AppCache: Run a quick integrity check on the sqlite database when opening.

sql/connection.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_CONNECTION_H_
 #define SQL_CONNECTION_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 136 matching lines @@
 
   // Record a sparse UMA histogram sample under
   // |name|+"."+|histogram_tag_|.  If |histogram_tag_| is empty, no
   // histogram is recorded.
   void AddTaggedHistogram(const std::string& name, size_t sample) const;
 
   // Run "PRAGMA integrity_check" and post each line of results into
   // |messages|.  Returns the success of running the statement - per
   // the SQLite documentation, if no errors are found the call should
   // succeed, and a single value "ok" should be in messages.
-  bool IntegrityCheck(std::vector<std::string>* messages);
+  bool FullIntegrityCheck(std::vector<std::string>* messages) {
+    return IntegrityCheck(messages, false);
+  }
+  bool QuickIntegrityCheck(std::vector<std::string>* messages) {
+    return IntegrityCheck(messages, true);
+  }
+  bool IntegrityCheck(std::vector<std::string>* messages, bool quick);

[Scott Hess - ex-Googler, 2013/12/06 00:44:00]

Move IntegrityCheck() to private, maybe call it "IntegrityCheckHelper(), and put
the in parameter before the out parameter.

I'm a little nervous about having these inline in the header.  There's no
performance reason for it (running the integrity check is like a billion times
more expensive than function-call overhead).  It maybe would make sense to move
them into the .cc and just have them pass in the pragma rather than passing a
bool which modifies the pragma.

It would be nice to have a unit test for both cases doing what they say.  I
_think_ that a quick check would probably succeed on the corruption helper which
messes up the index/table relationship, while a full check would not.

 
   // Initialization ------------------------------------------------------------
 
   // Initializes the SQL connection for the given file, returning true if the
   // file could be opened. You can call this or OpenInMemory.
   bool Open(const base::FilePath& path) WARN_UNUSED_RESULT;
 
   // Initializes the SQL connection for a temporary in-memory database. There
   // will be no associated file on disk, and the initial database will be
   // empty. You can call this or Open.
@@ skipping 417 matching lines @@
 
   // Tag for auxiliary histograms.
   std::string histogram_tag_;
 
   DISALLOW_COPY_AND_ASSIGN(Connection);
 };
 
 }  // namespace sql
 
 #endif  // SQL_CONNECTION_H_