refactor: add doWithResult for easier usage

go/pkg/db/retry.go

@@ -56,12 +56,5 @@ func WithRetry[T any](fn func() (T, error)) (T, error) {
 		}),
 	)
 
-	var result T
-	err := retrier.Do(func() error {
-		var retryErr error
-		result, retryErr = fn()
-		return retryErr
-	})
-
-	return result, err
+	return retry.DoWithResult(retrier, fn)
 }

go/pkg/retry/retry.go

@@ -12,7 +12,7 @@ type retry struct {
 	attempts int
 
 	// backoff is a function that returns the duration to wait before the next retry
-	// based on the current attempt number (zero-based)
+	// based on the current attempt number (starting at 1)
 	backoff func(n int) time.Duration
 
 	// shouldRetry is a function that determines if an error is retryable
@@ -24,14 +24,14 @@ type retry struct {
 	sleep func(d time.Duration)
 }
 
-// Build creates a new retry instance with default configuration.
+// New creates a new retry instance with default configuration.
 // Default configuration:
 //   - 3 retry attempts
 //   - Linear backoff starting at 100ms, increasing by 100ms per attempt
 //
 // Example:
 //
-//	r := retry.Build()
+//	r := retry.New()
 //	err := r.Do(func() error {
 //		// Simulate an operation that might fail
 //		resp, err := http.Get("https://api.example.com")
@@ -52,7 +52,7 @@ type retry struct {
 //
 // The retry behavior can be customized using Attempts() and Backoff():
 //
-// r := retry.Build(
+// r := retry.New(
 //
 //	retry.Attempts(5),
 //	retry.Backoff(func(n int) time.Duration {
@@ -90,7 +90,6 @@ func Attempts(attempts int) Apply {
 // should return the duration to wait before the next attempt.
 func Backoff(backoff func(n int) time.Duration) Apply {
 	return func(r *retry) *retry {
-
 		r.backoff = backoff
 		return r
 	}
@@ -154,3 +153,26 @@ func (r *retry) Do(fn func() error) error {
 
 	return err
 }
+
+// DoWithResult executes the given function with configured retry behavior and returns a result.
+// Works like Do() but for functions that return a value along with an error.
+// On failure, returns the result from the last attempt along with the final error.
+//
+// Example:
+//
+//	r := retry.New(retry.Attempts(3))
+//	user, err := retry.DoWithResult(r, func() (*User, error) {
+//		return fetchUserFromAPI(userID)
+//	})
+//	if err != nil {
+//		log.Printf("failed to fetch user after 3 attempts: %v", err)
+//	}
+func DoWithResult[T any](r *retry, fn func() (T, error)) (T, error) {
+	var result T
+	err := r.Do(func() error {
+		var retryErr error
+		result, retryErr = fn()
+		return retryErr
+	})
+	return result, err
+}

go/pkg/retry/retry_test.go

@@ -115,7 +115,6 @@ func TestRetry(t *testing.T) {
 			} else {
 				require.NoError(t, err)
 			}
-
 		})
 	}
 }
@@ -222,3 +221,74 @@ func TestShouldRetry(t *testing.T) {
 		})
 	}
 }
+
+func TestDoWithResult(t *testing.T) {
+	tests := []struct {
+		name           string
+		errorSequence  []error
+		resultSequence []string
+		expectedCalls  int
+		expectedResult string
+		expectedError  error
+		expectedSleep  time.Duration
+	}{
+		{
+			name:           "should return result on first success",
+			errorSequence:  []error{nil},
+			resultSequence: []string{"success"},
+			expectedCalls:  1,
+			expectedResult: "success",
+			expectedError:  nil,
+			expectedSleep:  0,
+		},
+		{
+			name:           "should return result after retries",
+			errorSequence:  []error{errors.New("temp"), errors.New("temp"), nil},
+			resultSequence: []string{"", "", "success"},
+			expectedCalls:  3,
+			expectedResult: "success",
+			expectedError:  nil,
+			expectedSleep:  300 * time.Millisecond,
+		},
+		{
+			name:           "should return last result on complete failure",
+			errorSequence:  []error{errors.New("fail1"), errors.New("fail2"), errors.New("fail3")},
+			resultSequence: []string{"result1", "result2", "result3"},
+			expectedCalls:  3,
+			expectedResult: "result3", // last attempt's result
+			expectedError:  errors.New("fail3"),
+			expectedSleep:  300 * time.Millisecond,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			retrier := New()
+			totalSleep := time.Duration(0)
+			retrier.sleep = func(d time.Duration) {
+				totalSleep += d
+			}
+
+			calls := 0
+			result, err := DoWithResult(retrier, func() (string, error) {
+				idx := calls
+				calls++
+				if idx < len(tt.errorSequence) {
+					return tt.resultSequence[idx], tt.errorSequence[idx]
+				}
+				return "", nil
+			})
+
+			require.Equal(t, tt.expectedCalls, calls, "unexpected number of calls")
+			require.Equal(t, tt.expectedSleep, totalSleep, "unexpected sleep duration")
+			require.Equal(t, tt.expectedResult, result, "unexpected result")
+
+			if tt.expectedError != nil {
+				require.Error(t, err)
+				require.Equal(t, tt.expectedError.Error(), err.Error())
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}