ddupg commented on a change in pull request #3405:
URL: https://github.com/apache/hbase/pull/3405#discussion_r656720923
##########
File path:
hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java
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@@ -163,6 +169,44 @@
private final ConcurrentNavigableMap<ServerName, ServerMetrics>
onlineServers =
new ConcurrentSkipListMap<>();
+ /**
+ * Store the snapshot of the current region server list, for improving read
performance.
+ * <p/>
+ * The hashCode is used to determine whether there are changes to the region
servers.
+ */
+ private static final class OnlineServerListSnapshot {
+
+ private static final HashFunction HASH = Hashing.murmur3_128();
+
+ final List<ServerName> servers;
+
+ final long hashCode;
+
+ public OnlineServerListSnapshot(List<ServerName> servers) {
+ this.servers = Collections.unmodifiableList(servers);
+ Hasher hasher = HASH.newHasher();
+ for (ServerName server : servers) {
+ hasher.putString(server.getServerName(), StandardCharsets.UTF_8);
+ }
+ this.hashCode = hasher.hash().asLong();
Review comment:
Does hash conflict need to be considered? Although the probability is
small.
And if a server go online and offline between a client two calls, the
hashCode is same for the client, is this expected?
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