Github user fpj commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/150#discussion_r96442215
--- Diff: src/java/main/org/apache/zookeeper/client/StaticHostProvider.java
---
@@ -87,15 +73,69 @@ public StaticHostProvider(Collection<InetSocketAddress>
serverAddresses)
Collections.shuffle(this.serverAddresses);
}
+ /**
+ * In Java 7, we have a method getHostString, but earlier versions do
not support it.
+ * This method is to provide a replacement for
InetSocketAddress.getHostString().
+ *
+ * It evaluates to a hostname if one is available and otherwise it
returns the
+ * string representation of the IP address.
+ *
+ * @param addr
+ * @return Hostname string of address parameter
+ */
+ private String getHostString(InetSocketAddress addr) {
+ String hostString;
+ InetAddress ia = addr.getAddress();
+
+ if (ia != null) {
+ // If the string starts with '/', then it has no hostname
+ // and we want to avoid the reverse lookup, so we return
+ // the string representation of the address.
+ if (ia.toString().startsWith("/")) {
+ hostString = ia.getHostAddress();
+ } else {
+ hostString = addr.getHostName();
+ }
+ } else {
+ // According to the Java 6 documentation, if the hostname is
+ // unresolved, then the string before the colon is the
hostname.
+ String addrString = addr.toString();
+ hostString = addrString.substring(0,
addrString.lastIndexOf(':'));
+ }
+
+ return hostString;
+ }
+
public int size() {
return serverAddresses.size();
}
public InetSocketAddress next(long spinDelay) {
- ++currentIndex;
- if (currentIndex == serverAddresses.size()) {
- currentIndex = 0;
+ // Handle possible connection error by re-resolving hostname if
possible
+ if (!connectedSinceNext) {
+ InetSocketAddress curAddr = serverAddresses.get(currentIndex);
+ if
(!curAddr.getHostString().equals(curAddr.getAddress().getHostAddress())) {
+ try {
+ int thePort = curAddr.getPort();
+ InetAddress resolvedAddresses[] =
InetAddress.getAllByName(getHostString(curAddr));
+ if (resolvedAddresses.length == 1) {
+ serverAddresses.set(currentIndex, new
InetSocketAddress(resolvedAddresses[0], thePort));
+ } else {
+ serverAddresses.remove(currentIndex);
+ for (InetAddress resolvedAddress :
resolvedAddresses) {
+ InetSocketAddress newAddr = new
InetSocketAddress(resolvedAddress, thePort);
+ if (!serverAddresses.contains(newAddr)) {
+ serverAddresses.add(newAddr);
+ }
+ }
+ }
+ } catch (UnknownHostException e) {
+ LOG.warn("Cannot re-resolve server: " + curAddr + "
UnknownHostException: " + e);
--- End diff --
If the `StaticHostProvider` constructor didn't throw an
`UnknownHostException`, then I'd think that all names and addresses we have are
good. I'm not sure what could cause an `UnknownHostException` in `next()` other
than some transient error. If that's right, then I'm not sure we should be
adding or removing anything.
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