wiki:Packages/SQLite

Version 35 (modified by C Rempel, on Jun 27, 2012 at 6:32:57 AM) (diff)

/* End of Report */

SQLite

Status: Exploratory

SQLite was originally designed to be an embedded database for on-board guided missile destroyers, for the US Navy The Definitive Guide to Sqlite By Michael Owens. Unlike many database program, SQLite is designed to be an itegral part of the embedded system. SQLite doesn't use interprocess communication, which makes it much faster than a database system that does.

Porting SQLite to RTEMS

This is a very rough first stab at porting SQLite to RTEMS. It's designed to help a developer that might be interested in designing the RTEMS_DBKit...

Note: there is room to port a stable release...

I also used the RTEMS Addon Packages to get the necessary configurations to build on rtems.

Development Repository Editon SQLite

To build SQLite from the development repository, you need TCL and fossil. TCL is part of the SQLite build system, while fossil is another version control system.

~$ sudo apt-get install tcl8.5 fossil

SQLite uses fossil for their development branch, so if you use their development branch, you have some steps to go through:

First, check out a "fossil" which is a single file with all the information

~/rtems-addon-packages$ fossil clone http://www.sqlite.org/cgi/src/dir trunk.fossil

Second, make and navigate into an sqlite directory:

~/rtems-addon-packages$ mkdir sqlite ~/rtems-addon-packages$ cd sqlite

Third, open the fossil file

~/rtems-addon-packages/sqlite$ fossil open ../trunk.fossil

Fourth, archive the sqlite folder (so you have an old copy to fall back on)...

~/rtems-addon-packages/sqlite$ cd .. ~/rtems-addon-packages$ tar -acf sqlite.fossil.tar.bz2 sqlite

DO NOT close the fossil file! It will remove manifest.uuid and not compile!

Makefile.sqlite

Just figured out how to get SQLite to compile! First, the sqlite command shell executable may NOT be necessary, which bypasses the need to figure out how to implement popen and pclose. To NOT build the command shell executable, I looked at the Makefile, and built the non sqlite3 make targets. Namely, lib_intall, and the sqlite3.h.

To avoid sys/mman.h dependency, I looked for sys/mman.h

$ grep -r "sys\/mman.h" rtems-addon-packages/sqlite

and found that defining SQLITE_OMIT_WAL would eliminate the mmap/munmap dependency.

I copied the Makefile below into rtems-addon-packages/RTEMS_Makefiles/Makefile.sqlite

#
# Configure/build/install the sqlite library
# -DSQLITE_OMIT_WAL removes mman dependency
# -DSQLITE_ENABLE_COLUMN_METADATA taken from sqlite/mkso.sh
# --disable-largefile makes a library for a 32-bit target on a 64-bit host
# --disable-amalgamation keeps the source code in separate files for the build
# copy the public header to the include directory
# finally, install the library

include ../RTEMS_Makefiles/Makefile.common

all:
	CFLAGS='-DSQLITE_OMIT_WAL=1 DSQLITE_ENABLE_COLUMN_METADATA=1'
	../sqlite/configure \
		--prefix=$(exec_prefix) \
		--build=i686-linux-gnu \
		--host=i386-rtems4.11 \
		--disable-largefile \
		--enable-cross-thread-connections \
		--disable-tcl \
		--disable-readline \
		--disable-amalgamation \
		--libdir=$(exec_prefix)/$(RTEMS_BSP)/lib \
		--includedir=$(exec_prefix)/$(RTEMS_BSP)/lib/include
	make sqlite3.h libsqlite3.la
	cp sqlite3.h $(exec_prefix)/$(RTEMS_BSP)/lib/include
	make lib_install

Testing Ideas

Originally I thought it would be necessary to define a src/os_rtems.c because of issues with shared memory support, and thus would need to use the network filesystem, but as that is no longer an issue, I would suggest using one of the network-demos with a filesystem as a code-base to copy and the SQLite quickstart guide as guideline for the database demo.

Next Steps

# Write an SQLite demo # Work on other database programs in the RTEMS_DBKit

End of Report

I'm truly amazed that SQLite had configurations that removed the multiprocessing, and memory mapping requirements!

= References =