dodb.cr/src/dodb/partition.cr

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require "file_utils"
require "json"
require "./indexer.cr"
class DODB::Partition(V) < DODB::Indexer(V)
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property name : String
property key_proc : Proc(V, String)
getter storage_root : String
# Required to remove an entry in the DB.
@storage : DODB::Storage(V)
def initialize(@storage, @storage_root, @name, @key_proc)
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::Dir.mkdir_p indexing_directory
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end
def check!(key, value, old_value)
return true # Partitions dont have collisions or overloads.
end
def index(key, value)
partition = key_proc.call value
symlink = get_partition_symlink(partition, key)
Dir.mkdir_p ::File.dirname symlink
# FIXME: Should not happen anymore. Should we remove this?
::File.delete symlink if ::File.exists? symlink
::File.symlink get_data_symlink(key), symlink
end
def deindex(key, value)
partition = key_proc.call value
symlink = get_partition_symlink(partition, key)
::File.delete symlink
end
def get(partition)
r_value = Array(V).new
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partition_directory = indexing_directory partition
return r_value unless Dir.exists? partition_directory
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Dir.each_child partition_directory do |child|
r_value << V.from_json ::File.read "#{partition_directory}/#{child}"
end
r_value
end
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def delete(partition)
delete partition, do true end
end
def delete(partition, &matcher)
partition_directory = indexing_directory partition
return unless Dir.exists? partition_directory
Dir.each_child partition_directory do |child|
path = "#{partition_directory}/#{child}"
item = V.from_json ::File.read path
if yield item
key = get_key path
@storage.delete key
end
end
end
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def indexing_directory : String
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"#{@storage_root}/partitions/by_#{@name}"
end
private def get_key(path : String) : Int32
::File.readlink(path)
.sub(/\.json$/, "")
.sub(/^.*\//, "")
.to_i
end
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private def indexing_directory(partition)
"#{indexing_directory}/#{partition}"
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end
private def get_partition_symlink(partition : String, key : String)
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"#{indexing_directory partition}/#{key}.json"
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end
private def get_data_symlink(key : String)
"../../../data/#{key}.json"
end
end