1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
// Copyright (c) 2011 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 "base/test/test_file_util.h"
#include <sys/mman.h>
#include <errno.h>
#include <stdint.h>
#include "base/files/file_util.h"
#include "base/files/memory_mapped_file.h"
#include "base/logging.h"
namespace base {
bool EvictFileFromSystemCache(const FilePath& file) {
// There aren't any really direct ways to purge a file from the UBC. From
// talking with Amit Singh, the safest is to mmap the file with MAP_FILE (the
// default) + MAP_SHARED, then do an msync to invalidate the memory. The next
// open should then have to load the file from disk.
int64_t length;
if (!GetFileSize(file, &length)) {
DLOG(ERROR) << "failed to get size of " << file.value();
return false;
}
// When a file is empty, we do not need to evict it from cache.
// In fact, an attempt to map it to memory will result in error.
if (length == 0) {
DLOG(WARNING) << "file size is zero, will not attempt to map to memory";
return true;
}
MemoryMappedFile mapped_file;
if (!mapped_file.Initialize(file)) {
DLOG(WARNING) << "failed to memory map " << file.value();
return false;
}
if (msync(const_cast<uint8_t*>(mapped_file.data()), mapped_file.length(),
MS_INVALIDATE) != 0) {
DLOG(WARNING) << "failed to invalidate memory map of " << file.value()
<< ", errno: " << errno;
return false;
}
return true;
}
} // namespace base
|
