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kreta_client: Add exponential backoff

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Kréta now randomly returns 500 status code responses when it feels like it, so if a request fails we retry with an exponential backoff.
This commit is contained in:
4831c0
2025-08-13 15:12:08 +02:00
parent 1768244685
commit 3ebbba074b
1 changed files with 62 additions and 31 deletions
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93
firka/lib/helpers/api/client/kreta_client.dart
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@@ -22,6 +22,10 @@ import '../model/student.dart';
import '../model/test.dart';
import '../token_grant.dart';
const backoffCount = 4;
const backoffMin = 100;
const backoffStep = 500;
class ApiResponse<T> {
T? response;
int statusCode;
@@ -104,7 +108,7 @@ class KretaClient {
}
Future<(dynamic, int, Object?, bool)> _cachingGet(
CacheId id, String url, bool forceCache) async {
CacheId id, String url, bool forceCache, int counter) async {
// it would be *ideal* to use xor and left shift here, however
// binary operations seem to round the number down to
// 32 bits for some reason???
@@ -117,12 +121,24 @@ class KretaClient {
if (forceCache && cache != null) {
return (jsonDecode(cache.cacheData!), 200, null, true);
}
(resp, statusCode) = await _authJson("GET", url);
if (statusCode >= 400) {
if (cache != null) {
return (jsonDecode(cache.cacheData!), statusCode, null, true);
try {
(resp, statusCode) = await _authJson("GET", url);
if (statusCode >= 400) {
if (cache != null) {
return (jsonDecode(cache.cacheData!), statusCode, null, true);
}
}
} catch (ex) {
if (ex is! DioException || counter >= backoffCount) {
rethrow;
}
await Future.delayed(
Duration(milliseconds: backoffMin + (counter * backoffStep)));
return _cachingGet(id, url, forceCache, counter + 1);
}
} catch (ex) {
if (cache != null) {
@@ -148,7 +164,7 @@ class KretaClient {
Future<ApiResponse<Student>> getStudent({bool forceCache = true}) async {
if (forceCache && studentCache != null) return studentCache!;
var (resp, status, ex, cached) = await _cachingGet(CacheId.getStudent,
KretaEndpoints.getStudentUrl(model.iss!), forceCache);
KretaEndpoints.getStudentUrl(model.iss!), forceCache, 0);
Student? student;
String? err;
@@ -173,7 +189,7 @@ class KretaClient {
{bool forceCache = true}) async {
if (forceCache && noticeBoardCache != null) return noticeBoardCache!;
var (resp, status, ex, cached) = await _cachingGet(CacheId.getNoticeBoard,
KretaEndpoints.getNoticeBoard(model.iss!), forceCache);
KretaEndpoints.getNoticeBoard(model.iss!), forceCache, 0);
var items = List<NoticeBoardItem>.empty(growable: true);
String? err;
@@ -202,7 +218,7 @@ class KretaClient {
return gradeCache!;
}
var (resp, status, ex, cached) = await _cachingGet(
CacheId.getGrades, KretaEndpoints.getGrades(model.iss!), forceCache);
CacheId.getGrades, KretaEndpoints.getGrades(model.iss!), forceCache, 0);
var items = List<Grade>.empty(growable: true);
String? err;
@@ -233,6 +249,7 @@ class KretaClient {
DateTime from,
DateTime? to,
bool forceCache,
int counter,
Future<void> Function(dynamic, int) storeCache) async {
var cacheKey = genCacheKey(from, model.studentId!);
var cache = await cacheModel.get(cacheKey);
@@ -256,26 +273,38 @@ class KretaClient {
return (items, 200, null, true);
}
if (toStr == null) {
(resp, statusCode) = await _authJson(
"GET",
"$endpoint?"
"datumTol=$fromStr");
} else {
(resp, statusCode) = await _authJson(
"GET",
"$endpoint?"
"datumTol=$fromStr&datumIg=$toStr");
}
if (statusCode >= 400) {
if (cache != null) {
var items = List<dynamic>.empty(growable: true);
for (var item in (cache as dynamic).values) {
items.add(jsonDecode(item));
}
return (items, statusCode, null, true);
try {
if (toStr == null) {
(resp, statusCode) = await _authJson(
"GET",
"$endpoint?"
"datumTol=$fromStr");
} else {
(resp, statusCode) = await _authJson(
"GET",
"$endpoint?"
"datumTol=$fromStr&datumIg=$toStr");
}
if (statusCode >= 400) {
if (cache != null) {
var items = List<dynamic>.empty(growable: true);
for (var item in (cache as dynamic).values) {
items.add(jsonDecode(item));
}
return (items, statusCode, null, true);
}
}
} catch (ex) {
if (ex is! DioException || counter >= backoffCount) {
rethrow;
}
await Future.delayed(
Duration(milliseconds: backoffMin + (counter * backoffStep)));
return _timedCachingGet(cacheModel, endpoint, from, to, forceCache,
counter + 1, storeCache);
}
} catch (ex) {
if (cache != null) {
@@ -313,7 +342,8 @@ class KretaClient {
KretaEndpoints.getTimeTable(model.iss!),
from,
to,
forceCache, (dynamic resp, int cacheKey) async {
forceCache,
0, (dynamic resp, int cacheKey) async {
TimetableCacheModel cache = TimetableCacheModel();
var rawClasses = List<String>.empty(growable: true);
@@ -353,7 +383,8 @@ class KretaClient {
KretaEndpoints.getHomework(model.iss!),
from,
null,
forceCache, (dynamic resp, int cacheKey) async {
forceCache,
0, (dynamic resp, int cacheKey) async {
HomeworkCacheModel cache = HomeworkCacheModel();
var rawClasses = List<String>.empty(growable: true);
@@ -458,7 +489,7 @@ class KretaClient {
Future<ApiResponse<List<Test>>> getTests({bool forceCache = true}) async {
var (resp, status, ex, cached) = await _cachingGet(
CacheId.getTests, KretaEndpoints.getTests(model.iss!), forceCache);
CacheId.getTests, KretaEndpoints.getTests(model.iss!), forceCache, 0);
var items = List<Test>.empty(growable: true);
String? err;
@@ -486,7 +517,7 @@ class KretaClient {
{bool forceCache = true}) async {
if (omissionsCache != null) return omissionsCache!;
var (resp, status, ex, cached) = await _cachingGet(CacheId.getOmissions,
KretaEndpoints.getOmissions(model.iss!), forceCache);
KretaEndpoints.getOmissions(model.iss!), forceCache, 0);
var items = List<Omission>.empty(growable: true);
String? err;