.Sleep(5 * time.Millisecond)
+		return errorToReturn
+	})
+
+	mockRequest := mocks.NewMockRequest(t)
+	mockConn := mocks.NewMockConnection(t)
+
+	// Create the circuit breaker middleware
+	middleware := NewCircuitBreakerMiddleware(treshold, period, recoverAfter)(mockHandler)
+
+	// Bring the circuit breaker to the Open state
+	err := middleware.Handle(mockConn, mockRequest)
+	if err != testError {
+		t.Errorf("Expected error %v, but got %v", testError, err)
+	}
+
+	// Test the Open state
+	errorToReturn = nil
+	OpenErrorCount := 0
+	SuccessCount := 0
+	results := make(chan error)
+
+	for i := 0; i < 2; i++ {
+		go func() {
+			results <- middleware.Handle(mockConn, mockRequest)
+		}()
+	}
+
+	for i := 0; i < 2; i++ {
+		select {
+		case err := <-results:
+			if err != ErrCircuitBreakerOpen && err != nil {
+				t.Errorf("Expected error %v, but got %v", ErrCircuitBreakerOpen, err)
+				continue
+			}
+
+			if err == ErrCircuitBreakerOpen {
+				OpenErrorCount++
+			} else if err == nil {
+				SuccessCount++
+			}
+
+		case <-time.After(100 * time.Millisecond):
+			t.Fatal("Expected error, but got none")
+		}
+	}
+
+	if OpenErrorCount != 1 {
+		t.Errorf("Expected 1 ErrCircuitBreakerOpen error, but got %d", OpenErrorCount)
+	}
+
+	if SuccessCount != 1 {
+		t.Errorf("Expected 1 test error, but got %d", SuccessCount)
+	}
+
+	// Confirm that the circuit breaker is now in the Closed state
+
+	for i := 0; i < 2; i++ {
+		go func() {
+			results <- middleware.Handle(mockConn, mockRequest)
+		}()
+	}
+
+	OpenErrorCount = 0
+	SuccessCount = 0
+
+	for i := 0; i < 2; i++ {
+		select {
+		case err := <-results:
+			if err != ErrCircuitBreakerOpen && err != nil {
+				t.Errorf("Expected error %v, but got %v", ErrCircuitBreakerOpen, err)
+				continue
+			}
+
+			if err == ErrCircuitBreakerOpen {
+				OpenErrorCount++
+			} else if err == nil {
+				SuccessCount++
+			}
+
+		case <-time.After(100 * time.Millisecond):
+			t.Fatal("Expected error, but got none")
+		}
+	}
+
+	if OpenErrorCount != 0 {
+		t.Errorf("Expected 0 ErrCircuitBreakerOpen error, but got %d", OpenErrorCount)
+	}
+
+	if SuccessCount != 2 {
+		t.Errorf("Expected 2 test error, but got %d", SuccessCount)
+	}
+}
+
+func TestNewCircuitBreakerMiddleware_ResetMeasureInterval(t *testing.T) {
+	treshold := uint(2)
+	period := 20 * time.Millisecond
+	recoverAfter := uint(1)
+
+	testError := fmt.Errorf("test error")
+
+	errorToReturn := testError
+
+	// Create a mock request handler
+	mockHandler := dispatch.RequestHandlerFunc(func(conn wasabi.Connection, req wasabi.Request) error {
+		time.Sleep(5 * time.Millisecond)
+		return errorToReturn
+	})
+
+	mockRequest := mocks.NewMockRequest(t)
+	mockConn := mocks.NewMockConnection(t)
+
+	// Create the circuit breaker middleware
+	middleware := NewCircuitBreakerMiddleware(treshold, period, recoverAfter)(mockHandler)
+
+	// Bring the circuit breaker to the Open state
+
+	if err := middleware.Handle(mockConn, mockRequest); err != testError {
+		t.Errorf("Expected error %v, but got %v", testError, err)
+	}
+
+	time.Sleep(period)
+
+	if err := middleware.Handle(mockConn, mockRequest); err != testError {
+		t.Errorf("Expected error %v, but got %v", testError, err)
+	}
+
+	// Confirm that the circuit breaker is now in the Closed state
+
+	errorToReturn = nil
+	results := make(chan error)
+
+	for i := 0; i < 2; i++ {
+		go func() {
+			results <- middleware.Handle(mockConn, mockRequest)
+		}()
+	}
+
+	OpenErrorCount := 0
+	SuccessCount := 0
+
+	for i := 0; i < 2; i++ {
+		select {
+		case err := <-results:
+			if err != ErrCircuitBreakerOpen && err != nil {
+				t.Errorf("Expected error %v, but got %v", ErrCircuitBreakerOpen, err)
+				continue
+			}
+
+			if err == ErrCircuitBreakerOpen {
+				OpenErrorCount++
+			} else if err == nil {
+				SuccessCount++
+			}
+
+		case <-time.After(100 * time.Millisecond):
+			t.Fatal("Expected error, but got none")
+		}
+	}
+
+	if OpenErrorCount != 0 {
+		t.Errorf("Expected 0 ErrCircuitBreakerOpen error, but got %d", OpenErrorCount)
+	}
+
+	if SuccessCount != 2 {
+		t.Errorf("Expected 2 test error, but got %d", SuccessCount)
+	}
+}