#!/usr/bin/bash
# setup the semaphore environment for the loading file
bats_semaphore_setup() {
export -f bats_semaphore_get_free_slot_count
export -f bats_semaphore_acquire_while_locked
export BATS_SEMAPHORE_DIR="$BATS_RUN_TMPDIR/semaphores"
if command -v flock >/dev/null; then
bats_run_under_lock() {
flock "$BATS_SEMAPHORE_DIR" "$@"
}
elif command -v shlock >/dev/null; then
bats_run_under_lock() {
local lockfile="$BATS_SEMAPHORE_DIR/shlock.lock"
while ! shlock -p $$ -f "$lockfile"; do
sleep 1
done
# we got the lock now, execute the command
"$@"
local status=$?
# free the lock
rm -f "$lockfile"
return $status
}
else
printf "ERROR: flock/shlock is required for parallelization within files!\n" >&2
exit 1
fi
}
# $1 - output directory for stdout/stderr
# $@ - command to run
# run the given command in a semaphore
# block when there is no free slot for the semaphore
# when there is a free slot, run the command in background
# gather the output of the command in files in the given directory
bats_semaphore_run() {
local output_dir=$1
shift
local semaphore_slot
semaphore_slot=$(bats_semaphore_acquire_slot)
bats_semaphore_release_wrapper "$output_dir" "$semaphore_slot" "$@" &
printf "%d\n" "$!"
}
# $1 - output directory for stdout/stderr
# $@ - command to run
# this wraps the actual function call to install some traps on exiting
bats_semaphore_release_wrapper() {
local output_dir="$1"
local semaphore_name="$2"
shift 2 # all other parameters will be use for the command to execute
# shellcheck disable=SC2064 # we want to expand the semaphore_name right now!
trap "status=$?; bats_semaphore_release_slot '$semaphore_name'; exit $status" EXIT
mkdir -p "$output_dir"
"$@" 2>"$output_dir/stderr" >"$output_dir/stdout"
local status=$?
# bash bug: the exit trap is not called for the background process
bats_semaphore_release_slot "$semaphore_name"
trap - EXIT # avoid calling release twice
return $status
}
bats_semaphore_acquire_while_locked() {
if [[ $(bats_semaphore_get_free_slot_count) -gt 0 ]]; then
local slot=0
while [[ -e "$BATS_SEMAPHORE_DIR/slot-$slot" ]]; do
(( ++slot ))
done
if [[ $slot -lt $BATS_SEMAPHORE_NUMBER_OF_SLOTS ]]; then
touch "$BATS_SEMAPHORE_DIR/slot-$slot" && printf "%d\n" "$slot" && return 0
fi
fi
return 1
}
# block until a semaphore slot becomes free
# prints the number of the slot that it received
bats_semaphore_acquire_slot() {
mkdir -p "$BATS_SEMAPHORE_DIR"
# wait for a slot to become free
# TODO: avoid busy waiting by using signals -> this opens op prioritizing possibilities as well
while true; do
# don't lock for reading, we are fine with spuriously getting no free slot
if [[ $(bats_semaphore_get_free_slot_count) -gt 0 ]]; then
bats_run_under_lock bash -c bats_semaphore_acquire_while_locked && break
fi
sleep 1
done
}
bats_semaphore_release_slot() {
# we don't need to lock this, since only our process owns this file
# and freeing a semaphore cannot lead to conflicts with others
rm "$BATS_SEMAPHORE_DIR/slot-$1" # this will fail if we had not acquired a semaphore!
}
bats_semaphore_get_free_slot_count() {
# find might error out without returning something useful when a file is deleted,
# while the directory is traversed -> only continue when there was no error
until used_slots=$(find "$BATS_SEMAPHORE_DIR" -name 'slot-*' 2>/dev/null | wc -l); do :; done
echo $(( BATS_SEMAPHORE_NUMBER_OF_SLOTS - used_slots ))
}
Mini Shell