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From "Xiang Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18389) Remove byte[] from sizeOf() of ClassSize, ClassSize.MemoryLayout and ClassSize.UnsafeLayout
Date Mon, 17 Jul 2017 09:05:00 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18389?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16089524#comment-16089524
] 

Xiang Li commented on HBASE-18389:
----------------------------------

Uploaded patch 000 to make some changes:
# In ClassSize.MemoryLayout and ClassSize.UnsafeLayout
## Remove byte[] b from the formal parameters of sizeOf(), and keep byte[] b
## Rename sizeOf() into sizeOfByteArray()
# In ClassSize
Replace sizeOf(byte[] b, int len) with 2 functions
## sizeOf(byte[] b). Used when the whole backing byte array is considered, such as in CellUtil.TagRewriteCell#heapSize(),
CellUtil.TagRewriteByteBufferCell#heapSize(), CellUtil.ValueAndTagRewriteCell#heapSize() and
CellUtil.ValueAndTagRewriteByteBufferCell#heapSize()
## sizeOfPartOfByteArray(int len). Used when the byte array backs (be shared by) multiple
objects, such as in KeyValue#heapSize()

It is like: 
* ClassSize#sizeOf(byte[]) and ClassSize#sizeOfByteArray(int) are the public interfaces to
be called when the memory consumption of a byte array is to be calculated. Callers only need
to care about it is the whole byte array to calculate or a part of it. 
* The sizeOfByteArray() of ClassSize.MemoryLayout and ClassSize.UnsafeLayout are hidden behind
ClassSize#sizeOf(byte[]) and ClassSize#sizeOfByteArray(int) to deal with the internal logic

> Remove byte[] from sizeOf() of ClassSize, ClassSize.MemoryLayout and ClassSize.UnsafeLayout
> -------------------------------------------------------------------------------------------
>
>                 Key: HBASE-18389
>                 URL: https://issues.apache.org/jira/browse/HBASE-18389
>             Project: HBase
>          Issue Type: Bug
>          Components: util
>            Reporter: Xiang Li
>            Assignee: Xiang Li
>            Priority: Minor
>
> In ClassSize class and its internal static class, sizeOf() function has 2 formal parameters:
byte[] b and int len. But the function's internal logic does not use or refer to byte[] b.
Could be removed.
> {code:title=hbase-common/src/main/java/org/apache/hadoop/hbase/util/ClassSize.java|borderStyle=solid}
> // Class of ClassSize
> public static long sizeOf(byte[] b, int len) {
>   return memoryLayout.sizeOf(b, len);
> }
> // Class of ClassSize.MemoryLayout
> long sizeOf(byte[] b, int len) {
>   return align(arrayHeaderSize() + len);
> }
> // Class of ClassSize.UnsafeLayout
> long sizeOf(byte[] b, int len) {
>   return align(arrayHeaderSize() + len * UnsafeAccess.theUnsafe.ARRAY_BYTE_INDEX_SCALE);
> }
> {code}



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