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53 lines
1.5 KiB
C++
53 lines
1.5 KiB
C++
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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/test/test_file_util.h"
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#include <sys/mman.h>
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#include <errno.h>
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#include <stdint.h>
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#include "base/files/file_util.h"
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#include "base/files/memory_mapped_file.h"
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#include "base/logging.h"
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namespace base {
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bool EvictFileFromSystemCache(const FilePath& file) {
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// There aren't any really direct ways to purge a file from the UBC. From
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// talking with Amit Singh, the safest is to mmap the file with MAP_FILE (the
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// default) + MAP_SHARED, then do an msync to invalidate the memory. The next
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// open should then have to load the file from disk.
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int64_t length;
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if (!GetFileSize(file, &length)) {
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DLOG(ERROR) << "failed to get size of " << file.value();
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return false;
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}
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// When a file is empty, we do not need to evict it from cache.
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// In fact, an attempt to map it to memory will result in error.
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if (length == 0) {
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DLOG(WARNING) << "file size is zero, will not attempt to map to memory";
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return true;
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}
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MemoryMappedFile mapped_file;
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if (!mapped_file.Initialize(file)) {
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DLOG(WARNING) << "failed to memory map " << file.value();
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return false;
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}
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if (msync(const_cast<uint8_t*>(mapped_file.data()), mapped_file.length(),
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MS_INVALIDATE) != 0) {
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DLOG(WARNING) << "failed to invalidate memory map of " << file.value()
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<< ", errno: " << errno;
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return false;
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}
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return true;
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}
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} // namespace base
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