Class: Conveyor::BaseChannel

Inherits:
Object
  • Object
show all
Defined in:
lib/conveyor/base_channel.rb

Overview

BaseChannel

Base implementation for channels. Not useful to instantiate directly.

Direct Known Subclasses

Channel

Defined Under Namespace

Modules: Flags

Constant Summary collapse

NAME_PATTERN = 
%r{\A[a-zA-Z\-0-9\_]+\Z}
BUCKET_SIZE = 
100_000
FORMAT_VERSION = 
1
BLOCK_SIZE = 
1000
CACHE_SIZE = 
100

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(directory) ⇒ BaseChannel

Returns a new instance of BaseChannel.



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# File 'lib/conveyor/base_channel.rb', line 41

def initialize directory
  @directory             = directory
  @data_files            = []
  @file_mutexes          = []
  @iterator              = 1 #TODO: move to Channel.rb
  @id_lock               = Mutex.new
  @index_file_lock       = Mutex.new
  @block_cache           = {}
  @block_last_used       = {}

  if File.exists?(@directory)
    if !File.directory?(@directory)
      raise "#{@directory} is not a directory"
    end
    load_channel
  else
    Dir.mkdir(@directory)
    setup_channel
  end

  @index_file.sync    = true
end

Class Method Details

.parse_headers(str, index_file = false) ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 24

def self.parse_headers str, index_file=false
  id, time, offset, length, hash, flags, file = str.split ' '
  {
    :id     => id.to_i(36),
    :time   => time.to_i(36),
    :offset => offset.to_i(36),
    :length => length.to_i(36),
    :hash   => hash,
    :flags  => flags.to_i(36),
    :file   => (index_file ? file.to_i(36) : nil)
  }
end

.valid_channel_name?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/conveyor/base_channel.rb', line 37

def self.valid_channel_name? name
  !!name.match(NAME_PATTERN)
end

Instance Method Details

#commit(data, time = nil) ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 68

def commit data, time=nil
  l = nil
  gzip = data.length >= 256
  if gzip
    compressed_data = StringIO.new
    g = Zlib::GzipWriter.new(compressed_data)
    g << data
    g.finish
    compressed_data.rewind
    compressed_data = compressed_data.read
    l = compressed_data.length
  else
    l = data.length
  end

  h = Digest::MD5.hexdigest(data)

  id_lock do
    i = @last_id + 1
    t = time || Time.now.to_i
    b = pick_bucket(i)
    flags = 0
    flags = flags | Flags::GZIP if gzip
    header, o = nil
    bucket_file(b) do |f|
      f.seek(0, IO::SEEK_END)
      o = f.pos
      header = "#{i.to_s(36)} #{t.to_i.to_s(36)} #{o.to_s(36)} #{l.to_s(36)} #{h} #{flags.to_s(36)}"
      f.write("#{header}\n")
      f.write((gzip ? compressed_data : data))
      f.write("\n")
    end

    @last_id = i
    index_offset = nil
    index_file_lock do
      @index_file.seek(0, IO::SEEK_END)
      index_offset = @index_file.pos
      @index_file.write "#{header} #{b.to_s(36)}\n"
    end
    block_num = block_num(i)
    if !@blocks[block_num]
      @blocks << {:offset => index_offset}
    end
    if @block_cache.key?(block_num)
      @block_cache[block_num] << {:id => i, :time => t, :offset => o, :length => l, :hash => h, :file => b}
    end
    i
  end
end

#delete! ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 148

def delete!
  FileUtils.rm_r(@directory)
  @data_files =[]
  @last_id = 0
  @blocks = []
end

#get(id, stream = false) ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 119

def get id, stream=false
  return nil unless id <= @last_id && id > 0

  index_entry = search_index(id)

  headers, content, compressed_content, g = nil
  bucket_file(index_entry[:file]) do |f|
    f.seek index_entry[:offset]
    headers  = self.class.parse_headers(f.readline.strip)
    compressed_content = f.read(index_entry[:length])
  end
  io = StringIO.new(compressed_content)
  if (headers[:flags] & Flags::GZIP) != 0
    g  = Zlib::GzipReader.new(io)
  else
    g = io
  end
  if stream
    [headers, g]
  else
    [headers, g.read]
  end
end

#get_nearest_after_timestamp(timestamp, stream = false) ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 143

def get_nearest_after_timestamp timestamp, stream=false
  i = nearest_after(timestamp)
  get(i) if i
end

#inspect ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 64

def inspect
  "<#{self.class} dir:'#{@directory.to_s}' last_id:#{@last_id} iterator:#{@iterator}>"
end

#rebuild_index ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 155

def rebuild_index
  files = Dir.glob(@directory + '/' + '[0-9]*')
  files = files.map{|f| [f, f.split('/').last.to_i]}
  files.sort!{|a,b| a[1] <=> b[1]}
  files.each do |(f, b)|
    File.open(f, 'r') do |file|
      puts "reading #{f}"
      while line = file.gets
        headers = self.class.parse_headers(line.strip)
        content = file.read(headers[:length])
        file.read(1)
        index_offset = nil
        header = "#{headers[:id].to_s(36)} #{headers[:time].to_s(36)} #{headers[:offset].to_s(36)} #{headers[:length].to_s(36)} #{headers[:hash]} #{headers[:flags].to_s(36)}"
        index_file_lock do
          @index_file.seek(0, IO::SEEK_END)
          index_offset = @index_file.pos
          @index_file.write "#{header} #{b.to_s(36)}\n"
        end
      end
    end
  end
end

#status ⇒ Object 



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# File 'lib/conveyor/base_channel.rb', line 178

def status
  {
    :directory        => @directory,
    :data_files => @data_files.collect{|f| {:path => f.path, :bytes => File.size(f.path)}},
    :iterator         => @iterator,
    :block_cache_keys => @block_cache.keys,
    :last_id => @last_id,
    :blocks => @blocks.length,
  }
end