Do not go to disk for reading hints file sizes

patch by Stefan Miklosovic; reviewed by Aleksey Yeschenko, Jon Haddad, Chris Lohfink for CASSANDRA-19477

CHANGES.txt

@@ -1,4 +1,5 @@
 4.1.5
+ * Do not go to disk for reading hints file sizes (CASSANDRA-19477)
  * Fix system_views.settings to handle array types (CASSANDRA-19475)
 Merged from 4.0:
  * Push LocalSessions info logs to debug (CASSANDRA-18335)

src/java/org/apache/cassandra/hints/HintsDescriptor.java

@@ -77,6 +77,8 @@ final class HintsDescriptor
     final UUID hostId;
     final int version;
     final long timestamp;
+    final String hintsFileName;
+    final String crc32FileName;
 
     final ImmutableMap<String, Object> parameters;
     final ParameterizedClass compressionConfig;
@@ -89,6 +91,8 @@ final class HintsDescriptor
         this.hostId = hostId;
         this.version = version;
         this.timestamp = timestamp;
+        hintsFileName = hostId + "-" + timestamp + '-' + version + ".hints";
+        crc32FileName = hostId + "-" + timestamp + '-' + version + ".crc32";
         compressionConfig = createCompressionConfig(parameters);
 
         EncryptionData encryption = createEncryption(parameters);
@@ -201,12 +205,12 @@ private EncryptionData(Cipher cipher, ICompressor compressor, ImmutableMap<Strin
 
     String fileName()
     {
-        return String.format("%s-%s-%s.hints", hostId, timestamp, version);
+        return hintsFileName;
     }
 
     String checksumFileName()
     {
-        return String.format("%s-%s-%s.crc32", hostId, timestamp, version);
+        return crc32FileName;
     }
 
     File file(File hintsDirectory)
@@ -219,6 +223,22 @@ File checksumFile(File hintsDirectory)
         return new File(hintsDirectory, checksumFileName());
     }
 
+    /** cached size of the represented hints file */
+    private transient volatile long hintsFileSize = -1L;
+
+    long hintsFileSize(File hintsDirectory)
+    {
+        long size = hintsFileSize;
+        if (size == -1L) // we may race and duplicate lookup the first time the size is being queried, but that is fine
+            hintsFileSize = size = file(hintsDirectory).length();
+        return size;
+    }
+
+    void hintsFileSize(long value)
+    {
+        hintsFileSize = value;
+    }
+
     int messagingVersion()
     {
         return messagingVersion(version);

src/java/org/apache/cassandra/hints/HintsStore.java

@@ -194,8 +194,8 @@ private void deleteHints(Predicate<HintsDescriptor> predicate)
                 if (predicate.test(descriptor))
                 {
                     cleanUp(descriptor);
-                    delete(descriptor);
                     removeSet.add(descriptor);
+                    delete(descriptor);
                 }
             }
         }
@@ -235,17 +235,20 @@ void markDispatchOffset(HintsDescriptor descriptor, InputPosition inputPosition)
         dispatchPositions.put(descriptor, inputPosition);
     }
 
-
     /**
      * @return the total size of all files belonging to the hints store, in bytes.
      */
+    @SuppressWarnings({ "resource" })
     long getTotalFileSize()
     {
         long total = 0;
         for (HintsDescriptor descriptor : Iterables.concat(dispatchDequeue, corruptedFiles))
-        {
-            total += descriptor.file(hintsDirectory).length();
-        }
+            total += descriptor.hintsFileSize(hintsDirectory);
+
+        HintsWriter currentWriter = getWriter();
+        if (null != currentWriter)
+            total += currentWriter.descriptor().hintsFileSize(hintsDirectory);
+
         return total;
     }
 

src/java/org/apache/cassandra/hints/HintsWriter.java

@@ -81,6 +81,7 @@ static HintsWriter create(File directory, HintsDescriptor descriptor) throws IOE
             ByteBuffer descriptorBytes = dob.buffer();
             updateChecksum(crc, descriptorBytes);
             channel.write(descriptorBytes);
+            descriptor.hintsFileSize(channel.position());
 
             if (descriptor.isEncrypted())
                 return new EncryptedHintsWriter(directory, descriptor, file, channel, fd, crc);
@@ -113,6 +114,7 @@ private void writeChecksum()
         }
     }
 
+    @Override
     public void close()
     {
         perform(file, Throwables.FileOpType.WRITE, this::doFsync, channel::close);
@@ -194,7 +196,6 @@ long position()
          * writes to the underlying channel when the buffer is overflown.
          *
          * @param hint the serialized hint (with CRC included)
-         * @throws IOException
          */
         void append(ByteBuffer hint) throws IOException
         {
@@ -223,11 +224,10 @@ void append(ByteBuffer hint) throws IOException
         /**
          * Serializes and appends the hint (with CRC included) to this session's aggregation buffer,
          * writes to the underlying channel when the buffer is overflown.
-         *
-         * Used mainly by tests and {@link LegacyHintsMigrator}
+         * <p>
+         * Used mainly by tests
          *
          * @param hint the unserialized hint
-         * @throws IOException
          */
         void append(Hint hint) throws IOException
         {
@@ -261,13 +261,14 @@ void append(Hint hint) throws IOException
 
         /**
          * Closes the session - flushes the aggregation buffer (if not empty), does page aligning, and potentially fsyncs.
-         * @throws IOException
          */
+        @Override
         public void close() throws IOException
         {
             flushBuffer();
             maybeFsync();
             maybeSkipCache();
+            descriptor.hintsFileSize(position());
         }
 
         private void flushBuffer() throws IOException

src/java/org/apache/cassandra/service/StorageProxy.java

@@ -2413,13 +2413,15 @@ public static boolean shouldHint(Replica replica, boolean tryEnablePersistentWin
         }
 
         long maxHintsSize = DatabaseDescriptor.getMaxHintsSizePerHost();
-        long actualTotalHintsSize = HintsService.instance.getTotalHintsSize(hostIdForEndpoint);
-        boolean hasHintsReachedMaxSize = maxHintsSize > 0 && actualTotalHintsSize > maxHintsSize;
-        if (hasHintsReachedMaxSize)
+        if (maxHintsSize > 0)
         {
-            Tracing.trace("Not hinting {} which has reached to the max hints size {} bytes on disk. The actual hints size on disk: {}",
-                          endpoint, maxHintsSize, actualTotalHintsSize);
-            return false;
+            long actualTotalHintsSize = HintsService.instance.getTotalHintsSize(hostIdForEndpoint);
+            if (actualTotalHintsSize > maxHintsSize)
+            {
+                Tracing.trace("Not hinting {} which has reached to the max hints size {} bytes on disk. The actual hints size on disk: {}",
+                              endpoint, maxHintsSize, actualTotalHintsSize);
+                return false;
+            }
         }
 
         return true;

test/distributed/org/apache/cassandra/distributed/test/HintsMaxSizeTest.java

@@ -0,0 +1,128 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.cassandra.distributed.test;
+
+import java.util.UUID;
+
+import org.junit.Test;
+
+import org.apache.cassandra.auth.CassandraRoleManager;
+import org.apache.cassandra.distributed.Cluster;
+import org.apache.cassandra.distributed.api.IInvokableInstance;
+import org.apache.cassandra.distributed.api.IIsolatedExecutor;
+import org.apache.cassandra.hints.HintsService;
+import org.apache.cassandra.io.util.File;
+import org.apache.cassandra.io.util.FileUtils;
+import org.apache.cassandra.metrics.StorageMetrics;
+import org.apache.cassandra.service.StorageService;
+
+import static java.lang.String.format;
+import static java.lang.String.valueOf;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.apache.cassandra.distributed.api.ConsistencyLevel.ONE;
+import static org.apache.cassandra.distributed.api.Feature.GOSSIP;
+import static org.apache.cassandra.distributed.api.Feature.NETWORK;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.awaitility.Awaitility.await;
+
+@SuppressWarnings("Convert2MethodRef")
+public class HintsMaxSizeTest extends TestBaseImpl
+{
+    @Test
+    public void testMaxHintedHandoffSize() throws Exception
+    {
+        try (Cluster cluster = init(Cluster.build(2)
+                                           .withDataDirCount(1)
+                                           .withConfig(config -> config.with(NETWORK, GOSSIP)
+                                                                       .set("hinted_handoff_enabled", true)
+                                                                       .set("max_hints_delivery_threads", "1")
+                                                                       .set("hints_flush_period", "1s")
+                                                                       .set("max_hints_size_per_host", "2MiB")
+                                                                       .set("max_hints_file_size", "1MiB"))
+                                           .start(), 2))
+        {
+            final IInvokableInstance node1 = cluster.get(1);
+            final IInvokableInstance node2 = cluster.get(2);
+
+            waitForExistingRoles(cluster);
+
+            String createTableStatement = format("CREATE TABLE %s.cf (k text PRIMARY KEY, c1 text) " +
+                                                 "WITH compaction = {'class': 'SizeTieredCompactionStrategy', 'enabled': 'false'} ", KEYSPACE);
+            cluster.schemaChange(createTableStatement);
+
+            UUID node2UUID = node2.callOnInstance((IIsolatedExecutor.SerializableCallable<UUID>) () -> StorageService.instance.getLocalHostUUID());
+
+            // shutdown the second node in a blocking manner
+            node2.shutdown().get();
+
+            // insert data and sleep every 10k to have a chance to flush hints
+            for (int i = 0; i < 70000; i++)
+            {
+                cluster.coordinator(1)
+                       .execute(withKeyspace("INSERT INTO %s.cf (k, c1) VALUES (?, ?);"),
+                                ONE, valueOf(i), UUID.randomUUID().toString());
+
+                if (i % 10000 == 0)
+                    await().atLeast(2, SECONDS).pollDelay(2, SECONDS).until(() -> true);
+            }
+
+            await().atLeast(3, SECONDS).pollDelay(3, SECONDS).until(() -> true);
+
+            // we see that metrics are updated
+            await().until(() -> node1.callOnInstance(() -> StorageMetrics.totalHints.getCount()) > 0);
+            // we do not have 100k of hints because it violated max_hints_size_per_host
+            assertThat(node1.callOnInstance(() -> StorageMetrics.totalHints.getCount())).isLessThan(70000);
+
+            assertHintsSizes(node1, node2UUID);
+
+            // restart the first node and check hints sizes again
+            // to be sure sizes were picked up correctly
+            node1.shutdown().get();
+            node1.startup();
+
+            assertHintsSizes(node1, node2UUID);
+        }
+    }
+
+    private void assertHintsSizes(IInvokableInstance node, UUID node2UUID)
+    {
+        // we indeed have some hints in its dir
+        File hintsDir = new File(node.config().getString("hints_directory"));
+        assertThat(FileUtils.folderSize(hintsDir)).isPositive();
+
+        // and there is positive size of hints on the disk for the second node
+        long totalHintsSize = node.appliesOnInstance((IIsolatedExecutor.SerializableFunction<UUID, Long>) secondNode -> {
+            return HintsService.instance.getTotalHintsSize(secondNode);
+        }).apply(node2UUID);
+
+        assertThat(totalHintsSize).isPositive();
+        // there might be small overflow in general, depending on hints flushing etc
+        assertThat(totalHintsSize).isLessThan(4 * 1000 * 1000);
+        assertThat(totalHintsSize).isGreaterThan(2 * 1000 * 1000);
+    }
+
+    private static void waitForExistingRoles(Cluster cluster)
+    {
+        cluster.forEach(instance -> {
+            await().pollDelay(1, SECONDS)
+                   .pollInterval(1, SECONDS)
+                   .atMost(60, SECONDS)
+                   .until(() -> instance.callOnInstance(CassandraRoleManager::hasExistingRoles));
+        });
+    }
+}

test/unit/org/apache/cassandra/hints/AlteredHints.java

@@ -37,6 +37,7 @@
 import org.apache.cassandra.db.Mutation;
 import org.apache.cassandra.db.RowUpdateBuilder;
 import org.apache.cassandra.schema.KeyspaceParams;
+import org.hamcrest.Matchers;
 
 import static org.apache.cassandra.utils.ByteBufferUtil.bytes;
 
@@ -100,6 +101,8 @@ public void multiFlushAndDeserializeTest() throws Exception
                     hintNum++;
                 }
             }
+
+            Assert.assertThat(descriptor.hintsFileSize(dir), Matchers.greaterThan(0L));
         }
 
         try (HintsReader reader = HintsReader.open(descriptor.file(dir)))

test/unit/org/apache/cassandra/hints/HintsCatalogTest.java

@@ -29,15 +29,18 @@
 import org.apache.cassandra.schema.Schema;
 import org.apache.cassandra.utils.Clock;
 import org.apache.cassandra.utils.FBUtilities;
+
 import org.junit.BeforeClass;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
 
+import static org.hamcrest.Matchers.greaterThan;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
 import static org.apache.cassandra.Util.dk;
@@ -146,22 +149,20 @@ public void exciseHintFiles() throws IOException
     }
 
     @Test
-    public void hintsTotalSizeTest() throws IOException
+    public void emptyHintsTotalSizeTest() throws IOException
     {
         File directory = new File(testFolder.newFolder());
         UUID hostId = UUID.randomUUID();
-        long now = Clock.Global.currentTimeMillis();
         long totalSize = 0;
         HintsCatalog catalog = HintsCatalog.load(directory, ImmutableMap.of());
         HintsStore store = catalog.get(hostId);
         assertEquals(totalSize, store.getTotalFileSize());
         for (int i = 0; i < 3; i++)
         {
-            HintsDescriptor descriptor = new HintsDescriptor(hostId, now + i);
-            writeDescriptor(directory, descriptor);
-            store.offerLast(descriptor);
-            assertTrue("Total file size should increase after writing more hints", store.getTotalFileSize() > totalSize);
-            totalSize = store.getTotalFileSize();
+            store.getOrOpenWriter();
+            store.closeWriter();
+            assertTrue("Even empty hint files should occupy some space as descriptor is written",
+                       store.getTotalFileSize() > 0);
         }
     }
 
@@ -243,5 +244,7 @@ private static void createHintFile(File directory, HintsDescriptor descriptor) t
                 session.append(hint);
             }
         }
+
+        assertThat(descriptor.hintsFileSize(directory), greaterThan(0L));
     }
 }

test/unit/org/apache/cassandra/hints/HintsReaderTest.java

@@ -29,6 +29,8 @@
 
 import com.google.common.collect.Iterables;
 import org.apache.cassandra.io.util.File;
+
+import org.junit.Assert;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -46,6 +48,7 @@
 import org.apache.cassandra.schema.Schema;
 import org.apache.cassandra.schema.SchemaTestUtil;
 import org.apache.cassandra.schema.TableMetadata;
+import org.hamcrest.Matchers;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
@@ -96,6 +99,8 @@ private void generateHints(int num, String ks) throws IOException
             }
             FileUtils.clean(buffer);
         }
+
+        Assert.assertThat(descriptor.hintsFileSize(directory), Matchers.greaterThan(0L));
     }
 
     private void readHints(int num, int numTable)