From: Brian Warner Date: Thu, 7 Aug 2008 04:22:22 +0000 (-0700) Subject: disk-watcher: first draft of a daemon to use the HTTP stats interface and its new... X-Git-Url: https://git.rkrishnan.org/pf/content/it.html?a=commitdiff_plain;h=46d0c9c995d383ae8d99e7bda53cb40fb997e4ec;p=tahoe-lafs%2Ftahoe-lafs.git disk-watcher: first draft of a daemon to use the HTTP stats interface and its new storage_server.disk_avail feature, to track changes in disk space over time --- diff --git a/misc/spacetime/diskwatcher.py b/misc/spacetime/diskwatcher.py new file mode 100644 index 00000000..7de54c9f --- /dev/null +++ b/misc/spacetime/diskwatcher.py @@ -0,0 +1,14 @@ + +# put this definition in a separate file, because axiom uses the +# fully-qualified classname as a database table name, so __builtin__ is kinda +# ugly. + +from axiom.item import Item +from axiom.attributes import text, integer, timestamp + +class Sample(Item): + url = text() + when = timestamp(indexed=True) + used = integer() + avail = integer() + diff --git a/misc/spacetime/diskwatcher.tac b/misc/spacetime/diskwatcher.tac new file mode 100644 index 00000000..b62b4415 --- /dev/null +++ b/misc/spacetime/diskwatcher.tac @@ -0,0 +1,256 @@ +# -*- python -*- + +""" +Run this tool with twistd in its own directory, with a file named 'urls.txt' +describing which nodes to query. It will request disk-usage numbers from the +nodes once per hour (or slower), and store them in a local database. It will +compute usage-per-unit time values over several time ranges and make them +available through an HTTP query (using ./webport). It will also provide an +estimate of how much time is left before the grid's storage is exhausted. + +Each line of urls.txt points to a single node. Each node should have its own +dedicated disk: if multiple nodes share a disk, only list one of them in +urls.txt (otherwise that space will be double-counted, confusing the +results). Each line should be in the form: + + http://host:webport/statistics?t=json + +""" + +# TODO: +# built-in graphs on web interface + + +import os.path, pprint, time, urllib +from datetime import timedelta +from twisted.application import internet, service, strports +from twisted.web import server, resource, http +from twisted.python import log +import simplejson +from axiom.attributes import AND +from axiom.store import Store +from epsilon import extime +from diskwatcher import Sample + +#from axiom.item import Item +#from axiom.attributes import text, integer, timestamp + +#class Sample(Item): +# url = text() +# when = timestamp() +# used = integer() +# avail = integer() + +#s = Store("history.axiom") +#ns = Store("new-history.axiom") +#for sa in s.query(Sample): +# diskwatcher.Sample(store=ns, +# url=sa.url, when=sa.when, used=sa.used, avail=sa.avail) +#print "done" + +HOUR = 3600 +DAY = 24*3600 +WEEK = 7*DAY +MONTH = 30*DAY +YEAR = 365*DAY + +class DiskWatcher(service.MultiService, resource.Resource): + POLL_INTERVAL = 60#1*HOUR + AVERAGES = {"60s": 60, + "5m": 5*60, + "30m": 30*60, + "1hr": 1*HOUR, + "1day": 1*DAY, + "2wk": 2*WEEK, + "4wk": 4*WEEK, + } + + def __init__(self): + assert os.path.exists("diskwatcher.tac") # run from the right directory + service.MultiService.__init__(self) + resource.Resource.__init__(self) + self.store = Store("history.axiom") + ts = internet.TimerService(self.POLL_INTERVAL, self.poll) + ts.setServiceParent(self) + + def startService(self): + service.MultiService.startService(self) + + try: + desired_webport = open("webport", "r").read().strip() + except EnvironmentError: + desired_webport = None + webport = desired_webport or "tcp:0" + root = self + serv = strports.service(webport, server.Site(root)) + serv.setServiceParent(self) + if not desired_webport: + got_port = serv._port.getHost().port + open("webport", "w").write("tcp:%d\n" % got_port) + + + def get_urls(self): + for url in open("urls.txt","r").readlines(): + if "#" in url: + url = url[:url.find("#")] + url = url.strip() + if not url: + continue + yield url + + def poll(self): + log.msg("polling..") + attempts = 0 + fetched = 0 + for url in self.get_urls(): + attempts += 1 + try: + when = extime.Time() + data = simplejson.load(urllib.urlopen(url)) + total = data[u"stats"][u"storage_server.disk_total"] + used = data[u"stats"][u"storage_server.disk_used"] + avail = data[u"stats"][u"storage_server.disk_avail"] + #print "%s : total=%s, used=%s, avail=%s" % (url, + # total, used, avail) + s = Sample(store=self.store, + url=unicode(url), when=when, used=used, avail=avail) + fetched += 1 + except: + log.msg("error while fetching: %s" % url) + log.err() + log.msg("fetched %d of %d" % (fetched, attempts)) + + def calculate(self): + timespans = [] + total_avail_space = self.find_total_avail_space() + pairs = [ (timespan,name) + for name,timespan in self.AVERAGES.items() ] + pairs.sort() + for (timespan,name) in pairs: + growth = self.growth(timespan) + print name, total_avail_space, growth + if growth is not None: + try: + timeleft = total_avail_space / growth + except ZeroDivisionError: + timeleft = None + timespans.append( (name, timespan, growth, timeleft) ) + return timespans + + def find_total_avail_space(self): + # this returns the sum of disk-avail stats for all servers that 1) + # are listed in urls.txt and 2) have responded recently. + now = extime.Time() + recent = now - timedelta(seconds=2*self.POLL_INTERVAL) + total_avail_space = 0 + for url in self.get_urls(): + url = unicode(url) + latest = list(self.store.query(Sample, + AND(Sample.url == url, + Sample.when > recent), + sort=Sample.when.descending, + limit=1)) + if latest: + total_avail_space += latest[0].avail + return total_avail_space + + + def growth(self, timespan): + """Calculate the bytes-per-second growth of the total disk-used stat, + over a period of TIMESPAN seconds (i.e. between the most recent + sample and the latest one that's at least TIMESPAN seconds ago), + summed over all nodes which 1) are listed in urls.txt, 2) have + responded recently, and 3) have a response at least as old as + TIMESPAN. If there are no nodes which meet these criteria, we'll + return None; this is likely to happen for the longer timespans (4wk) + until the gatherer has been running and collecting data for that + long.""" + + td = timedelta(seconds=timespan) + now = extime.Time() + then = now - td + recent = now - timedelta(seconds=2*self.POLL_INTERVAL) + + total_growth = 0.0 + num_nodes = 0 + + for url in self.get_urls(): + url = unicode(url) + latest = list(self.store.query(Sample, + AND(Sample.url == url, + Sample.when > recent), + sort=Sample.when.descending, + limit=1)) + if not latest: + #print "no latest sample from", url + continue # skip this node + latest = latest[0] + old = list(self.store.query(Sample, + AND(Sample.url == url, + Sample.when < then), + sort=Sample.when.descending, + limit=1)) + if not old: + #print "no old sample from", url + continue # skip this node + old = old[0] + duration = latest.when.asPOSIXTimestamp() - old.when.asPOSIXTimestamp() + if not duration: + print "only one sample from", url + continue + + rate = float(latest.used - old.used) / duration + #print url, rate + total_growth += rate + num_nodes += 1 + + if not num_nodes: + return None + return total_growth + + def getChild(self, path, req): + if path == "": + return self + return resource.Resource.getChild(self, path, req) + + def abbreviate_time(self, s): + def _plural(count, unit): + count = int(count) + if count == 1: + return "%d %s" % (count, unit) + return "%d %ss" % (count, unit) + if s is None: + return "unknown" + if s < 120: + return _plural(s, "second") + if s < 3*HOUR: + return _plural(s/60, "minute") + if s < 2*DAY: + return _plural(s/HOUR, "hour") + if s < 2*MONTH: + return _plural(s/DAY, "day") + if s < 4*YEAR: + return _plural(s/MONTH, "month") + return _plural(s/YEAR, "year") + + def render(self, req): + t = req.args.get("t", ["html"])[0] + ctype = "text/plain" + data = "" + if t == "html": + data = "" + for (name, timespan, growth, timeleft) in self.calculate(): + data += "%f bytes per second, %s remaining (over %s)\n" % \ + (growth, self.abbreviate_time(timeleft), name) + elif t == "json": + current = self.calculate() + #data = str(current) + "\n" # isn't that convenient? almost. + data = simplejson.dumps(current, indent=True) + else: + req.setResponseCode(http.BAD_REQUEST) + data = "Unknown t= %s\n" % t + req.setHeader("content-type", ctype) + return data + +application = service.Application("disk-watcher") +DiskWatcher().setServiceParent(application)