Building — APSW 3.8.11.1-r1 documentation

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# Building

## setup.py

Short story: You run `setup.py` but you should ideally follow the recommended way which will also fetch needed components for you.

Command | Result
--- | ---
python setup.py install test | Compiles APSW with default Python compiler, installs it into Python site library directory and then runs the test suite.
python setup.py install --user | (Python 2.6+, 3). Compiles APSW with default Python compiler and installs it into a subdirectory of your home directory. See PEP 370 for more details.
python setup.py build --compile=mingw32 install | On Windows this will use the free MinGW compiler instead of the Microsoft compilers.
python setup.py build_ext --force --inplace test | Compiles the extension but doesn’t install it. The resulting file will be in the current directory named apsw.so (Unix/Mac) or apsw.pyd (Windows). The test suite is then run. (Note on recent versions of CPython the extension filenames may be more complicated due to PEP 3149.)
python setup.py build --debug install | Compiles APSW with debug information. This also turns on assertions in APSW that double check the code assumptions. If you are using the SQLite amalgamation then assertions are turned on in that too. Note that this will considerably slow down APSW and SQLite.

## Additional `setup.py` flags

There are a number of APSW specific flags to commands you can specify.

### fetch

`setup.py` can automatically fetch SQLite and other optional components. You can set the environment variable `http_proxy` to control proxy usage for the download. Note the files downloaded are modified from their originals to ensure various names do not clash, adjust them to the download platform and to graft them cleanly into the APSW module. You should not commit them to source code control systems (download seperately if you need clean files).

If any files are downloaded then the build step will automatically use them. This still applies when you do later builds without re-fetching.

> python setup.py fetch options

fetch flag | Result
--- | ---
--version=VERSION | By default the SQLite download page is consulted to find the current SQLite version which you can override using this flag. Note You can also specify fossil as the version and the current development version from SQLite’s source tracking system will be used. (The system is named Fossil.) Note that checksums can’t be checked for fossil. You will also need TCL and make installed for the amalgamation to build as well as several other common Unix tools. (ie this is very unlikely to work on Windows.)
--missing-checksum-ok | Allows setup to continue if the checksum is missing.
--all | Gets all components listed below.
--sqlite | Automatically downloads the SQLite amalgamation. The amalgamation is the preferred way to use SQLite as you have total control over what components are included or excluded (see below) and have no dependencies on any existing libraries on your developer or deployment machines. The amalgamation includes the fts3, rtree and icu extensions. On non-Windows platforms, any existing `sqlite3/` directory will be erased and the downloaded code placed in a newly created `sqlite3/` directory.
--asyncvfs | Downloads the Asynchronous VFS

Note

The SQLite downloads are not digitally signed which means you have no way of verifying they were produced by the SQLite team or were not modified between the SQLite servers and your computer.

Consequently APSW ships with a checksums file that includes checksums for the various SQLite downloads. If the download does not match the checksum then it is rejected and an error occurs.

The SQLite download page is not checksummed, so in theory a bad guy could modify it to point at a malicious download version instead. (setup only uses the page to determine the current version number - the SQLite download site URL is hard coded.)

If the URL is not listed in the checksums file then setup aborts. You can use --missing-checksum-ok to continue. You are recommended instead to update the checksums file with the correct information.

Note

(This note only applies to non-Windows platforms.) By default the amalgamation will work on your platform. It detects the operating system (and compiler if relevant) and uses the appropriate APIs. However it then only uses the oldest known working APIs. For example it will use the sleep system call. More recent APIs may exist but the amalgamation needs to be told they exist. As an example sleep can only sleep in increments of one second while the usleep system call can sleep in increments of one microsecond. The default SQLite busy handler does small sleeps (eg 1/50th of a second) backing off as needed. If sleep is used then those will all be a minimum of a second. A second example is that the traditional APIs for getting time information are not re-entrant and cannot be used concurrently from multiple threads. Consequently SQLite has mutexes to ensure that concurrent calls do not happen. However you can tell it you have more recent re-entrant versions of the calls and it won’t need to bother with the mutexes.

After fetching the amalgamation, setup automatically determines what new APIs you have by running the `configure` script that comes with SQLite and noting the output. The information is placed in `sqlite3/sqlite3config.h`. The build stage will automatically take note of this as needed.

If you get the fossil version then the configure script does not work. Instead the fetch will save and re-use any pre-existing `sqlite3/sqlite3config.h`.

### build/build_ext

You can enable or omit certain functionality by specifying flags to the build and/or build_ext commands of `setup.py`.

> python setup.py build options

Note that the options do not accumulate. If you want to specify multiple enables or omits then you need to give the flag once and giving a comma seperated list. For example:

> python setup.py build --enable=fts3,fts3_parenthesis,rtree,icu

build/build_ext flag | Result
--- | ---
--enable-all-extensions | Enables the STAT4, FTS3/4, RTree, and ICU extensions if icu-config is on your path
--enable=fts3 --enable=fts4 | Enables the full text search extension. This flag only helps when using the amalgamation. If not using the amalgamation then you need to seperately ensure fts3/4 is enabled in the SQLite install. You are likely to want the parenthesis option on unless you have legacy code (–enable-all-extensions turns it on).
--enable=rtree | Enables the spatial table extension. This flag only helps when using the amalgamation. If not using the amalgamation then you need to seperately ensure rtree is enabled in the SQLite install.
--enable=icu | Enables the International Components for Unicode extension. Note that you must have the ICU libraries on your machine which setup will automatically try to find using `icu-config`. This flag only helps when using the amalgamation. If not using the amalgamation then you need to seperately ensure ICU is enabled in the SQLite install.
--omit=ITEM | Causes various functionality to be omitted. For example --omit=load_extension will omit code to do with loading extensions. If using the amalgamation then this will omit the functionality from APSW and SQLite, otherwise the functionality will only be omitted from APSW (ie the code will still be in SQLite, APSW just won’t call it). In almost all cases you will need to regenerate the SQLite source because the omits also alter the generated SQL parser. See the relevant SQLite documentation.

Note

Extension loading is enabled by default when using the amalgamation and disabled when using existing libraries as this most closely matches current practise. Use --omit=load_extension or --enable=load_extension to explicity disable/enable the extension loading code.

## Finding SQLite 3

SQLite 3 is needed during the build process. If you specify fetch --sqlite to the `setup.py` command line then it will automatically fetch the current version of the SQLite amalgamation. (The current version is determined by parsing the SQLite download page). You can manually specify the version, for example fetch --sqlite --version=3.7.4.

These methods are tried in order:

> Amalgamation

> > The file `sqlite3.c` and then `sqlite3/sqlite3.c` is looked for. The SQLite code is then statically compiled into the APSW extension and is invisible to the rest of the process. There are no runtime library dependencies on SQLite as a result. When you use fetch this is where it places the downloaded amalgamation.

> Local build

> > The header `sqlite3/sqlite3.h` and library `sqlite3/libsqlite3.a,so,dll` is looked for.

> User directories

> > If you are using Python 2.6+ or Python 3 and specified --user then your user directory is searched first. See PEP 370 for more details.

> System directories

> > The default compiler include path (eg `/usr/include`) and library path (eg `/usr/lib`) are used.

Note

If you compiled SQLite with any OMIT flags (eg `SQLITE_OMIT_LOAD_EXTENSION`) then you must include them in the `setup.py` command or file. For this example you could use setup.py build --omit=load_extension to add the same flags.

## Recommended

These instructions show how to build automatically downloading and using the amalgamation plus other Extensions. Any existing SQLite on your system is ignored at build time and runtime. (Note that you can even use APSW in the same process as a different SQLite is used by other libraries - this happens a lot on Mac.) You should follow these instructions with your current directory being where you extracted the APSW source to.

> Windows:

>       # Leave out --compile=mingw32 flag if using Microsoft compiler
>     > python setup.py fetch --all build --enable-all-extensions --compile=mingw32 install test

> Mac/Linux etc:

>     $ python setup.py fetch --all build --enable-all-extensions install test

Note

There will be some warnings during the compilation step about sqlite3.c, but they are harmless

The extension just turns into a single file apsw.so (Linux/Mac) or apsw.pyd (Windows). (More complicated name on Pythons implementing PEP 3149). You don’t need to install it and can drop it into any directory that is more convenient for you and that your code can reach. To just do the build and not install, leave out install from the lines above. (Use build_ext –inplace to have the extension put in the main directory.)

The test suite will be run. It will print the APSW file used, APSW and SQLite versions and then run lots of tests all of which should pass.

## Source distribution (advanced)

If you want to make a source distribution or a binary distribution that creates an intermediate source distribution such as bdist_rpm then you can have the SQLite amalgamation automatically included as part of it. If you specify the fetch command as part of the same command line then everything fetched is included in the source distribution. For example this will fetch all components, include them in the source distribution and build a rpm using those components:

    $ python setup.py fetch --all bdist_rpm

## Testing

SQLite itself is extensively tested. It has considerably more code dedicated to testing than makes up the actual database functionality.

APSW includes a `tests.py` file which uses the standard Python testing modules to verify correct operation. New code is developed alongside the tests. Reported issues also have test cases to ensure the issue doesn’t happen or doesn’t happen again.:

    $ python setup.py test
                   Python /usr/bin/python (2, 6, 6, 'final', 0)
    Testing with APSW file /space/apsw/apsw.so
              APSW version 3.7.4-r1
        SQLite lib version 3.7.4
    SQLite headers version 3007004
        Using amalgamation True
    ............................................................................
    ----------------------------------------------------------------------
    Ran 76 tests in 404.557s

    OK

The tests also ensure that as much APSW code as possible is executed including alternate paths through the code. 95.5% of the APSW code is executed by the tests. If you checkout the APSW source then there is a script tools/coverage.sh that enables extra code that deliberately induces extra conditions such as memory allocation failures, SQLite returning undocumented error codes etc. That brings coverage up to 99.6% of the code.

A memory checker Valgrind is used while running the test suite. The test suite is run multiple times to make any memory leaks or similar issues stand out. A checking version of Python is also used. See tools/valgrind.sh in the source.

To ensure compatibility with the various Python versions, a script downloads and compiles all supported Python versions in both 2 byte and 4 byte Unicode character configurations against the APSW and SQLite supported versions running the tests. See tools/megatest.py in the source.

In short both SQLite and APSW have a lot of testing!

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