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Pubnub C-core for the POSIX platform

This is the part of C-core for the POSIX platform. It has the (POSIX) platform-specific files and a sample Makefile (posix.mk), which will build sample programs:

  • pubnub_sync_sample: a "walk-through" of the "sync" interface (API)
  • pubnub_callback_sample: a "walk-through" of the "callback" interface (API)
  • cancel_subscribe_sync_sample: an example how to cancel a subscribe loop safely, using the "sync" interface
  • subscribe_publish_callback_sample: an example of how to have one outstanding publish and one outstanding subscribe transaction/operation at the same time, using the "callback" interface.
  • pubnub_console_sync: a simple command-line Pubnub console, using the "sync" interface
  • pubnub_console_callback: a simple command-line Pubnub console, using the "callback" interface

During the build, two (static) libraries will be created:

  • pubnub_sync.a: library for the "sync" interface
  • pubnub_callback.a: library for the "callback" interface

You are free to use these libraries in your projects, but keep in mind that they are configured for the purposes of the samples. Please check if those are right for you before using them.

The sources of the samples are in ../core/samples, and for the console in ../core/samples/console, as they are portable across all or most hosted platforms (POSIX, Windows...).

So, to build the samples, just execute:

make -f posix.mk

There are no special requirements for C-core on POSIX, it should just build on any regular POSIX system with a C compiler. To use a compiler of your choice (rather than the default one), say, clang, execute:

make -f posix.mk CC=clang

Build without the proxy support

To build without the proxy support, pass USE_PROXY=0 to Make, like:

make -f posix.mk USE_PROXY=0

Of course, if you have previously done a build, you will probably want to first clean up the artifacts of that previous build by invoking the clean target, like:

make -f posix.mk clean

OSX / Darwin remarks

While being a "mostly POSIX" compliant environment, OSX, in its "Darwin" OS base, doesn't support POSIX standard clock_gettime() API. This is well-known and often complained about, and the actual code to implement it is rather simple, so it is strange that Apple hasn't fixed this yet.

Anyway, to be able to work on OSX / Darwin, we have a small module that abstracts "getting a monotonic clock time", with an implementation for POSIX and another for Darwin. You have to link the right one, and we do that in posix.mk.

Makefile remarks

The Makefile is designed to be minimal and illustrate what modules you need and what #defines and compiler/link options, to build C-core. It is not designed to be just copy-pasted into your production Makefile, because there are way too many ways to "make a Makefile", we can't cover them all.

Footprint

Since C-core is designed to have low footprint, the question of "how big is it" often comes up.

We present some numbers here, but, please keep in mind that these are volatile, because they depend on:

  1. C-core itself, which changes with time
  2. your usage of the C-core
  3. your compiler and its version
  4. the C standard library you use and its version
  5. the compiler options you pass to compiler (foremost, optimization, but many others too)

So, the number can only give you some idea, and are not to be taken for granted.

Linux 64-bit, taken on 2017-05-03

These are the numbers gotten with the posix.mk makefile, with a GCC 4.8.4 on Linux Mint 17 (based on Ubuntu 14.04).

OOB - with proxy support

File size [KB]
pubnub_callback.a 496
pubnub_sync.a 428
pubnub_callback_sample executable 188
stripped pubnub_callback_sample 84
pubnub_sync_sample executable 168
stripped pubnub_sync_sample 68

Without proxy support

This needed slight changes in the makefile (define PUBNUB_PROXY_API to 0 and remove the proxy modules from the libraries):

File size [KB]
pubnub_callback.a 393
pubnub_sync.a 331
pubnub_callback_sample executable 139
stripped pubnub_callback_sample 63
pubnub_sync_sample executable 120
stripped pubnub_sync_sample 55