Histogram versions and extended error codes for SQLite databases.

sql/connection.cc

Index: sql/connection.cc
diff --git a/sql/connection.cc b/sql/connection.cc
index 29708e41164a95376d4ae7deb392214647b04e63..c64f023253fcc01cd6397ecb5ee9857b3e60bbc9 100644
--- a/sql/connection.cc
+++ b/sql/connection.cc
@@ -9,6 +9,7 @@
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/sparse_histogram.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
@@ -708,31 +709,51 @@ void Connection::StatementRefDeleted(StatementRef* ref) {
     open_statements_.erase(i);
 }
 
+void Connection::AddSparseHistogram(const std::string& suffix,
+                                    size_t sample) const {
+  if (histogram_prefix_.empty())
+    return;
+
+  // 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
+  // histogram_prefix_.
+  std::string full_histogram_name = histogram_prefix_ + suffix;
+  base::HistogramBase* histogram =
+      base::SparseHistogram::FactoryGet(
+          full_histogram_name,
+          base::HistogramBase::kUmaTargetedHistogramFlag);
+  if (histogram)
+    histogram->Add(sample);
+}
+
 int Connection::OnSqliteError(int err, sql::Statement *stmt) {
+  UMA_HISTOGRAM_SPARSE_SLOWLY("Sqlite.ExtendedError", err);
+  AddSparseHistogram(".ExtendedError", err);
+
+  // TODO(shess): Use of linear histograms predates existence of
+  // sparse histograms.  Remove the .Error histograms once the

[jar (doing other things), 2013/05/13 22:05:59]

I think you can nicely get away with using the existing names, and all the
histogram data *should* fit together with no problem.

[Scott Hess - ex-Googler, 2013/05/13 22:43:08]

Done.

+  // .ExtendedError histograms have reached stable.
+
   // 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()) {
+  if (!histogram_prefix_.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_.
+    std::string error_histogram_name = histogram_prefix_ + ".Error";
     base::HistogramBase* histogram =
         base::LinearHistogram::FactoryGet(
-            error_histogram_name_, 1, kSqliteErrorMax, kSqliteErrorMax + 1,
+            error_histogram_name, 1, kSqliteErrorMax, kSqliteErrorMax + 1,
             base::HistogramBase::kUmaTargetedHistogramFlag);
     if (histogram)
       histogram->Add(base_err);