Github user vdiravka commented on a diff in the pull request:
https://github.com/apache/drill/pull/877#discussion_r129834750
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/MetadataVersion.java
---
@@ -0,0 +1,124 @@
+/*
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.drill.exec.store.parquet;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ComparisonChain;
+import com.google.common.collect.Lists;
+import org.apache.drill.common.exceptions.DrillRuntimeException;
+
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+
+class MetadataVersion implements Comparable<MetadataVersion> {
+ /**
+ * String version starts from 'v' letter<p>
+ * First group is major metadata version (any number of digits, except a
single zero digit)<p>
+ * Next character is optional '.' (if minor version is specified)<p>
+ * Next group is optional, minor metadata version (any number of digits,
except a single zero digit)<p>
+ * Examples of correct metadata versions: v1, v10, v4.13
+ */
+ private static final String FORMAT = "v((?!0)\\d+)\\.?((?!0)\\d+)?";
+ private static final Pattern PATTERN = Pattern.compile(FORMAT);
+
+ private final int major;
+ private final int minor;
+
+ public MetadataVersion(int major, int minor) {
+ this.major = major;
+ this.minor = minor;
+ }
+
+ public MetadataVersion(String metadataVersion) {
+ Matcher matcher = PATTERN.matcher(metadataVersion);
+ if (!matcher.matches()) {
+ DrillRuntimeException.format("Could not parse metadata version '%s'
using format '%s'", metadataVersion, FORMAT);
+ }
+ this.major = Integer.parseInt(matcher.group(1));
+ this.minor = matcher.group(2) != null ?
Integer.parseInt(matcher.group(2)) : 0;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (!(o instanceof MetadataVersion)) {
+ return false;
+ }
+ MetadataVersion that = (MetadataVersion) o;
+ return this.major == that.major
+ && this.minor == that.minor;
+ }
+
+ @Override
+ public int hashCode() {
+ int result = major;
+ result = 31 * result + minor;
+ return result;
+ }
+
+ @Override
+ public String toString() {
+ return minor == 0 ? String.format("v%s1", major) :
String.format("v%s1.%s2", major, minor);
+ }
+
+ @Override
+ public int compareTo(MetadataVersion o) {
+ Preconditions.checkNotNull(o);
+ return ComparisonChain.start()
+ .compare(this.major, o.major)
+ .compare(this.minor, o.minor)
+ .result();
+ }
+
+/**
+ * Supported metadata versions.
+ * <p>
+ * Note: keep them synchronized with {@link
Metadata.ParquetTableMetadataBase} versions
+ */
+ public static class Constants {
+ /**
+ * Version 1: Introduces parquet file metadata caching.<br>
+ * See DRILL-2743
+ */
+ public static final String V1 = "v1";
--- End diff --
Makes sense. Also started using an `ImmutableList` here.
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