From: Kefu Chai <kchai@redhat.com>
Date: Tue, 31 Mar 2020 02:16:40 +0000 (+0800)
Subject: qa/tasks: use next(iter(..)) for accessing first element in a view
X-Git-Tag: v14.2.10~17^2~81
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=723f63edb1cf45eba653c2f6836ed0ceb4dfb6f4;p=ceph.git

qa/tasks: use next(iter(..)) for accessing first element in a view

in python2, dict.values() and dict.keys() return lists. but in python3,
they return views, which cannot be indexed directly using an integer index.

there are three use cases when we access these views in python3:

1. get the first element
2. get all the elements and then *might* want to access them by index
3. get the first element assuming there is only a single element in
   the view
4. iterate thru the view

in the 1st case, we cannot assume the number of elements, so to be
python3 compatible, we should use `next(iter(a_dict))` instead.

in the 2nd case, in this change, the view is materialized using
`list(a_dict)`.

in the 3rd case, we can just continue using the short hand of
```py
(first_element,) = a_dict.keys()
```
to unpack the view. this works in both python2 and python3.

in the 4th case, the existing code works in both python2 and python3, as
both list and view can be iterated using `iter`, and `len` works as
well.

Signed-off-by: Kefu Chai <kchai@redhat.com>
(cherry picked from commit d7258ea7fdcd81d4a88028a25b32ed5b278d0752)

Conflicts:
	qa/tasks/barbican.py
	qa/tasks/cbt.py
	qa/tasks/vault.py: trivial resolutions
---

diff --git a/qa/tasks/cbt.py b/qa/tasks/cbt.py
index 941694802cf..e234eff907b 100644
--- a/qa/tasks/cbt.py
+++ b/qa/tasks/cbt.py
@@ -44,7 +44,7 @@ class CBT(Task):
             )
 
         benchmark_config = self.config.get('benchmarks')
-        benchmark_type = benchmark_config.keys()[0]
+        benchmark_type = next(iter(benchmark_config.keys()))
         if benchmark_type == 'librbdfio':
           testdir = misc.get_testdir(self.ctx)
           benchmark_config['librbdfio']['cmd_path'] = os.path.join(testdir, 'fio/fio')
@@ -78,7 +78,7 @@ class CBT(Task):
             cbt_depends = ['python3-yaml', 'python3-lxml', 'librbd-dev', 'collectl']
         self.first_mon.run(args=install_cmd + cbt_depends)
 
-        benchmark_type = self.cbt_config.get('benchmarks').keys()[0]
+        benchmark_type = next(iter(self.cbt_config.get('benchmarks').keys()))
         self.log.info('benchmark: %s', benchmark_type)
 
         if benchmark_type == 'librbdfio':
@@ -192,7 +192,7 @@ class CBT(Task):
 
     def setup(self):
         super(CBT, self).setup()
-        self.first_mon = self.ctx.cluster.only(misc.get_first_mon(self.ctx, self.config)).remotes.keys()[0]
+        self.first_mon = next(iter(self.ctx.cluster.only(misc.get_first_mon(self.ctx, self.config)).remotes.keys()))
         self.cbt_config = self.generate_cbt_config()
         self.log.info('cbt configuration is %s', self.cbt_config)
         self.cbt_dir = os.path.join(misc.get_archive_dir(self.ctx), 'cbt')
@@ -224,7 +224,7 @@ class CBT(Task):
                 '{tdir}/cbt'.format(tdir=testdir),
             ]
         )
-        benchmark_type = self.cbt_config.get('benchmarks').keys()[0]
+        benchmark_type = next(iter(self.cbt_config.get('benchmarks').keys()))
         if benchmark_type == 'librbdfio':
             self.first_mon.run(
                 args=[
diff --git a/qa/tasks/ceph_manager.py b/qa/tasks/ceph_manager.py
index a2479c6f997..d02f14592b7 100644
--- a/qa/tasks/ceph_manager.py
+++ b/qa/tasks/ceph_manager.py
@@ -1046,8 +1046,8 @@ class ObjectStoreTool:
             self.pgid = self.manager.get_object_pg_with_shard(self.pool,
                                                               self.object_name,
                                                               self.osd)
-        self.remote = self.manager.ctx.\
-            cluster.only('osd.{o}'.format(o=self.osd)).remotes.keys()[0]
+        self.remote = next(iter(self.manager.ctx.\
+            cluster.only('osd.{o}'.format(o=self.osd)).remotes.keys()))
         path = self.manager.get_filepath().format(id=self.osd)
         self.paths = ("--data-path {path} --journal-path {path}/journal".
                       format(path=path))
diff --git a/qa/tasks/ceph_objectstore_tool.py b/qa/tasks/ceph_objectstore_tool.py
index 9598e9073dd..94b9d19e913 100644
--- a/qa/tasks/ceph_objectstore_tool.py
+++ b/qa/tasks/ceph_objectstore_tool.py
@@ -242,7 +242,7 @@ def test_objectstore(ctx, config, cli_remote, REP_POOL, REP_NAME, ec=False):
                          REP_NAME, DATALINECOUNT)
     allremote = []
     allremote.append(cli_remote)
-    allremote += osds.remotes.keys()
+    allremote += list(osds.remotes.keys())
     allremote = list(set(allremote))
     for remote in allremote:
         cod_setup_remote_data(log, ctx, remote, NUM_OBJECTS, DATADIR,
diff --git a/qa/tasks/cephfs/filesystem.py b/qa/tasks/cephfs/filesystem.py
index e02d822e26f..d149387a698 100644
--- a/qa/tasks/cephfs/filesystem.py
+++ b/qa/tasks/cephfs/filesystem.py
@@ -662,7 +662,7 @@ class Filesystem(MDSCluster):
         if refresh or self.data_pools is None:
             self.get_pool_names(refresh = True)
         assert(len(self.data_pools) == 1)
-        return self.data_pools.values()[0]
+        return next(iter(self.data_pools.values()))
 
     def get_data_pool_id(self, refresh = False):
         """
@@ -672,12 +672,12 @@ class Filesystem(MDSCluster):
         if refresh or self.data_pools is None:
             self.get_pool_names(refresh = True)
         assert(len(self.data_pools) == 1)
-        return self.data_pools.keys()[0]
+        return next(iter(self.data_pools.keys()))
 
     def get_data_pool_names(self, refresh = False):
         if refresh or self.data_pools is None:
             self.get_pool_names(refresh = True)
-        return self.data_pools.values()
+        return list(self.data_pools.values())
 
     def get_metadata_pool_name(self):
         return self.metadata_pool_name
diff --git a/qa/tasks/check_counter.py b/qa/tasks/check_counter.py
index fc877f285b6..daa81973be7 100644
--- a/qa/tasks/check_counter.py
+++ b/qa/tasks/check_counter.py
@@ -45,7 +45,7 @@ class CheckCounter(Task):
         targets = self.config.get('counters', {})
 
         if cluster_name is None:
-            cluster_name = self.ctx.managers.keys()[0]
+            cluster_name = next(iter(self.ctx.managers.keys()))
 
         for daemon_type, counters in targets.items():
             # List of 'a', 'b', 'c'...
diff --git a/qa/tasks/devstack.py b/qa/tasks/devstack.py
index dc1c6a1f961..35620f7ea82 100644
--- a/qa/tasks/devstack.py
+++ b/qa/tasks/devstack.py
@@ -59,8 +59,8 @@ def install(ctx, config):
     if not isinstance(config, dict):
         raise TypeError("config must be a dict")
 
-    devstack_node = ctx.cluster.only(is_devstack_node).remotes.keys()[0]
-    an_osd_node = ctx.cluster.only(is_osd_node).remotes.keys()[0]
+    devstack_node = next(iter(ctx.cluster.only(is_devstack_node).remotes.keys()))
+    an_osd_node = next(iter(ctx.cluster.only(is_osd_node).remotes.keys()))
 
     devstack_branch = config.get("branch", "master")
     install_devstack(devstack_node, devstack_branch)
@@ -306,7 +306,7 @@ def exercise(ctx, config):
     if not isinstance(config, dict):
         raise TypeError("config must be a dict")
 
-    devstack_node = ctx.cluster.only(is_devstack_node).remotes.keys()[0]
+    devstack_node = next(iter(ctx.cluster.only(is_devstack_node).remotes.keys()))
 
     # TODO: save the log *and* preserve failures
     #devstack_archive_dir = create_devstack_archive(ctx, devstack_node)
@@ -333,8 +333,8 @@ def create_devstack_archive(ctx, devstack_node):
 def smoke(ctx, config):
     log.info("Running a basic smoketest...")
 
-    devstack_node = ctx.cluster.only(is_devstack_node).remotes.keys()[0]
-    an_osd_node = ctx.cluster.only(is_osd_node).remotes.keys()[0]
+    devstack_node = next(iter(ctx.cluster.only(is_devstack_node).remotes.keys()))
+    an_osd_node = next(iter(ctx.cluster.only(is_osd_node).remotes.keys()))
 
     try:
         create_volume(devstack_node, an_osd_node, 'smoke0', 1)
diff --git a/qa/tasks/dnsmasq.py b/qa/tasks/dnsmasq.py
index 717c9f01930..352ed246b6e 100644
--- a/qa/tasks/dnsmasq.py
+++ b/qa/tasks/dnsmasq.py
@@ -83,7 +83,7 @@ def setup_dnsmasq(remote, testdir, cnames):
     # restart dnsmasq
     remote.run(args=['sudo', 'systemctl', 'restart', 'dnsmasq'])
     # verify dns name is set
-    remote.run(args=['ping', '-c', '4', cnames.keys()[0]])
+    remote.run(args=['ping', '-c', '4', next(iter(cnames.keys()))])
 
     try:
         yield
diff --git a/qa/tasks/filestore_idempotent.py b/qa/tasks/filestore_idempotent.py
index 01b562905b2..319bef7686c 100644
--- a/qa/tasks/filestore_idempotent.py
+++ b/qa/tasks/filestore_idempotent.py
@@ -31,7 +31,7 @@ def task(ctx, config):
     clients = config.keys()
 
     # just use the first client...
-    client = clients[0];
+    client = next(iter(clients))
     (remote,) = ctx.cluster.only(client).remotes.keys()
 
     testdir = teuthology.get_testdir(ctx)
diff --git a/qa/tasks/mgr/test_crash.py b/qa/tasks/mgr/test_crash.py
index c45c24a48db..6607bec7d73 100644
--- a/qa/tasks/mgr/test_crash.py
+++ b/qa/tasks/mgr/test_crash.py
@@ -73,7 +73,7 @@ class TestCrash(MgrTestCase):
             self.assertIn(crash['crash_id'], retstr)
 
     def test_rm(self):
-        crashid = self.crashes.keys()[0]
+        crashid = next(iter(self.crashes.keys()))
         self.assertEqual(
             0,
             self.mgr_cluster.mon_manager.raw_cluster_cmd_result(
diff --git a/qa/tasks/radosgw_admin.py b/qa/tasks/radosgw_admin.py
index 63cb1375f35..b8e6008ce3e 100644
--- a/qa/tasks/radosgw_admin.py
+++ b/qa/tasks/radosgw_admin.py
@@ -272,7 +272,7 @@ def task(ctx, config):
     clients_from_config = config.keys()
 
     # choose first client as default
-    client = clients_from_config[0]
+    client = next(iter(clients_from_config))
 
     # once the client is chosen, pull the host name and  assigned port out of
     # the role_endpoints that were assigned by the rgw task
diff --git a/qa/tasks/radosgw_admin_rest.py b/qa/tasks/radosgw_admin_rest.py
index a2724e3ffb3..8902ca15c6e 100644
--- a/qa/tasks/radosgw_admin_rest.py
+++ b/qa/tasks/radosgw_admin_rest.py
@@ -130,7 +130,7 @@ def task(ctx, config):
     clients = config.keys()
 
     # just use the first client...
-    client = clients[0]
+    client = next(iter(clients))
 
     ##
     admin_user = 'ada'