Migration test and example.
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81
spec/test.cr
81
spec/test.cr
@ -5,6 +5,8 @@ require "uuid"
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require "../src/*"
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# FIXME: Split the test data in separate files. We don’t care about those here.
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class Ship
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include JSON::Serializable
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@ -57,11 +59,37 @@ class Ship
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end
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end
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class DODB::SpecDataBase < DODB::DataBase(String, Ship)
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def initialize
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::FileUtils.rm_rf "test-storage"
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# This will be used for migration testing, but basically it’s a variant of
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# the class above, a few extra fields, a few missing ones.
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class PrimitiveShip
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include JSON::Serializable
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initialize "test-storage"
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property id : String
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property name : String
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property wooden : Bool = false # Will be removed.
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property class_name : String # Will be renamed
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property flagship : Bool = false # Will be moved to tags.
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def initialize(@name, @class_name = "<unknown>", @id = UUID.random.to_s, @flagship = false)
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end
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class_getter kamikaze =
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PrimitiveShip.new("Kamikaze", "Kamikaze")
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class_getter asakaze =
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PrimitiveShip.new("Asakaze", "Kamikaze")
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class_getter all_ships : Array(PrimitiveShip) = [
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@@kamikaze,
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@@asakaze
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]
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end
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class DODB::SpecDataBase < DODB::DataBase(String, Ship)
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def initialize(storage_ext = "")
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storage_dir = "test-storage#{storage_ext}"
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::FileUtils.rm_rf storage_dir
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super storage_dir
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end
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end
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@ -270,9 +298,48 @@ describe "DODB::DataBase" do
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end
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end
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# Migration testing code will go here as soon as migration testing
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# becomes relevant (due to format changes or so). For small projects,
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# reindexing will work very well in the meantime.
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it "migrates properly" do
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old_db = DODB::DataBase(String, PrimitiveShip).new "test-storage-migration-origin"
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old_ships_by_name = old_db.new_index "name", &.name
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old_ships_by_class = old_db.new_partition "class", &.class_name
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PrimitiveShip.all_ships.each do |ship|
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old_db[ship.id] = ship
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end
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# At this point, the “old” DB is filled. Now we need to convert
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# to the new DB.
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new_db = DODB::SpecDataBase.new "-migration-target"
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new_ships_by_class = new_db.new_partition "class", &.class
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new_ships_by_tags = new_db.new_tags "tags", &.tags
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new_ships_by_tags = new_db.new_tags "tags", &.tags
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old_db.each do |id, ship|
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new_ship = Ship.new ship.name,
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class: ship.class_name,
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id: ship.id,
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tags: Array(String).new.tap { |tags|
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tags << "name ship" if ship.name == ship.class_name
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}
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new_db[new_ship.id] = new_ship
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end
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# At this point, the conversion is done, so… we’re making a few
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# arbitrary tests on the new data.
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old_db.each do |old_id, old_ship|
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ship = new_db[old_id]
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ship.id.should eq(old_ship.id)
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ship.class.should eq(old_ship.class_name)
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ship.tags.any?(&.==("name ship")).should be_true if ship.name == ship.class
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end
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end
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end
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end
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177
src/fsdb.cr
177
src/fsdb.cr
@ -1,177 +0,0 @@
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require "file_utils"
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require "json"
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require "./dodb/*"
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class DODB::DataBase(K, V)
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@indexers = [] of Indexer(V)
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def initialize(@directory_name : String)
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Dir.mkdir_p data_path
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end
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##
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# name is the name that will be used on the file system.
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def new_partition(name : String, &block : Proc(V, String))
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Partition(V).new(@directory_name, name, block).tap do |table|
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@indexers << table
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end
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end
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##
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# name is the name that will be used on the file system.
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def new_index(name : String, &block : Proc(V, String))
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Index(V).new(@directory_name, name, block).tap do |indexer|
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@indexers << indexer
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end
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end
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def new_tags(name : String, &block : Proc(V, Array(String)))
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Tags(V).new(@directory_name, name, block).tap do |tags|
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@indexers << tags
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end
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end
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def get_index(name : String, key)
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index = @indexers.find &.name.==(name)
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index.not_nil!.as(DODB::Index).get key
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end
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# FIXME: Is this “key” really a K, not just a String?
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def get_partition(table_name : String, partition_name : String)
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partition = @indexers.find &.name.==(table_name)
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partition.not_nil!.as(DODB::Partition).get partition_name
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end
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def get_tags(name, key : K)
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partition = @indexers.find &.name.==(name)
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partition.not_nil!.as(DODB::Tags).get name, key
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end
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def []?(key : K) : V?
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self[key]
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rescue MissingEntry
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# FIXME: Only rescue JSON and “no such file” errors.
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return nil
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end
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def [](key : K) : V
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raise MissingEntry.new(key) unless ::File.exists? file_path key
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read file_path key
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end
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def []=(key : K, value : V)
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old_value = self.[key]?
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check_collisions! key, value, old_value
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# Removes any old indices or partitions pointing to a value about
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# to be replaced.
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if old_value
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remove_partitions key, old_value
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end
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# Avoids corruption in case the application crashes while writing.
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file_path(key).tap do |path|
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::File.write "#{path}.new", value.to_json
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::FileUtils.mv "#{path}.new", path
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end
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write_partitions key, value
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end
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def check_collisions!(key : K, value : V, old_value : V?)
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@indexers.each &.check!(key, value, old_value)
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end
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def write_partitions(key : K, value : V)
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@indexers.each &.index(key, value)
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end
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def delete(key : K)
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value = self[key]?
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return if value.nil?
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begin
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::File.delete file_path key
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rescue
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# FIXME: Only intercept “no such file" errors
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end
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remove_partitions key, value
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value
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end
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def remove_partitions(key : K, value : V)
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@indexers.each &.deindex(key, value)
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end
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##
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# CAUTION: Very slow. Try not to use.
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# Can be useful for making dumps or to restore a database, however.
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def each
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dirname = data_path
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Dir.each_child dirname do |child|
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next if child.match /^\./
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full_path = "#{dirname}/#{child}"
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begin
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# FIXME: Only intercept JSON parsing errors.
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field = read full_path
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rescue
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next
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end
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# FIXME: Will only work for String. :(
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key = child.gsub /\.json$/, ""
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yield key, field
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end
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end
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##
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# CAUTION: Very slow. Try not to use.
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def to_h
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hash = ::Hash(K, V).new
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each do |key, value|
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hash[key] = value
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end
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hash
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end
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private def data_path
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"#{@directory_name}/data"
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end
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private def file_path(key : K)
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"#{data_path}/#{key.to_s}.json"
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end
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private def read(file_path : String)
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V.from_json ::File.read file_path
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end
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# A very slow operation that removes all indices and then rewrites
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# them all.
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def reindex_everything!
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old_data = to_h
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old_data.each do |key, value|
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self.delete key
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end
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old_data.each do |key, value|
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self[key] = value
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end
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end
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end
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