Overview

Description

WB is a disk based (sorted) associative-array package providing C, SCM, Java, and C# libraries. These associative arrays consist of variable length (0.B to 255.B) keys and values. Functions are provided to:

• create, destroy, open and close disk-files and associative arrays;
• insert, delete, retrieve, find next, and find previous (with respect to dictionary order of keys); and
• The atomic `put' and `rem' operations allow associations to be used for process mutexs.
• apply functions, delete, or modify values over a range of consecutive key values.

The (database) disk files interoperate between the various language libraries. The interface to the SCM Scheme implementation supports longer data values and SLIB relational databases. WB, SCM, and SLIB are packages of the GNU project.

The WB implementation has a file size limit of 2^32 * block size (default 2048.B) = 2^43 bytes (8796.GB). WB routinely runs with databases of several hundred Megabytes. WB does its own memory and disk management and maintains a RAM cache of recently used blocks.

Multiple associative arrays can reside in one disk file. Simultaneous access to multiple disk files is supported. A structure checking and garbage collecting program and a viewer are provided. Compiled, WB occupies approximately 66 kilobytes.

WB is implemented using a variant of B-tree structure. B-trees give slower access than hashing but are dynamic and provide an efficient determination of successor and predecessor keys. All operations are O(log(n)) in the size of the database. B-trees are commonly used by database systems for implementing index structures. B-trees are optimized for using the minimum number of disk operations for large data structures. Prefix and suffix key compression are used for storage efficiency in WB.

History

The origination of B-trees is credited to [BM72] R. Bayer and E. McCreight in 1972.

Working at Holland Mark Martin between 1991 and 1993, Roland Zito-Wolf, Jonathan Finger, and I (Aubrey Jaffer) wrote the Wanna B-tree system.

Jonathan Finger wrote a MUMPS-like byte-coded interpreter Sliced Bread using WB. The integrated system was heavily used by Holland Mark Martin for the rest of the decade.

In 1994 I wrote a Scheme implementation of the relational model with an independent object-oriented base-table layer for SLIB:

In 1996 Holland Mark Martin assigned the copyriht for WB to the Free Software Foundation. I released WB as a library for C and SCM. I also wrote `wbtab.scm', a base-table interface enabling SLIB's relational database to be backed by WB.

In 2002 I added color dictionary relational databases to SLIB.

In 2003 I added next and previous operations to the SLIB relational package, and wrote `rwb-isam.scm' for WB.

In 2004 I wrote FreeSnell, a program to compute optical properties of multilayer thin-film coatings. At the core of FreeSnell is a rwb-isam spectral refractive-index database for over 300 materials.

In 2006 I decided to reimplement ClearMethods' Water language on top of WB. In 2007, in order to make Water available on the great majority of browsers and servers, Ravi Gorrepati adapted Schlep (the SCM to C translator) to make translators to Java and C#. He also ported the support files and test programs to Java and C#.

I continue to maintain WB. The most recent information about WB can be found on WB's WWW home page:

File Organization

The source files for WB are written in the SCM dialect of Scheme:

`wbdefs.scm'

SCM configuration definitions.

`segs.scm'

`handle.scm'

`blink.scm'

`prev.scm'

`del.scm'

`ents.scm'

`scan.scm'

`stats.scm'

SCM code for WB-trees.

`blkio.scm'

wimpy POSIX interface to the disk. Replace this if you have a more direct interface to the disk.

These files are translated into the C, C#, and Java targets by SCM scripts named schlep, scm2cs, and scm2java respectively. The function and variable data types in the target languages are determined by pattern-matching the first-element strings in the associations schlep.typ, scm2cs.typ, and scm2java.typ respectively.

Files translated to C are put into the `wb/' directory. Files translated to Java are put into the `wb/java/' directory. Files translated to C# are concatenated with `wb/csharp/Cssys.cs' and `wb/csharp/Utils.cs' and written to `wb/csharp/Wb.cs'.

In the `Makefile':

`s2hfiles'

Derived *.h files for C.

`s2cfiles'

Derived *.c files for C.

`s2jfiles'

Derived java/*.java files for Java.

`csharp/Wb.cs'

Single derived source file for C#.

WB comes with a C utility program for database files stored on disk.

Program: wbcheck path

Checks the structure of the database named by path and reclaims temporary trees to the freelist.

Manifest

`wb.info'

documents the theory, data formats, and algorithms; the C and SCM interfaces to WB-tree.

`ChangeLog'

documents changes to the WB.

`example.scm'

example program using WB-tree in SCM.

`wbsys.h'

The primary C include file for using the WB layer is is wbsys.h, which includes several other files from the directory. wbsys.h also defines WB's internal data types.

`wbsys.c'

Shared data and low-level C accessors.

`wbsys.scm'

Shared data and low-level accessors for debugging in SCM.

`db.c'

C code for the SCM interface to WB-trees.

`db.scm'

code for SCM interface when debugging in SCM.

`schlep.scm'

SCM code which translates SCM code into C.

`schlep.typ'

rules relating variable names to types in generated C.

`scm2cs.scm'

SCM code which translates SCM code into C#.

`scm2cs.typ'

rules relating variable names to types in generated C#.

`scm2java.scm'

SCM code which translates SCM code into Java.

`scm2java.typ'

rules relating variable names to types in generated Java.

`test.scm'

file for testing WB-tree system.

`test2.scm'

more tests for WB-tree system.

`Makefile'

Unix makefile

`VMSBUILD.COM'

command script for compiling under VMS.

`all.scm'

loads all the SCM files for debugging.

`wbtab.scm'

SCM code allowing WB to implement SLIB relational databases.

`rwb-isam.scm'

SCM code allowing WB to implement SLIB relational databases with numerical and lexicographic key collations.

`wbcheck.c'

program for checking, repairing, and garbage collecting WB-tree databases.

`wbview'

SCM script for displaying low-level WB database associations.

Installation

WB unpacks into a directory called `wb'.

If you plan to use WB with SCM, the directories `scm' and `wb' should be in the same directory. Doing `make db.so' in the scm directory compiles a dynamically linkable object file from the WB C source. Including the `-F wb' option to an executable build compiles the WB interface into the executable. It is not necessary to compile anything in `wb' directory.

make all

Compiles `libwb', `wbscm.so', `java/wb.jar', `csharp/Wb.dll' and the `wbcheck' executable.

make install

Installs `libwb', `wbscm.so', `java/wb.jar', and `wbcheck' in the $(prefix) tree, as assigned in the `Makefile'.

Building from Scheme Sources

Scheme Infrastructure

SCM source is available from: http://swiss.csail.mit.edu/ftpdir/scm/scm-5e5.zip or ftp://swiss.csail.mit.edu/pub/scm/scm-5e5.zip

Also available as source RPM: http://swiss.csail.mit.edu/ftpdir/scm/scm-5e5-1.src.rpm or ftp://swiss.csail.mit.edu/pub/scm/scm-5e5-1.src.rpm

SLIB is a portable Scheme library which SCM uses: http://swiss.csail.mit.edu/ftpdir/scm/slib-3b1.zip or ftp://swiss.csail.mit.edu/pub/scm/slib-3b1.zip

Also available as RPM: http://swiss.csail.mit.edu/ftpdir/scm/slib-3b1-1.noarch.rpm or ftp://swiss.csail.mit.edu/pub/scm/slib-3b1-1.noarch.rpm

Testing Scheme Source

From the wb directory, do `scm all test'. This will load the Scheme version of WB-tree with test code. Typing `(main)' will construct a test database `z' in this directory. If this runs without errors then you are ready to build the C code. Exit from scm with `(quit)'.

Regenerating C Sources.

make all

Testing Compiled DBSCM

Run `scm -rwb -ltest'. This should build the test database `z' much more quickly than before.

Type `(quit)' to exit from DBSCM. Now run `./wbcheck z'. This will check the structure of the database and collect temporary files. This should reclaim 52 blocks and report no errors. If you run it again, no blocks will be collected.

License

This program 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 3 of the License, or (at your option) any later version.

This program 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 this program. If not, see <http://www.gnu.org/licenses/>.

GNU Free Documentation License

Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA

Everyone is permitted to copy and distribute verbatim copies
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ADDENDUM: How to use this License for your documents

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