#!/bin/bash

# Helper to setup a local LTTng tracing session with the appropriate
# settings for the lttng analyses scripts

SESSION_NAME="lttng-analysis-$RANDOM"

destroy()
{
	lttng destroy $SESSION_NAME >/dev/null
	echo ""
	echo "You can now launch the analyses scripts on /$TRACEPATH"
	exit 0
}

if test "$1" = "-h" -o "$1" = "--help"; then
	echo "usage : $0"
	exit 0
fi

pgrep -u root lttng-sessiond >/dev/null
if test $? != 0; then
	echo "Starting lttng-sessiond as root (trying sudo, start manually if \
it fails)"
	sudo lttng-sessiond -d
	if test $? != 0; then
		exit 1
	fi
fi

SUDO=""
groups|grep tracing >/dev/null
if test $? != 0; then
	echo "You are not a member of the tracing group, so you need root \
access, the script will try with sudo"
	SUDO="sudo"
fi

# check if lttng command if in the path
# check if the user can execute the command (with sudo if not in tracing group)
# check if lttng-modules is installed
$SUDO lttng list -k | grep sched_switch >/dev/null
if test $? != 0; then
	echo "Something went wrong executing \"$SUDO lttng list -k | grep sched_switch\", \
try to fix the problem manually and then start the script again"
fi

# if our random session name was already in use, add more randomness...
$SUDO lttng list | grep $SESSION_NAME
if test $? = 0; then
	SESSION_NAME="$SESSION_NAME-$RANDOM"
fi
$SUDO lttng list | grep $SESSION_NAME
if test $? = 0; then
	echo "Cannot create a random session name, something must be wrong"
	exit 2
fi

lttng create $SESSION_NAME >/tmp/lttngout
[[ $? != 0 ]] && exit 2
TRACEPATH=$(grep Traces /tmp/lttngout | cut -d'/' -f2-)
rm /tmp/lttngout

trap "destroy" SIGINT SIGTERM

lttng enable-channel -k chan1 --subbuf-size=8M >/dev/null
lttng enable-event -s $SESSION_NAME -k sched_switch,block_rq_complete,block_rq_issue,block_bio_remap,block_bio_backmerge,netif_receive_skb,net_dev_xmit,sched_process_fork,sched_process_exec,lttng_statedump_process_state,lttng_statedump_file_descriptor,lttng_statedump_block_device,writeback_pages_written,mm_vmscan_wakeup_kswapd,mm_page_free,mm_page_alloc,block_dirty_buffer,irq_handler_entry,irq_handler_exit,softirq_entry,softirq_exit,softirq_raise -c chan1 >/dev/null
[[ $? != 0 ]] && exit 2
lttng enable-event -s $SESSION_NAME -k -c chan1 --syscall -a >/dev/null
[[ $? != 0 ]] && exit 2
# if you want to add Perf counters, do something like that :
#lttng add-context -s $SESSION_NAME -k -t perf:cache-misses -t perf:major-faults -t perf:branch-load-misses >/dev/null

lttng start $SESSION_NAME >/dev/null
[[ $? != 0 ]] && exit 2

echo -n "The trace is now recording, press ctrl+c to stop it "

while true; do
	echo -n "."
	sleep 1
done

destroy