Troubleshooting C-Core SDK

Using the PUBNUB_ASSERT subsystem

The PUBNUB_ASSERT subsystem helps you catch and fix bugs when working with the C-Core SDK.

When your code encounters an unexpected condition, assertions immediately flag the problem and show exactly which file and line caused the error.

You can control how strict these checks are - use more thorough validation during development to catch more issues, or fewer checks in production for better performance.

Custom assertion handlers let you decide what happens when failures occur, from simple logging to triggering debugger breakpoints.

C-core has its own ASSERT module/subsystem. Its interface is in the header pubnub_assert.h. It is used in C-core modules themselves, but you can also use it in your code if you wish. It provides several levels of ASSERTs:

Level	Preprocessor Symbol	Description
highest	PUBNUB_ASSERT_LEVEL_EX	All checks enabled (compiled).
regular	PUBNUB_ASSERT_LEVEL	Only the long lasting checks are disabled, other are compiled.
lowest	PUBNUB_ASSERT_LEVEL_OPT	Only the checks with negligible execution length are enabled.
none	PUBNUB_ASSERT_LEVEL_NONE	All checks disabled.

The default level is highest, and that is the level used in our sample Makefiles.

If you want to troubleshoot performance by disabling checks, define PUBNUB_ASSERT_LEVEL_NONE.

Also, you can control what happens when an assertion fails. To do that, you set a callback function to be called, by using pubnub_assert_set_handler(), which should be called as early as possible in the execution of your program.

There are a few ready-made handlers which you can use and the default is pubnub_assert_handler_abort, which provides a similar operation as the C standard assert() macro - prints a report of the place and expression of the assertion and then aborts.

If you wish to provide your own handler, you need to define a function that conforms to the following typedef:

typedef void (*pubnub_assert_handler_t)(char const *s, char const *file, long line);

For example:

void dbg_break_assert_handler(char const *s, char const *file, long line)
{
    printf("Will hit breakpoint for '%s' in %s line %d\n", s, file, line);
    BREAK_IN_DEBUGGER; /* assuming you have such a macro */
}

Change the assertion level

To change the assertion level:

1. Edit the Makefile you wish to use to compile your client, for example posix.mk.

2. In the file, find the list of CFLAGS or DEFINES:

   CFLAGS = -g -D PUBNUB_THREADSAFE -D PUBNUB_LOG_LEVEL=PUBNUB_LOG_LEVEL_WARNING -Wall -D PUBNUB_ONLY_PUBSUB_API=$(ONLY_PUBSUB_API)
   (...)

3. Add the -D <level> where level is one of the preprocessor symbols found in this table, for example:

   CFLAGS = -g (...) -D PUBNUB_ASSERT_LEVEL_OPT