build-if-queued.sh

#!/bin/bash

# A wrapper around `build.sh` that uses the pulls from the build queue and provides
# some locking facilities so it can be used directly and via a periodic runner without
# conflicts.

__dirname="$(CDPATH= cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
. ${__dirname}/_lock.sh
. ${__dirname}/_decode_version.sh
queuefile="$(realpath ${__dirname}/../../var/build_queue)"

# quick checks before we bother with locks
if [ ! -f "$queuefile" ]; then
  exit 0
fi
if [ "$(wc -l $queuefile | cut -f1 -d' ')" = "0" ]; then
  exit 0
fi 

# another build is running, bail early
exit_if_locked "node-build"
acquire_lock "node-build"

# next build from the queue
fullversion="$(${__dirname}/queue-pop.sh)"

if [ "X$fullversion" != "X" ]; then
  decode "$fullversion"
  # only "release" versions are guaranteed to have source files available when they appear
  # in the indexes, the others promote components as they are available and source has a
  # lower priority
  # so if source doesn't exist, re-queue it and it'll be tried again next time, it's possible
  # that a version gets stuck in the queue and this `curl` to be run over and over
  # but since it's a FIFO it shouldn't prevent others from running
  if curl --output /dev/null --silent --head --fail $source_url; then
    ${__dirname}/build.sh $fullversion
  else
    echo "Source file for ${fullversion} does not exist, queueing for retry"
    ${__dirname}/queue-push.sh $fullversion
  fi
fi

release_lock