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

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReaderIoStats.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReaderIoStats.java
index cf925c914de24da58addb802517a2ce9d4e8214b..c35801f3b051ddaf620422c6c0e9a75687fc4ad4 100644 (file)
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReaderIoStats.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReaderIoStats.java
@@ -67,10 +67,16 @@ public class DfsReaderIoStats {
                /** 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 class DfsReaderIoStats {
        }
 
        /**
-        * 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 class DfsReaderIoStats {
        }
 
        /**
-        * 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 class DfsReaderIoStats {
        }
 
        /**
-        * Get total microseconds spent reading blocks.
+        * Get total microseconds spent reading blocks during cache misses.
         *
         * @return total microseconds spent reading blocks.
         */