forked from Baguette/dodb.cr
152 lines
3.1 KiB
Crystal
152 lines
3.1 KiB
Crystal
require "file_utils"
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require "json"
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require "./exceptions.cr"
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require "./indexer.cr"
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class DODB::Index(V) < DODB::Indexer(V)
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property name : String
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property key_proc : Proc(V, String | NoIndex) | Proc(V, String)
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getter storage_root : String
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@storage : DODB::Storage(V)
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def initialize(@storage, @storage_root, @name, @key_proc)
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Dir.mkdir_p indexing_directory
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end
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def check!(key, value, old_value)
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index_key = key_proc.call value
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symlink = file_path_index index_key.to_s
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# FIXME: Check it’s not pointing to “old_value”, if any, before raising.
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if ::File.exists? symlink
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if old_value
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old_key = key_proc.call old_value
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return if symlink == file_path_index old_key.to_s
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end
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raise IndexOverload.new "index '#{@name}' is overloaded for key '#{key}'"
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end
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end
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def index(key, value)
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index_key = key_proc.call value
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return if index_key.is_a? NoIndex
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symlink = file_path_index index_key
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Dir.mkdir_p ::File.dirname symlink
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# FIXME: Now that this is done in check!, can we remove it?
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if ::File.exists? symlink
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raise Exception.new "symlink already exists: #{symlink}"
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end
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::File.symlink get_data_symlink_index(key), symlink
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end
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def deindex(key, value)
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index_key = key_proc.call value
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return if index_key.is_a? NoIndex
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symlink = file_path_index index_key
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::File.delete symlink
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end
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def get(index : String) : V
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file_path = file_path_index index
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raise MissingEntry.new(@name, index) unless ::File.exists? file_path
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V.from_json ::File.read file_path
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end
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def get?(index : String) : V?
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get index
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rescue MissingEntry
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nil
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end
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# FIXME: Unlock on exception.
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def safe_get(index : String) : Nil
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@storage.request_lock @name, index
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internal_key = get_key(index).to_s
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@storage.request_lock internal_key
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yield get index
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@storage.release_lock internal_key
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@storage.release_lock @name, index
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end
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def safe_get?(index : String, &block : Proc(V | Nil, Nil)) : Nil
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safe_get index, &block
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rescue MissingEntry
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yield nil
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end
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def get_key(index : String) : Int32
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file_path = file_path_index index
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raise MissingEntry.new(@name, index) unless ::File.exists? file_path
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::File.readlink(file_path)
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.sub(/\.json$/, "")
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.sub(/^.*\//, "")
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.to_i
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end
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def get_with_key(index : String) : Tuple(V, Int32)
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key = get_key index
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value = @storage[key]
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{value, key}
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end
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# in case new_value hasn't changed its index
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def update(new_value : V)
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index = key_proc.call new_value
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raise Exception.new "new value is not indexable" if index.is_a? NoIndex
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update index, new_value
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end
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def update(index : String, new_value : V)
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_, key = get_with_key index
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@storage[key] = new_value
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end
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def update_or_create(index : String, new_value : V)
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update index, new_value
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rescue MissingEntry
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@storage << new_value
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end
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def delete(index : String)
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key = get_key index
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@storage.delete key
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end
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def indexing_directory : String
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"#{@storage_root}/indices/by_#{@name}"
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end
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private def file_path_index(index_key : String)
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"#{indexing_directory}/#{index_key}.json"
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end
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private def get_data_symlink_index(key : String)
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"../../data/#{key}.json"
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end
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end
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