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initial framework to allow KV object to have different data backends
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| Original file line number | Original file line | Diff line number | Diff line change |
|---|---|---|---|
| @@ -0,0 +1,166 @@ | |||
| require "rubygems" | |||
| require "fileutils" | |||
| require "json" | |||
| require "kv/exception" | |||
| require "kv/node" | |||
| require "kv/util" | |||
| require "uuidtools" | |||
|
|
|||
| class KV | |||
| class Backend | |||
| class File | |||
| public | |||
| def self.create_kvdb(kvdb_path) | |||
| kvdb_metadata_path = File.join(kvdb_path, ".kvdb") | |||
| kvdb_metadata = { | |||
| "version" => "1", | |||
| "mapping" => {}, | |||
| } | |||
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|
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| if File.exists?(kvdb_path) | |||
| raise KV::Error.new("#{kvdb_path} exists, cannot create a kvdb there") | |||
| end | |||
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|
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| FileUtils.mkdir_p(kvdb_path) | |||
| File.open(kvdb_metadata_path, "w+") do |f| | |||
| f.puts kvdb_metadata.to_json | |||
| end | |||
| end # def self.create_kvdb | |||
|
|
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| public | |||
| def initialize(opts) | |||
| @opts = { | |||
| :path => nil, | |||
| }.merge(opts) | |||
|
|
|||
| if @opts[:path].nil? | |||
| raise KV::Error.new("missing :path argument to constructor") | |||
| end | |||
|
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| @kvdb_metadata_path = ::File.join(@opts[:path], ".kvdb") | |||
| if !::File.exists?(@kvdb_metadata_path) | |||
| raise KV::Error.new("can't see #{@kvdb_metadata_path}") | |||
| end | |||
|
|
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| @nodes = {} | |||
|
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| load_metadata | |||
| end # def initialize | |||
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| private | |||
| def load_metadata | |||
| begin | |||
| @kvdb_metadata = JSON.parse(::File.read(@kvdb_metadata_path)) | |||
| rescue | |||
| raise KV::Error.new("error parsing #{@kvdb_metadata_path}: #{$!}") | |||
| end | |||
|
|
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| if ! @kvdb_metadata["mapping"].is_a?(Hash) | |||
| raise KV::Error.new("corrupt metadata, mapping is not a hash") | |||
| end | |||
|
|
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| if ! @kvdb_metadata.member?("version") | |||
| raise KV::Error.new("corrupt metadata, version is missing") | |||
| end | |||
|
|
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| # TODO(petef): some day handle the ability to have multiple versions. | |||
| if @kvdb_metadata["version"] != "1" | |||
| raise KV::Error.new("unknown metadata version #{@kvdb_metadata["version"].inspect}") | |||
| end | |||
| end # def load_metadata | |||
|
|
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| private | |||
| def write_metadata | |||
| ::File.open(@kvdb_metadata_path, "w+") { |f| f.puts @kvdb_metadata.to_json } | |||
| end # def write_metadata | |||
|
|
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| public | |||
| def node_path(node_name) | |||
| if ! node_name.is_a?(String) | |||
| raise "node_path takes a String, not: #{node_name.inspect}" | |||
| end | |||
| if @kvdb_metadata["mapping"][node_name] | |||
| return @kvdb_metadata["mapping"][node_name] | |||
| end | |||
|
|
|||
| # get a UUID, build a path | |||
| uuid = UUIDTools::UUID.sha1_create(UUIDTools::UUID_OID_NAMESPACE, | |||
| node_name).to_s | |||
| path = ::File.join(@opts[:path], | |||
| uuid[0..0], | |||
| uuid[1..1], | |||
| uuid[2..2], | |||
| uuid) | |||
| @kvdb_metadata["mapping"][node_name] = path | |||
|
|
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| # re-write metadata | |||
| write_metadata | |||
|
|
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| return path | |||
| end # def node_path | |||
|
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| public | |||
| def node(node_name) | |||
| @nodes[node_name] ||= KV::Node.new(node_name, node_path(node_name)) | |||
| return @nodes[node_name] | |||
| end | |||
|
|
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| public | |||
| def node?(node_name) | |||
| return @kvdb_metadata["mapping"].keys.member?(node_name) | |||
| end | |||
|
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| public | |||
| def nodes | |||
| return @kvdb_metadata["mapping"].keys.sort | |||
| end # def nodes | |||
|
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| public | |||
| def expand(key_path, verbose = false, raise_on_bad_node_name = true) | |||
| res = [] | |||
| # key_path must be a full key_path or just a node name | |||
| node_name, key, index = KV::Util.expand_key_path(key_path) | |||
|
|
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| if ! node?(node_name) | |||
| if raise_on_bad_node_name | |||
| raise KV::Error, "node #{node_name} does not exist" | |||
| else | |||
| return res | |||
| end | |||
| end | |||
|
|
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| node = self.node(node_name) | |||
| if key.nil? | |||
| node.attrs.to_hash.each do |key, values| | |||
| res.push(*expand_values(node, key, values, true)) | |||
| end | |||
| elsif node[key] | |||
| res.push(*expand_values(node, key, node[key], verbose)) | |||
| end | |||
|
|
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| return res.sort | |||
| end # def expand | |||
|
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| private | |||
| def expand_values(node, key, values, verbose) | |||
| res = [] | |||
| values = [values] unless values.is_a?(Array) | |||
|
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| index = values.length > 1 ? 0 : nil | |||
|
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| values.each do |value| | |||
| if verbose | |||
| index_suffix = index ? "##{index}" : "" | |||
| res << "#{node.name}##{key}#{index_suffix}: #{value}" | |||
| index += 1 if index | |||
| else | |||
| res << value | |||
| end | |||
| end | |||
|
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| return res | |||
| end # def expand_values | |||
| end # class File | |||
| end # class Backend | |||
| end # class KV | |||