Ruby Binding of Tokyo Cabinet

Tokyo Cabinet: a modern implementation of DBM

INTRODUCTION

Tokyo Cabinet is a library of routines for managing a database. The database is a simple data file containing records, each is a pair of a key and a value. Every key and value is serial bytes with variable length. Both binary data and character string can be used as a key and a value. There is neither concept of data tables nor data types. Records are organized in hash table, B+ tree, or fixed-length array.

As for database of hash table, each key must be unique within a database, so it is impossible to store two or more records with a key overlaps. The following access methods are provided to the database: storing a record with a key and a value, deleting a record by a key, retrieving a record by a key. Moreover, traversal access to every key are provided, although the order is arbitrary. These access methods are similar to ones of DBM (or its followers: NDBM and GDBM) library defined in the UNIX standard. Tokyo Cabinet is an alternative for DBM because of its higher performance.

As for database of B+ tree, records whose keys are duplicated can be stored. Access methods of storing, deleting, and retrieving are provided as with the database of hash table. Records are stored in order by a comparison function assigned by a user. It is possible to access each record with the cursor in ascending or descending order. According to this mechanism, forward matching search for strings and range search for integers are realized.

As for database of fixed-length array, records are stored with unique natural numbers. It is impossible to store two or more records with a key overlaps. Moreover, the length of each record is limited by the specified length. Provided operations are the same as ones of hash database.

Table database is also provided as a variant of hash database. Each record is identified by the primary key and has a set of named columns. Although there is no concept of data schema, it is possible to search for records with complex conditions efficiently by using indices of arbitrary columns.

Setting

Install the latest version of Tokyo Cabinet beforehand and get the package of the Ruby binding of Tokyo Cabinet.

Enter the directory of the extracted package then perform installation.

ruby extconf.rb
make
su
make install

The package tokyocabinet should be loaded in each source file of application programs.

require 'tokyocabinet'

All symbols of Tokyo Cabinet are defined in the module TokyoCabinet. You can access them without any prefix by including the module.

include TokyoCabinet

EXAMPLE

The following code is an example to use a hash database.

require 'tokyocabinet'
include TokyoCabinet

# create the object
hdb = HDB::new

# open the database
if !hdb.open("casket.tch", HDB::OWRITER | HDB::OCREAT)
  ecode = hdb.ecode
  STDERR.printf("open error: %s\n", hdb.errmsg(ecode))
end

# store records
if !hdb.put("foo", "hop") ||
    !hdb.put("bar", "step") ||
    !hdb.put("baz", "jump")
  ecode = hdb.ecode
  STDERR.printf("put error: %s\n", hdb.errmsg(ecode))
end

# retrieve records
value = hdb.get("foo")
if value
  printf("%s\n", value)
else
  ecode = hdb.ecode
  STDERR.printf("get error: %s\n", hdb.errmsg(ecode))
end

# traverse records
hdb.iterinit
while key = hdb.iternext
  value = hdb.get(key)
  if value
    printf("%s:%s\n", key, value)
  end
end

# hash-like usage
hdb["quux"] = "touchdown"
printf("%s\n", hdb["quux"])
hdb.each do |key, value|
  printf("%s:%s\n", key, value)
end

# close the database
if !hdb.close
  ecode = hdb.ecode
  STDERR.printf("close error: %s\n", hdb.errmsg(ecode))
end

The following code is an example to use a B+ tree database.

require 'tokyocabinet'
include TokyoCabinet

# create the object
bdb = BDB::new

# open the database
if !bdb.open("casket.tcb", BDB::OWRITER | BDB::OCREAT)
  ecode = bdb.ecode
  STDERR.printf("open error: %s\n", bdb.errmsg(ecode))
end

# store records
if !bdb.put("foo", "hop") ||
    !bdb.put("bar", "step") ||
    !bdb.put("baz", "jump")
  ecode = bdb.ecode
  STDERR.printf("put error: %s\n", bdb.errmsg(ecode))
end

# retrieve records
value = bdb.get("foo")
if value
  printf("%s\n", value)
else
  ecode = bdb.ecode
  STDERR.printf("get error: %s\n", bdb.errmsg(ecode))
end

# traverse records
cur = BDBCUR::new(bdb)
cur.first
while key = cur.key
  value = cur.val
  if value
    printf("%s:%s\n", key, value)
  end
  cur.next
end

# hash-like usage
bdb["quux"] = "touchdown"
printf("%s\n", bdb["quux"])
bdb.each do |key, value|
  printf("%s:%s\n", key, value)
end

# close the database
if !bdb.close
  ecode = bdb.ecode
  STDERR.printf("close error: %s\n", bdb.errmsg(ecode))
end

The following code is an example to use a fixed-length database.

require 'tokyocabinet'
include TokyoCabinet

# create the object
fdb = FDB::new

# open the database
if !fdb.open("casket.tcf", FDB::OWRITER | FDB::OCREAT)
  ecode = fdb.ecode
  STDERR.printf("open error: %s\n", fdb.errmsg(ecode))
end

# store records
if !fdb.put(1, "one") ||
    !fdb.put(12, "twelve") ||
    !fdb.put(144, "one forty four")
  ecode = fdb.ecode
  STDERR.printf("put error: %s\n", fdb.errmsg(ecode))
end

# retrieve records
value = fdb.get(1)
if value
  printf("%s\n", value)
else
  ecode = fdb.ecode
  STDERR.printf("get error: %s\n", fdb.errmsg(ecode))
end

# traverse records
fdb.iterinit
while key = fdb.iternext
  value = fdb.get(key)
  if value
    printf("%s:%s\n", key, value)
  end
end

# hash-like usage
fdb[1728] = "seventeen twenty eight"
printf("%s\n", fdb[1728])
fdb.each do |key, value|
  printf("%s:%s\n", key, value)
end

# close the database
if !fdb.close
  ecode = fdb.ecode
  STDERR.printf("close error: %s\n", fdb.errmsg(ecode))
end

The following code is an example to use a table database.

require 'tokyocabinet'
include TokyoCabinet

# create the object
tdb = TDB::new

# open the database
if !tdb.open("casket.tct", TDB::OWRITER | TDB::OCREAT)
  ecode = tdb.ecode
  STDERR.printf("open error: %s\n", tdb.errmsg(ecode))
end

# store a record
pkey = tdb.genuid
cols = { "name" => "mikio", "age" => "30", "lang" => "ja,en,c" }
if !tdb.put(pkey, cols)
  ecode = tdb.ecode
  STDERR.printf("get error: %s\n", tdb.errmsg(ecode))
end

# store another record
cols = { "name" => "falcon", "age" => "31", "lang" => "ja", "skill" => "cook,blog" }
if !tdb.put("x12345", cols)
  ecode = tdb.ecode
  STDERR.printf("get error: %s\n", tdb.errmsg(ecode))
end

# search for records
qry = TDBQRY::new(tdb)
qry.addcond("age", TDBQRY::QCNUMGE, "20")
qry.addcond("lang", TDBQRY::QCSTROR, "ja,en")
qry.setorder("name", TDBQRY::QOSTRASC)
qry.setlimit(10)
res = qry.search
res.each do |rkey|
  rcols = tdb.get(rkey)
  printf("name:%s\n", rcols["name"])
end

# hash-like usage
tdb["joker"] = { "name" => "ozma", "lang" => "en", "skill" => "song,dance" }
printf("%s\n", tdb["joker"]["name"])
tdb.each do |key, value|
  printf("%s:%s\n", key, value["name"])
end

# close the database
if !tdb.close
  ecode = tdb.ecode
  STDERR.printf("close error: %s\n", tdb.errmsg(ecode))
end

The following code is an example to use an abstract database.

require 'tokyocabinet'
include TokyoCabinet

# create the object
adb = ADB::new

# open the database
if !adb.open("casket.tch")
  STDERR.printf("open error\n")
end

# store records
if !adb.put("foo", "hop") ||
    !adb.put("bar", "step") ||
    !adb.put("baz", "jump")
  STDERR.printf("put error\n")
end

# retrieve records
value = adb.get("foo")
if value
  printf("%s\n", value)
else
  STDERR.printf("get error\n")
end

# traverse records
adb.iterinit
while key = adb.iternext
  value = adb.get(key)
  if value
    printf("%s:%s\n", key, value)
  end
end

# hash-like usage
adb["quux"] = "touchdown"
printf("%s\n", adb["quux"])
adb.each do |key, value|
  printf("%s:%s\n", key, value)
end

# close the database
if !adb.close
  STDERR.printf("close error\n")
end

LICENSE

Copyright (C) 2006-2010 FAL Labs
All rights reserved.

Tokyo Cabinet is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License or any later version.  Tokyo Cabinet is distributed in the
hope that it will be useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.  See the GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with Tokyo Cabinet; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA.