Class: Mmapper::File

Inherits:
Object
  • Object
show all
Defined in:
lib/mmapper.rb,
ext/mmapper.c

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ Object 



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# File 'ext/mmapper.c', line 34

static VALUE mmap_file_initialize(VALUE self, VALUE path) {
  mmap_file *m;
  const char *c_path = StringValueCStr(path);
  Data_Get_Struct(self, mmap_file, m);

  m->fd = open(c_path, O_RDWR);
  if (m->fd < 0)
    rb_sys_fail("open");

  m->size = lseek(m->fd, 0, SEEK_END);
  lseek(m->fd, 0, SEEK_SET);

  m->map = mmap(NULL, m->size, PROT_READ | PROT_WRITE, MAP_SHARED, m->fd, 0);
  if (m->map == MAP_FAILED)
    rb_sys_fail("mmap");

  return self;
}

Instance Method Details

#find_matching_line(prefix) ⇒ Object 



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# File 'lib/mmapper.rb', line 5

def find_matching_line(prefix)
  low = 0
  high = size

  while low < high
    mid = (low + high) / 2
    line_start = find_line_start(mid)
    line = read_line_at(line_start)

    return nil if line.nil?

    if line < prefix
      low = mid + 1
    else
      high = mid
    end

  end

  final_line_start = find_line_start(low)
  line = read_line_at(final_line_start)

  if line&.start_with?(prefix)
    line
  else
    nil
  end
end

#read(offset_val, length_val) ⇒ Object 



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# File 'ext/mmapper.c', line 53

static VALUE mmap_file_read(VALUE self, VALUE offset_val, VALUE length_val) {
  mmap_file *m;
  Data_Get_Struct(self, mmap_file, m);

  long offset = NUM2LONG(offset_val);
  long length = NUM2LONG(length_val);

  if (offset < 0 || offset + length > (long)m->size)
    rb_raise(rb_eArgError, "read out of bounds");

  return rb_str_new((char *)m->map + offset, length);
}

#size ⇒ Object 



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# File 'ext/mmapper.c', line 83

static VALUE mmap_file_size(VALUE self) {
  mmap_file *m;
  Data_Get_Struct(self, mmap_file, m);
  return LONG2NUM(m->size);
}

#write(offset_val, str_val) ⇒ Object 



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# File 'ext/mmapper.c', line 66

static VALUE mmap_file_write(VALUE self, VALUE offset_val, VALUE str_val) {
  mmap_file *m;
  Data_Get_Struct(self, mmap_file, m);

  long offset = NUM2LONG(offset_val);
  StringValue(str_val);
  long len = RSTRING_LEN(str_val);

  if (offset < 0 || offset + len > (long)m->size)
    rb_raise(rb_eArgError, "write out of bounds");

  memcpy((char *)m->map + offset, RSTRING_PTR(str_val), len);
  msync(m->map, m->size, MS_SYNC);

  return Qtrue;
}