lib.chron

Schedulers, timers, and time-contingent eventing for the C programming language

Library Features

• Simple, fully programmable interfaces for
  • single-use aka 'one shot' timers
  • periodic timers
  • exponential timers
• rescheduling
• cancellation
• consistent exception-handling
• Hierarchical Timer Wheels

Install

Via clib:

clib install MatthewZito/lib.chron

From Source:

git clone https://github.com/MatthewZito/lib.chron
cd lib.chron && make

Hierarchical Timer Wheel

The Timer Wheel implementation this library offers is implemented as a ring buffer data structure with numbered slots. Each slot contains a pointer to a linked list of elements, each sub-slots for scheduled events.

When scheduling an event k, we assign an integer value r where r is the number of full revolutions that must occur before event k is invoked.

The Timer Wheel is further optimized in that the linked list must store events such that r is ascending; if on revolution 3 we iterate the linked list, invoking any events whose r value is 3 or less, we can stop iterating the moment we scan a list node whose r value is greater than 3.

In this way, we never search the linked list; in traversing each slot on the wheel's internal ring buffer, we maintain a time complexity of 0(1).

Dynamic Linking

Linking to lib.chron:

# 1) include and use lib.chron in your project
# 2) generate object file for your project
gcc -I ../path/to/libchron -c main.c -o main.o
# 3) generate shared object file
make
# 4) link your project to lib.chron
gcc -o main main.o -L../path/to/libchron -llibchron
# you may need to add the lib location to your PATH

Linking to lib.chron on Windows:

# 1) include and use lib.chron in your project
# 2) generate object file for your project
gcc -I ../path/to/libchron -c main.c -o main.o
# 3) generate shared object file
make win
# 3) link your project to lib.chron
gcc -o main.exe main.o -L /path/to/lib.chron -llib_chron.dll
# you may need to add the lib location to your PATH