SimpleCache: more histograms watching how index is loaded.

SimpleCache: more histograms watching how index is loaded.

The index is stale in about 50% of cases and often takes longer than 10s to
restore. We need to watch this closer: looking at sizes of the cache on load,
speculating on per-entry overhead for loading.

BUG=none

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=204619

[pasko, 2013-06-05 10:01:47]

Gavin, Felipe, please take a look.

[gavinp, 2013-06-05 16:33:33]

lgtm

[pasko, 2013-06-05 17:19:07]

Jim, please take a look

[jar (doing other things), 2013-06-05 18:17:54]

LGTM with a nits.

https://codereview.chromium.org/16286015/diff/1/net/disk_cache/simple/simple_...
File net/disk_cache/simple/simple_index.cc (right):

https://codereview.chromium.org/16286015/diff/1/net/disk_cache/simple/simple_...
net/disk_cache/simple/simple_index.cc:421: (base::TimeTicks::Now() - start));
nit: no need for redundant parens.  Good macro do this tsuff for you (if it
needs to be done ;-) ).

https://codereview.chromium.org/16286015/diff/1/tools/metrics/histograms/hist...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/16286015/diff/1/tools/metrics/histograms/hist...
tools/metrics/histograms/histograms.xml:9277: <summary>Number of entries loaded
from the index.</summary>
Please indicate when this sample is taken.   Is this a hash table, and this
happens when we try to look for a single resource??

[pasko, 2013-06-05 18:35:23]

https://codereview.chromium.org/16286015/diff/1/tools/metrics/histograms/hist...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/16286015/diff/1/tools/metrics/histograms/hist...
tools/metrics/histograms/histograms.xml:9277: <summary>Number of entries loaded
from the index.</summary>
On 2013/06/05 18:17:54, jar wrote:
> Please indicate when this sample is taken.   Is this a hash table, and this
> happens when we try to look for a single resource??

Done. It happens on index start.

[pasko, 2013-06-05 18:39:37]

https://codereview.chromium.org/16286015/diff/1/net/disk_cache/simple/simple_...
File net/disk_cache/simple/simple_index.cc (right):

https://codereview.chromium.org/16286015/diff/1/net/disk_cache/simple/simple_...
net/disk_cache/simple/simple_index.cc:421: (base::TimeTicks::Now() - start));
On 2013/06/05 18:17:54, jar wrote:
> nit: no need for redundant parens.  Good macro do this tsuff for you (if it
> needs to be done ;-) ).

Done.

[commit-bot: I haz the power, 2013-06-05 18:40:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pasko@chromium.org/16286015/10003

[commit-bot: I haz the power, 2013-06-05 23:48:10]

Retried try job too often on android_dbg for step(s) slave_steps
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=android_db...

[commit-bot: I haz the power, 2013-06-06 11:37:45]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pasko@chromium.org/16286015/10003

[commit-bot: I haz the power, 2013-06-06 11:37:53]

Failed to apply patch for net/disk_cache/simple/simple_index.cc:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file net/disk_cache/simple/simple_index.cc
  Hunk #1 FAILED at 416.
  Hunk #2 FAILED at 424.
  2 out of 2 hunks FAILED -- saving rejects to file
net/disk_cache/simple/simple_index.cc.rej

Patch:       net/disk_cache/simple/simple_index.cc
Index: net/disk_cache/simple/simple_index.cc
diff --git a/net/disk_cache/simple/simple_index.cc
b/net/disk_cache/simple/simple_index.cc
index
46d1b215652a4e0e37276ee55516578e3247c06f..610b7f2fff2e4f5e782c55c0ffea4e0b8174726f
100644
--- a/net/disk_cache/simple/simple_index.cc
+++ b/net/disk_cache/simple/simple_index.cc
@@ -416,6 +416,8 @@ void SimpleIndex::InitializeInternal(
     index_file_entries = SimpleIndexFile::LoadFromDisk(index_filename);
     UMA_HISTOGRAM_TIMES("SimpleCache.IndexLoadTime",
                         (base::TimeTicks::Now() - start));
+    UMA_HISTOGRAM_COUNTS("SimpleCache.IndexEntriesLoaded",
+                         index_file_entries->size());
   }
 
   UMA_HISTOGRAM_BOOLEAN("SimpleCache.IndexStale", index_stale);
@@ -424,8 +426,10 @@ void SimpleIndex::InitializeInternal(
   if (!index_file_entries) {
     const base::TimeTicks start = base::TimeTicks::Now();
     index_file_entries = SimpleIndex::RestoreFromDisk(index_filename);
-    UMA_HISTOGRAM_TIMES("SimpleCache.IndexRestoreTime",
-                        (base::TimeTicks::Now() - start));
+    UMA_HISTOGRAM_MEDIUM_TIMES("SimpleCache.IndexRestoreTime",
+                               base::TimeTicks::Now() - start);
+    UMA_HISTOGRAM_COUNTS("SimpleCache.IndexEntriesRestored",
+                         index_file_entries->size());
 
     // When we restore from disk we write the merged index file to disk right
     // away, this might save us from having to restore again next time.

[commit-bot: I haz the power, 2013-06-06 12:11:17]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pasko@chromium.org/16286015/30001

[commit-bot: I haz the power, 2013-06-06 15:23:54]

Step "update" is always a major failure.
Look at the try server FAQ for more details.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win&number...

[commit-bot: I haz the power, 2013-06-06 16:09:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pasko@chromium.org/16286015/30001

[commit-bot: I haz the power, 2013-06-06 22:05:46]

Change committed as 204619