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Date: Wed, 1 Apr 2015 04:02:52 +0000 (UTC)
From: "Sean Busbey (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12609935.1349195576000.88704.1427860972796@Atlassian.JIRA>
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 <JIRA.12609935.1349195576046@arcas>
Subject: [jira] [Commented] (HBASE-6919) Remove unnecessary cast from
 Bytes.readVLong
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    [ https://issues.apache.org/jira/browse/HBASE-6919?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14389953#comment-14389953 ] 

Sean Busbey commented on HBASE-6919:
------------------------------------

Hurm. I don't see anything in TestBytes that covers VLong. mind adding a simple round-trip test?

> Remove unnecessary cast from Bytes.readVLong
> --------------------------------------------
>
>                 Key: HBASE-6919
>                 URL: https://issues.apache.org/jira/browse/HBASE-6919
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: James Taylor
>            Priority: Minor
>              Labels: beginners
>         Attachments: HBASE-6919-v1.patch, HBASE-6919.patch
>
>
> Remove the throws IOException so that caller doesn't have to catch and ignore.
> {code}
>   public static long readVLong(final byte [] buffer, final int offset)
>   throws IOException
> {code}
> Also, add
> {code}
>   public static int readVInt(final byte [] buffer, final int offset)
>   throws IOException {
>     return (int)readVLong(buffer,offset);
>   }
> {code}
> and these are useful too:
> {code}
>     /**
>      * Put long as variable length encoded number at the offset in
>      * the result byte array.
>      * @param vint Integer to make a vint of.
>      * @param result buffer to put vint into
>      * @return Vint length in bytes of vint
>      */
>     public static int vintToBytes(byte[] result, int offset, final long vint) {
>       long i = vint;
>       if (i >= -112 && i <= 127) {
>         result[offset] = (byte) i;
>         return 1;
>       }
>       int len = -112;
>       if (i < 0) {
>         i ^= -1L; // take one's complement'
>         len = -120;
>       }
>       long tmp = i;
>       while (tmp != 0) {
>         tmp = tmp >> 8;
>         len--;
>       }
>       result[offset++] = (byte) len;
>       len = (len < -120) ? -(len + 120) : -(len + 112);
>       for (int idx = len; idx != 0; idx--) {
>         int shiftbits = (idx - 1) * 8;
>         long mask = 0xFFL << shiftbits;
>         result[offset++] = (byte)((i & mask) >> shiftbits);
>       }
>       return len + 1;
>     }
>     /**
>      * Decode a vint from the buffer pointed at to by ptr and
>      * increment the offset of the ptr by the length of the
>      * vint.
>      * @param ptr a pointer to a byte array buffer
>      * @return the decoded vint value as an int
>      */
>     public static int vintFromBytes(ImmutableBytesWritable ptr) {
>         return (int) vlongFromBytes(ptr);
>     }
>     
>     /**
>      * Decode a vint from the buffer pointed at to by ptr and
>      * increment the offset of the ptr by the length of the
>      * vint.
>      * @param ptr a pointer to a byte array buffer
>      * @return the decoded vint value as a long
>      */
>     public static long vlongFromBytes(ImmutableBytesWritable ptr) {
>         final byte [] buffer = ptr.get();
>         final int offset = ptr.getOffset();
>         byte firstByte = buffer[offset];
>         int len = WritableUtils.decodeVIntSize(firstByte);
>         if (len == 1) {
>             ptr.set(buffer, offset+1, ptr.getLength());
>             return firstByte;
>         }
>         long i = 0;
>         for (int idx = 0; idx < len-1; idx++) {
>             byte b = buffer[offset + 1 + idx];
>             i = i << 8;
>             i = i | (b & 0xFF);
>         }
>         ptr.set(buffer, offset+len, ptr.getLength());
>         return (WritableUtils.isNegativeVInt(firstByte) ? ~i : i);
>     }
> {code}


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