[ML] Add log structure finder functionality (#32788)

This change adds a library to ML that can be used to deduce a log
file's structure given only a sample of the log file.

Eventually this will be used to add an endpoint to ML to make the
functionality available to end users, but this will follow in a
separate change.

The functionality is split into a library so that it can also be
used by a command line tool without requiring the command line
tool to include all server code.

Author: David Roberts

x-pack/plugin/ml/log-structure-finder/build.gradle

@@ -0,0 +1,36 @@
+import org.elasticsearch.gradle.precommit.PrecommitTasks
+
+apply plugin: 'elasticsearch.build'
+
+archivesBaseName = 'x-pack-log-structure-finder'
+
+description = 'Common code for reverse engineering log structure'
+
+dependencies {
+    compile "org.elasticsearch:elasticsearch-core:${version}"
+    compile "org.elasticsearch:elasticsearch-x-content:${version}"
+    compile project(':libs:grok')
+    compile "com.ibm.icu:icu4j:${versions.icu4j}"
+    compile "net.sf.supercsv:super-csv:${versions.supercsv}"
+
+    testCompile "org.elasticsearch.test:framework:${version}"
+}
+
+configurations {
+    testArtifacts.extendsFrom testRuntime
+}
+task testJar(type: Jar) {
+    appendix 'test'
+    from sourceSets.test.output
+}
+artifacts {
+    // normal es plugins do not publish the jar but we need to since users need it for Transport Clients and extensions
+    archives jar
+    testArtifacts testJar
+}
+
+forbiddenApisMain {
+    // log-structure-finder does not depend on server, so cannot forbid server methods
+    signaturesURLs = [PrecommitTasks.getResource('/forbidden/jdk-signatures.txt')]
+}
+

x-pack/plugin/ml/log-structure-finder/licenses/icu4j-62.1.jar.sha1

@@ -0,0 +1 @@
+7a4d00d5ec5febd252a6182e8b6e87a0a9821f81

x-pack/plugin/ml/log-structure-finder/licenses/icu4j-LICENSE.txt

@@ -0,0 +1,33 @@
+ICU License - ICU 1.8.1 and later
+
+COPYRIGHT AND PERMISSION NOTICE
+
+Copyright (c) 1995-2012 International Business Machines Corporation and others
+
+All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, and/or sell copies of the
+Software, and to permit persons to whom the Software is furnished to do so,
+provided that the above copyright notice(s) and this permission notice appear
+in all copies of the Software and that both the above copyright notice(s) and
+this permission notice appear in supporting documentation.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
+IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE
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+ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
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+Except as contained in this notice, the name of a copyright holder shall not
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+
+All trademarks and registered trademarks mentioned herein are the property of
+their respective owners.

x-pack/plugin/ml/log-structure-finder/licenses/icu4j-NOTICE.txt

@@ -0,0 +1,3 @@
+ICU4J, (under lucene/analysis/icu) is licensed under an MIT style license
+(modules/analysis/icu/lib/icu4j-LICENSE-BSD_LIKE.txt) and Copyright (c) 1995-2012
+International Business Machines Corporation and others

x-pack/plugin/ml/log-structure-finder/licenses/super-csv-2.4.0.jar.sha1

@@ -0,0 +1 @@
+017f8708c929029dde48bc298deaf3c7ae2452d3

x-pack/plugin/ml/log-structure-finder/licenses/super-csv-LICENSE.txt

@@ -0,0 +1,203 @@
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x-pack/plugin/ml/log-structure-finder/licenses/super-csv-NOTICE.txt

@@ -0,0 +1,35 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.ml.logstructurefinder;
+
+import org.supercsv.prefs.CsvPreference;
+
+import java.io.IOException;
+import java.util.List;
+
+public class CsvLogStructureFinderFactory implements LogStructureFinderFactory {
+
+    /**
+     * Rules are:
+     * - The file must be valid CSV
+     * - It must contain at least two complete records
+     * - There must be at least two fields per record (otherwise files with no commas could be treated as CSV!)
+     * - Every CSV record except the last must have the same number of fields
+     * The reason the last record is allowed to have fewer fields than the others is that
+     * it could have been truncated when the file was sampled.
+     */
+    @Override
+    public boolean canCreateFromSample(List<String> explanation, String sample) {
+        return SeparatedValuesLogStructureFinder.canCreateFromSample(explanation, sample, 2, CsvPreference.EXCEL_PREFERENCE, "CSV");
+    }
+
+    @Override
+    public LogStructureFinder createFromSample(List<String> explanation, String sample, String charsetName, Boolean hasByteOrderMarker)
+        throws IOException {
+        return SeparatedValuesLogStructureFinder.makeSeparatedValuesLogStructureFinder(explanation, sample, charsetName, hasByteOrderMarker,
+            CsvPreference.EXCEL_PREFERENCE, false);
+    }
+}