Fetching topologies using timestamp-callback map

A device comprising:

• a processing resource;
• and
• a non-transitory machine-readable storage medium comprising instructions executable by the processing resource to:
• determine a timestamp for a callback function, wherein the callback function fetches a topology for a network device from a topology service;
• insert a reference to the callback function into a node of a timestamp-callback map, wherein the node includes a list of references to unique callback functions associated with the timestamp;
• for the unique callback functions, create respective worker threads at a time indicated in the timestamp, wherein the respective worker threads invoke the unique callback functions to fetch topologies for network devices from the topology service.

A non-transitory machine-readable storage medium comprising instructions that, when executed, cause a processing resource of a device to:

• create a first worker thread to:
• receive a port configuration message for a port of a network device;
• determine a timestamp for a callback function, wherein the callback function fetches, from a topology service, a topology for the network device;
• insert a reference to the callback function in a binary search tree, wherein the binary search tree includes a plurality of nodes, each node including a respective timestamp and a respective list of unique callback functions;
• create a management thread to:
• identify, from the plurality of nodes in the binary search tree, a node including a lowest timestamp, wherein the lowest timestamp indicates an earliest time value;
• set an alarm for the lowest timestamp in a timer, wherein the alarm generates a notification at a time corresponding to the earliest time value;
• and
• in response to the notification, spawn second worker threads to invoke the unique callback functions at the time to fetch topologies for network devices from a topology service.