base/test/test_file_util_mac.cc

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/test/test_file_util.h"
   6
   7 #include <sys/mman.h>
   8 #include <errno.h>
   9 #include "base/logging.h"
  10 #include "base/file_util.h"
  11
  12 namespace file_util {
  13
  14 bool EvictFileFromSystemCache(const FilePath& file) {
  15   // There aren't any really direct ways to purge a file from the UBC.  From
  16   // talking with Amit Singh, the safest is to mmap the file with MAP_FILE (the
  17   // default) + MAP_SHARED, then do an msync to invalidate the memory.  The next
  18   // open should then have to load the file from disk.
  19
  20   int64 length;
  21   if (!file_util::GetFileSize(file, &length)) {
  22     DLOG(ERROR) << "failed to get size of " << file.value();
  23     return false;
  24   }
  25
  26   // When a file is empty, we do not need to evict it from cache.
  27   // In fact, an attempt to map it to memory will result in error.
  28   if (length == 0) {
  29     DLOG(WARNING) << "file size is zero, will not attempt to map to memory";
  30     return true;
  31   }
  32
  33   file_util::MemoryMappedFile mapped_file;
  34   if (!mapped_file.Initialize(file)) {
  35     DLOG(WARNING) << "failed to memory map " << file.value();
  36     return false;
  37   }
  38
  39   if (msync(const_cast<uint8*>(mapped_file.data()), mapped_file.length(),
  40             MS_INVALIDATE) != 0) {
  41     DLOG(WARNING) << "failed to invalidate memory map of " << file.value()
  42                   << ", errno: " << errno;
  43     return false;
  44   }
  45
  46   return true;
  47 }
  48
  49 }  // namespace file_util