Github user anmolnar commented on a diff in the pull request: https://github.com/apache/zookeeper/pull/451#discussion_r166341540 --- Diff: src/java/main/org/apache/zookeeper/client/StaticHostProvider.java --- @@ -58,48 +61,122 @@ public StaticHostProvider(Collection<InetSocketAddress> serverAddresses) { for (InetSocketAddress address : serverAddresses) { try { - InetAddress ia = address.getAddress(); - InetAddress resolvedAddresses[] = InetAddress.getAllByName((ia != null) ? ia.getHostAddress() : - address.getHostName()); + InetAddress resolvedAddresses[] = InetAddress.getAllByName(getHostString(address)); for (InetAddress resolvedAddress : resolvedAddresses) { - // If hostName is null but the address is not, we can tell that - // the hostName is an literal IP address. Then we can set the host string as the hostname - // safely to avoid reverse DNS lookup. - // As far as i know, the only way to check if the hostName is null is use toString(). - // Both the two implementations of InetAddress are final class, so we can trust the return value of - // the toString() method. - if (resolvedAddress.toString().startsWith("/") - && resolvedAddress.getAddress() != null) { - this.serverAddresses.add( - new InetSocketAddress(InetAddress.getByAddress( - address.getHostName(), - resolvedAddress.getAddress()), - address.getPort())); - } else { - this.serverAddresses.add(new InetSocketAddress(resolvedAddress.getHostAddress(), address.getPort())); - } + this.serverAddresses.add(new InetSocketAddress(resolvedAddress, address.getPort())); } } catch (UnknownHostException e) { LOG.error("Unable to connect to server: {}", address, e); } } - + if (this.serverAddresses.isEmpty()) { throw new IllegalArgumentException( "A HostProvider may not be empty!"); } Collections.shuffle(this.serverAddresses); } + /** + * Evaluate to a hostname if one is available and otherwise it returns the + * string representation of the IP address. + * + * 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(). + * + * @param addr + * @return Hostname string of address parameter + */ + private String getHostString(InetSocketAddress addr) { + String hostString = ""; + + if (addr == null) { + return hostString; + } + if (!addr.isUnresolved()) { + InetAddress ia = addr.getAddress(); + + // 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(); } + // Counts the number of addresses added and removed during + // the last call to next. Used mainly for test purposes. + // See StasticHostProviderTest. + private int nextAdded = 0; + private int nextRemoved = 0; + + public int getNextAdded() { + return nextAdded; + } + + public int getNextRemoved() { + return nextRemoved; + } + 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); + String curHostString = getHostString(curAddr); + if (!curHostString.equals(curAddr.getAddress().getHostAddress())) { + LOG.info("Resolving again hostname: {}", getHostString(curAddr)); + try { + int thePort = curAddr.getPort(); + InetAddress resolvedAddresses[] = InetAddress.getAllByName(curHostString); + nextAdded = 0; + nextRemoved = 0; + if (resolvedAddresses.length == 1) { + serverAddresses.set(currentIndex, new InetSocketAddress(resolvedAddresses[0], thePort)); + nextAdded = nextRemoved = 1; + LOG.debug("Newly resolved address: {}", resolvedAddresses[0]); + } else { + int i = 0; + while (i < serverAddresses.size()) { + if (getHostString(serverAddresses.get(i)).equals(curHostString) && --- End diff -- It seems that this change makes things a little a bit even more complicated, because `next()` method needs to have a list of IP addresses to iterate on. Maintenance is easier with a Map, but I need to find a way to use it as a list.
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