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fix: rss failures with exponential blacklist #1362

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fix: rss failures with exponential blacklist #1362

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83fbf83
fix: rss failures with exponential blacklist
ankitsmt211 Dec 21, 2025
128454e
refactor: helper and magic numbers
ankitsmt211 Dec 21, 2025
7da18dc
chore: log level for skips to debug
ankitsmt211 Dec 21, 2025
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64 changes: 58 additions & 6 deletions application/src/main/java/org/togetherjava/tjbot/features/rss/RSSHandlerRoutine.java
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@

import com.apptasticsoftware.rssreader.Item;
import com.apptasticsoftware.rssreader.RssReader;
import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
import net.dv8tion.jda.api.EmbedBuilder;
import net.dv8tion.jda.api.JDA;
import net.dv8tion.jda.api.entities.channel.concrete.TextChannel;
Expand Down Expand Up @@ -48,7 +50,7 @@
* <p>
* To include a new RSS feed, simply define an {@link RSSFeed} entry in the {@code "rssFeeds"} array
* within the configuration file, adhering to the format shown below:
*
*
* <pre>
* {@code
* {
Expand All @@ -58,7 +60,7 @@
* }
* }
* </pre>
*
* <p>
* Where:
* <ul>
* <li>{@code url} represents the URL of the RSS feed.</li>
Expand All @@ -70,6 +72,9 @@
*/
public final class RSSHandlerRoutine implements Routine {

private record FailureState(int count, ZonedDateTime lastFailure) {
}

private static final Logger logger = LoggerFactory.getLogger(RSSHandlerRoutine.class);
private static final int MAX_CONTENTS = 1000;
private static final ZonedDateTime ZONED_TIME_MIN =
Expand All @@ -84,6 +89,14 @@ public final class RSSHandlerRoutine implements Routine {
private final int interval;
private final Database database;

private final Cache<String, FailureState> circuitBreaker =
Caffeine.newBuilder().expireAfterWrite(7, TimeUnit.DAYS).maximumSize(500).build();

private static final int DEAD_RSS_FEED_FAILURE_THRESHOLD = 15;
private static final double BACKOFF_BASE = 2.0;
private static final double BACKOFF_EXPONENT_OFFSET = 1.0;
private static final double MAX_BACKOFF_HOURS = 24.0;

/**
* Constructs an RSSHandlerRoutine with the provided configuration and database.
*
Expand Down Expand Up @@ -117,7 +130,14 @@ public Schedule createSchedule() {

@Override
public void runRoutine(@Nonnull JDA jda) {
this.config.feeds().forEach(feed -> sendRSS(jda, feed));
this.config.feeds().forEach(feed -> {
if (isBackingOff(feed.url())) {
logger.debug("Skipping RSS feed (Backing off): {}", feed.url());
return;
}

sendRSS(jda, feed);
});
}

/**
Expand Down Expand Up @@ -257,7 +277,6 @@ private void postItem(List<TextChannel> textChannels, Item rssItem, RSSFeed feed
* @param rssFeedRecord the record representing the RSS feed, can be null if not found in the
* database
* @param lastPostedDate the last posted date to be updated
*
* @throws DateTimeParseException if the date cannot be parsed
*/
private void updateLastDateToDatabase(RSSFeed feedConfig, @Nullable RssFeedRecord rssFeedRecord,
Expand Down Expand Up @@ -400,9 +419,26 @@ private MessageCreateData constructMessage(Item item, RSSFeed feedConfig) {
*/
private List<Item> fetchRSSItemsFromURL(String rssUrl) {
try {
return rssReader.read(rssUrl).toList();
List<Item> items = rssReader.read(rssUrl).toList();
circuitBreaker.invalidate(rssUrl);
return items;
} catch (IOException e) {
logger.error("Could not fetch RSS from URL ({})", rssUrl, e);
FailureState oldState = circuitBreaker.getIfPresent(rssUrl);
int newCount = (oldState == null) ? 1 : oldState.count() + 1;

if (newCount >= DEAD_RSS_FEED_FAILURE_THRESHOLD) {
logger.error(
"Possibly dead RSS feed URL: {} - Failed {} times. Please remove it from config.",
rssUrl, newCount);
}
circuitBreaker.put(rssUrl, new FailureState(newCount, ZonedDateTime.now()));

long blacklistedHours = calculateWaitHours(newCount);

logger.warn(
"RSS fetch failed for {} (Attempt #{}). Backing off for {} hours. Reason: {}",
rssUrl, newCount, blacklistedHours, e.getMessage(), e);

return List.of();
}
}
Expand All @@ -424,4 +460,20 @@ private static ZonedDateTime getZonedDateTime(@Nullable String date, String form

return ZonedDateTime.parse(date, DateTimeFormatter.ofPattern(format));
}

private long calculateWaitHours(int failureCount) {
return (long) Math.min(Math.pow(BACKOFF_BASE, failureCount - BACKOFF_EXPONENT_OFFSET),
MAX_BACKOFF_HOURS);
}

private boolean isBackingOff(String url) {
FailureState state = circuitBreaker.getIfPresent(url);
if (state == null)
return false;

long waitHours = calculateWaitHours(state.count());
ZonedDateTime retryAt = state.lastFailure().plusHours(waitHours);

return ZonedDateTime.now().isBefore(retryAt);
}
}
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