tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index c2084d5e258b616d3dc75723ebcc454deee951d2..5a00a9c63edaf1c09788af7d42ba4d99e12a8f16 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -66700,6 +66700,34 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Version of pre-existing database at startup.</summary>
 </histogram>
 
+<histogram name="Sqlite.VfsEvents" enum="SqliteVfsEvents">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    I/O operations measured by browser-process SQLite VFS wrapper.
+  </summary>
+</histogram>
+
+<histogram name="Sqlite.VfsFetch" units="bytes">

[jwd, 2017/03/07 22:33:57]

Can you reformulate the Fetch, Read, and Write histograms to use histogram
suffixes. Documentation about it is at the top of the file.

[Scott Hess - ex-Googler, 2017/03/07 23:02:06]

Sorry, rework them in what way?

I can't really integrate them into the existing Sqlite.X.* suffix system,
because the vfs itself is a singleton.  Though I suppose I could write up a
pragma or something to pass a string down for customization purposes, if it
becomes necessary.

[Maria, 2017/03/08 06:27:38]

I think what jwd@ is suggesting is something like this:

<histogram name="Sqlite.Vfs">
...
</histogram>

<histogram_suffixes name="VfsSuffixes">
  <suffix name="Events" label="events"/>
  <suffix name="Fetch" ../>
  <suffix name="Read" .. />
  <suffix name="Write" ../>
  <affected-histogram name="Sqlite.Vfs"/>
</histogram_suffixes>

And then in your code you'd just pass Sqlite.Vfs_Read as the name of the
histogram instead of Sqlite.VfsRead

[jwd, 2017/03/08 15:37:46]

Yes exactly, I was just suggestion a change to the histograms.xml part.

+  <owner>shess@chromium.org</owner>
+  <summary>
+    Amounts passed to browser-process SQLite VFS xFetch() function.
+  </summary>
+</histogram>
+
+<histogram name="Sqlite.VfsRead" units="bytes">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    Amounts passed to browser-process SQLite VFS xRead() function.
+  </summary>
+</histogram>
+
+<histogram name="Sqlite.VfsWrite" units="bytes">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    Amounts passed to browser-process SQLite VFS xWrite() function.
+  </summary>
+</histogram>
+
 <histogram name="Sqlite.Web.Error" enum="SqliteErrorCode">
   <obsolete>
     Moved to Sqlite.Error.Web in M-27.
@@ -109709,6 +109737,21 @@ from previous Chrome versions.
   <int value="5" label="DEPRECATION_RAZE_FAILED">Raze failed.</int>
 </enum>
 
+<enum name="SqliteVfsEvents" type="int">
+  <summary>I/O events from browser-process SQLite VFS wrapper.</summary>
+  <int value="0" label="VFS_OPEN">Calls to xOpen().</int>
+  <int value="1" label="VFS_DELETE">Calls to xDelete().</int>
+  <int value="2" label="VFS_ACCESS">Calls to xAccess().</int>
+  <int value="3" label="VFS_FULLPATHNAME">Calls to xFullPath().</int>
+  <int value="4" label="VFS_IO_CLOSE">Calls to xClose().</int>
+  <int value="5" label="VFS_IO_READ">Calls to xRead().</int>
+  <int value="6" label="VFS_IO_WRITE">Calls to xWrite().</int>
+  <int value="7" label="VFS_IO_TRUNCATE">Calls to xTruncate().</int>
+  <int value="8" label="VFS_IO_SYNC">Calls to xSync().</int>
+  <int value="9" label="VFS_IO_FILESIZE">Calls to xFileSize().</int>
+  <int value="10" label="VFS_IO_FETCH">Calls to xFetch().</int>
+</enum>
+
 <enum name="SRIResourceIntegrityMismatchEvent" type="int">
   <int value="0" label="CHECKING_FOR_INTEGRITY_MISMATCH"/>
   <int value="1" label="REFETCH_DUE_TO_INTEGRITY_MISMATCH"/>