Add diagnostics to debug database open problems.

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/file_path.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
 #include "sql/statement.h"
 #include "third_party/sqlite/sqlite3.h"
 
 namespace {
 
 // Spin for up to a second waiting for the lock to clear when setting
 // up the database.
@@ skipping 510 matching lines @@
 bool Connection::OpenInternal(const std::string& file_name) {
   AssertIOAllowed();
 
   if (db_) {
     DLOG(FATAL) << "sql::Connection is already open.";
     return false;
   }
 
   int err = sqlite3_open(file_name.c_str(), &db_);
   if (err != SQLITE_OK) {
+    // Histogram failures specific to initial open for debugging
+    // purposes.
+    UMA_HISTOGRAM_ENUMERATION("Sqlite.OpenFailure", err & 0xff, 50);
+
     OnSqliteError(err, NULL);
     Close();
     db_ = NULL;
     return false;
   }
 
+  // sqlite3_open() does not actually read the database file (unless a
+  // hot journal is found).  Successfully executing this pragma on an
+  // existing database requires a valid header on page 1.
+  // TODO(shess): For now, just probing to see what the lay of the
+  // land is.  If it's mostly SQLITE_NOTADB, then the database should
+  // be razed.
+  err = ExecuteAndReturnErrorCode("PRAGMA auto_vacuum");
+  if (err != SQLITE_OK)
+    UMA_HISTOGRAM_ENUMERATION("Sqlite.OpenProbeFailure", err & 0xff, 50);
+
   // Enable extended result codes to provide more color on I/O errors.
   // Not having extended result codes is not a fatal problem, as
   // Chromium code does not attempt to handle I/O errors anyhow.  The
   // current implementation always returns SQLITE_OK, the DCHECK is to
   // quickly notify someone if SQLite changes.
   err = sqlite3_extended_result_codes(db_, 1);
   DCHECK_EQ(err, SQLITE_OK) << "Could not enable extended result codes";
 
   // If indicated, lock up the database before doing anything else, so
   // that the following code doesn't have to deal with locking.
@@ skipping 82 matching lines @@
 
 int Connection::OnSqliteError(int err, sql::Statement *stmt) {
   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