#!/usr/bin/python

"""\
Run Rivet analyses on HepMC events read from a file or Unix pipe

Examples:

  %prog [options] <hepmcfile> [<hepmcfile2> ...]

  or

  mkfifo fifo.hepmc
  my_generator -o fifo.hepmc &
  %prog [options] fifo.hepmc


ENVIRONMENT:
 * RIVET_ANALYSIS_PATH: list of paths to be searched for plugin
     analysis libraries at runtime
 * RIVET_DATA_PATH: list of paths to be searched for data files
 * See the documentation for more environment variables.
"""

from __future__ import print_function
import os, sys

## Load the rivet module
try:
    import rivet
except:
    ## If rivet loading failed, try to bootstrap the Python path!
    try:
        # TODO: Is this a good idea? Maybe just notify the user that their PYTHONPATH is wrong?
        import commands
        modname = sys.modules[__name__].__file__
        binpath = os.path.dirname(modname)
        rivetconfigpath = os.path.join(binpath, "rivet-config")
        rivetpypath = commands.getoutput(rivetconfigpath + " --pythonpath")
        sys.path.append(rivetpypath)
        import rivet
    except:
        sys.stderr.write("The rivet Python module could not be loaded: is your PYTHONPATH set correctly?\n")
        sys.exit(5)

rivet.util.check_python_version()
rivet.util.set_process_name("rivet")

import time, datetime, logging, signal

## Parse command line options
from optparse import OptionParser, OptionGroup
parser = OptionParser(usage=__doc__, version="rivet v%s" % rivet.version())

anagroup = OptionGroup(parser, "Analysis handling")
anagroup.add_option("-a", "--analysis", "--analyses", dest="ANALYSES", action="append",
                    default=[], metavar="ANA",
                    help="add an analysis (or comma-separated list of analyses) to the processing list.")
anagroup.add_option("--list-analyses", "--list", dest="LIST_ANALYSES", action="store_true",
                    default=False, help="show the list of available analyses' names. With -v, it shows the descriptions, too")
anagroup.add_option("--list-keywords", "--keywords", dest="LIST_KEYWORDS", action="store_true",
                    default=False, help="show the list of available keywords.")
anagroup.add_option("--list-used-analyses", action="store_true", dest="LIST_USED_ANALYSES",
                    default=False, help="list the analyses used by this command (after subtraction of inappropriate ones)")
anagroup.add_option("--show-analysis", "--show-analyses", "--show", dest="SHOW_ANALYSES", action="append",
                    default=[], help="show the details of an analysis")
anagroup.add_option("--show-bibtex", dest="SHOW_BIBTEX", action="store_true",
                    default=False, help="show BibTeX entries for all used analyses")
anagroup.add_option("--analysis-path", dest="ANALYSIS_PATH", metavar="PATH", default=None,
                    help="specify the analysis search path (cf. $RIVET_ANALYSIS_PATH).")
# TODO: remove/deprecate the append?
anagroup.add_option("--analysis-path-append", dest="ANALYSIS_PATH_APPEND", metavar="PATH", default=None,
                    help="append to the analysis search path (cf. $RIVET_ANALYSIS_PATH).")
anagroup.add_option("--pwd", dest="ANALYSIS_PATH_PWD", action="store_true", default=False,
                    help="append the current directory (pwd) to the analysis/data search paths (cf. $RIVET_ANALYSIS_PATH).")
# TODO: add control for more paths?
parser.add_option_group(anagroup)


extragroup = OptionGroup(parser, "Extra run settings")
extragroup.add_option("-o", "-H", "--histo-file", dest="HISTOFILE",
                      default="Rivet.yoda", help="specify the output histo file path (default = %default)")
extragroup.add_option("-p", "--preload-file", dest="PRELOADFILE",
                      default=None, help="specify and old yoda file to initialize (default = %default)")
extragroup.add_option("--no-histo-file", dest="WRITE_DATA", action="store_false", default=True,
                      help="don't write out any histogram file at the end of the run (default = write)")
extragroup.add_option("-x", "--cross-section", dest="CROSS_SECTION",
                      default=None, metavar="XS",
                      help="specify the signal process cross-section in pb")
extragroup.add_option("-n", "--nevts", dest="MAXEVTNUM", type="int",
                      default=None, metavar="NUM",
                      help="restrict the max number of events to process")
extragroup.add_option("--nskip", dest="EVTSKIPNUM", type="int",
                      default=0, metavar="NUM",
                      help="skip NUM events read from input before beginning processing")
extragroup.add_option("--runname", dest="RUN_NAME", default=None, metavar="NAME",
                      help="give an optional run name, to be prepended as a 'top level directory' in histo paths")
extragroup.add_option("--ignore-beams", dest="IGNORE_BEAMS", action="store_true", default=False,
                      help="ignore input event beams when checking analysis compatibility. "
                      "WARNING: analyses may not work correctly, or at all, with inappropriate beams")
parser.add_option_group(extragroup)


timinggroup = OptionGroup(parser, "Timeouts and periodic operations")
timinggroup.add_option("--event-timeout", dest="EVENT_TIMEOUT", type="int",
                       default=21600, metavar="NSECS",
                       help="max time in whole seconds to wait for an event to be generated from the specified source (default = %default)")
timinggroup.add_option("--run-timeout", dest="RUN_TIMEOUT", type="int",
                       default=None, metavar="NSECS",
                       help="max time in whole seconds to wait for the run to finish. This can be useful on batch systems such "
                       "as the LCG Grid where tokens expire on a fixed wall-clock and can render long Rivet runs unable to write "
                       "out the final histogram file (default = unlimited)")
timinggroup.add_option("--histo-interval", dest="HISTO_WRITE_INTERVAL", type=int,
                       default=1000, help="specify the number of events between histogram file updates, default = %default. "
                       "Set to 0 to only write out at the end of the run. Note that intermediate histograms will be those "
                       "from the analyze step only: analysis finalizing is currently not executed until the end of the run.")
parser.add_option_group(timinggroup)


verbgroup = OptionGroup(parser, "Verbosity control")
parser.add_option("-l", dest="NATIVE_LOG_STRS", action="append",
                  default=[], help="set a log level in the Rivet library")
verbgroup.add_option("-v", "--verbose", action="store_const", const=logging.DEBUG, dest="LOGLEVEL",
                     default=logging.INFO, help="print debug (very verbose) messages")
verbgroup.add_option("-q", "--quiet", action="store_const", const=logging.WARNING, dest="LOGLEVEL",
                     default=logging.INFO, help="be very quiet")
parser.add_option_group(verbgroup)
opts, args = parser.parse_args()


## Override/modify analysis search path
if opts.ANALYSIS_PATH:
    rivet.setAnalysisLibPaths(opts.ANALYSIS_PATH.split(":"))
    rivet.setAnalysisDataPaths(opts.ANALYSIS_PATH.split(":"))
if opts.ANALYSIS_PATH_APPEND:
    for ap in opts.ANALYSIS_PATH_APPEND.split(":"):
        rivet.addAnalysisLibPath(ap)
        rivet.addAnalysisDataPath(ap)
if opts.ANALYSIS_PATH_PWD:
    rivet.addAnalysisLibPath(os.path.abspath("."))
    rivet.addAnalysisDataPath(os.path.abspath("."))


## Configure logging
logging.basicConfig(level=opts.LOGLEVEL, format="%(message)s")
for l in opts.NATIVE_LOG_STRS:
    name, level = None, None
    try:
        name, level = l.split("=")
    except:
        name = "Rivet"
        level = l
    ## Fix name
    if name != "Rivet" and not name.startswith("Rivet."):
        name = "Rivet." + name
    try:
        ## Get right error type
        level = rivet.LEVELS.get(level.upper(), None)
        logging.debug("Setting log level: %s %d" % (name, level))
        rivet.setLogLevel(name, level)
    except:
        logging.warning("Couldn't process logging string '%s'" % l)



############################
## Listing available analyses/keywords


def getAnalysesByKeyword(alist, kstring):
    add, veto, ret = [], [], []
    bits = [i for i in kstring.replace("^@", "@^").split("@") if len(i) > 0]
    for b in bits:
        if b.startswith("^"):
            veto.append(b.strip("^"))
        else:
            add.append(b)

    add = set(add)
    veto = set(veto)

    for a in alist:
        kwds = set([i.lower() for i in rivet.AnalysisLoader.getAnalysis(a).keywords()])
        if kwds.intersection(veto) and len(kwds.intersection(add)) == len(list(add)):
            ret.append(a)
    return ret


## List of analyses
all_analyses = rivet.AnalysisLoader.analysisNames()
if opts.LIST_ANALYSES:
    ## Treat args as case-insensitive regexes if present
    regexes = None
    if args:
        import re
        regexes = [re.compile(arg, re.I) for arg in args]
    # import tempfile, subprocess
    # tf, tfpath = tempfile.mkstemp(prefix="rivet-list.")
    names = []
    msg = []
    for aname in all_analyses:
        if not regexes:
            toshow = True
        else:
            toshow = False
            for regex in regexes:
                if regex.search(aname):
                    toshow = True
                    break
        if toshow:
            names.append(aname)
            msg.append('')
            if opts.LOGLEVEL <= logging.INFO:
                a = rivet.AnalysisLoader.getAnalysis(aname)
                st = "" if a.status() == "VALIDATED" else ("[%s] " % a.status())
                # detex will very likely introduce some non-ASCII chars from
                # greek names in analysis titles.
                # The u"" prefix and explicit print encoding are necessary for
                # py2 to handle this properly
                msg[-1] = u"%s%s" % (st, a.summary())
                if opts.LOGLEVEL < logging.INFO:
                    if a.keywords():
                        msg[-1] += u"  [%s]" % " ".join(a.keywords())
                    if a.luminosityfb():
                        msg[-1] += u"  [ \int L = %s fb^{-1} ]" % a.luminosityfb()
    msg = rivet.util.detex(msg)
    retlist = '\n'.join([ u"%-25s   %s" % (a,m) for a,m in zip(names,msg) ])
    if type(u'') is not str:
        retlist = retlist.encode('utf-8')
    print(retlist)
    sys.exit(0)


def getKeywords(alist):
    all_keywords = []
    for a in alist:
        all_keywords.extend(rivet.AnalysisLoader.getAnalysis(a).keywords())
    all_keywords = [i.lower() for i in all_keywords]
    return sorted(list(set(all_keywords)))


## List keywords
if opts.LIST_KEYWORDS:
    # a = rivet.AnalysisLoader.getAnalysis(aname)
    for k in getKeywords(all_analyses):
        print(k)
    sys.exit(0)


## Show analyses' details
if len(opts.SHOW_ANALYSES) > 0:
    toshow = []
    for i, a in enumerate(opts.SHOW_ANALYSES):
        a_up = a.upper()
        if a_up in all_analyses and a_up not in toshow:
            toshow.append(a_up)
        else:
            ## Treat as a case-insensitive regex
            import re
            regex = re.compile(a, re.I)
            for ana in all_analyses:
                if regex.search(ana) and a_up not in toshow:
                    toshow.append(ana)

    msgs = []
    for i, name in enumerate(sorted(toshow)):
        import textwrap
        ana = rivet.AnalysisLoader.getAnalysis(name)

        msg = ""
        msg += name + "\n"
        msg += (len(name) * "=") + "\n\n"
        msg += rivet.util.detex(ana.summary()) + "\n\n"
        msg += "Status: " + ana.status() + "\n\n"

        # TODO: reduce to only show Inspire in v3
        if ana.inspireId():
            msg += "Inspire ID: " + ana.inspireId() + "\n"
            msg += "Inspire URL: http://inspire-hep.net/record/" + ana.inspireId() + "\n"
            msg += "HepData URL: http://hepdata.net/record/ins" + ana.inspireId() + "\n"
        elif ana.spiresId():
            msg += "Spires ID: " + ana.spiresId() + "\n"
            msg += "Inspire URL: http://inspire-hep.net/search?p=find+key+" + ana.spiresId() + "\n"
            msg += "HepData URL: http://hepdata.cedar.ac.uk/view/irn" + ana.spiresId() + "\n"

        if ana.year():
            msg += "Year of publication: " + ana.year() + "\n"
        if ana.bibKey():
            msg += "BibTeX key: " + ana.bibKey() + "\n"

        msg += "Authors:\n"
        for a in ana.authors():
            msg += "  " + a + "\n"
        msg += "\n"

        msg += "Description:\n"
        twrap = textwrap.TextWrapper(width=75, initial_indent=2*" ", subsequent_indent=2*" ")
        msg += twrap.fill(rivet.util.detex(ana.description())) + "\n\n"

        if ana.experiment():
            msg += "Experiment: " + ana.experiment()
            if ana.collider():
                msg += "(%s)" % ana.collider()
            msg += "\n"
        # TODO: move this formatting into Analysis or a helper function?
        if ana.requiredBeams():
            def pid_to_str(pid):
                if pid == 11:
                    return "e-"
                elif pid == -11:
                    return "e+"
                elif pid == 2212:
                    return "p+"
                elif pid == -2212:
                    return "p-"
                elif pid == 10000:
                    return "*"
                else:
                    return str(pid)
            beamstrs = []
            for bp in ana.requiredBeams():
                beamstrs.append(pid_to_str(bp[0]) + " " + pid_to_str(bp[1]))
            msg += "Beams:" + ", ".join(beamstrs) + "\n"

        if ana.requiredEnergies():
            msg += "Beam energies:" + "; ".join(["(%0.1f, %0.1f) GeV\n" % (epair[0], epair[1]) for epair in ana.requiredEnergies()])
        else:
            msg += "Beam energies: ANY\n"

        if ana.runInfo():
            msg += "Run details:\n"
            twrap = textwrap.TextWrapper(width=75, initial_indent=2*" ", subsequent_indent=4*" ")
            for l in ana.runInfo().split("\n"):
                msg += twrap.fill(l) + "\n"

        if ana.luminosityfb():
            msg+= "\nIntegrated data luminosity = %s inverse fb.\n"%ana.luminosityfb()

        if ana.keywords():
            msg += "\nAnalysis keywords:"
            for k in ana.keywords():
                msg += " %s"%k
            msg+= "\n\n"

        if ana.references():
            msg += "\n" + "References:\n"
            for r in ana.references():
                url = None
                if r.startswith("arXiv:"):
                    code = r.split()[0].replace("arXiv:", "")
                    url = "http://arxiv.org/abs/" + code
                elif r.startswith("doi:"):
                    code = r.replace("doi:", "")
                    url = "http://dx.doi.org/" + code
                if url is not None:
                    r += " - " + url
                msg += "  " + r + "\n"

        ## Add to the output
        msgs.append(msg)

    ## Write the combined messages to a temporary file and page it
    if msgs:
        try:
            import tempfile, subprocess
            tffd, tfpath = tempfile.mkstemp(prefix="rivet-show.")
            os.write(tffd, u"\n\n".join(msgs).encode('utf-8'))
            if sys.stdout.isatty():
                pager = subprocess.Popen(["less", "-FX", tfpath]) #, stdin=subprocess.PIPE)
                pager.communicate()
            else:
                f = open(tfpath)
                print(f.read())
                f.close()
        finally:
            os.unlink(tfpath) #< always clean up
    sys.exit(0)



############################
## Actual analysis runs



## We allow comma-separated lists of analysis names -- normalise the list here
newanas = []
for a in opts.ANALYSES:
    if "," in a:
        newanas += a.split(",")
    elif "@" in a: #< NB. this bans combination of ana lists and keywords in a single arg
        temp = getAnalysesByKeyword(all_analyses, a)
        for i in temp:
            newanas.append(i)
    else:
        newanas.append(a)
opts.ANALYSES = newanas


## Parse supplied cross-section
if opts.CROSS_SECTION is not None:
    xsstr = opts.CROSS_SECTION
    try:
        opts.CROSS_SECTION = float(xsstr)
    except:
        import re
        suffmatch = re.search(r"[^\d.]", xsstr)
        if not suffmatch:
            raise ValueError("Bad cross-section string: %s" % xsstr)
        factor = base = None
        suffstart = suffmatch.start()
        if suffstart != -1:
            base = xsstr[:suffstart]
            suffix = xsstr[suffstart:].lower()
            if suffix == "mb":
                factor = 1e+9
            elif suffix == "mub":
                factor = 1e+6
            elif suffix == "nb":
                factor = 1e+3
            elif suffix == "pb":
                factor = 1
            elif suffix == "fb":
                factor = 1e-3
            elif suffix == "ab":
                factor = 1e-6
        if factor is None or base is None:
            raise ValueError("Bad cross-section string: %s" % xsstr)
        xs = float(base) * factor
        opts.CROSS_SECTION = xs


## Print the available CLI options!
#if opts.LIST_OPTIONS:
#    for o in parser.option_list:
#        print(o.get_opt_string())
#    sys.exit(0)


## Set up signal handling
RECVD_KILL_SIGNAL = None
def handleKillSignal(signum, frame):
    "Declare us as having been signalled, and return to default handling behaviour"
    global RECVD_KILL_SIGNAL
    logging.critical("Signal handler called with signal " + str(signum))
    RECVD_KILL_SIGNAL = signum
    signal.signal(signum, signal.SIG_DFL)
## Signals to handle
signal.signal(signal.SIGTERM, handleKillSignal);
signal.signal(signal.SIGHUP,  handleKillSignal);
signal.signal(signal.SIGINT,  handleKillSignal);
signal.signal(signal.SIGUSR1, handleKillSignal);
signal.signal(signal.SIGUSR2, handleKillSignal);
try:
    signal.signal(signal.SIGXCPU, handleKillSignal);
except:
    pass



## Identify HepMC files/streams
## TODO: check readability, deal with stdin
if len(args) > 0:
    HEPMCFILES = args
else:
    HEPMCFILES = ["-"]


## Event number logging
def logNEvt(n, starttime, maxevtnum):
    if n % 10000 == 0:
        nevtloglevel = logging.CRITICAL
    elif n % 1000 == 0:
        nevtloglevel = logging.WARNING
    elif n % 100 == 0:
        nevtloglevel = logging.INFO
    else:
        nevtloglevel = logging.DEBUG
    currenttime = datetime.datetime.now().replace(microsecond=0)
    elapsedtime = currenttime - starttime
    logging.log(nevtloglevel, "Event %d (%s elapsed)" % (n, str(elapsedtime)))
    # if maxevtnum is None:
    #     logging.log(nevtloglevel, "Event %d (%s elapsed)" % (n, str(elapsedtime)))
    # else:
    #     remainingtime = (maxevtnum-n) * elapsedtime.total_seconds() / float(n)
    #     eta = time.strftime("%a %b %d %H:%M", datetime.localtime(currenttime + remainingtime))
    #     logging.log(nevtloglevel, "Event %d (%d s elapsed / %d s left) -> ETA: %s" %
    #                 (n, elapsedtime, remainingtime, eta))


## Do some checks on output histo file, before we stat the event loop
histo_parentdir = os.path.dirname(os.path.abspath(opts.HISTOFILE))
if not os.path.exists(histo_parentdir):
  logging.error('Parent path of output histogram file does not exist: %s\nExiting.' % histo_parentdir)
  sys.exit(4)
if not os.access(histo_parentdir,os.W_OK):
  logging.error('Insufficient permissions to write output histogram file to directory %s\nExiting.' % histo_parentdir)
  sys.exit(4)


## Set up analysis handler
RUNNAME = opts.RUN_NAME or ""
ah = rivet.AnalysisHandler(RUNNAME)
ah.setIgnoreBeams(opts.IGNORE_BEAMS)

for a in opts.ANALYSES:
    ## Print warning message and exit if not a valid analysis name
    if not a in all_analyses:
        logging.warning("'%s' is not a known Rivet analysis! Do you need to set RIVET_ANALYSIS_PATH or use the --pwd switch?\n" % a)
        # TODO: lay out more neatly, or even try for a "did you mean XXXX?" heuristic?
        logging.warning("There are %d currently available analyses:\n" % len(all_analyses) + ", ".join(all_analyses))
        sys.exit(1)
    logging.debug("Adding analysis '%s'" % a)
    ah.addAnalysis(a)

if opts.PRELOADFILE is not None:
    ah.readData(opts.PRELOADFILE)


if opts.SHOW_BIBTEX:
    bibs = []
    for aname in sorted(ah.analysisNames()):
        ana = rivet.AnalysisLoader.getAnalysis(aname)
        bibs.append("% " + aname + "\n" + ana.bibTeX())
    if bibs:
        print("\nBibTeX for used Rivet analyses:\n")
        print("% --------------------------\n")
        print("\n\n".join(bibs) + "\n")
        print("% --------------------------\n")


## Read and process events
run = rivet.Run(ah)
if opts.CROSS_SECTION is not None:
    logging.info("User-supplied cross-section = %e pb" % opts.CROSS_SECTION)
    run.setCrossSection(opts.CROSS_SECTION)
if opts.LIST_USED_ANALYSES is not None:
    run.setListAnalyses(opts.LIST_USED_ANALYSES)

## Print platform type
import platform
starttime = datetime.datetime.now().replace(microsecond=0)
logging.info("Rivet %s running on machine %s (%s) at %s" % \
             (rivet.version(), platform.node(), platform.machine(), str(starttime)))


def min_nonnull(a, b):
    "A version of min which considers None to always be greater than a real number"
    if a is None: return b
    if b is None: return a
    return min(a, b)

## Set up an event timeout handler
class TimeoutException(Exception):
    pass
if opts.EVENT_TIMEOUT or opts.RUN_TIMEOUT:
    def evttimeouthandler(signum, frame):
        logging.warn("It has taken more than %d secs to get an event! Is the input event stream working?" %
                     min_nonnull(opts.EVENT_TIMEOUT, opts.RUN_TIMEOUT))
        raise TimeoutException("Event timeout")
    signal.signal(signal.SIGALRM, evttimeouthandler)


## Init run based on one event
hepmcfile = HEPMCFILES[0]
## Apply a file-level weight derived from the filename
hepmcfileweight = 1.0
if ":" in hepmcfile:
    hepmcfile, hepmcfileweight = hepmcfile.rsplit(":", 1)
    hepmcfileweight = float(hepmcfileweight)
try:
    if opts.EVENT_TIMEOUT or opts.RUN_TIMEOUT:
        signal.alarm(min_nonnull(opts.EVENT_TIMEOUT, opts.RUN_TIMEOUT))
        init_ok = run.init(hepmcfile, hepmcfileweight)
    signal.alarm(0)
    if not init_ok:
        logging.error("Failed to initialise using event file '%s'... exiting" % hepmcfile)
        sys.exit(2)
except TimeoutException as te:
    logging.error("Timeout in initialisation from event file '%s'... exiting" % hepmcfile)
    sys.exit(3)
except:
    logging.warning("Could not read from '%s'" % hepmcfile)
    sys.exit(3)

## Event loop
evtnum = 0
for fileidx, hepmcfile in enumerate(HEPMCFILES):
    ## Apply a file-level weight derived from the filename
    hepmcfileweight = 1.0
    if ":" in hepmcfile:
        hepmcfile, hepmcfileweight = hepmcfile.rsplit(":", 1)
        hepmcfileweight = float(hepmcfileweight)

    ## Open next HepMC file (NB. this doesn't apply to the first file: it was already used for the run init)
    if fileidx > 0:
        try:
            run.openFile(hepmcfile, hepmcfileweight)
        except:
            logging.warning("Could not read from '%s'" % hepmcfile)
            continue
        if not run.readEvent():
            logging.warning("Could not read events from '%s'" % hepmcfile)
            continue

    ## Announce new file
    msg = "Reading events from '%s'" % hepmcfile
    if hepmcfileweight != 1.0:
        msg += " (file weight = %e)" % hepmcfileweight
    logging.info(msg)

    ## The event loop
    while opts.MAXEVTNUM is None or evtnum-opts.EVTSKIPNUM < opts.MAXEVTNUM:
        evtnum += 1

        ## Optional event skipping
        if evtnum <= opts.EVTSKIPNUM:
            logging.debug("Skipping event #%i" % evtnum)
            run.skipEvent();
            continue

        ## Only log the event number once we're actually processing
        logNEvt(evtnum, starttime, opts.MAXEVTNUM)

        ## Process this event
        processed_ok = run.processEvent()
        if not processed_ok:
            logging.warn("Event processing failed for evt #%i!" % evtnum)
            break

        ## Set flag to exit event loop if run timeout exceeded
        if opts.RUN_TIMEOUT and (time.time() - starttime) > opts.RUN_TIMEOUT:
            logging.warning("Run timeout of %d secs exceeded... exiting gracefully" % opts.RUN_TIMEOUT)
            RECVD_KILL_SIGNAL = True

        ## Exit the loop if signalled
        if RECVD_KILL_SIGNAL is not None:
            break

        ## Read next event (with timeout handling if requested)
        try:
            if opts.EVENT_TIMEOUT:
                signal.alarm(opts.EVENT_TIMEOUT)
            read_ok = run.readEvent()
            signal.alarm(0)
            if not read_ok:
                break
        except TimeoutException as te:
            logging.error("Timeout in reading event from '%s'... exiting" % hepmcfile)
            sys.exit(3)

        ## Write a histo file snapshot if appropriate
        if opts.HISTO_WRITE_INTERVAL is not None and opts.HISTO_WRITE_INTERVAL > 0:
            if evtnum % opts.HISTO_WRITE_INTERVAL == 0:
                ah.writeData(opts.HISTOFILE)


## Print end-of-loop messages
loopendtime = datetime.datetime.now().replace(microsecond=0)
logging.info("Finished event loop at %s" % str(loopendtime))
logging.info("Cross-section = %e pb" % ah.crossSection())
print()


## Finalize and write out data file
run.finalize()
if opts.WRITE_DATA:
    ah.writeData(opts.HISTOFILE)
print()
endtime = datetime.datetime.now().replace(microsecond=0)
logging.info("Rivet run completed at %s, time elapsed = %s" % (str(endtime), str(endtime-starttime)))
print()
logging.info("Histograms written to %s" % os.path.abspath(opts.HISTOFILE))
