January

• 2020-01-15

  • Establish invariants for a unit test in the setup.

    In concrete terms, in JUnit for example, use @Before methods to make sure that the state of the world fits the assumptions made in the tests. In the same manner, use @After to ensure that post conditions are also "as expected".

• 2020-01-16

  • Cross Datacenter Replication (XDR) | Aerospike

    Provides inter-cluster replication at teh namespace or optionally set
    granularity level.

    This is an Aerospike Enterprise Edition feature.

  • Namespace Retention Configuration | Aerospike

    • Aerospike can be configured to expire or evict least recently updated data.

    • Expiration and eviction algorithms use records TTL (Time To Live) value to determine eligibility for removal.

    • default-ttl can be set at a namespace level. See the documentation

      above for examples.

  • Checking docker exposed ports can be done by docker port command - https://docs.docker.com/engine/reference/commandline/port/

  • AssertJ test for equality ignoring fields can be done via isEqualToComparingOnlyGivenFields, as in the following example,

    assertThat(testVersion)
        .isEqualToComparingOnlyGivenFields(sourceVersion, "supplySourceList", "name", "defaultSeatId");

• 2020-01-17

  • Java EnumMap and EnumSet optimisations - https://stackoverflow.com/questions/16637288/optimization-done-by-an-enummap-enumset

  • dig

• 2020-01-19

  • syscall perturbation

    • System call perturbation using Strace

    • Observability and Chaos Engineering on System Calls for Containerized Applications in Docker

• 2020-01-20

  • CompletionStage

    • Examples of usage - https://dzone.com/articles/20-examples-of-using-javas-completablefuture

  • GNU grep -o option for --only-matching entries in a search - pretty useful in practice.

• 2020-01-21

  • Julia DataFrame Cheat Sheet - https://jcharistech.wordpress.com/julia-dataframes-cheat-sheets/

  • Blue Green deployment.

  • Ansible forks with -f option.

    • More on Ansible performance tuning - https://www.ansible.com/blog/ansible-performance-tuning.

• 2020-01-22

  • Semantic Patches for Java Program Transformation - this is a port of Coccinelle for Java.

• 2020-01-23

  • Lua named arguments

• 2020-01-24

  • Screen window splitting - https://tomlee.co/2011/10/gnu-screen-splitting/

    • Unlike on tmux a shell has to be spawned explicitly after splitting.

    • To do a vertical split - Ctrl+a | then Ctrl+TAB to go to the other

      split. Then as usual, use Ctrl+a c to create a window.

    • For a horizontal split use Ctrl+a S.

• 2020-01-25

  • enchive - Encrypted personal archives - this is a tool from Chris Wellons.

• 2020-01-27

  • sar

  • Java CopyOnWriteArrayList

• 2020-01-31

  • OmitStackTraceInFastThrow - https://github.com/SAP/SapMachine/issues/501