Re: [cx-oracle-users] Wheels again

[Anthony T. <ant...@gm...>]

Thanks for these suggestions. It will take some time to consider which
approach to take. I'll reply back again when I have a positive decision
made.

One concern that eliminates a few of these possibilities is portability.
cx_Oracle runs on more than just Windows so Windows-specific code/concepts
can't be used. Creating differently named modules (for client version) or
creating a wrapper module that imports the right sub-module at run-time are
the two top choices I am considering right now. If anyone else has any
thoughts on which approach would be best to take, I'd love to hear from you.

Anthony

On Thu, Apr 21, 2016 at 7:24 PM, Kubo Takehiro <ku...@ji...> wrote:

> Hi,
>
> I know a little about python and nothing about wheels.
> However I have three ideas.
>
> 1. Distribute cx_Oracle compiled for Oracle 10g.
>
> Oracle client library ABI keeps backward compatibility on Windows.
> When a binary file is compiled for Oracle 10g, it works with Oracle
> 10g, 11g and 12c.
> However it cannot use features depends on Oracle 11g and 12c clients.
>
> 2. Check Oracle client version at runtime.
>
> This is ideal for pre-compiled packages but not practical because this
> needs
> too many changes in cx_Oracle.
>
> Add the following code to Module_Initialize() in cx_Oracle.c
>
>    HMODULE hMod = GetModuleHandle("OCI.DLL");
>    void (*func)(sword*, sword*, sword*, sword*, sword*) = (void
> (*)(sword*, sword*, sword*, sword*, sword*))GetProcAddress(hMod,
> "OCIClientVersion");
>    if (func == NULL) {
>      oracle_version_hex = ORACLE_VERSION(10, 1)
>    } else {
>      sword major, minor, update, patch, port;
>      (*func)(&major, &minor, &update, &patch, &port);
>      oracle_version_hex = ORACLE_VERSION(major, minor);
>    }
>
> and rewrite code such as
>     #if ORACLE_VERSION_HEX >= ORACLE_VERSION(11,1)
>       ...
>     #endif
> to
>     if (oracle_client_hex >= ORACLE_VERSION(11,1)) {
>       ...
>     }
>
> Use function pointers retrieved by GetProcAddress() for functions
> added in Oracle 11g and 12c,
>
> 3. Add a bootstrap module if wheels can include more than one module.
>
> Compile cx_Oracle for Oracle 10.1, 10.2, 11.1, 11.2 and 12.1 and rename
> them
> to cx_Oracle.10.1.dll, cx_Oracle.10.2.dll, cx_Oracle.11.1.dll,
> cx_Oracle.11.2.dll and cx_Oracle.12.1.dll respectively.
>
> Compile the following code as cx_Oracle.dll.
>
>     // This is incomplete code. no error checks.
>
>     typedef int sword;
>
>     static void *get_init_func(const char *init_func_name)
>     {
>       HMODULE hMod;
>       void (*func)(sword*, sword*, sword*, sword*, sword*);
>       char dll_name[30];
>       char dll_full_path[MAX_PATH];
>
>       // Get the Oracle client version and fill dll_name.
>       hMod = LoadLibrary("OCI.DLL");
>       func = (void (*)(sword*, sword*, sword*, sword*,
> sword*))GetProcAddress(hMod, "OCIClientVersion");
>       if (func == NULL) {
>         strcpy(dll_name, "cx_Oracle.10.1.dll");
>       } else {
>         sword major, minor, update, patch, port;
>         (*func)(&major, &minor, &update, &patch, &port);
>         sprintf(dll_name, "cx_Oracle.%d.%d.dll", major, minor);
>       }
>       FreeLibrary(hMod);
>
>       // get the current module handle.
>       GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
> &get_init_func, &hMod);
>       ...  fill dll_full_path with the directory name containing the
> current module by using GetModuleFileName(hMod, ...).
>       ...  append dll_name to dll_full_path.
>
>       // Load the real cx_Oracle module and get the module initializer
> function.
>       hMod = LoadLibrary(dll_full_path);
>       return GetProcAddress(hMod, init_func_name);
>     }
>
>     #if PY_MAJOR_VERSION >= 3
>     PyMODINIT_FUNC PyInit_cx_Oracle(void)
>     {
>       PyObject *(*init)(void) =
> (PyObject*(*)(void))get_init_func("PyInit_cx_Oracle");
>       return (*init)();
>     }
>     #else
>     void initcx_Oracle(void)
>     {
>       void (*init)(void) = (void(*)(void))get_init_func("initcx_Oracle");
>       (*init)();
>     }
>     #endif
>
>
> Put cx_Oracle.dll, cx_Oracle.10.1.dll, cx_Oracle.10.2.dll,
> cx_Oracle.11.1.dll, cx_Oracle.11.2.dll
> and cx_Oracle.12.1.dll in a directory.
>
>
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