Atlas Runtime
README

Data Structures

This directory contains several data structures, each implemented in a few flavors. An Atlas-based program typically requires:

  • Calls to NVM_Initialize/NVM_Finalize
  • Creating/closing a persistent region
  • Allocating data structures from a persistent region using nvm_alloc
  • Writing restart code to find a reusable persistent data structure, if it exists
  • Enclosing updates within a durable section, if required.
  • If a program is written with locks, no changes are required to maintain consistency of updates within these lock-held sections.

Details of the programs in this folder follow:

  1. alarm_clock is a simple program that sets, updates, cancels a bunch of alarms. alarm_clock_nvm is the corresponding persistent version using Atlas APIs where the alarm information is kept around for later reuse.
  1. cow_array_list is a vanilla implementation of a multithreaded copy-on-write array implementation, inspired by Java CopyOnWriteArrayList. cow_array_list_nvm is the corresponding persistent array implementation using Atlas APIs.
  1. queue shows a vanilla implementation of a multithreaded queue (Adapted from Michael & Scott, Simple, Fast, and Practical Non-Blocking and Blocking Concurrent Queue Algorithms, PODC 1996.) queue_nvm is the corresponding persistent queue using Atlas APIs.
  1. sll is a vanilla serial singly linked list; sll_ll is a persistent serial singly linked list, written using a low-level API that essentially uses only persistent syncs. sll_mt and sll_mt_ll are multithreaded variants. sll_nvm is a persistent serial singly linked list, written using Atlas APIs.
  1. stores and stores_nvm are transient and persistent versions respectively of an array sweep.

When <ATLAS_BUILD>/tests/run_quick_test is invoked, the script simulates crash/recovery for each of these tests. First, every program is run to completion, then deliberately crashed, recovered, and then run again.

In order to invoke any of the tests manually, do the following, for example for queue_nvm: 

$ cd <ATLAS_BUILD>
$ ./tests/data_structures/queue_nvm

If the program fails for some reason, the recovery process must be initiated before the program can be run again. For that purpose, invoke tools/recover <program executable name>. For example, for queue_nvm: 

$ ./tools/recover queue_nvm

Once recovery is done, the program can be run again as before. For example, 

$ ./tests/data_structures/queue_nvm

If all persistent regions need to be cleaned out for some reason, invoke tools/clean_mem. tools/del_log and tools/del_rgn can be used to selectively remove a process log and a specific persistent region respectively.