Utility method for length estimation of utf8

common/src/main/java/io/druid/common/utils/StringUtils.java

@@ -0,0 +1,47 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets 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 io.druid.common.utils;
+
+/**
+ */
+public class StringUtils extends com.metamx.common.StringUtils
+{
+  // should be used only for estimation
+  // returns the same result with StringUtils.fromUtf8(value).length for valid string values
+  // does not check validity of format and returns over-estimated result for invalid string (see UT)
+  public static int estimatedBinaryLengthAsUTF8(String value)
+  {
+    int length = 0;
+    for (int i = 0; i < value.length(); i++) {
+      char var10 = value.charAt(i);
+      if (var10 < 0x80) {
+        length += 1;
+      } else if (var10 < 0x800) {
+        length += 2;
+      } else if (Character.isSurrogate(var10)) {
+        length += 4;
+        i++;
+      } else {
+        length += 3;
+      }
+    }
+    return length;
+  }
+}

common/src/test/java/io/druid/common/utils/StringUtilsTest.java

@@ -0,0 +1,80 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets 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 io.druid.common.utils;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.UnsupportedEncodingException;
+
+/**
+ */
+public class StringUtilsTest
+{
+  // copied from https://github.com/druid-io/druid/pull/2612
+  public final static String[] TEST_STRINGS = new String[]{
+      "peach", "péché", "pêche", "sin", "",
+      "☃", "C", "c", "Ç", "ç", "G", "g", "Ğ", "ğ", "I", "ı", "İ", "i",
+      "O", "o", "Ö", "ö", "S", "s", "Ş", "ş", "U", "u", "Ü", "ü", "ä",
+      "\uD841\uDF0E",
+      "\uD841\uDF31",
+      "\uD844\uDC5C",
+      "\uD84F\uDCB7",
+      "\uD860\uDEE2",
+      "\uD867\uDD98",
+      "\u006E\u0303",
+      "\u006E",
+      "\uFB00",
+      "\u0066\u0066",
+      "Å",
+      "\u00C5",
+      "\u212B"
+  };
+
+  @Test
+  public void binaryLengthAsUTF8Test() throws UnsupportedEncodingException
+  {
+    for (String string : TEST_STRINGS) {
+      Assert.assertEquals(StringUtils.toUtf8(string).length, StringUtils.estimatedBinaryLengthAsUTF8(string));
+    }
+  }
+
+  @Test
+  public void binaryLengthAsUTF8InvalidTest() throws UnsupportedEncodingException
+  {
+    // we can fix this but looks trivial case, imho
+    String invalid = "\uD841";  // high only
+    Assert.assertEquals(1, StringUtils.toUtf8(invalid).length);
+    Assert.assertEquals(4, StringUtils.estimatedBinaryLengthAsUTF8(invalid));
+
+    invalid = "\uD841\uD841";  // high + high
+    Assert.assertEquals(2, StringUtils.toUtf8(invalid).length);
+    Assert.assertEquals(4, StringUtils.estimatedBinaryLengthAsUTF8(invalid));
+
+    invalid = "\uD841\u0050";  // high + char
+    Assert.assertEquals(2, StringUtils.toUtf8(invalid).length);
+    Assert.assertEquals(4, StringUtils.estimatedBinaryLengthAsUTF8(invalid));
+
+    invalid = "\uDEE2\uD841";  // low + high
+    Assert.assertEquals(2, StringUtils.toUtf8(invalid).length);
+    Assert.assertEquals(4, StringUtils.estimatedBinaryLengthAsUTF8(invalid));
+  }
+
+}

processing/src/main/java/io/druid/query/metadata/SegmentAnalyzer.java

@@ -26,10 +26,10 @@
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import com.google.common.primitives.Longs;
-import com.metamx.common.StringUtils;
 import com.metamx.common.guava.Accumulator;
 import com.metamx.common.guava.Sequence;
 import com.metamx.common.logger.Logger;
+import io.druid.common.utils.StringUtils;
 import io.druid.granularity.QueryGranularity;
 import io.druid.query.dimension.DefaultDimensionSpec;
 import io.druid.query.metadata.metadata.ColumnAnalysis;
@@ -206,7 +206,7 @@ private ColumnAnalysis analyzeStringColumn(
       for (int i = 0; i < cardinality; ++i) {
         String value = bitmapIndex.getValue(i);
         if (value != null) {
-          size += StringUtils.toUtf8(value).length * bitmapIndex.getBitmap(bitmapIndex.getIndex(value)).size();
+          size += StringUtils.estimatedBinaryLengthAsUTF8(value) * bitmapIndex.getBitmap(bitmapIndex.getIndex(value)).size();
         }
       }
     }
@@ -272,7 +272,7 @@ public Long accumulate(Long accumulated, Cursor cursor)
                 for (int i = 0; i < vals.size(); ++i) {
                   final String dimVal = selector.lookupName(vals.get(i));
                   if (dimVal != null && !dimVal.isEmpty()) {
-                    current += StringUtils.toUtf8(dimVal).length;
+                    current += StringUtils.estimatedBinaryLengthAsUTF8(dimVal);
                   }
                 }
                 cursor.advance();