From: Matthias Kruk <m@m10k.eu>
Date: Wed, 14 Apr 2021 00:08:25 +0000 (+0900)
Subject: watchbot: Add repository monitoring script
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=39f8add49bf655f506dd2fdd76a5baadcfc8bd3b;p=foundry

watchbot: Add repository monitoring script

This commit adds a script that can be used to monitor local repositories
for changes, and add them to a work queue when they need to be rebuilt.
---

39f8add49bf655f506dd2fdd76a5baadcfc8bd3b
diff --git a/watchbot.sh b/watchbot.sh
new file mode 100755
index 0000000..59d39ea
--- /dev/null
+++ b/watchbot.sh
@@ -0,0 +1,188 @@
+#!/bin/bash
+
+sem="watchbot"
+
+watch_repos() {
+	local queue="$1"
+	local watches=("${@:2}")
+
+	local nwatches
+	local heads
+	local i
+
+	heads=()
+	nwatches="${#watches[@]}"
+
+	if ! sem_init "$sem" 0; then
+		log_info "Another instance is already running"
+		return 1
+	fi
+
+	for (( i = 0; i < nwatches; i++ )); do
+		heads["$i"]=$(<"${watches[$i]}")
+	done
+
+	while ! sem_trywait "$sem"; do
+		log_debug "Watching $nwatches files: ${watches[@]}"
+		if ! inotifywait -qq -t 15 "${watches[@]}"; then
+			continue
+		fi
+
+		for (( i = 0; i < nwatches; i++ )); do
+			local cur_head
+
+			cur_head=$(<"${watches[$i]}")
+
+			log_debug "${watches[$i]}: ${heads[$i]} -> $cur_head"
+
+			if [[ "$cur_head" != "${heads[$i]}" ]]; then
+				if ! queue_put "$queue" "${watches[$i]}"; then
+					log_error "Could not place item in queue"
+					continue
+				fi
+
+				heads["$i"]="$cur_head"
+			fi
+		done
+	done
+
+	if ! sem_destroy "$sem"; then
+		log_error "Could not clean up semaphore $sem"
+	fi
+
+	return 0
+}
+
+stop() {
+	if ! sem_post "$sem"; then
+		log_info "Looks like no instances are running"
+		return 1
+	fi
+
+	return 0
+}
+
+watchlist_add() {
+	local opt="$1"
+	local repo="$2"
+
+	watchlist+=("$repo")
+	return 0
+}
+
+watch_to_head() {
+	local watch="$1"
+
+	local repo
+	local branch
+	local head
+
+	if [[ "$watch" == *"#"* ]]; then
+		repo="${watch%#*}"
+		branch="${watch##*#}"
+	else
+		repo="$watch"
+		branch="master"
+	fi
+
+	if [ -d "$repo/.git" ]; then
+		head="$repo/.git/refs/heads/$branch"
+	else
+		head="$repo/refs/heads/$branch"
+	fi
+
+	if ! [ -e "$head" ]; then
+		return 1
+	fi
+
+	log_debug "Resolved $watch to $head"
+
+	echo "$head"
+	return 0
+}
+
+verbosity_increase() {
+	local verbosity
+
+	verbosity=$(log_get_verbosity)
+	((verbosity++))
+	log_set_verbosity "$verbosity"
+	return 0
+}
+
+verbosity_decrease() {
+	local verbosity
+
+	verbosity=$(log_get_verbosity)
+	((verbosity--))
+	log_set_verbosity "$verbosity"
+	return 0
+}
+
+main() {
+	declare -ag watchlist # will be gone once forked to the background
+	local watches
+	local queue
+	local watch
+
+	opt_add_arg "r" "repo"    "yes" "" "Repository to watch (format: /repo/path[#branch])" watchlist_add
+	opt_add_arg "q" "queue"   "yes" "" "Queue used to distribute work"
+	opt_add_arg "s" "stop"    "no"  0  "Stop a running instance"
+	opt_add_arg "v" "verbose" "no"  0  "Be more verbose"                                   verbosity_increase
+	opt_add_arg "w" "shush"   "no"  0  "Be less verbose"                                   verbosity_decrease
+
+	if ! opt_parse "$@"; then
+		return 1
+	fi
+
+	if (( $(opt_get "stop") > 0 )); then
+		if ! stop; then
+			return 1
+		fi
+
+		return 0
+	fi
+
+	queue=$(opt_get "queue")
+
+	if [ -z "$queue" ]; then
+		log_error "Need a queue"
+		return 1
+	fi
+
+	watches=()
+
+	for watch in "${watchlist[@]}"; do
+		local head
+
+		if ! head=$(watch_to_head "$watch"); then
+			log_error "Cannot resolve $watch"
+			return 1
+		fi
+
+		watches+=("$head")
+	done
+
+	if (( ${#watches[@]} == 0 )); then
+		log_error "Nothing to watch"
+		return 1
+	fi
+
+	start "$queue" "${watches[@]}" </dev/null &>/dev/null &
+	disown
+
+	return 0
+}
+
+{
+	if ! . toolbox.sh; then
+		exit 1
+	fi
+
+	if ! include "log" "opt" "sem" "queue"; then
+		exit 1
+	fi
+
+	main "$@"
+	exit "$?"
+}