IO-Queue

IO-Queue is a header only library that implements a C11 Unbounded Non-Intrusive Lockless Single Consumer Multiple Producer FIFO Queue. It excels at taking I/O bound work from many threads and instead performing that I/O bound work on a seperate thread.

Usage

Simply include io_queue.h, there are no dependencies (other than a compiler that supports the atomic C11 standard library components).

Create a queue using the IoQueue structure:

IoQueue my_queue;
io_queue_init(&my_queue, sizeof(int));

To put data in the queue use the io_queue_push function. Pushing supports copying and moving. Pushing is considered a producer operation. Any thread can safely execute this operation at any time.

int in = 1;
io_queue_push(&my_queue, &in);

To check for data in the queue the io_queue_has_front function should be used. Checking the front is considered a consumer operation, only one thread may safely execute this at one time.

if (io_queue_has_front(&my_queue) == IO_QUEUE_RESULT_TRUE)
{
	// do something
}

To get data out of the queue the io_queue_front function is used. You should always check that there is data in queue before calling front as there is no built in check. If no data is in the queue when front is called a segfault is likely (or an assertion failure). Getting data is considered a consumer operation, only one thread may safely execute this at one time.

if (io_queue_has_front(&my_queue) == IO_QUEUE_RESULT_TRUE)
{
	int out;
	io_queue_front(&my_queue, &out);
}

To remove an item from the queue the io_queue_pop function is used. You should always check that there is data in queue before popping as there is no built in check. If no data is in the queue when pop is called a segfault is likely (or an assertion failure). Popping is considered a consumer operation, only one thread may safely execute this at one time.

if (io_queue_has_front(&my_queue) == IO_QUEUE_RESULT_TRUE)
{
	io_queue_pop(&my_queue);
}

Always make sure the queue is empty before letting it fall out of scope or freeing it, otherwise you'll leak memory. The io_queue_clear function is a convenient way to nuke the queue.

io_queue_clear(&my_queue);

Test

Tests are successful if there is no output. Example build command with gcc on windows:

gcc -ggdb -Wall test.c -o test.exe