http: add support for HTTP 429 rate limit retries

Documentation/config/http.adoc

@@ -315,6 +315,30 @@ http.keepAliveCount::
 	unset, curl's default value is used. Can be overridden by the
 	`GIT_HTTP_KEEPALIVE_COUNT` environment variable.
 
+http.retryAfter::
+	Default wait time in seconds before retrying when a server returns
+	HTTP 429 (Too Many Requests) without a Retry-After header. If set
+	to -1 (the default), Git will fail immediately when encountering
+	a 429 response without a Retry-After header. When a Retry-After
+	header is present, its value takes precedence over this setting.
+	Can be overridden by the `GIT_HTTP_RETRY_AFTER` environment variable.
+	See also `http.maxRetries` and `http.maxRetryTime`.
+
+http.maxRetries::
+	Maximum number of times to retry after receiving HTTP 429 (Too Many
+	Requests) responses. Set to 0 (the default) to disable retries.
+	Can be overridden by the `GIT_HTTP_MAX_RETRIES` environment variable.
+	See also `http.retryAfter` and `http.maxRetryTime`.
+
+http.maxRetryTime::
+	Maximum time in seconds to wait for a single retry attempt when
+	handling HTTP 429 (Too Many Requests) responses. If the server
+	requests a delay (via Retry-After header) or if `http.retryAfter`
+	is configured with a value that exceeds this maximum, Git will fail
+	immediately rather than waiting. Default is 300 seconds (5 minutes).
+	Can be overridden by the `GIT_HTTP_MAX_RETRY_TIME` environment
+	variable. See also `http.retryAfter` and `http.maxRetries`.
+
 http.noEPSV::
 	A boolean which disables using of EPSV ftp command by curl.
 	This can be helpful with some "poor" ftp servers which don't

http-push.c

@@ -716,6 +716,10 @@ static int fetch_indices(void)
 	case HTTP_MISSING_TARGET:
 		ret = 0;
 		break;
+	case HTTP_RATE_LIMITED:
+		error("rate limited by '%s', please try again later", repo->url);
+		ret = -1;
+		break;
 	default:
 		ret = -1;
 	}
@@ -1548,6 +1552,10 @@ static int remote_exists(const char *path)
 	case HTTP_MISSING_TARGET:
 		ret = 0;
 		break;
+	case HTTP_RATE_LIMITED:
+		error("rate limited by '%s', please try again later", url);
+		ret = -1;
+		break;
 	case HTTP_ERROR:
 		error("unable to access '%s': %s", url, curl_errorstr);
 		/* fallthrough */

http-walker.c

@@ -414,6 +414,11 @@ static int fetch_indices(struct walker *walker, struct alt_base *repo)
 		repo->got_indices = 1;
 		ret = 0;
 		break;
+	case HTTP_RATE_LIMITED:
+		error("rate limited by '%s', please try again later", repo->base);
+		repo->got_indices = 0;
+		ret = -1;
+		break;
 	default:
 		repo->got_indices = 0;
 		ret = -1;