Application counters in Linux? (and OSX?)

Question

I'm trying to figure out if there is a library that gives me something near the equivalent of Windows custom performance counters (described here http://geekswithblogs.net/.NETonMyMind/archive/2006/08/20/88549.aspx)

Basically, I'm looking for something that can be used to both track global counters within an application, and (ideally) something that presents that information via a well-defined interface to other applications/users. These are application statistics; stuff like memory and disk can be captured in other ways, but I'm looking to expose throughput/transactions/"widgets" handled during the lifetime of my application.

I've seen this question:

Concept of "Performance Counters" in Linux/Unix

and this one

Registry level counters in Linux accessible from Java

but neither is quite what I'm looking for. I don't want to write a static file (this is dynamic information after all; I should be able to get at it even if the disk is full etc.), and would rather avoid a homegrown set of code if at all possible. Ideally, at least on Linux, this data would (I think) be surfaced through /proc in some manner, though it's not clear to me if that can be done from userland (this is less important, as long as it is surfaced in some way to clients.)

But back to the crux of the question: is there any built-in or suitable 3rd-party library that gives me custom global (thread-safe, performant) counters suitable for application metrics that I can use on Linux and other *NIXy operating systems? (And can be interfaced from C/C++?)

Answer 1

In addition to @user964970 comment/solution, I suggest making it OS agnostic.

Use an OS agnostic API, like ACE or BOOST, to create your own library, supplying a named-semaphore write-protected-counter, placed inside a named-shared-memory segment.

This should be your library's API :

long * createCounter(const char * name); // Create a counter
                                         // Will create a named semaphore and a named
                                         // shared memory segment, holding the counter     
                                         // value. Will return pointer to counter
long * getCounter(const char * name); // Get existing counter pointer
                                      // in the calling process' address space
long incCounter(const char * name);   // increment existing counter