From 7d7e93ad4e0083ac1a23f21fdec4525c1d9f3595 Mon Sep 17 00:00:00 2001
From: Jon Bratseth <bratseth@gmail.com>
Date: Tue, 1 Dec 2020 13:11:23 +0100
Subject: Auto-repair on unrecoverable failure

---
 .../hosted/provision/autoscale/QuestMetricsDb.java | 58 ++++++++++++++++------
 1 file changed, 43 insertions(+), 15 deletions(-)

(limited to 'node-repository')

diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/QuestMetricsDb.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/QuestMetricsDb.java
index 946d47e9246..ad989d5abfd 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/QuestMetricsDb.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/QuestMetricsDb.java
@@ -9,6 +9,7 @@ import com.yahoo.io.IOUtils;
 import com.yahoo.vespa.defaults.Defaults;
 import io.questdb.cairo.CairoConfiguration;
 import io.questdb.cairo.CairoEngine;
+import io.questdb.cairo.CairoException;
 import io.questdb.cairo.DefaultCairoConfiguration;
 import io.questdb.cairo.TableWriter;
 import io.questdb.cairo.sql.Record;
@@ -48,7 +49,7 @@ public class QuestMetricsDb extends AbstractComponent implements MetricsDb {
 
     private final Clock clock;
     private final String dataDir;
-    private final CairoEngine engine;
+    private CairoEngine engine;
 
     private long highestTimestampAdded = 0;
 
@@ -64,7 +65,10 @@ public class QuestMetricsDb extends AbstractComponent implements MetricsDb {
             && ! new File(Defaults.getDefaults().vespaHome()).exists())
             dataDir = "data"; // We're injected, but not on a node with Vespa installed
         this.dataDir = dataDir;
+        initializeDb();
+    }
 
+    private void initializeDb() {
         IOUtils.createDirectory(dataDir + "/" + tableName);
 
         // silence Questdb's custom logging system
@@ -80,24 +84,37 @@ public class QuestMetricsDb extends AbstractComponent implements MetricsDb {
     @Override
     public void add(Collection<Pair<String, MetricSnapshot>> snapshots) {
         try (TableWriter writer = engine.getWriter(newContext().getCairoSecurityContext(), tableName)) {
-            for (var snapshot : snapshots) {
-                long atMillis = adjustIfRecent(snapshot.getSecond().at().toEpochMilli(), highestTimestampAdded);
-                if (atMillis < highestTimestampAdded) continue; // Ignore old data
-                highestTimestampAdded = atMillis;
-                TableWriter.Row row = writer.newRow(atMillis * 1000); // in microseconds
-                row.putStr(0, snapshot.getFirst());
-                row.putFloat(2, (float)snapshot.getSecond().cpu());
-                row.putFloat(3, (float)snapshot.getSecond().memory());
-                row.putFloat(4, (float)snapshot.getSecond().disk());
-                row.putLong(5, snapshot.getSecond().generation());
-                row.putBool(6, snapshot.getSecond().inService());
-                row.putBool(7, snapshot.getSecond().stable());
-                row.append();
+            add(snapshots, writer);
+        }
+        catch (CairoException e) {
+            if (e.getMessage().contains("Cannot read offset")) {
+                // This error seems non-recoverable
+                repair(e);
+                try (TableWriter writer = engine.getWriter(newContext().getCairoSecurityContext(), tableName)) {
+                    add(snapshots, writer);
+                }
             }
-            writer.commit();
         }
     }
 
+    private void add(Collection<Pair<String, MetricSnapshot>> snapshots, TableWriter writer) {
+        for (var snapshot : snapshots) {
+            long atMillis = adjustIfRecent(snapshot.getSecond().at().toEpochMilli(), highestTimestampAdded);
+            if (atMillis < highestTimestampAdded) continue; // Ignore old data
+            highestTimestampAdded = atMillis;
+            TableWriter.Row row = writer.newRow(atMillis * 1000); // in microseconds
+            row.putStr(0, snapshot.getFirst());
+            row.putFloat(2, (float)snapshot.getSecond().cpu());
+            row.putFloat(3, (float)snapshot.getSecond().memory());
+            row.putFloat(4, (float)snapshot.getSecond().disk());
+            row.putLong(5, snapshot.getSecond().generation());
+            row.putBool(6, snapshot.getSecond().inService());
+            row.putBool(7, snapshot.getSecond().stable());
+            row.append();
+        }
+        writer.commit();
+    }
+
     @Override
     public List<NodeTimeseries> getNodeTimeseries(Instant startTime, Set<String> hostnames) {
         try (SqlCompiler compiler = new SqlCompiler(engine)) {
@@ -152,6 +169,17 @@ public class QuestMetricsDb extends AbstractComponent implements MetricsDb {
             engine.close();
     }
 
+    /**
+     * Repairs this db on corruption.
+     *
+     * @param e the exception indicating corruption
+     */
+    private void repair(CairoException e) {
+        log.log(Level.WARNING, "QuestDb seems corrupted, wiping data and starting over", e);
+        IOUtils.recursiveDeleteDir(new File(dataDir));
+        initializeDb();
+    }
+
     private void ensureExists(String tableName) {
         SqlExecutionContext context = newContext();
         if (0 == engine.getStatus(context.getCairoSecurityContext(), new Path(), tableName)) return;
-- 
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