Class: SimpleMmap::FileWindow

Inherits:
Object
  • Object
show all
Defined in:
lib/simple_mmap/file_window.rb

Overview

Represents a window into a mmap()‘ed file, using a familiar index syntax for getting single bytes or Ranges of bytes within that FileWindow

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ FileWindow

Create a mmap’ed window for file at path You are responsible for closing it when you’re done using #close



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# File 'lib/simple_mmap/file_window.rb', line 28

def initialize(path)
  @path = path
  @offset = 0
  @mmap = SimpleMmap::MappedFile.new(@path)
end

Instance Attribute Details

#offset ⇒ Object Also known as: pos

The current offset



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# File 'lib/simple_mmap/file_window.rb', line 43

def offset
  @offset
end

#path ⇒ Object (readonly)

Returns the value of attribute path.



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# File 'lib/simple_mmap/file_window.rb', line 33

def path
  @path
end

Instance Method Details

#[](*index) ⇒ Object

Read data from the mmap’ed file. Takes the same arguments as Array/String#[] (eg [2], [2,5], [2..5] or [2…5]) The current offset will be tracked accordingly



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# File 'lib/simple_mmap/file_window.rb', line 62

def [](*index)
  if index.length == 1
    index = index.first
  end
  case index
  when Array
    offset, length = index
  when Fixnum
    offset = index
    length = 0
  when Range
    offset = index.begin
    length = index.end - index.begin
    unless index.exclude_end?
      length += 1
    end
  end
  
  @offset = offset + length

  if length.zero?
    @mmap.read_window_data(offset, 1)
  else
    @mmap.read_window_data(offset, length)
  end
end

#close ⇒ Object Also known as: unmap

unmaps the mmap’ed file



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# File 'lib/simple_mmap/file_window.rb', line 36

def close
  @mmap.close
  @mmap = nil
end

#read(length) ⇒ Object

Read length bytes starting from the current offset



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# File 'lib/simple_mmap/file_window.rb', line 90

def read(length)
  data = @mmap.read_window_data(@offset, length)
  @offset += length
  data
end

#seek(to_pos) ⇒ Object

Move the current offset to to_pos



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# File 'lib/simple_mmap/file_window.rb', line 55

def seek(to_pos)
  self.pos = to_pos
end

#size ⇒ Object

Return size of mapped file



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# File 'lib/simple_mmap/file_window.rb', line 97

def size
  @mmap.size
end