#!/usr/bin/env python3

# Process file generated by using GBUILD_TRACE=file with make.
# The file needs adjusting for viewing in Chromium's "chrome://tracing' URL.
# See solenv/gbuild/Trace.mk for details.

import os
import re
import sys

if len(sys.argv) != 2:
    print ("Usage: " + sys.argv[0] + " [trace.json]", file=sys.stderr)
    sys.exit(1)

filename=sys.argv[1]

with open(filename) as infile:
    lines = [ line.rstrip('\n') for line in infile ]

if len(lines) == 0 :
    print( "Empty file?", file=sys.stderr)
    sys.exit(1)

if lines[0] == '{"traceEvents": [':
    print( "File already processed", file=sys.stderr)
    sys.exit(3)

# sort items by time (parallel writes may not write them in time order)
def linekey(line):
    match = re.match( r'^.*, "ts": ([0-9]*)[0-9][0-9][0-9],.*$', line )
    assert match, "Unknown line: " + line
    return int(match.group(1))
lines.sort( key=linekey )

# 'chrome://tracing' shows several rows, we use those to show build parallelism,
# but we need to assign the proper ids by allocating them as slots.
slots = []
# start time of each slot
slot_start_time = []

def make_slot_string(type, detail):
    return type + '#' + detail

def allocate_slot(type, detail):
    for index in range(len(slots)):
        if slots[index] == "":
            slots[index] = make_slot_string(type, detail)
            return index + 1
    index = len(slots)
    slots.append(make_slot_string(type, detail))
    slot_start_time.append(0)
    return index + 1

def free_slot(type, detail):
    for index in range(len(slots)):
        if slots[index] == make_slot_string(type, detail):
            slots[index] = ""
            return index + 1
    assert False, "free_slot(" + type + "," + detail + ") not found"

# key: Type (e.g. CXX), value: time total
totals_time = {}
totals_count = {}

# time of the first item, to rebase all times to 0
start_time = 0

with open(filename + ".tmp", "w") as outfile:
    print( '{"traceEvents": [', file=outfile)
    for iline in range(len(lines)):
        line = lines[iline]
        # "ts" needs converting nanoseconds -> milliseconds
        match = re.match( r'^{"name": "([^"]*)", "ph": "(.)",.*"ts": ([0-9]*)[0-9][0-9][0-9],"args":{"message":"([^"]*)"}.*$', line )
        if not match:
            print( "Unknown line: " + line, file=sys.stderr)
            sys.exit(2)
        if start_time == 0:
            start_time = int(match.group(3))
        # "tid" needs replacing with proper slot
        tid = "0"
        # "ph"
        if match.group(2) == 'B':
            tid = allocate_slot(match.group(1), match.group(4)) # "name", "args"
            slot_start_time[tid-1] = int(match.group(3))
        elif match.group(2) == 'E':
            tid = free_slot(match.group(1), match.group(4)) # "name", "args"
            if match.group(1) not in totals_time:
                totals_time[match.group(1)] = 0
                totals_count[match.group(1)] = 0
            totals_time[match.group(1)] += int(match.group(3)) - slot_start_time[tid-1]
            totals_count[match.group(1)] += 1
        line = re.sub( r'"ts": [0-9]+,', '"ts": ' + str(int(match.group(3)) - start_time) + ",", line)
        line = re.sub( r'"tid": 1,', '"tid": ' + str(tid) + ",", line)
        if match.group(2) == 'i':
            rline = line
            # mark as affecting all slots
            line = re.sub( r'}},$', '}, "s": "p"},', line)
            print(line, file=outfile)
            # Chromium search doesn't find 'i' items, add extra 'R' for that
            rline = re.sub( r', "ph": "i",', ', "ph": "R",', rline)
            rline = re.sub( r', "tid": [0-9]+,', ',', rline)
            print(rline, file=outfile)
        else:
            print(line, file=outfile)
        # TODO: By the first time "[DEP]: LNK:Executable/makedepend.exe" is invoked the build tools
        # are not built yet, so the invocation fails, doesn't abort the build for some reason,
        # but the matching line about it ending is missing. So add the missing end line if it is
        # by another start line for it instead of an end line.
        if match.group(1) == "DEP" and match.group(4) == "[DEP]: LNK:Executable/makedepend.exe" and match.group(2) == "B":
            for iline2 in range(iline+1,len(lines)): # search following lines
                line2 = lines[iline2]
                match2 = re.match( r'^{"name": "([^"]*)", "ph": "(.)",.*"ts": ([0-9]*)[0-9][0-9][0-9],"args":{"message":"([^"]*)"}.*$', line2 )
                if match2.group(1) == "DEP" and match2.group(4) == "[DEP]: LNK:Executable/makedepend.exe":
                    if match2.group(2) == "E":
                        break # it has a matching close
                    if match2.group(2) == "B":
                        print(re.sub( r', "ph": "B",', ', "ph": "E",', line), file=outfile) # close the starting line
                        free_slot(match.group(1), match.group(4))
                        break

    total_num = 0
    for total in sorted(totals_time, key=totals_time.get, reverse=True):
        note = ""
        if total == "EXTERNAL":
            note = ',"note": "minimum (cannot detect parallelism)"'
        print( '{"pid":2,"tid":' + str(total_num) + ',"ts":0,"dur":' + str(totals_time[total]) + ',"ph":"X","name":"' + total
            + '","args":{"count":"' + str(totals_count[total]) + '"' + note + '}},', file=outfile)
        total_num += 1

    print( '{"pid":1,"tid":0,"ts":0,"ph":"M","name":"process_name","args":{"name":"gbuild"}},', file=outfile)
    print( '{"pid":2,"tid":0,"ts":0,"ph":"M","name":"process_name","args":{"name":"totals"}}]}', file=outfile)

for index in range(len(slots)):
    if slots[index] != "":
        print( "Unclosed range: " + slots[index], file=sys.stderr)

os.rename(filename + ".tmp", filename)