prefer use of java.util.zip.CRC32C

src/main/java/org/xerial/snappy/PureJavaCrc32C.java

@@ -48,8 +48,7 @@ public int getIntegerValue()
     /** {@inheritDoc} */
     public long getValue()
     {
-        long ret = crc;
-        return (~ret) & 0xffffffffL;
+        return (~crc) & 0xffffffffL;
     }
 
     /** {@inheritDoc} */

src/main/java/org/xerial/snappy/SnappyFramed.java

@@ -1,125 +1,165 @@
-/*
- * Created: Apr 12, 2013
- */
-package org.xerial.snappy;
-
-import java.io.IOException;
-import java.nio.ByteBuffer;
-import java.nio.channels.ReadableByteChannel;
-
-/**
- * Constants and utilities for implementing x-snappy-framed.
- *
- * @author Brett Okken
- * @since 1.1.0
- */
-final class SnappyFramed
-{
-    public static final int COMPRESSED_DATA_FLAG = 0x00;
-
-    public static final int UNCOMPRESSED_DATA_FLAG = 0x01;
-
-    public static final int STREAM_IDENTIFIER_FLAG = 0xff;
-
-    private static final int MASK_DELTA = 0xa282ead8;
-
-    /**
-     * The header consists of the stream identifier flag, 3 bytes indicating a
-     * length of 6, and "sNaPpY" in ASCII.
-     */
-    public static final byte[] HEADER_BYTES = new byte[] {
-            (byte) STREAM_IDENTIFIER_FLAG, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61,
-            0x50, 0x70, 0x59};
-
-    public static int maskedCrc32c(byte[] data)
-    {
-        return maskedCrc32c(data, 0, data.length);
-    }
-
-    public static int maskedCrc32c(byte[] data, int offset, int length)
-    {
-        final PureJavaCrc32C crc32c = new PureJavaCrc32C();
-        crc32c.update(data, offset, length);
-        return mask(crc32c.getIntegerValue());
-    }
-
-    /**
-     * Checksums are not stored directly, but masked, as checksumming data and
-     * then its own checksum can be problematic. The masking is the same as used
-     * in Apache Hadoop: Rotate the checksum by 15 bits, then add the constant
-     * 0xa282ead8 (using wraparound as normal for unsigned integers). This is
-     * equivalent to the following C code:
-     * <p/>
-     * <pre>
-     * uint32_t mask_checksum(uint32_t x) {
-     *     return ((x >> 15) | (x << 17)) + 0xa282ead8;
-     * }
-     * </pre>
-     */
-    public static int mask(int crc)
-    {
-        // Rotate right by 15 bits and add a constant.
-        return ((crc >>> 15) | (crc << 17)) + MASK_DELTA;
-    }
-
-    static final int readBytes(ReadableByteChannel source, ByteBuffer dest)
-            throws IOException
-    {
-        // tells how many bytes to read.
-        final int expectedLength = dest.remaining();
-
-        int totalRead = 0;
-
-        // how many bytes were read.
-        int lastRead = source.read(dest);
-
-        totalRead = lastRead;
-
-        // if we did not read as many bytes as we had hoped, try reading again.
-        if (lastRead < expectedLength) {
-            // as long the buffer is not full (remaining() == 0) and we have not reached EOF (lastRead == -1) keep reading.
-            while (dest.remaining() != 0 && lastRead != -1) {
-                lastRead = source.read(dest);
-
-                // if we got EOF, do not add to total read.
-                if (lastRead != -1) {
-                    totalRead += lastRead;
-                }
-            }
-        }
-
-        if (totalRead > 0) {
-            dest.limit(dest.position());
-        }
-        else {
-            dest.position(dest.limit());
-        }
-
-        return totalRead;
-    }
-
-    static int skip(final ReadableByteChannel source, final int skip, final ByteBuffer buffer)
-            throws IOException
-    {
-        if (skip <= 0) {
-            return 0;
-        }
-
-        int toSkip = skip;
-        int skipped = 0;
-        while (toSkip > 0 && skipped != -1) {
-            buffer.clear();
-            if (toSkip < buffer.capacity()) {
-                buffer.limit(toSkip);
-            }
-
-            skipped = source.read(buffer);
-            if (skipped > 0) {
-                toSkip -= skipped;
-            }
-        }
-
-        buffer.clear();
-        return skip - toSkip;
-    }
-}
+/*
+ * Created: Apr 12, 2013
+ */
+package org.xerial.snappy;
+
+import java.io.IOException;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.nio.ByteBuffer;
+import java.nio.channels.ReadableByteChannel;
+import java.util.function.Supplier;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.zip.Checksum;
+
+/**
+ * Constants and utilities for implementing x-snappy-framed.
+ *
+ * @author Brett Okken
+ * @since 1.1.0
+ */
+final class SnappyFramed
+{
+    public static final int COMPRESSED_DATA_FLAG = 0x00;
+
+    public static final int UNCOMPRESSED_DATA_FLAG = 0x01;
+
+    public static final int STREAM_IDENTIFIER_FLAG = 0xff;
+
+    private static final int MASK_DELTA = 0xa282ead8;
+
+    private static final Supplier<Checksum> CHECKSUM_SUPPLIER;
+
+    static
+    {
+        Supplier<Checksum> supplier = null;
+        try
+        {
+            final Class crc32cClazz = Class.forName("java.util.zip.CRC32C");
+            final MethodHandles.Lookup lookup = MethodHandles.publicLookup();
+
+            final MethodHandle conHandle = lookup.findConstructor(crc32cClazz, MethodType.methodType(void.class))
+                                                 .asType(MethodType.methodType(Checksum.class));
+            supplier = () -> {
+                try
+                {
+                    return (Checksum) conHandle.invokeExact();
+                }
+                catch (Throwable e)
+                {
+                    throw new IllegalStateException(e);
+                }
+            };
+        }
+        catch(Throwable t)
+        {
+            Logger.getLogger(SnappyFramed.class.getName())
+                  .log(Level.FINE, "java.util.zip.CRC32C not loaded, using PureJavaCrc32C", t);
+            supplier = null;
+        }
+
+        CHECKSUM_SUPPLIER = supplier != null ? supplier : PureJavaCrc32C::new;
+    }
+
+    /**
+     * The header consists of the stream identifier flag, 3 bytes indicating a
+     * length of 6, and "sNaPpY" in ASCII.
+     */
+    public static final byte[] HEADER_BYTES = new byte[] {
+            (byte) STREAM_IDENTIFIER_FLAG, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61,
+            0x50, 0x70, 0x59};
+
+    public static Checksum getCRC32C()
+    {
+        return CHECKSUM_SUPPLIER.get();
+    }
+
+    public static int maskedCrc32c(Checksum crc32c, byte[] data, int offset, int length)
+    {
+        crc32c.reset();
+        crc32c.update(data, offset, length);
+        return mask((int) crc32c.getValue());
+    }
+
+    /**
+     * Checksums are not stored directly, but masked, as checksumming data and
+     * then its own checksum can be problematic. The masking is the same as used
+     * in Apache Hadoop: Rotate the checksum by 15 bits, then add the constant
+     * 0xa282ead8 (using wraparound as normal for unsigned integers). This is
+     * equivalent to the following C code:
+     * <p/>
+     * <pre>
+     * uint32_t mask_checksum(uint32_t x) {
+     *     return ((x >> 15) | (x << 17)) + 0xa282ead8;
+     * }
+     * </pre>
+     */
+    public static int mask(int crc)
+    {
+        // Rotate right by 15 bits and add a constant.
+        return ((crc >>> 15) | (crc << 17)) + MASK_DELTA;
+    }
+
+    static final int readBytes(ReadableByteChannel source, ByteBuffer dest)
+            throws IOException
+    {
+        // tells how many bytes to read.
+        final int expectedLength = dest.remaining();
+
+        int totalRead = 0;
+
+        // how many bytes were read.
+        int lastRead = source.read(dest);
+
+        totalRead = lastRead;
+
+        // if we did not read as many bytes as we had hoped, try reading again.
+        if (lastRead < expectedLength) {
+            // as long the buffer is not full (remaining() == 0) and we have not reached EOF (lastRead == -1) keep reading.
+            while (dest.remaining() != 0 && lastRead != -1) {
+                lastRead = source.read(dest);
+
+                // if we got EOF, do not add to total read.
+                if (lastRead != -1) {
+                    totalRead += lastRead;
+                }
+            }
+        }
+
+        if (totalRead > 0) {
+            dest.limit(dest.position());
+        }
+        else {
+            dest.position(dest.limit());
+        }
+
+        return totalRead;
+    }
+
+    static int skip(final ReadableByteChannel source, final int skip, final ByteBuffer buffer)
+            throws IOException
+    {
+        if (skip <= 0) {
+            return 0;
+        }
+
+        int toSkip = skip;
+        int skipped = 0;
+        while (toSkip > 0 && skipped != -1) {
+            buffer.clear();
+            if (toSkip < buffer.capacity()) {
+                buffer.limit(toSkip);
+            }
+
+            skipped = source.read(buffer);
+            if (skipped > 0) {
+                toSkip -= skipped;
+            }
+        }
+
+        buffer.clear();
+        return skip - toSkip;
+    }
+}