components/policy/core/common/cloud/resource_cache.h

   1 // Copyright (c) 2013 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 #ifndef COMPONENTS_POLICY_CORE_COMMON_CLOUD_RESOURCE_CACHE_H_
   6 #define COMPONENTS_POLICY_CORE_COMMON_CLOUD_RESOURCE_CACHE_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11
  12 #include "base/basictypes.h"
  13 #include "base/callback_forward.h"
  14 #include "base/files/file_path.h"
  15 #include "base/memory/ref_counted.h"
  16 #include "components/policy/policy_export.h"
  17
  18 namespace base {
  19 class SequencedTaskRunner;
  20 }
  21
  22 namespace policy {
  23
  24 // Manages storage of data at a given path. The data is keyed by a key and
  25 // a subkey, and can be queried by (key, subkey) or (key) lookups.
  26 // The contents of the cache have to be manually cleared using Delete() or
  27 // Purge*().
  28 // The class can be instantiated on any thread but from then on, it must be
  29 // accessed via the |task_runner| only. The |task_runner| must support file I/O.
  30 class POLICY_EXPORT ResourceCache {
  31  public:
  32   explicit ResourceCache(const base::FilePath& cache_path,
  33                          scoped_refptr<base::SequencedTaskRunner> task_runner);
  34   virtual ~ResourceCache();
  35
  36   // Stores |data| under (key, subkey). Returns true if the store suceeded, and
  37   // false otherwise.
  38   bool Store(const std::string& key,
  39              const std::string& subkey,
  40              const std::string& data);
  41
  42   // Loads the contents of (key, subkey) into |data| and returns true. Returns
  43   // false if (key, subkey) isn't found or if there is a problem reading the
  44   // data.
  45   bool Load(const std::string& key,
  46             const std::string& subkey,
  47             std::string* data);
  48
  49   // Loads all the subkeys of |key| into |contents|.
  50   void LoadAllSubkeys(const std::string& key,
  51                       std::map<std::string, std::string>* contents);
  52
  53   // Deletes (key, subkey).
  54   void Delete(const std::string& key, const std::string& subkey);
  55
  56   // Deletes all the subkeys of |key|.
  57   void Clear(const std::string& key);
  58
  59   // Deletes the subkeys of |key| for which the |filter| returns true.
  60   typedef base::Callback<bool(const std::string&)> SubkeyFilter;
  61   void FilterSubkeys(const std::string& key, const SubkeyFilter& filter);
  62
  63   // Deletes all keys not in |keys_to_keep|, along with their subkeys.
  64   void PurgeOtherKeys(const std::set<std::string>& keys_to_keep);
  65
  66   // Deletes all the subkeys of |key| not in |subkeys_to_keep|.
  67   void PurgeOtherSubkeys(const std::string& key,
  68                          const std::set<std::string>& subkeys_to_keep);
  69
  70  private:
  71   // Points |path| at the cache directory for |key| and returns whether the
  72   // directory exists. If |allow_create| is |true|, the directory is created if
  73   // it did not exist yet.
  74   bool VerifyKeyPath(const std::string& key,
  75                      bool allow_create,
  76                      base::FilePath* path);
  77
  78   // Points |path| at the file in which data for (key, subkey) should be stored
  79   // and returns whether the parent directory of this file exists. If
  80   // |allow_create_key| is |true|, the directory is created if it did not exist
  81   // yet. This method does not check whether the file at |path| exists or not.
  82   bool VerifyKeyPathAndGetSubkeyPath(const std::string& key,
  83                                      bool allow_create_key,
  84                                      const std::string& subkey,
  85                                      base::FilePath* subkey_path);
  86
  87   base::FilePath cache_dir_;
  88
  89   // Task runner that |this| runs on.
  90   scoped_refptr<base::SequencedTaskRunner> task_runner_;
  91
  92   DISALLOW_COPY_AND_ASSIGN(ResourceCache);
  93 };
  94
  95 }  // namespace policy
  96
  97 #endif  // COMPONENTS_POLICY_CORE_COMMON_CLOUD_RESOURCE_CACHE_H_