ruby-cdb

This package provides Ruby interface to Dan Bernstein’s cdb (constant database) library. For the information about cdb itself, see library author’s website cr.yp.to/cdb.html.

Installation Process

% tar xvzf ruby-cdb-x.y.tar.gz
% cd ruby-cdb
% more README
% (cd cdb; make)
% ruby extconf.rb
% make
% strip cdb.so  (optional)
% su root -c 'make site-install'

done.

Note for Linux users

If you are using Linux, you may encounter errors like this.

./load cdbget cdb.a buffer.a unix.a byte.a 
cdb.a(cdb.o)(.text+0x11e):cdb.c: undefined reference to `_errno'
cdb.a(cdb.o)(.text+0x19b):cdb.c: undefined reference to `_errno'

If this is your case, try adding gcc -include option.

% echo gcc -O2 -include /usr/include/errno.h > cdb/conf-cc
% (cd cdb; make)

See following URLs for details.

 http://cr.yp.to/docs/unixport.html#errno
 http://www.thedjbway.org/errno.html

Reporting Bugs

If you find bugs, please contact <okahashi@gmail.com>.

Usage

• class CDB

  obj = CDB.new(file)

  open file and setup it as a CDB object.
  

  CDB.open(file) {|obj| .. }

  same as:
  
  obj = CDB.new(file)
  begin
    ..
  ensure
    obj.close
  end
  

  CDB.each(file) {|key, data| .. }

  same as:
  
  CDB.open(file) {|obj|
    obj.each {|key, data|
      ..
    }
  }
  

  CDB.each(file, key) {|data| .. }

  same as:
  
  CDB.open(file) {|obj|
    obj.each(key) {|data|
      ..
    }
  }
  

  CDB.create(file, tmp, mode = 0644) {|obj| .. }

  same as:
  
  CDBMake.open(tmp, mode) {|obj|
    ..
  }
  File.rename(tmp, file)
  

  CDB.edit(file, tmp, mode = nil) {|ary| .. }

  open and read file <file>, yield block with an associative array
  <ary>, write updated <ary> to <tmp> as cdb, and rename <tmp> to
  <file>.  (<ary> = [ [key, data], [key, data] .. ])
  If <mode> is unspecified, File.stat(file).mode is used.
  
  Note that in case <file> contains a large amount of data, they
  are all read into memory (<ary>).  If this is not preferable,
  using CDB.update or class CDBMake directly is recommended.
  

  CDB.update(file, tmp, mode = nil) {|read, write| .. }

  same as:
  
  CDB.open(file) {|read|
    CDBMake.open(tmp, mode) {|write|
      ..
    }
  }
  File.rename(tmp, file)
  
  If <mode> is unspecified, File.stat(file).mode is used.
  

  CDB.dump(file)

  dump cdb data in cdbdump(1) format.
  

  obj.find(key) obj

  return the first data associated with <key>.
  

  obj.each {|key, data| .. }

  iterate over data in whole database.
  

  obj.each(key) {|data| .. }

  iterate over data associated with <key>.
  

  obj.close

  unmmap and close file.
  

  obj.read(pos, len)

  read <len> bytes from the byte position <pos> in the database.
  Since file size check is not performed for now, too large arguments
  may cause segmentation fault.
  

• class CDBMake

  obj = CDBMake.new(file, mode = 0644)

  open write-only file <file>.  <mode> is passed to open(2).
  

  CDBMake.open(file, mode = 0644) {|obj| .. }

  same as:
  
  obj = CDBMake.new(file, mode)
  begin
    ..
  ensure
    obj.finish
  end
  

  obj.add(key, data) obj = data

  store <data> under <key> in the database.  Note that multiple
  calls with the same <key> DO NOT override former data.
  

  obj.finish

  sync added data to the disk and close file.