前面分析知道session超时由leader负责,假设某个session长时间没心跳超时,SessionTrackImpl入口
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if (set != null) {
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for (SessionImpl s : set.sessions) {
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setSessionClosing(s.sessionId);
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expirer.expire(s);
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}
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}
session失效是一个proposal过程
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private void close(long sessionId) {
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submitRequest(null, sessionId, OpCode.closeSession, 0, null, null);
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}
leader段执行处理链,PrepRequestProcessor执行,closeSession的request没有txn内容
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case OpCode.closeSession:
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HashSet<String> es = zks.getZKDatabase()
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.getEphemerals(request.sessionId);
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synchronized (zks.outstandingChanges) {
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for (ChangeRecord c : zks.outstandingChanges) {
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if (c.stat == null) {
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es.remove(c.path);
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} else if (c.stat.getEphemeralOwner() == request.sessionId) {
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es.add(c.path);
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}
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}
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for (String path2Delete : es) {
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addChangeRecord(new ChangeRecord(request.hdr.getZxid(),
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path2Delete, null, 0, null));
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}
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zks.sessionTracker.setSessionClosing(request.sessionId);
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}
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LOG.info("Processed session termination for sessionid: 0x"
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+ Long.toHexString(request.sessionId));
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break;
之后leader通过ProposalRequestProcessor发起投票,并写入log,follower处理投票,写入log并ack。然后leader commit请求,leader和follower都进入FinalRequestProcessor处理。先是datatree处理
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case OpCode.closeSession:
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killSession(header.getClientId(), header.getZxid());
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break;
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void killSession(long session, long zxid) {
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HashSet<String> list = ephemerals.remove(session);
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if (list != null) {
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for (String path : list) {
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try {
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deleteNode(path, zxid);
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if (LOG.isDebugEnabled()) {
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LOG
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.debug("Deleting ephemeral node " + path
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+ " for session 0x"
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+ Long.toHexString(session));
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}
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} catch (NoNodeException e) {
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LOG.warn("Ignoring NoNodeException for path " + path
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+ " while removing ephemeral for dead session 0x"
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+ Long.toHexString(session));
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}
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}
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}
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}
然后FinalRequestProcessor删除session
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else if (opCode == OpCode.closeSession) {
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sessionTracker.removeSession(sessionId);
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}
然后FinalRequestProcessor关闭连接
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if (request.hdr != null && request.hdr.getType() == OpCode.closeSession) {
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ServerCnxnFactory scxn = zks.getServerCnxnFactory();
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if (scxn != null && request.cnxn == null) {
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scxn.closeSession(request.sessionId);
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return;
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}
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}
closeSession就是把session从内存数据结构中删除。
遍历连接集合,关闭sessionid对应的那个连接
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private void closeSessionWithoutWakeup(long sessionId) {
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HashSet<NIOServerCnxn> cnxns;
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synchronized (this.cnxns) {
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cnxns = (HashSet<NIOServerCnxn>)this.cnxns.clone();
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}
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for (NIOServerCnxn cnxn : cnxns) {
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if (cnxn.getSessionId() == sessionId) {
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try {
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cnxn.close();
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} catch (Exception e) {
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LOG.warn("exception during session close", e);
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}
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break;
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}
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}
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}
以上就完成了server端session超时的处理
1.leader发起closeSession的Proposal
2.该session对应的server的FinalRequestProcessor中关闭连接
3.server端发起的session超时处理不需要返回client信息,如果是client主动关闭session,则需要返回closeConn的信息,然后再关闭连接
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