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DfsReaderIoStats: Clarify that "blocks" are really cache misses 

The previous wording was ambiguous as to whether these were blocks
requested from the cache (hits + misses) or read from underlying storage
(misses only).

They are in fact recording only misses:
Accumulator#{readBlock,readBlockBytes,readBlockMicros} are only
incremented from BlockBasedFile#readOneBlock, which is only called from
the cache miss path in DfsBlockCache#getOrLoad (line 391).

Change-Id: I0135cd1e76d09c1e28e0f1833b34c312511c66ce
This commit is contained in:
Dave Borowitz 2018-01-11 13:14:02 -05:00 committed by David Pursehouse
parent 49cb6ba5dd
commit 879372eb72
1 changed files with 13 additions and 5 deletions
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18
org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReaderIoStats.java
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@ -67,10 +67,16 @@ public static class Accumulator {
/** Total number of block cache hits. */
long blockCacheHit;
/** Total number of discrete blocks read from pack file(s). */
/**
* Total number of discrete blocks actually read from pack file(s), that is,
* block cache misses.
*/
long readBlock;
/** Total number of compressed bytes read as block sized units. */
/**
* Total number of compressed bytes read during cache misses, as block sized
* units.
*/
long readBlockBytes;
/** Total microseconds spent reading {@link #readBlock} blocks. */
@ -144,7 +150,8 @@ public long getBlockCacheHits() {
}
/**
* Get total number of discrete blocks read from pack file(s).
* Get total number of discrete blocks actually read from pack file(s), that
* is, block cache misses.
*
* @return total number of discrete blocks read from pack file(s).
*/
@ -153,7 +160,8 @@ public long getReadBlocksCount() {
}
/**
* Get total number of compressed bytes read as block sized units.
* Get total number of compressed bytes read during cache misses, as block
* sized units.
*
* @return total number of compressed bytes read as block sized units.
*/
@ -162,7 +170,7 @@ public long getReadBlocksBytes() {
}
/**
* Get total microseconds spent reading blocks.
* Get total microseconds spent reading blocks during cache misses.
*
* @return total microseconds spent reading blocks.
*/