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 10 #include "base/logging.h" 11 #include "base/file_util.h" 12 #include "base/files/memory_mapped_file.h" 13 14 namespace base { 15 EvictFileFromSystemCache(const FilePath & file)16bool EvictFileFromSystemCache(const FilePath& file) { 17 // There aren't any really direct ways to purge a file from the UBC. From 18 // talking with Amit Singh, the safest is to mmap the file with MAP_FILE (the 19 // default) + MAP_SHARED, then do an msync to invalidate the memory. The next 20 // open should then have to load the file from disk. 21 22 int64 length; 23 if (!GetFileSize(file, &length)) { 24 DLOG(ERROR) << "failed to get size of " << file.value(); 25 return false; 26 } 27 28 // When a file is empty, we do not need to evict it from cache. 29 // In fact, an attempt to map it to memory will result in error. 30 if (length == 0) { 31 DLOG(WARNING) << "file size is zero, will not attempt to map to memory"; 32 return true; 33 } 34 35 MemoryMappedFile mapped_file; 36 if (!mapped_file.Initialize(file)) { 37 DLOG(WARNING) << "failed to memory map " << file.value(); 38 return false; 39 } 40 41 if (msync(const_cast<uint8*>(mapped_file.data()), mapped_file.length(), 42 MS_INVALIDATE) != 0) { 43 DLOG(WARNING) << "failed to invalidate memory map of " << file.value() 44 << ", errno: " << errno; 45 return false; 46 } 47 48 return true; 49 } 50 51 } // namespace base 52