text: // Copyright 2014 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 "net/disk_cache/simple/simple_util.h"
  
  #include <windows.h>
  
  #include "base/files/file_util.h"
  #include "base/format_macros.h"
  #include "base/rand_util.h"
  #include "base/strings/string_util.h"
  #include "base/strings/stringprintf.h"
  #include "net/disk_cache/cache_util.h"
  
  namespace disk_cache {
  namespace simple_util {
  
  bool SimpleCacheDeleteFile(const base::FilePath& path) {
    // Even if a file was opened with FLAG_WIN_SHARE_DELETE, it is not possible to
    // create a new file with the same name until the original file is actually
    // deleted. To allow new files to be created with the new name right away,
    // the file is renamed before it is deleted.
  
    // Why a random name? Because if the name was derived from our original name,
    // then churn on a particular cache entry could cause flakey behaviour.
  
    // TODO(morlovich): Ensure these "todelete_" files are cleaned up on periodic
    // directory sweeps.
    const base::FilePath rename_target =
        path.DirName().AppendASCII(base::StringPrintf("todelete_%016" PRIx64,
                                                      base::RandUint64()));
  
    bool rename_succeeded =
        !!MoveFile(path.value().c_str(), rename_target.value().c_str());
    if (rename_succeeded)
      return DeleteCacheFile(rename_target);
  
    // The rename did not succeed. The fallback behaviour is to delete the file in
    // place, which might cause some flake.
    return DeleteCacheFile(path);
  }
  
  }  // namespace simple_util
  }  // namespace disk_cache
  