google-api-ruby-client/lib/google/api_client/service/simple_file_store.rb

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# Copyright 2013 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
module Google
class APIClient
class Service
# Simple file store to be used in the event no ActiveSupport cache store
# is provided. This is not thread-safe, and does not support a number of
# features (such as expiration), but it's useful for the simple purpose of
# caching discovery documents to disk.
# Implements the basic cache methods of ActiveSupport::Cache::Store in a
# limited fashion.
class SimpleFileStore
# Creates a new SimpleFileStore.
#
# @param [String] file_path
# The path to the cache file on disk.
# @param [Object] options
# The options to be used with this SimpleFileStore. Not implemented.
def initialize(file_path, options = nil)
@file_path = file_path.to_s
end
# Returns true if a key exists in the cache.
#
# @param [String] name
# The name of the key. Will always be converted to a string.
# @param [Object] options
# The options to be used with this query. Not implemented.
def exist?(name, options = nil)
read_file
@cache.nil? ? nil : @cache.include?(name.to_s)
end
# Fetches data from the cache and returns it, using the given key.
# If the key is missing and no block is passed, returns nil.
# If the key is missing and a block is passed, executes the block, sets
# the key to its value, and returns it.
#
# @param [String] name
# The name of the key. Will always be converted to a string.
# @param [Object] options
# The options to be used with this query. Not implemented.
# @yield [String]
# optional block with the default value if the key is missing
def fetch(name, options = nil)
read_file
if block_given?
entry = read(name.to_s, options)
if entry.nil?
value = yield name.to_s
write(name.to_s, value)
return value
else
return entry
end
else
return read(name.to_s, options)
end
end
# Fetches data from the cache, using the given key.
# Returns nil if the key is missing.
#
# @param [String] name
# The name of the key. Will always be converted to a string.
# @param [Object] options
# The options to be used with this query. Not implemented.
def read(name, options = nil)
read_file
@cache.nil? ? nil : @cache[name.to_s]
end
# Writes the value to the cache, with the key.
#
# @param [String] name
# The name of the key. Will always be converted to a string.
# @param [Object] value
# The value to be written.
# @param [Object] options
# The options to be used with this query. Not implemented.
def write(name, value, options = nil)
read_file
@cache = {} if @cache.nil?
@cache[name.to_s] = value
write_file
return nil
end
# Deletes an entry in the cache.
# Returns true if an entry is deleted.
#
# @param [String] name
# The name of the key. Will always be converted to a string.
# @param [Object] options
# The options to be used with this query. Not implemented.
def delete(name, options = nil)
read_file
return nil if @cache.nil?
if @cache.include? name.to_s
@cache.delete name.to_s
write_file
return true
else
return nil
end
end
protected
# Read the entire cache file from disk.
# Will avoid reading if there have been no changes.
def read_file
if !File.exists? @file_path
@cache = nil
else
# Check for changes after our last read or write.
if @last_change.nil? || File.mtime(@file_path) > @last_change
File.open(@file_path) do |file|
@cache = Marshal.load(file)
@last_change = file.mtime
end
end
end
return @cache
end
# Write the entire cache contents to disk.
def write_file
File.open(@file_path, 'w') do |file|
Marshal.dump(@cache, file)
end
@last_change = File.mtime(@file_path)
end
end
end
end
end