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: v15.2.4~42^2~61
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=054866234e8446b902965a58681c87bd64992f72;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)
---

diff --git a/qa/tasks/barbican.py b/qa/tasks/barbican.py
index 0ce4aefb7d0b..e191476c4329 100644
--- a/qa/tasks/barbican.py
+++ b/qa/tasks/barbican.py
@@ -172,7 +172,7 @@ def configure_barbican(ctx, config):
     Configure barbican paste-api and barbican-api.
     """
     assert isinstance(config, dict)
-    (cclient, cconfig) = config.items()[0]
+    (cclient, cconfig) = next(iter(config.items()))
 
     keystone_role = cconfig.get('use-keystone-role', None)
     if keystone_role is None:
@@ -239,7 +239,7 @@ def create_secrets(ctx, config):
     Create a main and an alternate s3 user.
     """
     assert isinstance(config, dict)
-    (cclient, cconfig) = config.items()[0]
+    (cclient, cconfig) = next(iter(config.items()))
 
     rgw_user = cconfig['rgw_user']
 
diff --git a/qa/tasks/cbt.py b/qa/tasks/cbt.py
index c5567a05d020..3255107add60 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 in ['librbdfio', 'fio']:
           testdir = misc.get_testdir(self.ctx)
           benchmark_config[benchmark_type]['cmd_path'] = os.path.join(testdir, 'fio/fio')
@@ -80,7 +80,7 @@ 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 in ['librbdfio', 'fio']:
@@ -201,7 +201,7 @@ 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')
@@ -233,7 +233,7 @@ 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 in ['librbdfio', 'fio']:
             self.first_mon.run(
                 args=[
diff --git a/qa/tasks/ceph_manager.py b/qa/tasks/ceph_manager.py
index 42b437355868..39d2b0bc9195 100644
--- a/qa/tasks/ceph_manager.py
+++ b/qa/tasks/ceph_manager.py
@@ -1239,8 +1239,8 @@ 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 8636fdb6f3f0..602cc85991b7 100644
--- a/qa/tasks/ceph_objectstore_tool.py
+++ b/qa/tasks/ceph_objectstore_tool.py
@@ -240,7 +240,7 @@ 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 093bb73efc0a..71c9a2ae6ab1 100644
--- a/qa/tasks/cephfs/filesystem.py
+++ b/qa/tasks/cephfs/filesystem.py
@@ -691,7 +691,7 @@ 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):
         """
@@ -701,12 +701,12 @@ 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 fc877f285b6c..daa81973be73 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 943a9ffffa22..ba3d29aab539 100644
--- a/qa/tasks/devstack.py
+++ b/qa/tasks/devstack.py
@@ -58,8 +58,8 @@ 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)
@@ -305,7 +305,7 @@ 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)
@@ -332,8 +332,8 @@ 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 2bf3feaf0837..ad2772a641ff 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 01b562905b21..319bef7686c7 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 149221e9f607..cb67975be4d2 100644
--- a/qa/tasks/mgr/test_crash.py
+++ b/qa/tasks/mgr/test_crash.py
@@ -74,7 +74,7 @@ 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 e1348a21cf3f..c7ef3ad87f25 100644
--- a/qa/tasks/radosgw_admin.py
+++ b/qa/tasks/radosgw_admin.py
@@ -271,7 +271,7 @@ 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 50f88ea85700..ae47bec4929a 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'
diff --git a/qa/tasks/vault.py b/qa/tasks/vault.py
index 34efc4f970c6..1265513408bc 100644
--- a/qa/tasks/vault.py
+++ b/qa/tasks/vault.py
@@ -128,7 +128,7 @@ def setup_vault(ctx, config):
     """
     Mount Transit or KV version 2 secrets engine
     """
-    (cclient, cconfig) = config.items()[0]
+    (cclient, cconfig) = next(iter(config.items()))
     engine = cconfig.get('engine')
 
     if engine == 'kv':
@@ -169,7 +169,7 @@ def send_req(ctx, cconfig, client, path, body, method='POST'):
 
 @contextlib.contextmanager
 def create_secrets(ctx, config):
-    (cclient, cconfig) = config.items()[0]
+    (cclient, cconfig) = next(iter(config.items()))
     engine = cconfig.get('engine')
     prefix = cconfig.get('prefix')
     secrets = cconfig.get('secrets')