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digitalmars.D - Equivalent of DllMain for OSX dynamic libraries?

reply Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:
Hello,


We've just open-sourced another D project at Facebook (just a developer 
beta), an ODBC driver for the Presto database engine: 
https://github.com/prestodb/presto-odbc.

The Windows version works well now, and Mark Isaacson (the author of the 
driver and incidentally my intern) is working already on the OSX port 
using iODBC. We've hit a number of issues, the most basic one being that 
shared static this() initializers don't seem to be called for our driver.

Could you folks help us out?


Thanks,

Andrei
Jul 25 2014
next sibling parent "Xiaoxi" <xiaoxi 163.com> writes:
On Friday, 25 July 2014 at 22:15:15 UTC, Andrei Alexandrescu 
wrote:

 Hello,


 We've just open-sourced another D project at Facebook (just a 
 developer beta), an ODBC driver for the Presto database engine: 
 https://github.com/prestodb/presto-odbc.

 The Windows version works well now, and Mark Isaacson (the 
 author of the driver and incidentally my intern) is working 
 already on the OSX port using iODBC. We've hit a number of 
 issues, the most basic one being that shared static this() 
 initializers don't seem to be called for our driver.

 Could you folks help us out?


 Thanks,

 Andrei


I found this an interesting read:
http://blogs.embarcadero.com/eboling/2010/01/29/5639
Jul 25 2014
prev sibling next sibling parent reply "Dicebot" <public dicebot.lv> writes:
On Friday, 25 July 2014 at 22:15:15 UTC, Andrei Alexandrescu 
wrote:

 We've just open-sourced another D project at Facebook (just a 
 developer beta), an ODBC driver for the Presto database engine: 
 https://github.com/prestodb/presto-odbc.


Why no D.announce ?
Jul 25 2014
parent Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:
On 7/25/14, 6:42 PM, Dicebot wrote:

 On Friday, 25 July 2014 at 22:15:15 UTC, Andrei Alexandrescu wrote:

 We've just open-sourced another D project at Facebook (just a
 developer beta), an ODBC driver for the Presto database engine:
 https://github.com/prestodb/presto-odbc.


 Why no D.announce ?


It's just a developer beta, we don't want to make a splash about it. -- 
Andrei
Jul 25 2014
prev sibling next sibling parent reply "Jacob Carlborg" <doob me.com> writes:
On Friday, 25 July 2014 at 22:15:15 UTC, Andrei Alexandrescu 
wrote:


 We've just open-sourced another D project at Facebook (just a 
 developer beta), an ODBC driver for the Presto database engine: 
 https://github.com/prestodb/presto-odbc.

 The Windows version works well now, and Mark Isaacson (the 
 author of the driver and incidentally my intern) is working 
 already on the OSX port using iODBC. We've hit a number of 
 issues, the most basic one being that shared static this() 
 initializers don't seem to be called for our driver.


There is no equivalent to DllMain on OS X or Posix for that 
matter. The closest you get is the GCC/Clang attribute 
__attribute__((constructor)), but that requires using a C file, 
if not LDC or GDC supports that attribute.

Just for the record, dynamic libraries doesn't work yet on OS X 
in D. At least not properly. This might be the reason why shared 
static this() isn't called.

Documentation for dynamic libraries on OS X:

https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/DynamicLibraries/000-Introduction/Introduction.html
Jul 26 2014
next sibling parent reply "Kagamin" <spam here.lot> writes:
On Saturday, 26 July 2014 at 08:37:39 UTC, Jacob Carlborg wrote:

 There is no equivalent to DllMain on OS X or Posix for that 
 matter. The closest you get is the GCC/Clang attribute 
 __attribute__((constructor)), but that requires using a C file, 
 if not LDC or GDC supports that attribute.


Like this? 
http://wiki.dlang.org/LDC-specific_language_changes#LDC_global_crt_ctor_and_LDC_global_crt_dtor
Jul 26 2014
parent Jacob Carlborg <doob me.com> writes:
On 2014-07-26 14:11, Kagamin wrote:


 Like this?
 http://wiki.dlang.org/LDC-specific_language_changes#LDC_global_crt_ctor_and_LDC_global_crt_dtor


I would guess so.

-- 
/Jacob Carlborg
Aug 04 2014
prev sibling parent Iain Buclaw via Digitalmars-d <digitalmars-d puremagic.com> writes:
On 26 July 2014 09:37, Jacob Carlborg via Digitalmars-d
<digitalmars-d puremagic.com> wrote:

 On Friday, 25 July 2014 at 22:15:15 UTC, Andrei Alexandrescu wrote:


 We've just open-sourced another D project at Facebook (just a developer
 beta), an ODBC driver for the Presto database engine:
 https://github.com/prestodb/presto-odbc.

 The Windows version works well now, and Mark Isaacson (the author of the
 driver and incidentally my intern) is working already on the OSX port using
 iODBC. We've hit a number of issues, the most basic one being that shared
 static this() initializers don't seem to be called for our driver.



 There is no equivalent to DllMain on OS X or Posix for that matter. The
 closest you get is the GCC/Clang attribute __attribute__((constructor)), but
 that requires using a C file, if not LDC or GDC supports that attribute.

 Just for the record, dynamic libraries doesn't work yet on OS X in D. At
 least not properly. This might be the reason why shared static this() isn't
 called.



shared static this() shouldn't be called directly when the library
loads.  It's invocation is handled by D runtime module
loaders/unloaders.
Jul 26 2014
prev sibling parent Martin Nowak <code dawg.eu> writes:
On 07/26/2014 12:15 AM, Andrei Alexandrescu wrote:

 Hello,


 We've just open-sourced another D project at Facebook (just a developer
 beta), an ODBC driver for the Presto database engine:
 https://github.com/prestodb/presto-odbc.

 The Windows version works well now, and Mark Isaacson (the author of the
 driver and incidentally my intern) is working already on the OSX port
 using iODBC. We've hit a number of issues, the most basic one being that
 shared static this() initializers don't seem to be called for our driver.

 Could you folks help us out?


 Thanks,

 Andrei


So this is a statically linked shared D library with a C interface, 
right? This is the only kind of shared libraries currently supported on 
OSX. It means that each lib comes with it's own private copy of 
phobos/druntime, so you got to be careful to not run into ODR issues 
(https://issues.dlang.org/show_bug.cgi?id=7020).

Short answer:

Load the library, get the address of rt_init and call it from your C 
program.

Long answer:

It's a bad practice to automatically initialize dynamic libraries during 
loading because it can lead to deadlocks (on the runtime loader lock). 
Also loading/unloading is globally synchronized and you don't want to 
perform long-running computations while holding the loader lock.

The common pattern is to provide init/fini functions in your library 
which are explicitly called by a user. So you should add 
presto_init/presto_fini functions and call 
Runtime.initialize()/Runtime.finalize() within those functions.
When the C program loads your library it will have to call presto_init 
before using it and presto_fini before unloading it.
Here is an example of this pattern 
https://github.com/D-Programming-Language/druntime/blob/dc559c3ef2916102c6f295d70c3941644e545bf2/test/shared/src/host.c.

If you absolutely need automatic initialization, you can add a C file 
with constructor/destructor functions to your project.

extern void rt_init();
extern void rt_term();

void presto_init() __attribute__((constructor));
void presto_init()
{
   rt_init();
   //...
}

void presto_fini() __attribute__((destructor));
void presto_fini()
{
   //...
   rt_term();
}

The runtime linker will call those functions during loading/unloading.
But once again, we went with explicit initialization because implicit 
init/fini didn't work out too well 
(https://issues.dlang.org/show_bug.cgi?id=11378).
Jul 29 2014