[sql] Stats gathering for sql/ APIs.

sql/statement.h

 // 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.
 
 #ifndef SQL_STATEMENT_H_
 #define SQL_STATEMENT_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
@@ skipping 132 matching lines @@
   bool ColumnBlobAsString16(int col, base::string16* val) const;
   bool ColumnBlobAsVector(int col, std::vector<char>* val) const;
   bool ColumnBlobAsVector(int col, std::vector<unsigned char>* val) const;
 
   // Diagnostics --------------------------------------------------------------
 
   // Returns the original text of sql statement. Do not keep a pointer to it.
   const char* GetSQLStatement();
 
  private:
+  friend class Connection;
+
   // This is intended to check for serious errors and report them to the
   // connection object. It takes a sqlite error code, and returns the same
   // code. Currently this function just updates the succeeded flag, but will be
   // enhanced in the future to do the notification.
   int CheckError(int err);
 
   // Contraction for checking an error code against SQLITE_OK. Does not set the
   // succeeded flag.
   bool CheckOk(int err) const;
 
   // Should be called by all mutating methods to check that the statement is
   // valid. Returns true if the statement is valid. DCHECKS and returns false
   // if it is not.
   // The reason for this is to handle two specific cases in which a Statement
   // may be invalid. The first case is that the programmer made an SQL error.
   // Those cases need to be DCHECKed so that we are guaranteed to find them
   // before release. The second case is that the computer has an error (probably
   // out of disk space) which is prohibiting the correct operation of the
   // database. Our testing apparatus should not exhibit this defect, but release
   // situations may. Therefore, the code is handling disjoint situations in
   // release and test. In test, we're ensuring correct SQL. In release, we're
   // ensuring that contracts are honored in error edge cases.
   bool CheckValid() const;
 
+  // Helper for Run() and Step(), calls sqlite3_step() and histograms based on
+  // the results.  The checked value from sqlite3_step() is returned.

[rmcilroy, 2015/05/21 22:54:48]

"and histograms based on the results if |timer_flag| is true."

[Scott Hess - ex-Googler, 2015/05/21 23:42:37]

Done, maybe, but in terms of "How would I use this" I'm not sure it helps :-).

+  int InnerStep(bool timer_flag);

[rmcilroy, 2015/05/21 22:54:48]

Maybe call StepInternal would be clearer?

[Scott Hess - ex-Googler, 2015/05/21 23:42:37]

Done.

+
+  // sql::Connection uses cached statments for transactions, but tracks their
+  // runtime independently.
+  bool RunWithoutTimers();
+
   // The actual sqlite statement. This may be unique to us, or it may be cached
   // by the connection, which is why it's refcounted. This pointer is
   // guaranteed non-NULL.
   scoped_refptr<Connection::StatementRef> ref_;
 
   // Set after Step() or Run() are called, reset by Reset().  Used to
   // prevent accidental calls to API functions which would not work
   // correctly after stepping has started.
   bool stepped_;
 
   // See Succeeded() for what this holds.
   bool succeeded_;
 
   DISALLOW_COPY_AND_ASSIGN(Statement);
 };
 
 }  // namespace sql
 
 #endif  // SQL_STATEMENT_H_