1 # Copyright 2013 Google Inc.
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
19 # Simple file store to be used in the event no ActiveSupport cache store
20 # is provided. This is not thread-safe, and does not support a number of
21 # features (such as expiration), but it's useful for the simple purpose of
22 # caching discovery documents to disk.
23 # Implements the basic cache methods of ActiveSupport::Cache::Store in a
27 # Creates a new SimpleFileStore.
29 # @param [String] file_path
30 # The path to the cache file on disk.
31 # @param [Object] options
32 # The options to be used with this SimpleFileStore. Not implemented.
33 def initialize(file_path, options = nil)
34 @file_path = file_path.to_s
37 # Returns true if a key exists in the cache.
39 # @param [String] name
40 # The name of the key. Will always be converted to a string.
41 # @param [Object] options
42 # The options to be used with this query. Not implemented.
43 def exist?(name, options = nil)
45 @cache.nil? ? nil : @cache.include?(name.to_s)
48 # Fetches data from the cache and returns it, using the given key.
49 # If the key is missing and no block is passed, returns nil.
50 # If the key is missing and a block is passed, executes the block, sets
51 # the key to its value, and returns it.
53 # @param [String] name
54 # The name of the key. Will always be converted to a string.
55 # @param [Object] options
56 # The options to be used with this query. Not implemented.
58 # optional block with the default value if the key is missing
59 def fetch(name, options = nil)
62 entry = read(name.to_s, options)
64 value = yield name.to_s
65 write(name.to_s, value)
71 return read(name.to_s, options)
75 # Fetches data from the cache, using the given key.
76 # Returns nil if the key is missing.
78 # @param [String] name
79 # The name of the key. Will always be converted to a string.
80 # @param [Object] options
81 # The options to be used with this query. Not implemented.
82 def read(name, options = nil)
84 @cache.nil? ? nil : @cache[name.to_s]
87 # Writes the value to the cache, with the key.
89 # @param [String] name
90 # The name of the key. Will always be converted to a string.
91 # @param [Object] value
92 # The value to be written.
93 # @param [Object] options
94 # The options to be used with this query. Not implemented.
95 def write(name, value, options = nil)
97 @cache = {} if @cache.nil?
98 @cache[name.to_s] = value
103 # Deletes an entry in the cache.
104 # Returns true if an entry is deleted.
106 # @param [String] name
107 # The name of the key. Will always be converted to a string.
108 # @param [Object] options
109 # The options to be used with this query. Not implemented.
110 def delete(name, options = nil)
112 return nil if @cache.nil?
113 if @cache.include? name.to_s
114 @cache.delete name.to_s
124 # Read the entire cache file from disk.
125 # Will avoid reading if there have been no changes.
127 if !File.exist? @file_path
130 # Check for changes after our last read or write.
131 if @last_change.nil? || File.mtime(@file_path) > @last_change
132 File.open(@file_path) do |file|
133 @cache = Marshal.load(file)
134 @last_change = file.mtime
141 # Write the entire cache contents to disk.
143 File.open(@file_path, 'w') do |file|
144 Marshal.dump(@cache, file)
146 @last_change = File.mtime(@file_path)