mgr/vol: add comments to explain queuing data structures

Add some comment to explains the purpose and details of data structures
that are used for queuing of async jobs since right now it's not obvious
from initialization.

Signed-off-by: Rishabh Dave <ridave@redhat.com>

diff --git a/src/pybind/mgr/volumes/fs/async_job.py b/src/pybind/mgr/volumes/fs/async_job.py
index 6834e3e240b335a5d8c73b69fd28d292e51d8ebb..132d990862b49351f918ca6b10a94577c8b1fb69 100644 (file)
--- a/src/pybind/mgr/volumes/fs/async_job.py
+++ b/src/pybind/mgr/volumes/fs/async_job.py
@@ -118,10 +118,16 @@ class AsyncJobs(threading.Thread):
     def __init__(self, volume_client, name_pfx, nr_concurrent_jobs):
         threading.Thread.__init__(self, name="{0}.tick".format(name_pfx))
         self.vc = volume_client
-        # queue of volumes for starting async jobs
+        # self.q is a deque of names of a volumes for which async jobs needs
+        # to be started.
         self.q = deque()  # type: deque
-        # volume => job tracking
+
+        # self.jobs is a dictionary where volume name is the key and value is
+        # a tuple containing two members: the async job and an instance of
+        # threading.Thread that performs that job.
+        # in short, self.jobs = {volname: (async_job, thread instance)}.
         self.jobs = {}
+
         # lock, cv for kickstarting jobs
         self.lock = threading.Lock()
         self.cv = threading.Condition(self.lock)