Deeper histogram for SQLITE_IOERR.

sql/connection.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sql/connection.h"
 
 #include <string.h>
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 696 matching lines @@
   else
     open_statements_.erase(i);
 }
 
 int Connection::OnSqliteError(int err, sql::Statement *stmt) {
   // Strip extended error codes.
   int base_err = err&0xff;
 
   static size_t kSqliteErrorMax = 50;
   UMA_HISTOGRAM_ENUMERATION("Sqlite.Error", base_err, kSqliteErrorMax);
+  if (base_err == SQLITE_IOERR) {
+    // TODO(shess): Consider folding the IOERR range into the main
+    // histogram directly.  Perhaps 30..49?  The downside risk would
+    // be that SQLite core adds a bunch of codes and this becomes a
+    // complicated mapping.
+    static size_t kSqliteIOErrorMax = 20;
+    UMA_HISTOGRAM_ENUMERATION("Sqlite.Error.IOERR", err>>8, kSqliteIOErrorMax);
+  }
+
   if (!error_histogram_name_.empty()) {
     // TODO(shess): The histogram macros create a bit of static
     // storage for caching the histogram object.  Since SQLite is
     // being used for I/O, generally without error, this code
     // shouldn't execute often enough for such caching to be crucial.
     // If it becomes an issue, the object could be cached alongside
     // error_histogram_name_.
     base::HistogramBase* histogram =
         base::LinearHistogram::FactoryGet(
             error_histogram_name_, 1, kSqliteErrorMax, kSqliteErrorMax + 1,
             base::HistogramBase::kUmaTargetedHistogramFlag);
     if (histogram)
       histogram->Add(base_err);
   }
 
   // Always log the error.
   LOG(ERROR) << "sqlite error " << err
              << ", errno " << GetLastErrno()
              << ": " << GetErrorMessage();
 
   if (error_delegate_.get())
     return error_delegate_->OnError(err, this, stmt);
 
   // The default handling is to assert on debug and to ignore on release.
   DLOG(FATAL) << GetErrorMessage();
   return err;
 }
 
 }  // namespace sql