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..760a076aac81b1d3fe7c6b7e4e49b2ad1fcf82e4 100644
--- a/sql/connection.cc
+++ b/sql/connection.cc
@@ -708,6 +708,25 @@ void Connection::StatementRefDeleted(StatementRef* ref) {
     open_statements_.erase(i);
 }
 
+void Connection::AddLinearHistogram(const std::string& suffix,

[jar (doing other things), 2013/05/07 23:46:41]

It is also tempting to use the sparse histogram to record teh error code.  I'm
*guessing* they are far and few between.

+                                    size_t sample, size_t sample_max) const {

[jar (doing other things), 2013/05/07 23:46:41]

nit: one arg per line

[Scott Hess - ex-Googler, 2013/05/08 19:56:18]

Done.

+  if (!histogram_prefix_.empty()) {

[jar (doing other things), 2013/05/07 23:46:41]

nit: personal preference.  Early return on empty() would make this easier to
read... and you wouldn't need to indent the rest of this code.

[Scott Hess - ex-Googler, 2013/05/08 19:56:18]

Done.  I had pulled it out of the earlier context as-is and hadn't thought to
revisit such decisions.

+    // 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::LinearHistogram::FactoryGet(
+            full_histogram_name, 1, sample_max, sample_max + 1,
+            base::HistogramBase::kUmaTargetedHistogramFlag);
+    if (histogram)
+      histogram->Add(sample);
+  }
+}
+
 int Connection::OnSqliteError(int err, sql::Statement *stmt) {
   // Strip extended error codes.
   int base_err = err&0xff;
@@ -723,20 +742,7 @@ int Connection::OnSqliteError(int err, sql::Statement *stmt) {
     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);
-  }
+  AddLinearHistogram(".Error", base_err, kSqliteErrorMax);
 
   // Always log the error.
   LOG(ERROR) << "sqlite error " << err