diff options
-rw-r--r-- | unsafe/src/main/java/org/apache/spark/unsafe/Platform.java | 27 | ||||
-rw-r--r-- | unsafe/src/test/java/org/apache/spark/unsafe/PlatformUtilSuite.java | 61 |
2 files changed, 82 insertions, 6 deletions
diff --git a/unsafe/src/main/java/org/apache/spark/unsafe/Platform.java b/unsafe/src/main/java/org/apache/spark/unsafe/Platform.java index 1c16da9829..0d6b215fe5 100644 --- a/unsafe/src/main/java/org/apache/spark/unsafe/Platform.java +++ b/unsafe/src/main/java/org/apache/spark/unsafe/Platform.java @@ -107,12 +107,27 @@ public final class Platform { public static void copyMemory( Object src, long srcOffset, Object dst, long dstOffset, long length) { - while (length > 0) { - long size = Math.min(length, UNSAFE_COPY_THRESHOLD); - _UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, size); - length -= size; - srcOffset += size; - dstOffset += size; + // Check if dstOffset is before or after srcOffset to determine if we should copy + // forward or backwards. This is necessary in case src and dst overlap. + if (dstOffset < srcOffset) { + while (length > 0) { + long size = Math.min(length, UNSAFE_COPY_THRESHOLD); + _UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, size); + length -= size; + srcOffset += size; + dstOffset += size; + } + } else { + srcOffset += length; + dstOffset += length; + while (length > 0) { + long size = Math.min(length, UNSAFE_COPY_THRESHOLD); + srcOffset -= size; + dstOffset -= size; + _UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, size); + length -= size; + } + } } diff --git a/unsafe/src/test/java/org/apache/spark/unsafe/PlatformUtilSuite.java b/unsafe/src/test/java/org/apache/spark/unsafe/PlatformUtilSuite.java new file mode 100644 index 0000000000..693ec6ec58 --- /dev/null +++ b/unsafe/src/test/java/org/apache/spark/unsafe/PlatformUtilSuite.java @@ -0,0 +1,61 @@ +/* + * 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.spark.unsafe; + +import org.junit.Assert; +import org.junit.Test; + +public class PlatformUtilSuite { + + @Test + public void overlappingCopyMemory() { + byte[] data = new byte[3 * 1024 * 1024]; + int size = 2 * 1024 * 1024; + for (int i = 0; i < data.length; ++i) { + data[i] = (byte)i; + } + + Platform.copyMemory(data, Platform.BYTE_ARRAY_OFFSET, data, Platform.BYTE_ARRAY_OFFSET, size); + for (int i = 0; i < data.length; ++i) { + Assert.assertEquals((byte)i, data[i]); + } + + Platform.copyMemory( + data, + Platform.BYTE_ARRAY_OFFSET + 1, + data, + Platform.BYTE_ARRAY_OFFSET, + size); + for (int i = 0; i < size; ++i) { + Assert.assertEquals((byte)(i + 1), data[i]); + } + + for (int i = 0; i < data.length; ++i) { + data[i] = (byte)i; + } + Platform.copyMemory( + data, + Platform.BYTE_ARRAY_OFFSET, + data, + Platform.BYTE_ARRAY_OFFSET + 1, + size); + for (int i = 0; i < size; ++i) { + Assert.assertEquals((byte)i, data[i + 1]); + } + } +} |