Initialize the simple cache backend at runtime.

net/disk_cache/cache_util.cc

+// Copyright (c) 2012 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/cache_util.h"
+
+#include "base/file_util.h"
+#include "base/location.h"
+#include "base/stringprintf.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/threading/worker_pool.h"
+
+namespace {
+
+const int kMaxOldFolders = 100;
+
+// Returns a fully qualified name from path and name, using a given name prefix
+// and index number. For instance, if the arguments are "/foo", "bar" and 5, it
+// will return "/foo/old_bar_005".
+base::FilePath GetPrefixedName(const base::FilePath& path,
+                               const std::string& name,
+                               int index) {
+  std::string tmp = base::StringPrintf("%s%s_%03d", "old_",
+                                       name.c_str(), index);
+  return path.AppendASCII(tmp);
+}
+
+// This is a simple callback to cleanup old caches.
+void CleanupCallback(const base::FilePath& path, const std::string& name) {
+  for (int i = 0; i < kMaxOldFolders; i++) {
+    base::FilePath to_delete = GetPrefixedName(path, name, i);
+    disk_cache::DeleteCache(to_delete, true);
+  }
+}
+
+// Returns a full path to rename the current cache, in order to delete it. path
+// is the current folder location, and name is the current folder name.
+base::FilePath GetTempCacheName(const base::FilePath& path,
+                                const std::string& name) {
+  // We'll attempt to have up to kMaxOldFolders folders for deletion.
+  for (int i = 0; i < kMaxOldFolders; i++) {
+    base::FilePath to_delete = GetPrefixedName(path, name, i);
+    if (!file_util::PathExists(to_delete))
+      return to_delete;
+  }
+  return base::FilePath();
+}
+
+}  // namespace
+
+namespace disk_cache {
+
+// In order to process a potentially large number of files, we'll rename the
+// cache directory to old_ + original_name + number, (located on the same parent
+// directory), and spawn a worker thread to delete all the files on all the
+// stale cache directories. The whole process can still fail if we are not able
+// to rename the cache directory (for instance due to a sharing violation), and
+// in that case a cache for this profile (on the desired path) cannot be
+// created.
+bool DelayedCacheCleanup(const base::FilePath& full_path) {
+  // GetTempCacheName() and MoveCache() use synchronous file
+  // operations.
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+
+  base::FilePath current_path = full_path.StripTrailingSeparators();
+
+  base::FilePath path = current_path.DirName();
+  base::FilePath name = current_path.BaseName();
+#if defined(OS_POSIX)
+  std::string name_str = name.value();
+#elif defined(OS_WIN)
+  // We created this file so it should only contain ASCII.
+  std::string name_str = WideToASCII(name.value());
+#endif
+
+  base::FilePath to_delete = GetTempCacheName(path, name_str);
+  if (to_delete.empty()) {
+    LOG(ERROR) << "Unable to get another cache folder";
+    return false;
+  }
+
+  if (!disk_cache::MoveCache(full_path, to_delete)) {
+    LOG(ERROR) << "Unable to move cache folder " << full_path.value() << " to "
+               << to_delete.value();
+    return false;
+  }
+
+  base::WorkerPool::PostTask(
+      FROM_HERE, base::Bind(&CleanupCallback, path, name_str), true);
+  return true;
+}
+
+}  // namespace disk_cache