[sql] Remove mmap before Raze().

sql/connection_unittest.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 <stddef.h>
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
@@ skipping 836 matching lines @@
         db().IsSQLValid(kSimpleSql);
       }, "Illegal use of connection without a db");
   }
 #endif
 }
 
 // TODO(shess): Spin up a background thread to hold other_db, to more
 // closely match real life.  That would also allow testing
 // RazeWithTimeout().
 
+// On Windows, truncate silently fails against a memory-mapped file.  One goal
+// of Raze() is to truncate the file to remove blocks which generate I/O errors.
+// Test that Raze() turns off memory mapping so that the file is truncated.
+// [This would not cover the case of multiple connections where one of the other
+// connections is memory-mapped.  That is infrequent in Chromium.]
+TEST_F(SQLConnectionTest, RazeTruncate) {
+  // The empty database has 0 or 1 pages.  Raze() should leave it with exactly 1
+  // page.  Not checking directly because auto_vacuum on Android adds a freelist
+  // page.
+  ASSERT_TRUE(db().Raze());
+  int64_t expected_size;
+  ASSERT_TRUE(base::GetFileSize(db_path(), &expected_size));
+  ASSERT_GT(expected_size, 0);
+
+  // Cause the database to take a few pages.
+  const char* kCreateSql = "CREATE TABLE foo (id INTEGER PRIMARY KEY, value)";
+  ASSERT_TRUE(db().Execute(kCreateSql));
+  for (size_t i = 0; i < 24; ++i) {
+    ASSERT_TRUE(
+        db().Execute("INSERT INTO foo (value) VALUES (randomblob(1024))"));
+  }
+  int64_t db_size;
+  ASSERT_TRUE(base::GetFileSize(db_path(), &db_size));
+  ASSERT_GT(db_size, expected_size);
+
+  // Make a query covering most of the database file to make sure that the
+  // blocks are actually mapped into memory.  Empirically, the truncate problem
+  // doesn't seem to happen if no blocks are mapped.
+  EXPECT_EQ("24576",
+            ExecuteWithResult(&db(), "SELECT SUM(LENGTH(value)) FROM foo"));
+
+  ASSERT_TRUE(db().Raze());
+  ASSERT_TRUE(base::GetFileSize(db_path(), &db_size));
+  ASSERT_EQ(expected_size, db_size);
+}
+
 #if defined(OS_ANDROID)
 TEST_F(SQLConnectionTest, SetTempDirForSQL) {
 
   sql::MetaTable meta_table;
   // Below call needs a temporary directory in sqlite3
   // On Android, it can pass only when the temporary directory is set.
   // Otherwise, sqlite3 doesn't find the correct directory to store
   // temporary files and will report the error 'unable to open
   // database file'.
   ASSERT_TRUE(meta_table.Init(&db(), 4, 4));
@@ skipping 759 matching lines @@
   if (DLOG_IS_ON(FATAL)) {
     db().set_error_callback(base::Bind(&IgnoreErrorCallback));
     ASSERT_DEATH({
         db().GetUniqueStatement("SELECT x");
       }, "SQL compile error no such column: x");
   }
 #endif
 }
 
 }  // namespace sql