openstack/swift
Code Issues Proposed changes

Remove _ensure_flush() from SSYNC receiver

Browse Source 
The Receiver._ensure_flush() method in ssync_receiver.py has
the following comment:

    Sends a blank line sufficient to flush buffers.

    This is to ensure Eventlet versions that don't support
    eventlet.minimum_write_chunk_size will send any previous data
    buffered.

    If https://bitbucket.org/eventlet/eventlet/pull-request/37
    ever gets released in an Eventlet version, we should make
    this yield only for versions older than that.

The reference pull request was included with eventlet 0.14 [1] and
swift now requires >=0.16.1 so it is safe to remove _ensure_flush()
and save > 8k bytes per SSYNC response.

[1] 4bd654205a

Change-Id: I367e9a6e92b7ea75fe7e5795cded212657de57ed
This commit is contained in:
Alistair Coles 2015-04-27 16:39:23 +01:00
parent 3aa06f185a
commit 191f2a00bd
2 changed files with 9 additions and 24 deletions
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27
swift/obj/ssync_receiver.py
View File

@ -89,8 +89,9 @@ class Receiver(object):
try: try:
# Double try blocks in case our main error handlers fail. # Double try blocks in case our main error handlers fail.
try: try:
for data in self._ensure_flush(): # Need to send something to trigger wsgi to return response
yield data # headers and kick off the ssync exchange.
yield '\r\n'
# If semaphore is in use, try to acquire it, non-blocking, and # If semaphore is in use, try to acquire it, non-blocking, and
# return a 503 if it fails. # return a 503 if it fails.
if self.app.replication_semaphore: if self.app.replication_semaphore:
@ -142,20 +143,6 @@ class Receiver(object):
except Exception: except Exception:
pass # We're okay with the above failing. pass # We're okay with the above failing.
def _ensure_flush(self):
"""
Sends a blank line sufficient to flush buffers.
This is to ensure Eventlet versions that don't support
eventlet.minimum_write_chunk_size will send any previous data
buffered.
If https://bitbucket.org/eventlet/eventlet/pull-request/37
ever gets released in an Eventlet version, we should make
this yield only for versions older than that.
"""
yield ' ' * eventlet.wsgi.MINIMUM_CHUNK_SIZE + '\r\n'
def initialize_request(self): def initialize_request(self):
""" """
Basic validation of request and mount check. Basic validation of request and mount check.
@ -163,7 +150,9 @@ class Receiver(object):
This function will be called before attempting to acquire a This function will be called before attempting to acquire a
replication semaphore lock, so contains only quick checks. replication semaphore lock, so contains only quick checks.
""" """
# The following is the setting we talk about above in _ensure_flush. # This environ override has been supported since eventlet 0.14:
# https://bitbucket.org/eventlet/eventlet/commits/ \
# 4bd654205a4217970a57a7c4802fed7ff2c8b770
self.request.environ['eventlet.minimum_write_chunk_size'] = 0 self.request.environ['eventlet.minimum_write_chunk_size'] = 0
self.device, self.partition, self.policy = \ self.device, self.partition, self.policy = \
request_helpers.get_name_and_placement(self.request, 2, 2, False) request_helpers.get_name_and_placement(self.request, 2, 2, False)
@ -250,8 +239,6 @@ class Receiver(object):
yield '\r\n'.join(object_hashes) yield '\r\n'.join(object_hashes)
yield '\r\n' yield '\r\n'
yield ':MISSING_CHECK: END\r\n' yield ':MISSING_CHECK: END\r\n'
for data in self._ensure_flush():
yield data
def updates(self): def updates(self):
""" """
@ -385,5 +372,3 @@ class Receiver(object):
(failures, successes)) (failures, successes))
yield ':UPDATES: START\r\n' yield ':UPDATES: START\r\n'
yield ':UPDATES: END\r\n' yield ':UPDATES: END\r\n'
for data in self._ensure_flush():
yield data

6
test/unit/obj/test_ssync_sender.py
View File

@ -1830,14 +1830,14 @@ class TestSsyncReplication(TestBaseSsync):
self.assertFalse(results['tx_updates']) self.assertFalse(results['tx_updates'])
self.assertFalse(results['rx_updates']) self.assertFalse(results['rx_updates'])
# Minimal receiver response as read by sender: # Minimal receiver response as read by sender:
# 2 * 4098 <-- _ensure_flush() twice # 2 <-- initial \r\n to start ssync exchange
# + 23 <-- :MISSING CHECK START\r\n # + 23 <-- :MISSING CHECK START\r\n
# + 2 <-- \r\n (minimal missing check response) # + 2 <-- \r\n (minimal missing check response)
# + 21 <-- :MISSING CHECK END\r\n # + 21 <-- :MISSING CHECK END\r\n
# + 17 <-- :UPDATES START\r\n # + 17 <-- :UPDATES START\r\n
# + 15 <-- :UPDATES END\r\n # + 15 <-- :UPDATES END\r\n
# TOTAL = 8274 # TOTAL = 80
self.assertEqual(8274, trace.get('readline_bytes')) self.assertEqual(80, trace.get('readline_bytes'))
if __name__ == '__main__': if __name__ == '__main__':