eolivelli commented on a change in pull request #911: ZOOKEEPER-3365: Use
Concurrent HashMap in NettyServerCnxnFactory
URL: https://github.com/apache/zookeeper/pull/911#discussion_r275141538
##########
File path:
zookeeper-server/src/main/java/org/apache/zookeeper/server/NettyServerCnxnFactory.java
##########
@@ -512,44 +511,34 @@ public InetSocketAddress getLocalAddress() {
return localAddress;
}
- private void addCnxn(NettyServerCnxn cnxn) {
+ private void addCnxn(final NettyServerCnxn cnxn) {
cnxns.add(cnxn);
- synchronized (ipMap){
- InetAddress addr =
-
((InetSocketAddress)cnxn.getChannel().remoteAddress()).getAddress();
- Set<NettyServerCnxn> s = ipMap.get(addr);
- if (s == null) {
- s = new HashSet<>();
- ipMap.put(addr, s);
+ InetAddress addr =
+ ((InetSocketAddress)
cnxn.getChannel().remoteAddress()).getAddress();
+
+ ipMap.compute(addr, (a, cnxnSet) -> {
+ if (cnxnSet == null) {
+ cnxnSet = new HashSet<>();
}
- s.add(cnxn);
- }
+ cnxnSet.add(cnxn);
+ return cnxnSet;
+ });
}
-
+
void removeCnxnFromIpMap(NettyServerCnxn cnxn, InetAddress remoteAddress) {
- synchronized (ipMap) {
- Set<NettyServerCnxn> s = ipMap.get(remoteAddress);
- if (s != null) {
- s.remove(cnxn);
- if (s.isEmpty()) {
- ipMap.remove(remoteAddress);
- }
- return;
- }
+ ipMap.compute(remoteAddress, (addr, cnxnSet) -> {
+ if (cnxnSet == null) {
+ LOG.error("Unexpected remote address {} when removing cnxn {}",
+ remoteAddress, cnxn);
+ cnxnSet = Collections.emptySet();
}
- // Fallthrough and log errors outside the synchronized block
- LOG.error(
- "Unexpected null set for remote address {} when removing cnxn
{}",
- remoteAddress,
- cnxn);
+ cnxnSet.remove(cnxn);
+ return cnxnSet.isEmpty() ? null : cnxnSet;
+ });
}
- private int getClientCnxnCount(InetAddress addr) {
- synchronized (ipMap) {
- Set<NettyServerCnxn> s = ipMap.get(addr);
- if (s == null) return 0;
- return s.size();
- }
+ private int getClientCnxnCount(final InetAddress addr) {
+ return ipMap.getOrDefault(addr, Collections.emptySet()).size();
Review comment:
We have to synchronize access to the HashSet.
It is not enough to protect write access operation but you have to guard
even this call to *size()*
Should we use a concurrent set ?
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