From: Daira Hopwood Date: Tue, 4 Aug 2015 16:58:37 +0000 (+0100) Subject: test_storage.py: ss -> server for cases that will remain a server after the server... X-Git-Url: https://git.rkrishnan.org/%5B/frontends/%22file:/somewhere?a=commitdiff_plain;h=a4f784e2505c9b4b2f8b4e721c00763f3cce3a4e;p=tahoe-lafs%2Ftahoe-lafs.git test_storage.py: ss -> server for cases that will remain a server after the server/account split. Signed-off-by: David-Sarah Hopwood --- diff --git a/src/allmydata/test/test_storage.py b/src/allmydata/test/test_storage.py index 3a12fab0..86c20f1a 100644 --- a/src/allmydata/test/test_storage.py +++ b/src/allmydata/test/test_storage.py @@ -316,10 +316,10 @@ class Server(unittest.TestCase): def create(self, name, reserved_space=0, klass=StorageServer): workdir = self.workdir(name) - ss = klass(workdir, "\x00" * 20, reserved_space=reserved_space, - stats_provider=FakeStatsProvider()) - ss.setServiceParent(self.sparent) - return ss + server = klass(workdir, "\x00" * 20, reserved_space=reserved_space, + stats_provider=FakeStatsProvider()) + server.setServiceParent(self.sparent) + return server def test_create(self): self.create("test_create") @@ -772,9 +772,9 @@ class MutableServer(unittest.TestCase): def create(self, name): workdir = self.workdir(name) - ss = StorageServer(workdir, "\x00" * 20) - ss.setServiceParent(self.sparent) - return ss + server = StorageServer(workdir, "\x00" * 20) + server.setServiceParent(self.sparent) + return server def test_create(self): self.create("test_create") @@ -1404,10 +1404,10 @@ class MDMFProxies(unittest.TestCase, ShouldFailMixin): def create(self, name): workdir = self.workdir(name) - ss = StorageServer(workdir, "\x00" * 20) - ss.setServiceParent(self.sparent) - return ss + server = StorageServer(workdir, "\x00" * 20) + server.setServiceParent(self.sparent) + return server def build_test_mdmf_share(self, tail_segment=False, empty=False): # Start with the checkstring @@ -2782,27 +2782,27 @@ class Stats(unittest.TestCase): def create(self, name): workdir = self.workdir(name) - ss = StorageServer(workdir, "\x00" * 20) - ss.setServiceParent(self.sparent) - return ss + server = StorageServer(workdir, "\x00" * 20) + server.setServiceParent(self.sparent) + return server def test_latencies(self): - ss = self.create("test_latencies") + server = self.create("test_latencies") for i in range(10000): - ss.add_latency("allocate", 1.0 * i) + server.add_latency("allocate", 1.0 * i) for i in range(1000): - ss.add_latency("renew", 1.0 * i) + server.add_latency("renew", 1.0 * i) for i in range(20): - ss.add_latency("write", 1.0 * i) + server.add_latency("write", 1.0 * i) for i in range(10): - ss.add_latency("cancel", 2.0 * i) - ss.add_latency("get", 5.0) + server.add_latency("cancel", 2.0 * i) + server.add_latency("get", 5.0) - output = ss.get_latencies() + output = server.get_latencies() self.failUnlessEqual(sorted(output.keys()), sorted(["allocate", "renew", "cancel", "write", "get"])) - self.failUnlessEqual(len(ss.latencies["allocate"]), 1000) + self.failUnlessEqual(len(server.latencies["allocate"]), 1000) self.failUnless(abs(output["allocate"]["mean"] - 9500) < 1, output) self.failUnless(abs(output["allocate"]["01_0_percentile"] - 9010) < 1, output) self.failUnless(abs(output["allocate"]["10_0_percentile"] - 9100) < 1, output) @@ -2812,7 +2812,7 @@ class Stats(unittest.TestCase): self.failUnless(abs(output["allocate"]["99_0_percentile"] - 9990) < 1, output) self.failUnless(abs(output["allocate"]["99_9_percentile"] - 9999) < 1, output) - self.failUnlessEqual(len(ss.latencies["renew"]), 1000) + self.failUnlessEqual(len(server.latencies["renew"]), 1000) self.failUnless(abs(output["renew"]["mean"] - 500) < 1, output) self.failUnless(abs(output["renew"]["01_0_percentile"] - 10) < 1, output) self.failUnless(abs(output["renew"]["10_0_percentile"] - 100) < 1, output) @@ -2822,7 +2822,7 @@ class Stats(unittest.TestCase): self.failUnless(abs(output["renew"]["99_0_percentile"] - 990) < 1, output) self.failUnless(abs(output["renew"]["99_9_percentile"] - 999) < 1, output) - self.failUnlessEqual(len(ss.latencies["write"]), 20) + self.failUnlessEqual(len(server.latencies["write"]), 20) self.failUnless(abs(output["write"]["mean"] - 9) < 1, output) self.failUnless(output["write"]["01_0_percentile"] is None, output) self.failUnless(abs(output["write"]["10_0_percentile"] - 2) < 1, output) @@ -2832,7 +2832,7 @@ class Stats(unittest.TestCase): self.failUnless(output["write"]["99_0_percentile"] is None, output) self.failUnless(output["write"]["99_9_percentile"] is None, output) - self.failUnlessEqual(len(ss.latencies["cancel"]), 10) + self.failUnlessEqual(len(server.latencies["cancel"]), 10) self.failUnless(abs(output["cancel"]["mean"] - 9) < 1, output) self.failUnless(output["cancel"]["01_0_percentile"] is None, output) self.failUnless(abs(output["cancel"]["10_0_percentile"] - 2) < 1, output) @@ -2842,7 +2842,7 @@ class Stats(unittest.TestCase): self.failUnless(output["cancel"]["99_0_percentile"] is None, output) self.failUnless(output["cancel"]["99_9_percentile"] is None, output) - self.failUnlessEqual(len(ss.latencies["get"]), 1) + self.failUnlessEqual(len(server.latencies["get"]), 1) self.failUnless(output["get"]["mean"] is None, output) self.failUnless(output["get"]["01_0_percentile"] is None, output) self.failUnless(output["get"]["10_0_percentile"] is None, output) @@ -2869,17 +2869,18 @@ class BucketCounterTest(unittest.TestCase, CrawlerTestMixin, ReallyEqualMixin): def test_bucket_counter(self): basedir = "storage/BucketCounter/bucket_counter" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20) + server = StorageServer(basedir, "\x00" * 20) + bucket_counter = server.bucket_counter # finish as fast as possible - ss.bucket_counter.slow_start = 0 - ss.bucket_counter.cpu_slice = 100.0 + bucket_counter.slow_start = 0 + bucket_counter.cpu_slice = 100.0 - d = ss.bucket_counter.set_hook('after_prefix') + d = server.bucket_counter.set_hook('after_prefix') - ss.setServiceParent(self.s) + server.setServiceParent(self.s) - w = StorageStatus(ss) + w = StorageStatus(server) # this sample is before the crawler has started doing anything html = w.renderSynchronously() @@ -2891,25 +2892,25 @@ class BucketCounterTest(unittest.TestCase, CrawlerTestMixin, ReallyEqualMixin): self.failUnlessIn("Next crawl in", s) def _after_first_prefix(prefix): - ss.bucket_counter.save_state() - state = ss.bucket_counter.get_state() + server.bucket_counter.save_state() + state = bucket_counter.get_state() self.failUnlessEqual(prefix, state["last-complete-prefix"]) - self.failUnlessEqual(prefix, ss.bucket_counter.prefixes[0]) + self.failUnlessEqual(prefix, bucket_counter.prefixes[0]) html = w.renderSynchronously() s = remove_tags(html) self.failUnlessIn(" Current crawl ", s) self.failUnlessIn(" (next work in ", s) - return ss.bucket_counter.set_hook('after_cycle') + return bucket_counter.set_hook('after_cycle') d.addCallback(_after_first_prefix) def _after_first_cycle(cycle): self.failUnlessEqual(cycle, 0) - progress = ss.bucket_counter.get_progress() + progress = bucket_counter.get_progress() self.failUnlessReallyEqual(progress["cycle-in-progress"], False) d.addCallback(_after_first_cycle) - d.addBoth(self._wait_for_yield, ss.bucket_counter) + d.addBoth(self._wait_for_yield, bucket_counter) def _after_yield(ign): html = w.renderSynchronously() @@ -2922,58 +2923,60 @@ class BucketCounterTest(unittest.TestCase, CrawlerTestMixin, ReallyEqualMixin): def test_bucket_counter_cleanup(self): basedir = "storage/BucketCounter/bucket_counter_cleanup" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20) + server = StorageServer(basedir, "\x00" * 20) + bucket_counter = server.bucket_counter # finish as fast as possible - ss.bucket_counter.slow_start = 0 - ss.bucket_counter.cpu_slice = 100.0 + bucket_counter.slow_start = 0 + bucket_counter.cpu_slice = 100.0 - d = ss.bucket_counter.set_hook('after_prefix') + d = bucket_counter.set_hook('after_prefix') - ss.setServiceParent(self.s) + server.setServiceParent(self.s) def _after_first_prefix(prefix): - ss.bucket_counter.save_state() - state = ss.bucket_counter.state + bucket_counter.save_state() + state = bucket_counter.state self.failUnlessEqual(prefix, state["last-complete-prefix"]) - self.failUnlessEqual(prefix, ss.bucket_counter.prefixes[0]) + self.failUnlessEqual(prefix, bucket_counter.prefixes[0]) # now sneak in and mess with its state, to make sure it cleans up # properly at the end of the cycle state["bucket-counts"][-12] = {} state["storage-index-samples"]["bogusprefix!"] = (-12, []) - ss.bucket_counter.save_state() + bucket_counter.save_state() - return ss.bucket_counter.set_hook('after_cycle') + return bucket_counter.set_hook('after_cycle') d.addCallback(_after_first_prefix) def _after_first_cycle(cycle): self.failUnlessEqual(cycle, 0) - progress = ss.bucket_counter.get_progress() + progress = bucket_counter.get_progress() self.failUnlessReallyEqual(progress["cycle-in-progress"], False) - s = ss.bucket_counter.get_state() + s = bucket_counter.get_state() self.failIf(-12 in s["bucket-counts"], s["bucket-counts"].keys()) self.failIf("bogusprefix!" in s["storage-index-samples"], s["storage-index-samples"].keys()) d.addCallback(_after_first_cycle) - d.addBoth(self._wait_for_yield, ss.bucket_counter) + d.addBoth(self._wait_for_yield, bucket_counter) return d def test_bucket_counter_eta(self): basedir = "storage/BucketCounter/bucket_counter_eta" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20) + server = StorageServer(basedir, "\x00" * 20) + bucket_counter = server.bucket_counter # finish as fast as possible - ss.bucket_counter.slow_start = 0 - ss.bucket_counter.cpu_slice = 100.0 + bucket_counter.slow_start = 0 + bucket_counter.cpu_slice = 100.0 - d = ss.bucket_counter.set_hook('after_prefix') + d = bucket_counter.set_hook('after_prefix') - ss.setServiceParent(self.s) + server.setServiceParent(self.s) - w = StorageStatus(ss) + w = StorageStatus(server) def _check_1(prefix1): # no ETA is available yet @@ -2981,7 +2984,7 @@ class BucketCounterTest(unittest.TestCase, CrawlerTestMixin, ReallyEqualMixin): s = remove_tags(html) self.failUnlessIn("complete (next work", s) - return ss.bucket_counter.set_hook('after_prefix') + return bucket_counter.set_hook('after_prefix') d.addCallback(_check_1) def _check_2(prefix2): @@ -2990,7 +2993,7 @@ class BucketCounterTest(unittest.TestCase, CrawlerTestMixin, ReallyEqualMixin): s = remove_tags(html) self.failUnlessIn("complete (ETA ", s) d.addCallback(_check_2) - d.addBoth(self._wait_for_yield, ss.bucket_counter) + d.addBoth(self._wait_for_yield, bucket_counter) return d class InstrumentedLeaseCheckingCrawler(LeaseCheckingCrawler): @@ -3080,20 +3083,20 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): def BROKEN_test_basic(self): basedir = "storage/LeaseCrawler/basic" fileutil.make_dirs(basedir) - ss = InstrumentedStorageServer(basedir, "\x00" * 20) + server = InstrumentedStorageServer(basedir, "\x00" * 20) # make it start sooner than usual. - lc = ss.lease_checker + lc = server.lease_checker lc.slow_start = 0 lc.cpu_slice = 500 lc.stop_after_first_bucket = True - webstatus = StorageStatus(ss) + webstatus = StorageStatus(server) # create a few shares, with some leases on them - self.make_shares(ss) + self.make_shares(server) [immutable_si_0, immutable_si_1, mutable_si_2, mutable_si_3] = self.sis # add a non-sharefile to exercise another code path - fn = os.path.join(ss.sharedir, + fn = os.path.join(server.sharedir, storage_index_to_dir(immutable_si_0), "not-a-share") f = open(fn, "wb") @@ -3109,7 +3112,7 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): self.failUnlessIn("history", initial_state) self.failUnlessEqual(initial_state["history"], {}) - ss.setServiceParent(self.s) + server.setServiceParent(self.s) DAY = 24*60*60 @@ -3220,7 +3223,7 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): self.failUnlessEqual(rec["configured-sharebytes"], 0) def _get_sharefile(si): - return list(ss._iter_share_files(si))[0] + return list(server._iter_share_files(si))[0] def count_leases(si): return len(list(_get_sharefile(si).get_leases())) self.failUnlessEqual(count_leases(immutable_si_0), 1) @@ -3263,24 +3266,24 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): fileutil.make_dirs(basedir) # setting expiration_time to 2000 means that any lease which is more # than 2000s old will be expired. - ss = InstrumentedStorageServer(basedir, "\x00" * 20, - expiration_enabled=True, - expiration_mode="age", - expiration_override_lease_duration=2000) + server = InstrumentedStorageServer(basedir, "\x00" * 20, + expiration_enabled=True, + expiration_mode="age", + expiration_override_lease_duration=2000) # make it start sooner than usual. - lc = ss.lease_checker + lc = server.lease_checker lc.slow_start = 0 lc.stop_after_first_bucket = True - webstatus = StorageStatus(ss) + webstatus = StorageStatus(server) # create a few shares, with some leases on them - self.make_shares(ss) + self.make_shares(server) [immutable_si_0, immutable_si_1, mutable_si_2, mutable_si_3] = self.sis def count_shares(si): - return len(list(ss._iter_share_files(si))) + return len(list(server._iter_share_files(si))) def _get_sharefile(si): - return list(ss._iter_share_files(si))[0] + return list(server._iter_share_files(si))[0] def count_leases(si): return len(list(_get_sharefile(si).get_leases())) @@ -3317,7 +3320,7 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): sf3 = _get_sharefile(mutable_si_3) self.backdate_lease(sf3, self.renew_secrets[4], now - 1000) - ss.setServiceParent(self.s) + server.setServiceParent(self.s) d = fireEventually() # examine the state right after the first bucket has been processed @@ -3403,24 +3406,24 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): # is more than 2000s old will be expired. now = time.time() then = int(now - 2000) - ss = InstrumentedStorageServer(basedir, "\x00" * 20, - expiration_enabled=True, - expiration_mode="cutoff-date", - expiration_cutoff_date=then) + server = InstrumentedStorageServer(basedir, "\x00" * 20, + expiration_enabled=True, + expiration_mode="cutoff-date", + expiration_cutoff_date=then) # make it start sooner than usual. - lc = ss.lease_checker + lc = server.lease_checker lc.slow_start = 0 lc.stop_after_first_bucket = True - webstatus = StorageStatus(ss) + webstatus = StorageStatus(server) # create a few shares, with some leases on them - self.make_shares(ss) + self.make_shares(server) [immutable_si_0, immutable_si_1, mutable_si_2, mutable_si_3] = self.sis def count_shares(si): - return len(list(ss._iter_share_files(si))) + return len(list(server._iter_share_files(si))) def _get_sharefile(si): - return list(ss._iter_share_files(si))[0] + return list(server._iter_share_files(si))[0] def count_leases(si): return len(list(_get_sharefile(si).get_leases())) @@ -3461,7 +3464,7 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): sf3 = _get_sharefile(mutable_si_3) self.backdate_lease(sf3, self.renew_secrets[4], new_expiration_time) - ss.setServiceParent(self.s) + server.setServiceParent(self.s) d = fireEventually() # examine the state right after the first bucket has been processed @@ -3576,17 +3579,17 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): def BROKEN_test_limited_history(self): basedir = "storage/LeaseCrawler/limited_history" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20) + server = StorageServer(basedir, "\x00" * 20) # make it start sooner than usual. - lc = ss.lease_checker + lc = server.lease_checker lc.slow_start = 0 lc.cpu_slice = 500 # create a few shares, with some leases on them - self.make_shares(ss) - ss.setServiceParent(self.s) + self.make_shares(server) + server.setServiceParent(self.s) def _wait_until_15_cycles_done(): last = lc.state["last-cycle-finished"] if last is not None and last >= 15: @@ -3608,15 +3611,15 @@ class LeaseCrawler(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): def BROKEN_test_unpredictable_future(self): basedir = "storage/LeaseCrawler/unpredictable_future" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20) + server = StorageServer(basedir, "\x00" * 20) # make it start sooner than usual. - lc = ss.lease_checker + lc = server.lease_checker lc.slow_start = 0 lc.cpu_slice = -1.0 # stop quickly - self.make_shares(ss) + self.make_shares(server) - ss.setServiceParent(self.s) + server.setServiceParent(self.s) d = fireEventually() def _check(ignored): @@ -3829,9 +3832,9 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): basedir = "storage/WebStatus/status" fileutil.make_dirs(basedir) nodeid = "\x00" * 20 - ss = StorageServer(basedir, nodeid) - ss.setServiceParent(self.s) - w = StorageStatus(ss, "nickname") + server = StorageServer(basedir, nodeid) + server.setServiceParent(self.s) + w = StorageStatus(server, "nickname") d = self.render1(w) def _check_html(html): self.failUnlessIn("

Storage Server Status

", html) @@ -3852,6 +3855,7 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): d.addCallback(_check_json) return d + def render_json(self, page): d = self.render1(page, args={"t": ["json"]}) return d @@ -3865,16 +3869,16 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): # (test runs on all platforms). basedir = "storage/WebStatus/status_no_disk_stats" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20) - ss.setServiceParent(self.s) - w = StorageStatus(ss) + server = StorageServer(basedir, "\x00" * 20) + server.setServiceParent(self.s) + w = StorageStatus(server) html = w.renderSynchronously() self.failUnlessIn("

Storage Server Status

", html) s = remove_tags(html) self.failUnlessIn("Accepting new shares: Yes", s) self.failUnlessIn("Total disk space: ?", s) self.failUnlessIn("Space Available to Tahoe: ?", s) - self.failUnless(ss.get_available_space() is None) + self.failUnless(server.get_available_space() is None) def test_status_bad_disk_stats(self): def call_get_disk_stats(whichdir, reserved_space=0): @@ -3885,16 +3889,16 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): # show that no shares will be accepted, and get_available_space() should be 0. basedir = "storage/WebStatus/status_bad_disk_stats" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20) - ss.setServiceParent(self.s) - w = StorageStatus(ss) + server = StorageServer(basedir, "\x00" * 20) + server.setServiceParent(self.s) + w = StorageStatus(server) html = w.renderSynchronously() self.failUnlessIn("

Storage Server Status

", html) s = remove_tags(html) self.failUnlessIn("Accepting new shares: No", s) self.failUnlessIn("Total disk space: ?", s) self.failUnlessIn("Space Available to Tahoe: ?", s) - self.failUnlessEqual(ss.get_available_space(), 0) + self.failUnlessEqual(server.get_available_space(), 0) def test_status_right_disk_stats(self): GB = 1000000000 @@ -3905,8 +3909,8 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): basedir = "storage/WebStatus/status_right_disk_stats" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20, reserved_space=reserved) - expecteddir = ss.sharedir + server = StorageServer(basedir, "\x00" * 20, reserved_space=reserved) + expecteddir = server.sharedir def call_get_disk_stats(whichdir, reserved_space=0): self.failUnlessEqual(whichdir, expecteddir) @@ -3922,8 +3926,8 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): } self.patch(fileutil, 'get_disk_stats', call_get_disk_stats) - ss.setServiceParent(self.s) - w = StorageStatus(ss) + server.setServiceParent(self.s) + w = StorageStatus(server) html = w.renderSynchronously() self.failUnlessIn("

Storage Server Status

", html) @@ -3934,14 +3938,14 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): self.failUnlessIn("Disk space free (non-root): 3.00 GB", s) self.failUnlessIn("Reserved space: - 1.00 GB", s) self.failUnlessIn("Space Available to Tahoe: 2.00 GB", s) - self.failUnlessEqual(ss.get_available_space(), 2*GB) + self.failUnlessEqual(server.get_available_space(), 2*GB) def test_readonly(self): basedir = "storage/WebStatus/readonly" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20, readonly_storage=True) - ss.setServiceParent(self.s) - w = StorageStatus(ss) + server = StorageServer(basedir, "\x00" * 20, readonly_storage=True) + server.setServiceParent(self.s) + w = StorageStatus(server) html = w.renderSynchronously() self.failUnlessIn("

Storage Server Status

", html) s = remove_tags(html) @@ -3950,9 +3954,9 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): def test_reserved(self): basedir = "storage/WebStatus/reserved" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20, reserved_space=10e6) - ss.setServiceParent(self.s) - w = StorageStatus(ss) + server = StorageServer(basedir, "\x00" * 20, reserved_space=10e6) + server.setServiceParent(self.s) + w = StorageStatus(server) html = w.renderSynchronously() self.failUnlessIn("

Storage Server Status

", html) s = remove_tags(html) @@ -3961,9 +3965,9 @@ class WebStatus(unittest.TestCase, pollmixin.PollMixin, WebRenderingMixin): def test_huge_reserved(self): basedir = "storage/WebStatus/reserved" fileutil.make_dirs(basedir) - ss = StorageServer(basedir, "\x00" * 20, reserved_space=10e6) - ss.setServiceParent(self.s) - w = StorageStatus(ss) + server = StorageServer(basedir, "\x00" * 20, reserved_space=10e6) + server.setServiceParent(self.s) + w = StorageStatus(server) html = w.renderSynchronously() self.failUnlessIn("

Storage Server Status

", html) s = remove_tags(html)