Package com.frostwire.jlibtorrent

Class AnnounceEntry

java.lang.Object
com.frostwire.jlibtorrent.AnnounceEntry
public final class AnnounceEntry extends Object
Metadata for a single tracker in a torrent's announce list.

AnnounceEntry represents one tracker used for peer discovery and seedstats. A torrent typically lists multiple trackers organized in "tiers" - the client tries trackers in order of tier (lowest first), and within each tier tries all trackers before moving to the next tier. This provides redundancy and load balancing.

Tracker Tiers: 

 Tier 0 (Primary):    [tracker1.com, tracker2.com]
 Tier 1 (Secondary):  [tracker3.com, tracker4.com]
 Tier 2 (Fallback):   [tracker5.com]

 The client tries all tier-0 trackers first. If they all fail or are slow,
 it tries tier-1, and so on.

Getting Trackers from a Torrent: 

 TorrentInfo ti = new TorrentInfo(torrentFile);

 // Get all trackers sorted by tier
 for (AnnounceEntry tracker : ti.trackers()) {
     System.out.println("Tier " + tracker.tier() + ": " + tracker.url());
 }

 // Example output:
 // Tier 0: http://tracker1.example.com:80/announce
 // Tier 0: udp://tracker2.example.com:6969/announce
 // Tier 1: http://tracker3.example.com:80/announce

Tracker URL Schemes: 

 // HTTP tracker
 "http://tracker.example.com:80/announce"

 // HTTPS tracker (secure)
 "https://secure-tracker.example.com:443/announce"

 // UDP tracker (lightweight)
 "udp://tracker.example.com:6969/announce"

 // UDP tracker with IPv6
 "udp://[2001:db8::1]:6969/announce"

Modifying Tracker Lists: 

 TorrentInfo ti = new TorrentInfo(torrentFile);

 // Add a tracker to tier 0 (primary)
 ti.addTracker("http://new-tracker.example.com:80/announce", 0);

 // Add a fallback tracker to tier 2
 ti.addTracker("http://fallback.example.com:80/announce", 2);

 // Remove a tracker (create new list without it)
 // Note: JlibtorrentAPI doesn't provide direct removal, rebuild the list if needed

Tracker Statistics (Per Session): 

 AnnounceEntry tracker = ...;

 // Get current state of this tracker
 List<AnnounceEndpoint> endpoints = tracker.endpoints();
 for (AnnounceEndpoint ep : endpoints) {
     System.out.println("Endpoint: " + ep.toString());
 }

 // Optional tracker ID (for private trackers)
 String trackerId = tracker.trackerId();
 if (!trackerId.isEmpty()) {
     System.out.println("This is a private tracker, trackerId: " + trackerId);
 }

 // Failure handling
 int failLimit = tracker.failLimit();
 System.out.println("Max failures before blacklisting: " + failLimit);

 // Verification status
 boolean verified = tracker.isVerified();
 System.out.println("Has received valid response: " + verified);

Tracker Tier Strategy: 

 // Check and prioritize working trackers
 List<AnnounceEntry> allTrackers = ti.trackers();

 // Group by tier
 Map<Integer, List<AnnounceEntry>> byTier = new TreeMap<>();
 for (AnnounceEntry tracker : allTrackers) {
     byTier.computeIfAbsent(tracker.tier(), k -> new ArrayList<>())
           .add(tracker);
 }

 // Primary trackers (tier 0)
 List<AnnounceEntry> primaryTrackers = byTier.get(0);
 System.out.println("Primary trackers: " + primaryTrackers.size());

 // Backup trackers (tier > 0)
 List<AnnounceEntry> backupTrackers = allTrackers.stream()
     .filter(t -> t.tier() > 0)
     .collect(Collectors.toList());
 System.out.println("Backup trackers: " + backupTrackers.size());

Private vs Public Torrents: - Public torrents: Use DHT (no private bit set), multiple public trackers - Private torrents: Require tracker (DHT disabled), use tracker-issued tracker IDs 

 // Check if likely private torrent
 List<AnnounceEntry> trackers = ti.trackers();
 boolean hasPrivateTracker = trackers.stream()
     .anyMatch(t -> !t.trackerId().isEmpty());
 System.out.println("Likely private torrent: " + hasPrivateTracker);
See Also:

  • Constructor Details

    • AnnounceEntry

      public AnnounceEntry(com.frostwire.jlibtorrent.swig.announce_entry e)
      Parameters:
      e - the native object

    • AnnounceEntry

      public AnnounceEntry(String url)
      Constructs a tracker announce entry with u as the URL.
      Parameters:
      url - the tracker url

  • Method Details

    • swig

      public com.frostwire.jlibtorrent.swig.announce_entry swig()
      Returns:
      the native object

    • endpoints

      public List<AnnounceEndpoint> endpoints()

    • url

      public String url()
      Tracker URL as it appeared in the torrent file.
      Returns:
      the tracker url

    • url

      public void url(String value)

    • trackerId

      public String trackerId()
      The current &trackerid= argument passed to the tracker. this is optional and is normally empty (in which case no trackerid is sent).
      Returns:
      the trackerid url argument

    • trackerId

      public void trackerId(String value)

    • tier

      public int tier()
      The tier this tracker belongs to.
      Returns:
      the tier number

    • tier

      public void tier(short value)

    • failLimit

      public int failLimit()
      The max number of failures to announce to this tracker in a row, before this tracker is not used anymore. 0 means unlimited.
      Returns:
      the max number of failures allowed

    • failLimit

      public void failLimit(short value)

    • source

      public int source()
      A bitmask specifying which sources we got this tracker from.
      Returns:
      the source bitmask

    • isVerified

      public boolean isVerified()
      Set to true the first time we receive a valid response from this tracker.
      Returns:
      if the tracker has received a valid response