From 42198320795da41599b53a13d0bc69ee0c8401a4 Mon Sep 17 00:00:00 2001
From: Harald Musum <musum@oath.com>
Date: Wed, 31 Oct 2018 11:44:02 +0100
Subject: Cache disk usage, check every 5 minutes

---
 .../node/admin/maintenance/StorageMaintainer.java     | 19 +++++++++++++++++--
 .../node/admin/maintenance/StorageMaintainerTest.java |  7 ++++++-
 2 files changed, 23 insertions(+), 3 deletions(-)

(limited to 'node-admin')

diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainer.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainer.java
index 00dd841efc6..713a6b23683 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainer.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainer.java
@@ -43,11 +43,16 @@ public class StorageMaintainer {
     private static final Logger logger = Logger.getLogger(StorageMaintainer.class.getName());
     private static final DateTimeFormatter DATE_TIME_FORMATTER = DateTimeFormatter
             .ofPattern("yyyyMMddHHmmss").withZone(ZoneOffset.UTC);
+    private static final Duration checkDiskUsageInterval = Duration.ofMinutes(5);
 
     private final DockerOperations dockerOperations;
     private final CoredumpHandler coredumpHandler;
     private final Path archiveContainerStoragePath;
 
+    private Instant lastDiskUsageCheck = Instant.EPOCH;
+    // We cache disk usage to avoid doing expensive disk operations so often
+    private Optional<Long> diskUsage = Optional.empty();
+
     public StorageMaintainer(DockerOperations dockerOperations, CoredumpHandler coredumpHandler, Path archiveContainerStoragePath) {
         this.dockerOperations = dockerOperations;
         this.coredumpHandler = coredumpHandler;
@@ -174,11 +179,21 @@ public class StorageMaintainer {
     public Optional<Long> getDiskUsageFor(NodeAgentContext context) {
         Path containerDir = context.pathOnHostFromPathInNode("/");
         try {
-            return Optional.of(getDiskUsedInBytes(containerDir));
+            diskUsage = getDiskUsageFor(containerDir);
         } catch (Throwable e) {
             context.log(logger, LogLevel.WARNING, "Problems during disk usage calculations in " + containerDir.toAbsolutePath(), e);
-            return Optional.empty();
+            diskUsage = Optional.empty();
+        }
+        return diskUsage;
+    }
+
+    Optional<Long> getDiskUsageFor(Path containerDir) throws IOException, InterruptedException {
+        Instant now = Instant.now();
+        if (now.isAfter(lastDiskUsageCheck.plus(checkDiskUsageInterval))) {
+            diskUsage = Optional.of(getDiskUsedInBytes(containerDir));
+            lastDiskUsageCheck = now;
         }
+        return diskUsage;
     }
 
     // Public for testing
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainerTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainerTest.java
index d537cb40214..abd4e5b76cf 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainerTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/StorageMaintainerTest.java
@@ -28,6 +28,7 @@ import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -198,9 +199,13 @@ public class StorageMaintainerTest {
             int writeSize = 10000;
             Files.write(folder.newFile().toPath(), new byte[writeSize]);
 
-            long usedBytes = storageMaintainer.getDiskUsedInBytes(folder.getRoot().toPath());
+            long usedBytes = storageMaintainer.getDiskUsageFor(folder.getRoot().toPath()).get();
             if (usedBytes * 4 < writeSize || usedBytes > writeSize * 4)
                 fail("Used bytes is " + usedBytes + ", but wrote " + writeSize + " bytes, not even close.");
+
+            // Write another file, since disk usage is cached it should not change
+            Files.write(folder.newFile().toPath(), new byte[writeSize]);
+            assertEquals(usedBytes, (long) storageMaintainer.getDiskUsageFor(folder.getRoot().toPath()).get());
         }
 
         @Test
-- 
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