aboutsummaryrefslogtreecommitdiffstats
path: root/activesupport/lib/active_support/cache/file_store.rb
blob: 89bdb741d01175d2d4be504f5e37e12baf93a62e (plain) (blame)
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
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
require 'active_support/core_ext/file/atomic'
require 'active_support/core_ext/string/conversions'
require 'active_support/core_ext/object/inclusion'
require 'uri/common'

module ActiveSupport
  module Cache
    # A cache store implementation which stores everything on the filesystem.
    #
    # FileStore implements the Strategy::LocalCache strategy which implements
    # an in-memory cache inside of a block.
    class FileStore < Store
      attr_reader :cache_path

      DIR_FORMATTER = "%03X"
      FILENAME_MAX_SIZE = 228 # max filename size on file system is 255, minus room for timestamp and random characters appended by Tempfile (used by atomic write)
      EXCLUDED_DIRS = ['.', '..'].freeze

      def initialize(cache_path, options = nil)
        super(options)
        @cache_path = cache_path.to_s
        extend Strategy::LocalCache
      end

      def clear(options = nil)
        root_dirs = Dir.entries(cache_path).reject{|f| f.in?(EXCLUDED_DIRS + [".gitkeep"])}
        FileUtils.rm_r(root_dirs.collect{|f| File.join(cache_path, f)})
      end

      def cleanup(options = nil)
        options = merged_options(options)
        each_key(options) do |key|
          entry = read_entry(key, options)
          delete_entry(key, options) if entry && entry.expired?
        end
      end

      def increment(name, amount = 1, options = nil)
        file_name = key_file_path(namespaced_key(name, options))
        lock_file(file_name) do
          options = merged_options(options)
          if num = read(name, options)
            num = num.to_i + amount
            write(name, num, options)
            num
          else
            nil
          end
        end
      end

      def decrement(name, amount = 1, options = nil)
        file_name = key_file_path(namespaced_key(name, options))
        lock_file(file_name) do
          options = merged_options(options)
          if num = read(name, options)
            num = num.to_i - amount
            write(name, num, options)
            num
          else
            nil
          end
        end
      end

      def delete_matched(matcher, options = nil)
        options = merged_options(options)
        instrument(:delete_matched, matcher.inspect) do
          matcher = key_matcher(matcher, options)
          search_dir(cache_path) do |path|
            key = file_path_key(path)
            delete_entry(key, options) if key.match(matcher)
          end
        end
      end

      protected

        def read_entry(key, options)
          file_name = key_file_path(key)
          if File.exist?(file_name)
            File.open(file_name) { |f| Marshal.load(f) }
          end
        rescue
          nil
        end

        def write_entry(key, entry, options)
          file_name = key_file_path(key)
          ensure_cache_path(File.dirname(file_name))
          File.atomic_write(file_name, cache_path) {|f| Marshal.dump(entry, f)}
          true
        end

        def delete_entry(key, options)
          file_name = key_file_path(key)
          if File.exist?(file_name)
            begin
              File.delete(file_name)
              delete_empty_directories(File.dirname(file_name))
              true
            rescue => e
              # Just in case the error was caused by another process deleting the file first.
              raise e if File.exist?(file_name)
              false
            end
          end
        end

      private
        # Lock a file for a block so only one process can modify it at a time.
        def lock_file(file_name, &block) # :nodoc:
          if File.exist?(file_name)
            File.open(file_name, 'r+') do |f|
              begin
                f.flock File::LOCK_EX
                yield
              ensure
                f.flock File::LOCK_UN
              end
            end
          else
            yield
          end
        end

        # Translate a key into a file path.
        def key_file_path(key)
          fname = URI.encode_www_form_component(key)
          hash = Zlib.adler32(fname)
          hash, dir_1 = hash.divmod(0x1000)
          dir_2 = hash.modulo(0x1000)
          fname_paths = []

          # Make sure file name doesn't exceed file system limits.
          begin
            fname_paths << fname[0, FILENAME_MAX_SIZE]
            fname = fname[FILENAME_MAX_SIZE..-1]
          end until fname.blank?

          File.join(cache_path, DIR_FORMATTER % dir_1, DIR_FORMATTER % dir_2, *fname_paths)
        end

        # Translate a file path into a key.
        def file_path_key(path)
          fname = path[cache_path.to_s.size..-1].split(File::SEPARATOR, 4).last
          URI.decode_www_form_component(fname, Encoding::UTF_8)
        end

        # Delete empty directories in the cache.
        def delete_empty_directories(dir)
          return if dir == cache_path
          if Dir.entries(dir).reject{|f| f.in?(EXCLUDED_DIRS)}.empty?
            File.delete(dir) rescue nil
            delete_empty_directories(File.dirname(dir))
          end
        end

        # Make sure a file path's directories exist.
        def ensure_cache_path(path)
          FileUtils.makedirs(path) unless File.exist?(path)
        end

        def search_dir(dir, &callback)
          return if !File.exist?(dir)
          Dir.foreach(dir) do |d|
            next if d.in?(EXCLUDED_DIRS)
            name = File.join(dir, d)
            if File.directory?(name)
              search_dir(name, &callback)
            else
              callback.call name
            end
          end
        end
    end
  end
end