From ad3633906838b4a3a7e49c27814471f976019520 Mon Sep 17 00:00:00 2001
From: Håkon Hallingstad <hakon@verizonmedia.com>
Date: Fri, 15 May 2020 00:09:08 +0200
Subject: Ignore missing children from optimistic read of suspended hosts

Also: Remove test for existence of path, which would normally turn up in the
negative, and instead catch NoNodeException on the next if path does not exist,
at the expense of exception thrown/caught.  This should be cheaper than
actually hitting ZK.
---
 .../orchestrator/status/HostInfosServiceImpl.java  | 39 ++++++++++++++--------
 1 file changed, 26 insertions(+), 13 deletions(-)

(limited to 'orchestrator')

diff --git a/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/status/HostInfosServiceImpl.java b/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/status/HostInfosServiceImpl.java
index cbb6902066e..d5cf0b39fda 100644
--- a/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/status/HostInfosServiceImpl.java
+++ b/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/status/HostInfosServiceImpl.java
@@ -4,7 +4,6 @@ package com.yahoo.vespa.orchestrator.status;
 
 import com.yahoo.config.provision.ApplicationId;
 import com.yahoo.jdisc.Timer;
-import java.util.logging.Level;
 import com.yahoo.path.Path;
 import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.applicationmodel.HostName;
@@ -14,12 +13,12 @@ import com.yahoo.vespa.orchestrator.status.json.WireHostInfo;
 import org.apache.zookeeper.KeeperException.NoNodeException;
 
 import java.time.Instant;
+import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
+import java.util.logging.Level;
 import java.util.logging.Logger;
-import java.util.stream.Collectors;
 
 /**
  * Handles all ZooKeeper data structures related to each active application, including HostInfo.
@@ -42,18 +41,32 @@ public class HostInfosServiceImpl implements HostInfosService {
     public HostInfos getHostInfos(ApplicationInstanceReference reference) {
         ApplicationId application = OrchestratorUtil.toApplicationId(reference);
         String hostsRootPath = hostsPath(application);
-        if (uncheck(() -> curator.framework().checkExists().forPath(hostsRootPath)) == null) {
+
+        List<String> hostnames;
+        try {
+            hostnames = curator.framework().getChildren().forPath(hostsRootPath);
+        } catch (NoNodeException e) {
             return new HostInfos();
-        } else {
-            List<String> hostnames = uncheck(() -> curator.framework().getChildren().forPath(hostsRootPath));
-            Map<HostName, HostInfo> hostInfos = hostnames.stream().collect(Collectors.toMap(
-                    hostname -> new HostName(hostname),
-                    hostname -> {
-                        byte[] bytes = uncheck(() -> curator.framework().getData().forPath(hostsRootPath + "/" + hostname));
-                        return WireHostInfo.deserialize(bytes);
-                    }));
-            return new HostInfos(hostInfos);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
         }
+
+        var hostInfos = new HashMap<HostName, HostInfo>();
+        for (var hostname : hostnames) {
+            byte[] bytes;
+            try {
+                bytes = curator.framework().getData().forPath(hostsRootPath + "/" + hostname);
+            } catch (NoNodeException e) {
+                // OK, node has been removed since getChildren()
+                continue;
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
+
+            hostInfos.put(new HostName(hostname), WireHostInfo.deserialize(bytes));
+        }
+
+        return new HostInfos(hostInfos);
     }
 
     @Override
-- 
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