signal.adoc

signal

The signal command is how scripts inform other scripts that they have reached a specific point in execution. Scripts can wait-for a specific point in execution qDup will pause the script until all signal for that point have occurred.

scripts:
  doThis:
  - sh: doThis.sh
  - signal: ready

  doThat:
  - wait-for: ready
  - sh: doThat.sh

The signal and wait-for will ensure doThis.sh finishes before doThat.sh starts even if they are run on different hosts. qDup will wait for all signal: ready before starting the sh: doThat.sh. If the doThis script was in a role with 4 hosts then qDup will expect for calls to signal: ready before the wait-for ends.

qDup will analyze the scripts and try to calculate the expected number of times signal will be called for each named signal but there are times it cannot identify the signal name.

scripts:
  tricy:
  - signal: ${{easy}} #defined in yaml
  - sh: doSimething.sh
  - regex: name=(?<hard>.*)
  - signal: ${{hard}} #created a runtime
state:
  easy: static

qDup can calculate the signal name for signal: ${{easy}} because it is defined in the state section and does not get changed by a set-state or regex but it cannot calculate the name for signal: ${{hard}} because it is created during script execution. If a signal name needs to be defined at execution then it is up to the script author to set the signal count. We currently set the signal count with set-signal: ${{hard}} where is replaced with a number.

Runtime signal names are seldom necessary and normally only happen when coordinating loops in more than one script.