Summary

This library restricts instance quantity on *nix system.

Compatibility

OS

• Linux
• Unix
• OS X Darwin Kernel Version 16.7.0

Compiler

• Apple LLVM version 8.1.0 (clang-802.0.42)
• gcc
• g++

Programming language

• C
• C++

Usage

#include "instance_restriction.h"

int main()
{
    if (ReachedMaximumInstance())
    {
        perror("Too many instances.");
    }

    return EXIT_SUCCESS;
}

Mechanism

This library will create lock file LOCK_PREFIX + count + LOCK_SUFFIX and put current pid in it once it runs. (Defined in instance_restriction.h)

When try to run another process, ReachedMaximumInstance will check the existence of lock file. If lock file exists already, it will check if pid logged in lock file is still running. If process is still running, it will check if has exceeded MAX_INSTANCE. If it has, then it will return 1. Otherwise, it will remove deprecated lock and create a new lock and return 0.

License

GPL v2.0