[GitHub] [ignite] anton-vinogradov commented on a change in pull request #8909: IGNITE-13581 Capture Data Change implementation

[GitBox <gi...@apache.org>]

anton-vinogradov commented on a change in pull request #8909:
URL: https://github.com/apache/ignite/pull/8909#discussion_r643190241



##########
File path: modules/core/src/main/java/org/apache/ignite/internal/cdc/ChangeDataCapture.java
##########
@@ -0,0 +1,545 @@
+/*
+ * 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.ignite.internal.cdc;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.Serializable;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.Stream;
+import org.apache.ignite.IgniteCheckedException;
+import org.apache.ignite.IgniteException;
+import org.apache.ignite.IgniteLogger;
+import org.apache.ignite.cdc.ChangeDataCaptureConfiguration;
+import org.apache.ignite.cdc.ChangeDataCaptureConsumer;
+import org.apache.ignite.cdc.ChangeDataCaptureEvent;
+import org.apache.ignite.configuration.DataStorageConfiguration;
+import org.apache.ignite.configuration.IgniteConfiguration;
+import org.apache.ignite.internal.IgniteInterruptedCheckedException;
+import org.apache.ignite.internal.IgnitionEx;
+import org.apache.ignite.internal.MarshallerContextImpl;
+import org.apache.ignite.internal.pagemem.wal.WALIterator;
+import org.apache.ignite.internal.processors.cache.binary.CacheObjectBinaryProcessorImpl;
+import org.apache.ignite.internal.processors.cache.persistence.filename.PdsFolderResolver;
+import org.apache.ignite.internal.processors.cache.persistence.filename.PdsFolderSettings;
+import org.apache.ignite.internal.processors.cache.persistence.wal.WALPointer;
+import org.apache.ignite.internal.processors.cache.persistence.wal.reader.IgniteWalIteratorFactory;
+import org.apache.ignite.internal.processors.resource.GridResourceIoc;
+import org.apache.ignite.internal.processors.resource.GridResourceLoggerInjector;
+import org.apache.ignite.internal.processors.resource.GridSpringResourceContext;
+import org.apache.ignite.internal.util.typedef.F;
+import org.apache.ignite.internal.util.typedef.internal.CU;
+import org.apache.ignite.internal.util.typedef.internal.U;
+import org.apache.ignite.lang.IgniteBiTuple;
+import org.apache.ignite.resources.LoggerResource;
+import org.apache.ignite.resources.SpringApplicationContextResource;
+import org.apache.ignite.resources.SpringResource;
+import org.apache.ignite.startup.cmdline.ChangeDataCaptureCommandLineStartup;
+
+import static org.apache.ignite.internal.IgniteKernal.NL;
+import static org.apache.ignite.internal.IgniteKernal.SITE;
+import static org.apache.ignite.internal.IgniteVersionUtils.ACK_VER_STR;
+import static org.apache.ignite.internal.IgniteVersionUtils.COPYRIGHT;
+import static org.apache.ignite.internal.pagemem.wal.record.WALRecord.RecordType.DATA_RECORD_V2;
+import static org.apache.ignite.internal.processors.cache.persistence.wal.FileWriteAheadLogManager.WAL_SEGMENT_FILE_FILTER;
+
+/**
+ * Change Data Capture(CDC) application.
+ * Application run independently of Ignite node process and provide ability for the {@link ChangeDataCaptureConsumer}
+ * to consume events({@link ChangeDataCaptureEvent}) from WAL segments.
+ * User should responsible {@link ChangeDataCaptureConsumer} implementation with custom consumption logic.
+ *
+ * Ignite node should be explicitly configured for using {@link ChangeDataCapture}.
+ * <ol>
+ *     <li>Set {@link DataStorageConfiguration#setChangeDataCaptureEnabled(boolean)} to true.</li>
+ *     <li>Optional: Set {@link DataStorageConfiguration#setChangeDataCaptureWalPath(String)} to path to the directory
+ *     to store WAL segments for CDC.</li>
+ *     <li>Optional: Set {@link DataStorageConfiguration#setWalForceArchiveTimeout(long)} to configure timeout for
+ *     force WAL rollover, so new events will be available for consumptions with the predicted time.</li>
+ * </ol>
+ *
+ * When {@link DataStorageConfiguration#getChangeDataCaptureWalPath()} is true then Ignite node on each WAL segment
+ * rollover creates hard link to archive WAL segment in
+ * {@link DataStorageConfiguration#getChangeDataCaptureWalPath()} directory. {@link ChangeDataCapture} application takes
+ * segment file and consumes events from it.
+ * After successful consumption (see {@link ChangeDataCaptureConsumer#onEvents(Iterator)}) WAL segment will be deleted
+ * from directory.
+ *
+ * Several Ignite nodes can be started on the same host.
+ * If your deployment done with custom consistent id then you should specify it via
+ * {@link IgniteConfiguration#setConsistentId(Serializable)} in provided {@link IgniteConfiguration}.
+ *
+ * Application works as follows:
+ * <ol>
+ *     <li>Search node work directory based on provided {@link IgniteConfiguration}.</li>
+ *     <li>Await for creation of CDC directory if it not exists.</li>
+ *     <li>Acquire file lock to ensure exclusive consumption.</li>
+ *     <li>Loads state of consumption if it exists.</li>
+ *     <li>Infinetely wait for new available segment and process it.</li>
+ * </ol>
+ *
+ * @see DataStorageConfiguration#setChangeDataCaptureEnabled(boolean)
+ * @see DataStorageConfiguration#setChangeDataCaptureWalPath(String)
+ * @see DataStorageConfiguration#setWalForceArchiveTimeout(long)
+ * @see ChangeDataCaptureCommandLineStartup
+ * @see ChangeDataCaptureConsumer
+ * @see DataStorageConfiguration#DFLT_WAL_CDC_PATH
+ */
+public class ChangeDataCapture implements Runnable {
+    /** */
+    public static final String ERR_MSG = "Persistence disabled. Capture Data Change can't run!";
+
+    /** State dir. */
+    public static final String STATE_DIR = "state";
+
+    /** Ignite configuration. */
+    private final IgniteConfiguration igniteCfg;
+
+    /** Spring resource context. */
+    private final GridSpringResourceContext ctx;
+
+    /** Change Data Capture configuration. */
+    private final ChangeDataCaptureConfiguration cdcCfg;
+
+    /** WAL iterator factory. */
+    private final IgniteWalIteratorFactory factory;
+
+    /** Events consumer. */
+    private final WALRecordsConsumer<?, ?> consumer;
+
+    /** Logger. */
+    private final IgniteLogger log;
+
+    /** Change Data Capture directory. */
+    private Path cdcDir;
+
+    /** Binary meta directory. */
+    private File binaryMeta;
+
+    /** Marshaller directory. */
+    private File marshaller;
+
+    /** Change Data Capture state. */
+    private ChangeDataCaptureConsumerState state;
+
+    /** Save state to start from. */
+    private WALPointer initState;
+
+    /** Stopped flag. */
+    private volatile boolean stopped;
+
+    /** Already processed segments. */
+    private final List<Path> processed = new ArrayList<>();
+
+    /**
+     * @param igniteCfg Ignite configuration.
+     * @param ctx Spring resource context.
+     * @param cdcCfg Change Data Capture configuration.
+     */
+    public ChangeDataCapture(
+        IgniteConfiguration igniteCfg,
+        GridSpringResourceContext ctx,
+        ChangeDataCaptureConfiguration cdcCfg) {
+        this.igniteCfg = new IgniteConfiguration(igniteCfg);
+        this.ctx = ctx;
+        this.cdcCfg = cdcCfg;
+
+        initWorkDir(this.igniteCfg);
+
+        log = logger(this.igniteCfg);
+
+        consumer = new WALRecordsConsumer<>(cdcCfg.getConsumer(), log);
+
+        factory = new IgniteWalIteratorFactory(log);
+    }
+
+    /** Runs Change Data Capture. */
+    @Override public void run() {
+        synchronized (this) {
+            if (stopped)
+                return;
+        }
+
+        try {
+            runX();
+        }
+        catch (Throwable e) {
+            e.printStackTrace();
+
+            throw new IgniteException(e);
+        }
+    }
+
+    /** Runs Change Data Capture application with possible exception. */
+    public void runX() throws Exception {
+        if (!CU.isPersistenceEnabled(igniteCfg)) {
+            log.error(ERR_MSG);
+
+            throw new IllegalArgumentException(ERR_MSG);
+        }
+
+        PdsFolderSettings<ChangeDataCaptureFileLockHolder> settings =
+            new PdsFolderResolver<>(igniteCfg, log, null, this::tryLock).resolve();
+
+        if (settings == null)
+            throw new IgniteException("Can't find PDS folder!");

Review comment:
       So, the message should be "PDS folder location can't be resolved"?
   And the question here is why?




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