[__jitsi_meet] Adapt jicofo and videobridge memory usage

This enables us to setup smaller jitsi instances that work reliably.

We set 3 threshholds:
- < 3G RAM: use 0.75G max memory
- < 5G RAM: use 1G max memory
- < 8G RAM: use 2G max memory
- >= 8G RAM: use 3G max memory (jitsi's default)

For more information as to why and how this is done, see:
https://gitlab.com/guifi-exo/projectes/-/issues/318
https://github.com/jitsi/jitsi-meet/issues/6589
as investigated back in the day by @pedro

Sponsored by:   camilion.eu, eXO.cat

type/__jitsi_meet/explorer/configured-memory

@@ -0,0 +1,15 @@
+#!/bin/sh -eu
+
+JICOFO="/usr/share/jicofo/jicofo.sh"
+VIDEOBRIDGE="/usr/share/jitsi-videobridge/lib/videobridge.rc"
+
+if [ -f "${JICOFO:?}" ]; then
+	jicofo_memory="$(grep JICOFO_MAX_MEMORY= "${JICOFO:?}" | cut -d= -f 2 | cut -d ";" -f 1)"
+fi
+if [ -f "${VIDEOBRIDGE:?}" ]; then
+	vb_memory="$(grep VIDEOBRIDGE_MAX_MEMORY= "${VIDEOBRIDGE:?}" | cut -d= -f 2)"
+fi
+cat <<EOF
+jicofo	${jicofo_memory:-n/a}
+videobridge	${vb_memory:-n/a}
+EOF

type/__jitsi_meet/gencode-remote

@@ -1,10 +1,43 @@
 #!/bin/sh -e
 
+memory="$(cat "${__global}/explorer/memory")"
+G="000000"  # Will totally eff up the zero-count otherwise
+# MAX_MEMORY will affect jicofo and videobridge
+#  As a rule of thumb, the machine's RAM should be more than 2.5 * MAX_MEMORY
+if [ "${memory}" -lt "3${G}" ]; then
+	# If you use this, let us know how it works!
+	MAX_MEMORY="768m"
+elif [ "${memory}" -lt "5${G}" ]; then
+	MAX_MEMORY="1024m"
+elif [ "${memory}" -lt "8${G}" ]; then
+	MAX_MEMORY="2048m"
+else
+	# Jitsi recommends running on 8G RAM and these are the defaults
+	MAX_MEMORY="3072m"
+fi
+
+if cut -f 2 "${__object}/explorer/configured-memory" | grep -qvE "^${MAX_MEMORY}$"; then
+	# At least one service has different memory settings
+	RESTART_SERVICES="YES"
+	cat <<-EOF
+	sed -i.tmp -E \
+		-e 's!^(#[[:space:]]*)?(VIDEOBRIDGE_MAX_MEMORY)=.*\$!\2=${MAX_MEMORY}!' \
+		/usr/share/jitsi-videobridge/lib/videobridge.rc
+	sed -i.tmp -E \
+		-e 's!^(JICOFO_MAX_MEMORY)[^;]+;!\1=${MAX_MEMORY};!' \
+		/usr/share/jicofo/jicofo.sh
+	EOF
+fi
+
 if grep -qE "^__file/etc/nginx" "${__messages_in}"; then
 	echo "service nginx reload"
 fi
 
 if grep -qE "^(__line/jitsi_jicofo_secured_domains|(__file|__link)/etc/prosody/conf.d/|__file/etc/jitsi/jicofo/jicofo.conf)" "${__messages_in}"; then
+	RESTART_SERVICES="YES"
+fi
+
+if [ -n "${RESTART_SERVICES}" ]; then
   echo "systemctl restart prosody"
   echo "systemctl restart jicofo"
   echo "systemctl restart jitsi-videobridge2"

type/__jitsi_meet/man.rst

@@ -36,6 +36,8 @@ If you can, please contribute updates to `__jitsi_meet` and
 Alternatively, you can help finance that work; get in touch with the type
 authors for that (see below).
 
+This type takes care of adapting the maximum memory used by jicofo and
+videobridge in function of the hosts installed memory.
 
 NOTE: This type currently does not deal with setting up coturn.
       For that, you might want to check `__coturn` in