Class: Ferret::Store::BufferedIndexInput

Inherits:
IndexInput
  • Object
show all
Defined in:
lib/ferret/store/buffered_index_io.rb,
ext/index_io.c

Overview

Base implementation class for buffered IndexInput

Instance Method Summary collapse

Methods inherited from IndexInput

#close, #length

Constructor Details

#initialize ⇒ BufferedIndexInput

Returns a new instance of BufferedIndexInput.



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# File 'lib/ferret/store/buffered_index_io.rb', line 85

def initialize
  @buffer = nil
  @buffer_start = 0
  @buffer_length = 0
  @buffer_position = 0
end

Instance Method Details

#initialize_copy(orig) ⇒ Object

Creates a clone of the BufferedIndexReader. Reading from a BufferedIndexInput should not change the state (read position) in the clone and vice-versa.



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# File 'lib/ferret/store/buffered_index_io.rb', line 143

def initialize_copy(o)
  super
  @buffer = o.buffer.clone if o.buffer
end

#pos ⇒ Object

Get the current position in the file, where the next read will occur.



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# File 'lib/ferret/store/buffered_index_io.rb', line 124

def pos()
  return @buffer_start + @buffer_position
end

#read_byte ⇒ Object

Read and return a single byte from the file



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# File 'lib/ferret/store/buffered_index_io.rb', line 93

def read_byte
  refill if (@buffer_position >= @buffer_length)
  byte = @buffer[@buffer_position]
  @buffer_position += 1
  return byte
end

#read_bytes(rbuf, roffset, rlen) ⇒ Object

Read len bytes into buffer starting at position offset in buffer

buffer

The string buffer to read the characters into.

offset

The position in buffer to start writing to.

len

the number of characters to read

returns

the buffer



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# File 'lib/ferret/store/buffered_index_io.rb', line 106

def read_bytes(buffer, offset, len)
  if (len < BUFFER_SIZE) 
    offset.upto(offset+len-1) do |i| # read byte-by-byte
      buffer[i] = read_byte
    end
  else                               # read all-at-once
    start = pos()
    seek_internal(start)
    read_internal(buffer, offset, len)

    @buffer_start = start + len      # adjust stream variables
    @buffer_position = 0
    @buffer_length = 0               # trigger refill on read
  end
  return buffer
end

#read_chars(rbuf, roffset, rlen) ⇒ Object 



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# File 'ext/index_io.c', line 140

static VALUE
frt_indexin_read_bytes(VALUE self, VALUE rbuf, VALUE roffset, VALUE rlen)
{
  int len, offset;

  len = FIX2INT(rlen);
  offset = FIX2INT(roffset);

  return frt_read_bytes(self, rbuf, offset, len);
}

#read_int ⇒ Object 



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# File 'ext/index_io.c', line 169

VALUE
frt_indexin_read_int(VALUE self)
{
  GET_MY_BUF;
  return LONG2NUM(((int)frt_read_byte(self, my_buf) << 24) |
                  ((int)frt_read_byte(self, my_buf) << 16) |
                  ((int)frt_read_byte(self, my_buf) << 8) |
                   (int)frt_read_byte(self, my_buf));
}

#read_long ⇒ Object 



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# File 'ext/index_io.c', line 179

VALUE
frt_indexin_read_long(VALUE self)
{
  GET_MY_BUF;
  return LL2NUM(((long long)frt_read_byte(self, my_buf) << 56) |
                ((long long)frt_read_byte(self, my_buf) << 48) |
                ((long long)frt_read_byte(self, my_buf) << 40) |
                ((long long)frt_read_byte(self, my_buf) << 32) |
                ((long long)frt_read_byte(self, my_buf) << 24) |
                ((long long)frt_read_byte(self, my_buf) << 16) |
                ((long long)frt_read_byte(self, my_buf) << 8) |
                 (long long)frt_read_byte(self, my_buf));
}

#read_string ⇒ Object 



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# File 'ext/index_io.c', line 258

static VALUE
frt_indexin_read_string(VALUE self)
{
  int length;
  char *str;
  GET_MY_BUF;
  length = (int)frt_read_vint(self, my_buf);
  str = ALLOC_N(char, length);

  frt_read_chars(self, str, 0, length);

  return rb_str_new(str, length);
}

#read_uint ⇒ Object 



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# File 'ext/index_io.c', line 193

static VALUE
frt_indexin_read_uint(VALUE self)
{
  GET_MY_BUF;
  return ULONG2NUM(((unsigned int)frt_read_byte(self, my_buf) << 24) |
                   ((unsigned int)frt_read_byte(self, my_buf) << 16) |
                   ((unsigned int)frt_read_byte(self, my_buf) << 8) |
                    (unsigned int)frt_read_byte(self, my_buf));
}

#read_ulong ⇒ Object 



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# File 'ext/index_io.c', line 203

static VALUE
frt_indexin_read_ulong(VALUE self)
{
  GET_MY_BUF;
  return ULL2NUM(((unsigned long long)frt_read_byte(self, my_buf) << 56) |
                 ((unsigned long long)frt_read_byte(self, my_buf) << 48) |
                 ((unsigned long long)frt_read_byte(self, my_buf) << 40) |
                 ((unsigned long long)frt_read_byte(self, my_buf) << 32) |
                 ((unsigned long long)frt_read_byte(self, my_buf) << 24) |
                 ((unsigned long long)frt_read_byte(self, my_buf) << 16) |
                 ((unsigned long long)frt_read_byte(self, my_buf) << 8) |
                  (unsigned long long)frt_read_byte(self, my_buf));
}

#read_vint ⇒ Object 



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# File 'ext/index_io.c', line 235

static VALUE
frt_indexin_read_vint(VALUE self)
{
  GET_MY_BUF;
  return ULL2NUM(frt_read_vint(self, my_buf));
}

#read_vlong ⇒ Object 



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# File 'ext/index_io.c', line 235

static VALUE
frt_indexin_read_vint(VALUE self)
{
  GET_MY_BUF;
  return ULL2NUM(frt_read_vint(self, my_buf));
}

#refill ⇒ Object

Refill the buffer from the file.



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# File 'lib/ferret/store/buffered_index_io.rb', line 170

def refill
  start = @buffer_start + @buffer_position
  last = start + BUFFER_SIZE
  if (last > length())               # don't read past EOF
    last = length()
  end
  @buffer_length = last - start
  if (@buffer_length <= 0)
    raise EOFError
  end

  if (@buffer == nil)
    @buffer = BUFFER.clone # allocate buffer lazily
  end
  read_internal(@buffer, 0, @buffer_length)

  @buffer_start = start
  @buffer_position = 0
end

#seek(rpos) ⇒ Object

Set the current position in the file, where the next read will occur.



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# File 'lib/ferret/store/buffered_index_io.rb', line 129

def seek(pos)
  if (pos >= @buffer_start and pos < (@buffer_start + @buffer_length))
    @buffer_position = pos - @buffer_start  # seek within buffer
  else 
    @buffer_start = pos
    @buffer_position = 0
    @buffer_length = 0               # trigger refill() on read()
    seek_internal(pos)
  end
end