#!/bin/bash
#
# Poor man's sampling profiler for NuttX.
#
# The stack folding script was inspired by stackcollapse-gdb.pl from the FlameGraph project.
#
# Usage: Install flamegraph.pl in your PATH, define the variables below, configure your .gdbinit, run the script and go
#        have a coffee. When you're back, you'll see the flamegraph. Note that frequent calls to GDB significantly
#        interfere with normal operation of the target, which means that you can't profile real-time tasks with it.
#
# Requirements: ARM GDB with Python support
#

set -e
root=$(dirname $0)/..

function die()
{
    echo "$@"
    exit 1
}

function usage()
{
    echo "Invalid usage. Supported options:"
    cat $0 | sed -n 's/^\s*--\([^)\*]*\).*/\1/p' # Don't try this at home.
    exit 1
}

which flamegraph.pl > /dev/null || die "Install flamegraph.pl first"

#
# Parsing the arguments. Read this section for usage info.
#
nsamples=0
sleeptime=0.1    # Doctors recommend 7-8 hours a day
taskname=
elf=$root/Build/px4fmu-v2_default.build/firmware.elf
append=0
fgfontsize=10
fgwidth=1900

for i in "$@"
do
    case $i in
        --nsamples=*)
            nsamples="${i#*=}"
            ;;
        --sleeptime=*)
            sleeptime="${i#*=}"
            ;;
        --taskname=*)
            taskname="${i#*=}"
            ;;
        --elf=*)
            elf="${i#*=}"
            ;;
        --append)
            append=1
            ;;
        --fgfontsize=*)
            fgfontsize="${i#*=}"
            ;;
        --fgwidth=*)
            fgwidth="${i#*=}"
            ;;
        *)
            usage
            ;;
    esac
    shift
done

#
# Temporary files
#
stacksfile=/tmp/pmpn-stacks.log
foldfile=/tmp/pmpn-folded.txt
graphfile=/tmp/pmpn-flamegraph.svg
gdberrfile=/tmp/pmpn-gdberr.log

#
# Sampling if requested. Note that if $append is true, the stack file will not be rewritten.
#
cd $root

if [[ $nsamples > 0 ]]
then
    [[ $append = 0 ]] && (rm -f $stacksfile; echo "Old stacks removed")

    echo "Sampling the task '$taskname'..."

    for x in $(seq 1 $nsamples)
    do
        if [[ "$taskname" = "" ]]
        then
            arm-none-eabi-gdb $elf --batch -ex "set print asm-demangle on" -ex bt \
                2> $gdberrfile \
                | sed -n 's/\(#.*\)/\1/p' \
                >> $stacksfile
        else
            arm-none-eabi-gdb $elf --batch -ex "set print asm-demangle on" \
                                           -ex "source $root/Debug/Nuttx.py" \
                                           -ex "show mybt $taskname" \
                2> $gdberrfile \
                | sed -n 's/0\.0:\(#.*\)/\1/p' \
                >> $stacksfile
        fi
        echo -e '\n\n' >> $stacksfile
        echo -ne "\r$x/$nsamples"
        sleep $sleeptime
    done

    echo
    echo "Stacks saved to $stacksfile"
else
    echo "Sampling skipped - set 'nsamples' to re-sample."
fi

#
# Folding the stacks.
#
[ -f $stacksfile ] || die "Where are the stack samples?"

cat $stacksfile | python -c "
#
# This stack folder correctly handles C++ types.
#

from __future__ import print_function, division
import fileinput, collections, os

def enforce(x, msg='Invalid input'):
    if not x:
        raise Exception(msg)

def split_first_part_with_parens(line):
    LBRACES = {'(':'()', '<':'<>', '[':'[]', '{':'{}'}
    RBRACES = {')':'()', '>':'<>', ']':'[]', '}':'{}'}
    braces = collections.defaultdict(int)
    out = ''
    for ch in line:
        out += ch
        # special cases
        if out.endswith('operator>') or out.endswith('operator->'):  # gotta love c++
            braces['<>'] += 1
        if out.endswith('operator<'):
            braces['<>'] -= 1
        # counting parens
        if ch in LBRACES.keys():
            braces[LBRACES[ch]] += 1
        if ch in RBRACES.keys():
            braces[RBRACES[ch]] -= 1
        # sanity check
        for v in braces.values():
            enforce(v >= 0, 'Unaligned braces: ' + str(dict(braces)))
        # termination condition
        if ch == ' ' and sum(braces.values()) == 0:
            break
    out = out.strip()
    return out, line[len(out):]

def parse(line):
    def take_path(line, output):
        line = line.strip()
        if line.startswith('at '):
            line = line[3:].strip()
        if line:
            output['file_full_path'] = line.rsplit(':', 1)[0].strip()
            output['file_base_name'] = os.path.basename(output['file_full_path'])
            output['line'] = int(line.rsplit(':', 1)[1])
        return output

    def take_args(line, output):
        line = line.lstrip()
        if line[0] == '(':
            output['args'], line = split_first_part_with_parens(line)
        return take_path(line.lstrip(), output)

    def take_function(line, output):
        output['function'], line = split_first_part_with_parens(line.lstrip())
        return take_args(line.lstrip(), output)

    def take_mem_loc(line, output):
        line = line.lstrip()
        if line.startswith('0x'):
            end = line.find(' ')
            num = line[:end]
            output['memloc'] = int(num, 16)
            line = line[end:].lstrip()
            end = line.find(' ')
            enforce(line[:end] == 'in')
            line = line[end:].lstrip()
        return take_function(line, output)

    def take_frame_num(line, output):
        line = line.lstrip()
        enforce(line[0] == '#')
        end = line.find(' ')
        num = line[1:end]
        output['frame_num'] = int(num)
        return take_mem_loc(line[end:], output)

    return take_frame_num(line, {})

stacks = collections.defaultdict(int)
current = ''

for line in fileinput.input():
    line = line.strip()
    if line:
        inf = parse(line)
        fun = inf['function']
        current = (fun + ';' + current) if current else fun
    elif current:
        stacks[current] += 1
        current = ''

for s, f in sorted(stacks.items(), key=lambda (s, f): s):
    print(s, f)
" > $foldfile

echo "Folded stacks saved to $foldfile"

#
# Graphing.
#
cat $foldfile | flamegraph.pl --fontsize=$fgfontsize --width=$fgwidth > $graphfile
echo "FlameGraph saved to $graphfile"

# On KDE, xdg-open prefers Gwenview by default, which doesn't handle interactive SVGs, so we need a browser.
# The current implementation is hackish and stupid. Somebody, please do something about it.
opener=xdg-open
which firefox       > /dev/null && opener=firefox
which google-chrome > /dev/null && opener=google-chrome

$opener $graphfile