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require "active_support/core_ext/marshal"
require "active_support/core_ext/file/atomic"
require "active_support/core_ext/string/conversions"
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
prepend Strategy::LocalCache
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)
FILEPATH_MAX_SIZE = 900 # max is 1024, plus some room
EXCLUDED_DIRS = [".", ".."].freeze
GITKEEP_FILES = [".gitkeep", ".keep"].freeze
def initialize(cache_path, options = nil)
super(options)
@cache_path = cache_path.to_s
end
# Deletes all items from the cache. In this case it deletes all the entries in the specified
# file store directory except for .keep or .gitkeep. Be careful which directory is specified in your
# config file when using +FileStore+ because everything in that directory will be deleted.
def clear(options = nil)
root_dirs = exclude_from(cache_path, EXCLUDED_DIRS + GITKEEP_FILES)
FileUtils.rm_r(root_dirs.collect { |f| File.join(cache_path, f) })
rescue Errno::ENOENT
end
# Preemptively iterates through all stored keys and removes the ones which have expired.
def cleanup(options = nil)
options = merged_options(options)
search_dir(cache_path) do |fname|
key = file_path_key(fname)
entry = read_entry(key, options)
delete_entry(key, options) if entry && entry.expired?
end
end
# Increments an already existing integer value that is stored in the cache.
# If the key is not found nothing is done.
def increment(name, amount = 1, options = nil)
modify_value(name, amount, options)
end
# Decrements an already existing integer value that is stored in the cache.
# If the key is not found nothing is done.
def decrement(name, amount = 1, options = nil)
modify_value(name, -amount, options)
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(path, options) if key.match(matcher)
end
end
end
private
def read_entry(key, options)
if File.exist?(key)
File.open(key) { |f| Marshal.load(f) }
end
rescue => e
logger.error("FileStoreError (#{e}): #{e.message}") if logger
nil
end
def write_entry(key, entry, options)
return false if options[:unless_exist] && File.exist?(key)
ensure_cache_path(File.dirname(key))
File.atomic_write(key, cache_path) { |f| Marshal.dump(entry, f) }
true
end
def delete_entry(key, options)
if File.exist?(key)
begin
File.delete(key)
delete_empty_directories(File.dirname(key))
true
rescue => e
# Just in case the error was caused by another process deleting the file first.
raise e if File.exist?(key)
false
end
end
end
# Lock a file for a block so only one process can modify it at a time.
def lock_file(file_name, &block)
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 normalize_key(key, options)
key = super
fname = URI.encode_www_form_component(key)
if fname.size > FILEPATH_MAX_SIZE
fname = Digest::MD5.hexdigest(key)
end
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 File.realpath(dir) == File.realpath(cache_path)
if exclude_from(dir, EXCLUDED_DIRS).empty?
Dir.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 EXCLUDED_DIRS.include?(d)
name = File.join(dir, d)
if File.directory?(name)
search_dir(name, &callback)
else
callback.call name
end
end
end
# Modifies the amount of an already existing integer value that is stored in the cache.
# If the key is not found nothing is done.
def modify_value(name, amount, options)
file_name = normalize_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
end
end
end
# Exclude entries from source directory
def exclude_from(source, excludes)
Dir.entries(source).reject { |f| excludes.include?(f) }
end
end
end
end
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