76 lines
2 KiB
Ruby
76 lines
2 KiB
Ruby
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# frozen_string_literal: true
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require 'digest'
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module AceOfBase
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# Implements our database.
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class Storage
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include Enumerable
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STORAGE_DIR = File.expand_path('../../data/', __dir__)
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Error = Class.new(AceOfBase::Error)
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def initialize(storage_dir = STORAGE_DIR)
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@storage_dir = storage_dir
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ensure_data_dir_exists_and_is_writable!
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end
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def store(record)
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with_write_locked_file_for_record(record) do |file|
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file.write(RecordSerialiser.encode(record))
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end
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end
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def retrieve(project, shot, version)
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with_read_locked_file(hash_for(project, shot, version)) do |file|
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RecordSerialiser.decode(file.read)
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end
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end
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def each
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Dir['*', base: storage_dir].each do |path|
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with_read_locked_file(path) do |file|
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yield RecordSerialiser.decode(file.read)
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end
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end
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end
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private
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attr_reader :storage_dir
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def ensure_data_dir_exists_and_is_writable!
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raise Error, format('Storage directory (%p) does not exist.', storage_dir) unless File.directory?(storage_dir)
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raise Error, format('Storage directory (%p) is not writable.', storage_dir) unless File.writable?(storage_dir)
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end
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def with_write_locked_file_for_record(record)
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target = File.join(storage_dir, hash_for(record.project, record.shot, record.version))
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File.open(target, File::CREAT | File::WRONLY, 0o600) do |file|
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raise Error, 'Unable to acquire exclusive lock.' unless file.flock(File::LOCK_EX | File::LOCK_NB)
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result = yield file
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file.flock(File::LOCK_UN)
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result
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end
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end
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def with_read_locked_file(path)
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target = File.join(storage_dir, path)
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File.open(target, File::RDONLY) do |file|
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file.flock(File::LOCK_SH)
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result = yield file
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file.flock(File::LOCK_UN)
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result
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end
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rescue Errno::ENOENT
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raise Error, 'Record not found'
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end
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def hash_for(project, shot, version)
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Digest::SHA1.hexdigest("#{project}|#{shot}|#{version}")
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end
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end
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end
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