refactor: split jikan client into transport/cache/rate subpackages
This commit is contained in:
323
integrations/jikan/transport/client.go
Normal file
323
integrations/jikan/transport/client.go
Normal file
@@ -0,0 +1,323 @@
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package transport
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import (
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"net"
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"net/http"
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"strconv"
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"strings"
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"time"
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"mal/integrations/jikan/rate"
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"mal/internal/observability"
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netutil "mal/pkg/net"
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)
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const slowLogThreshold = 750 * time.Millisecond
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type Client struct {
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HTTPClient *http.Client
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Limiter *rate.Limiter
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Metrics *observability.Metrics
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TraceEnabled func() bool
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}
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type Config struct {
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HTTPClient *http.Client
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Limiter *rate.Limiter
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Metrics *observability.Metrics
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TraceEnabled func() bool
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}
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type APIError struct {
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StatusCode int
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URL string
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}
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func (e *APIError) Error() string {
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return fmt.Sprintf("jikan api returned status %d", e.StatusCode)
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}
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func NewHTTPClient() *http.Client {
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return &http.Client{
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Timeout: 10 * time.Second,
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Transport: &http.Transport{
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MaxIdleConns: 10,
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IdleConnTimeout: 30 * time.Second,
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DisableKeepAlives: false,
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TLSHandshakeTimeout: 5 * time.Second,
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},
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}
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}
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func NewClient(cfg Config) *Client {
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return &Client{
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HTTPClient: cfg.HTTPClient,
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Limiter: cfg.Limiter,
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Metrics: cfg.Metrics,
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TraceEnabled: cfg.TraceEnabled,
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}
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}
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// IsRetryableError returns true if the error should trigger a retry.
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func IsRetryableError(err error) bool {
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if err == nil {
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return false
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}
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var apiErr *APIError
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if errors.As(err, &apiErr) {
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return isRetryableStatus(apiErr.StatusCode)
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}
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var netErr net.Error
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if errors.As(err, &netErr) {
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return true
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}
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if errors.Is(err, context.DeadlineExceeded) {
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return true
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}
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return false
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}
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// FetchWithRetry makes an HTTP request with exponential backoff on transient failures.
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func (c *Client) FetchWithRetry(ctx context.Context, urlStr string, out any) error {
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maxRetries := 5
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startedAt := time.Now()
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attempts := 0
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endpoint := metricsEndpoint(urlStr)
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logAndReturn := func(statusCode int, err error) error {
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c.Metrics.ObserveJikanRequest(endpoint, statusCode, time.Since(startedAt), err)
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c.logUpstream(urlStr, statusCode, attempts, startedAt, err)
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return err
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}
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for attempt := range maxRetries {
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attempts = attempt + 1
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if err := c.prepareRetryAttempt(ctx); err != nil {
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return logAndReturn(0, err)
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}
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resp, err := c.doRequest(ctx, urlStr)
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if err != nil {
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retry, requestErr := handleRequestRetry(ctx, err, attempt, maxRetries)
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if retry {
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continue
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}
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return logAndReturn(0, requestErr)
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}
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statusCode, retry, err := handleResponseRetry(ctx, resp, urlStr, out, attempt, maxRetries)
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if retry {
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continue
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}
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return logAndReturn(statusCode, err)
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}
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return logAndReturn(0, fmt.Errorf("max retries exceeded for %s", urlStr))
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}
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func (c *Client) prepareRetryAttempt(ctx context.Context) error {
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select {
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case <-ctx.Done():
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return fmt.Errorf("request canceled while retrying jikan request: %w", ctx.Err())
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default:
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}
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return c.Limiter.Wait(ctx)
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}
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func (c *Client) doRequest(ctx context.Context, urlStr string) (*http.Response, error) {
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, urlStr, nil)
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if err != nil {
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return nil, fmt.Errorf("failed to create jikan request: %w", err)
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}
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req.Header.Set("User-Agent", netutil.Generic)
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resp, err := c.HTTPClient.Do(req)
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if err != nil {
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return nil, err
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}
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return resp, nil
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}
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func handleRequestRetry(ctx context.Context, err error, attempt int, maxRetries int) (bool, error) {
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if errors.Is(err, context.Canceled) {
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return false, fmt.Errorf("request canceled while retrying jikan request: %w", err)
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}
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if attempt >= maxRetries-1 || !IsRetryableError(err) {
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return false, fmt.Errorf("jikan api error: %w", err)
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}
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if retryErr := waitForRetry(ctx, retryDelay(attempt)); retryErr != nil {
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return false, retryErr
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}
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return true, nil
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}
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func handleResponseRetry(ctx context.Context, resp *http.Response, urlStr string, out any, attempt int, maxRetries int) (int, bool, error) {
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if resp.StatusCode != http.StatusOK {
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return handleStatusRetry(ctx, resp, urlStr, out, attempt, maxRetries)
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}
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err := json.NewDecoder(resp.Body).Decode(out)
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_ = resp.Body.Close()
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if err == nil {
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return resp.StatusCode, false, nil
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}
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if attempt < maxRetries-1 {
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if retryErr := waitForRetry(ctx, retryDelay(attempt)); retryErr != nil {
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return resp.StatusCode, false, retryErr
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}
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return resp.StatusCode, true, nil
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}
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return resp.StatusCode, false, fmt.Errorf("failed to decode jikan response: %w", err)
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}
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func handleStatusRetry(ctx context.Context, resp *http.Response, urlStr string, out any, attempt int, maxRetries int) (int, bool, error) {
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statusCode := resp.StatusCode
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apiErr := &APIError{StatusCode: statusCode, URL: urlStr}
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retryAfter := time.Duration(0)
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if parsed, ok := parseRetryAfter(resp.Header.Get("Retry-After")); ok {
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retryAfter = parsed
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}
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if isRetryableStatus(statusCode) && attempt < maxRetries-1 {
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_ = resp.Body.Close()
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if retryErr := waitForRetry(ctx, max(retryAfter, retryDelay(attempt))); retryErr != nil {
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return statusCode, false, retryErr
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}
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return statusCode, true, nil
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}
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// Best-effort decode (often useful for debugging), but still treat non-200 as error.
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_ = json.NewDecoder(resp.Body).Decode(out)
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_ = resp.Body.Close()
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return statusCode, false, apiErr
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}
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func isRetryableStatus(statusCode int) bool {
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if statusCode == http.StatusTooManyRequests {
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return true
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}
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return statusCode >= 500 && statusCode <= 504
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}
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// retryDelay returns exponential backoff delay: 500ms, 1s, 2s, 4s, 8s (capped).
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func retryDelay(attempt int) time.Duration {
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base := 500 * time.Millisecond
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delay := base * time.Duration(1<<attempt)
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if delay > 8*time.Second {
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return 8 * time.Second
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}
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return delay
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}
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// parseRetryAfter parses Retry-After header value (seconds) into duration.
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func parseRetryAfter(value string) (time.Duration, bool) {
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trimmed := strings.TrimSpace(value)
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if trimmed == "" {
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return 0, false
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}
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seconds, err := strconv.Atoi(trimmed)
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if err != nil {
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return 0, false
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}
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if seconds <= 0 {
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return 0, false
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}
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return time.Duration(seconds) * time.Second, true
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}
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func waitForRetry(ctx context.Context, delay time.Duration) error {
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timer := time.NewTimer(delay)
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defer timer.Stop()
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select {
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case <-timer.C:
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return nil
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case <-ctx.Done():
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return fmt.Errorf("request canceled while retrying jikan request: %w", ctx.Err())
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}
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}
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func (c *Client) logUpstream(urlStr string, statusCode int, attempts int, startedAt time.Time, err error) {
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duration := time.Since(startedAt)
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traceEnabled := c.TraceEnabled != nil && c.TraceEnabled()
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if !traceEnabled && err == nil && statusCode < http.StatusBadRequest && duration < slowLogThreshold {
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return
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}
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level := observability.LogLevelInfo
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if err != nil || statusCode >= http.StatusInternalServerError {
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level = observability.LogLevelError
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} else if statusCode == http.StatusTooManyRequests || statusCode >= http.StatusBadRequest {
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level = observability.LogLevelWarn
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}
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observability.LogJSON(
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level,
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"jikan_upstream",
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"jikan",
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"",
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map[string]any{
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"url": urlStr,
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"endpoint": metricsEndpoint(urlStr),
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"status": statusCode,
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"attempts": attempts,
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"duration_ms": float64(duration.Microseconds()) / 1000,
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},
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err,
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)
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}
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func metricsEndpoint(urlStr string) string {
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trimmed := strings.TrimSpace(urlStr)
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if trimmed == "" {
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return "unknown"
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}
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prefix := "https://api.jikan.moe/v4"
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trimmed = strings.TrimPrefix(trimmed, prefix)
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if idx := strings.Index(trimmed, "?"); idx >= 0 {
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trimmed = trimmed[:idx]
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}
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parts := strings.Split(trimmed, "/")
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out := make([]string, 0, len(parts))
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for _, part := range parts {
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if part == "" {
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continue
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}
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if _, err := strconv.Atoi(part); err == nil {
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out = append(out, "{id}")
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continue
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}
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out = append(out, part)
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}
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if len(out) == 0 {
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return "/"
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}
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return "/" + strings.Join(out, "/")
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}
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