That works on Linux (and I guess *NIX) yes, but I'm not sure if Windows has a similar functionality. Even if it does, the use case here (a game engine/library) is most likely a statically linked binary, so I think it won't work there :-)
All in all this is an interesting discussion, but let's see some PRs and take it from there :-) On Mon, 2016-11-28 at 11:48 -0800, Max Kozlovsky wrote: > Each program can be linked with a separate malloc implementation if the > user so desires. Libraries don't need to be aware which implementation it > is. Different malloc implementation can be even substituted at run time on > platforms with dynamic linking support (LD_PRELOAD etc). > > On Mon, Nov 28, 2016 at 11:39 AM, Jens Auer <[email protected]> > wrote: > > > Hi, > > > > > > > > yes and no. If you overwrite it globally at compute-time every program on > > the system has to use your custom implementation. So if you deliver your > > ZeroMQ library with your program it will work, but what if my program wants > > a different custom allocator? > > > > > > > > Cheers, > > > > Jens > > > > > > > > *Von:* zeromq-dev [mailto:[email protected]] *Im > > Auftrag von *Max Kozlovsky > > *Gesendet:* Montag, 28. November 2016 20:36 > > *An:* ZeroMQ development list > > *Betreff:* Re: [zeromq-dev] On hooking memory allocations > > > > > > > > Hi, > > > > > > > > Would not globally overwriting malloc/free with the custom implementation > > achieve the desired behavior (instead of providing hooks for installing > > malloc overrides in each and every library)? > > > > > > > > Max > > > > > > > > On Mon, Nov 28, 2016 at 5:08 AM, Auer, Jens <[email protected]> wrote: > > > > Hi, > > > > I don't see a big problem with the C API except that C doesn't support > > overloads. So if the function has a new name, e.g. > > zmq_ctx_new_with_allocator, everything stays plain C. The default instance > > would be a > > > > static void* malloc_(size_t n, void*) {return malloc(n);} > > static void free_(void* ptr, size_t n, void*) {free(ptr);} > > > > allocator_t alloc{ > > NULL, > > malloc_, > > free_ > > }; > > > > context_t then stores the member and gets methods to forward memory > > allocations to the function pointers, passing the hint pointer as an > > additional argument. > > > > In my C++ code, I can then use an allocator > > static void* allocate(size_t n, void* obj) {return > > static_cast<std::allocator<char>>(obj)->allocate(n); } > > static void free_(void* ptr, size_t n, void*obj) { > > static_cast<std::allocator<char>>(obj)->deallocate(ptr, n); } > > > > std::allocator<char> a; > > allocator_t zmqAlloc{ > > &a, > > allocate, > > free_ > > }; > > > > void* ctx = zmq_ctx_new_with_allocator(&zmqAlloc); > > > > I think this should work? > > > > Best wishes, > > Jens > > > > -- > > Dr. Jens Auer | CGI | Software Engineer > > CGI Deutschland Ltd. & Co. KG > > Rheinstraße 95 | 64295 Darmstadt | Germany > > T: +49 6151 36860 154 > > [email protected] > > Unsere Pflichtangaben gemäß § 35a GmbHG / §§ 161, 125a HGB finden Sie > > unter de.cgi.com/pflichtangaben. > > > > CONFIDENTIALITY NOTICE: Proprietary/Confidential information belonging to > > CGI Group Inc. and its affiliates may be contained in this message. If you > > are not a recipient indicated or intended in this message (or responsible > > for delivery of this message to such person), or you think for any reason > > that this message may have been addressed to you in error, you may not use > > or copy or deliver this message to anyone else. In such case, you should > > destroy this message and are asked to notify the sender by reply e-mail. > > > > > -----Original Message----- > > > From: zeromq-dev [mailto:[email protected]] On Behalf > > Of > > > Luca Boccassi > > > Sent: 28 November 2016 12:30 > > > To: ZeroMQ development list > > > Subject: Re: [zeromq-dev] On hooking memory allocations > > > > > > That would work for an internal API, but given we expose a C API > > unfortunately I > > > don't think that would work as a public API :-( And I think for this use > > case they > > > would require a public API. > > > > > > As an external API, a new zmq_ctx_set that takes a callback would have > > been ideal, > > > but it only takes int. So perhaps a new zmq_ctx_set_allocator that takes > > a callback > > > pointer would be the next best. > > > > > > An alternative would be to have a system similar to what we use for the > > poll > > > implementation (epoll kqueue select etc), but this would be a build-time > > option, > > > and the implementation would have to be checked in, which I don't think > > is an > > > option for this case, right? > > > > > > On Mon, 2016-11-28 at 10:51 +0000, Auer, Jens wrote: > > > > Hi, > > > > > > > > I am just a user, but I would love to see this change. I have thinking > > > > about this and I would like to be able to pass a C++ allocator object > > > > to ZeroMQ, so a simple function hook is not enough. My idea is to > > > > define a struct in the interface > > > > > > > > struct allocator_t > > > > { > > > > void* hint; > > > > void* (allocate)(size_t, void*); > > > > void (deallocate)(void*, size_t, void*); }; > > > > > > > > and store this in the context object. Since I don't think that this > > should be > > > changed during runtime, I would create a new zmq_ctx_new overload which > > takes a > > > parameter of type allocator_t. The default value would be to call > > malloc/free. > > > > > > > > Cheers, > > > > Jens > > > > > > > > -- > > > > Jens Auer | CGI | Software-Engineer > > > > CGI (Germany) GmbH & Co. KG > > > > Rheinstraße 95 | 64295 Darmstadt | Germany > > > > T: +49 6151 36860 154 > > > > [email protected]<mailto:[email protected]> > > > > Unsere Pflichtangaben gemäß § 35a GmbHG / §§ 161, 125a HGB finden Sie > > unter > > > de.cgi.com/pflichtangaben<http://de.cgi.com/pflichtangaben>. > > > > > > > > CONFIDENTIALITY NOTICE: Proprietary/Confidential information belonging > > to CGI > > > Group Inc. and its affiliates may be contained in this message. If you > > are not a > > > recipient indicated or intended in this message (or responsible for > > delivery of this > > > message to such person), or you think for any reason that this message > > may have > > > been addressed to you in error, you may not use or copy or deliver this > > message to > > > anyone else. In such case, you should destroy this message and are asked > > to notify > > > the sender by reply e-mail. > > > > ________________________________ > > > > Von: zeromq-dev [[email protected]]" im Auftrag von > > > > "Petteri Salo [[email protected]] > > > > Gesendet: Montag, 28. November 2016 09:40 > > > > An: [email protected] > > > > Betreff: [zeromq-dev] On hooking memory allocations > > > > > > > > Hello, > > > > > > > > Let me first do a little introduction as I'm new to this list. I'm a > > software engineer > > > with 15+ years of experience working on games at a company called Remedy > > > Entertainment Ltd. We've done games for PC, and various games consoles > > over the > > > years. Most recently we did Quantum Break for Xbox One. > > > > > > > > I've now been tasked with evaluating ZeroMQ. One important feature of > > any > > > library we use in games is the ability to hook all memory allocations - > > this is to allow > > > the use of custom memory allocators and/or for tracking when and where > > memory is > > > allocated. > > > > > > > > I've searched the libzmq source code and there is about 150 uses of > > new, malloc, > > > realloc , etc. > > > > > > > > If we were to adopt libzmq we'd like to put in allocation hooks and > > that work > > > would then be something that we'd like to contribute back to the > > project. Having > > > those hooks in the main repository would then make it easier for us to > > adopt future > > > changes to the library. > > > > > > > > So, my question is would this kind of change be something that would be > > > accepted? Of course assuming that coding conventions, proper way of > > submitting > > > the patch etc. are followed. I do realize that one would want to see the > > actual code > > > before accepting. I'm interested in the principle of accepting a change > > such as this, > > > since it would introduce a new "rule" for working ión libzmq source code > > : "All > > > allocations shall go through an allocation hook." > > > > > > > > Best Regards, > > > > > > > > Petteri Salo
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