154 lines
3.2 KiB
Crystal
154 lines
3.2 KiB
Crystal
require "file_utils"
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require "./indexer.cr"
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class DODB::Partition(V) < DODB::Indexer(V)
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property name : String
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property key_proc : Proc(V, String)
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getter storage_root : String
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# Required to remove an entry in the DB.
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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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return true # Partitions don’t have collisions or overloads.
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end
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def index(key, value)
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partition = key_proc.call value
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symlink = get_partition_symlink(partition, key)
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Dir.mkdir_p ::File.dirname symlink
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# FIXME: Should not happen anymore. Should we remove this?
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::File.delete symlink if ::File.exists? symlink
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::File.symlink get_data_symlink(key), symlink
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end
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def deindex(key, value)
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partition = key_proc.call value
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symlink = get_partition_symlink(partition, key)
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begin
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::File.delete symlink
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rescue File::NotFoundError
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end
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end
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def get(partition) : Array(V)
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r_value = Array(V).new
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partition_directory = indexing_directory partition
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return r_value unless Dir.exists? partition_directory
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Dir.each_child partition_directory do |child|
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r_value << @storage[get_key child]
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end
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r_value
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end
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def get?(partition) : Array(V)?
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get partition
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rescue MissingEntry
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nil
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end
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def delete(partition)
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delete partition, do true end
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end
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def delete(partition, &matcher)
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partition_directory = indexing_directory partition
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return unless Dir.exists? partition_directory
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Dir.each_child partition_directory do |child|
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key = get_key child
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item = @storage[key]
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if yield item
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@storage.delete key
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end
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end
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end
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def indexing_directory : String
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"#{@storage_root}/partitions/by_#{@name}"
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end
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private def get_key(path : String) : Int32
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path.sub(/^.*\//, "").to_i
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end
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private def indexing_directory(partition)
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"#{indexing_directory}/#{partition}"
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end
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private def get_partition_symlink(partition : String, key : String)
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"#{indexing_directory partition}/#{key}"
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end
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private def get_data_symlink(key : String)
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"../../../data/#{key}"
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end
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end
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class DODB::CachedPartition(V) < DODB::Partition(V)
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# This hash contains the relation between the index key and the data keys.
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property data = Hash(String, Array(Int32)).new
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def index(key, value)
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super(key, value)
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partition = key_proc.call value
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array = if v = @data[partition]?
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v
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else
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Array(Int32).new
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end
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array << key.to_i
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@data[partition] = array
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end
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def deindex(key, value)
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super(key, value)
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partition = key_proc.call value
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if v = @data[partition]?
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v.delete key.to_i
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@data[partition] = v
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end
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end
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def get(partition)
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r_value = Array(Tuple(V, Int32)).new
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if keys = @data[partition]?
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keys.each do |data_key|
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r_value << { @storage[data_key], data_key }
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end
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else
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# Get the key from the database representation on the file-system.
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partition_directory = indexing_directory partition
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raise MissingEntry.new(@name, partition) unless Dir.exists? partition_directory
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Dir.each_child partition_directory do |child|
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r_value << { @storage[get_key child], get_key child }
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end
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@data[partition] = r_value.map &.[1]
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end
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r_value.map &.[0]
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end
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end
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