gatherer: Disallow multiple crawls of the same IP address

This might slow things down too much but let's see if gets us blocked
less.

gatherer/src/pandas/gatherer/core/GatherManager.java

@@ -10,6 +10,8 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
 import java.nio.file.Path;
 import java.time.Instant;
 import java.time.LocalDateTime;
@@ -105,14 +107,24 @@ Instance nextInstance(String gatherMethod, String threadName) {
  Instant startOfThisMinute = LocalDateTime.now().withSecond(0).atZone(ZoneId.systemDefault()).toInstant();
  for (Title title : titleRepository.fetchNewGathers(gatherMethod, Instant.now(), startOfThisMinute)) {
  String primarySeedHost = title.getPrimarySeedHost();
+ String ipAddress = null;
  if (primarySeedHost == null) {
  log.warn("Title.getPrimarySeedHost() returned null for title {}", title.getHumanId());
  primarySeedHost = "unknown";
- }
+ } else {
+ try {
+ var address = InetAddress.getByName(primarySeedHost);
+ ipAddress = address.getHostAddress();
+ } catch (UnknownHostException e) {
+ // oh well
+ }
+ }
  if (!currentlyGatheringTitles.containsKey(title.getId()) &&
- !currentlyGatheringHosts.containsKey(primarySeedHost)) {
+ !currentlyGatheringHosts.containsKey(primarySeedHost) &&
+ (ipAddress == null || currentlyGatheringHosts.containsKey(ipAddress))) {
  currentlyGatheringTitles.put(title.getId(), threadName);
  currentlyGatheringHosts.put(primarySeedHost, threadName);
+ if (ipAddress != null) currentlyGatheringHosts.put(ipAddress, threadName);
  return instanceService.createInstance(gatherMethod, title);
  }
  }