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segment.py
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segment.py
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import logging
import time
import json
import os
from splitio.api import APIException
from splitio.api.commons import FetchOptions
from splitio.tasks.util import workerpool
from splitio.models import segments
from splitio.util.backoff import Backoff
from splitio.sync import util
_LOGGER = logging.getLogger(__name__)
_ON_DEMAND_FETCH_BACKOFF_BASE = 10 # backoff base starting at 10 seconds
_ON_DEMAND_FETCH_BACKOFF_MAX_WAIT = 60 # don't sleep for more than 1 minute
_ON_DEMAND_FETCH_BACKOFF_MAX_RETRIES = 10
class SegmentSynchronizer(object):
def __init__(self, segment_api, split_storage, segment_storage):
"""
Class constructor.
:param segment_api: API to retrieve segments from backend.
:type segment_api: splitio.api.SegmentApi
:param split_storage: Split Storage.
:type split_storage: splitio.storage.InMemorySplitStorage
:param segment_storage: Segment storage reference.
:type segment_storage: splitio.storage.SegmentStorage
"""
self._api = segment_api
self._split_storage = split_storage
self._segment_storage = segment_storage
self._worker_pool = workerpool.WorkerPool(10, self.synchronize_segment)
self._worker_pool.start()
self._backoff = Backoff(
_ON_DEMAND_FETCH_BACKOFF_BASE,
_ON_DEMAND_FETCH_BACKOFF_MAX_WAIT)
def recreate(self):
"""
Create worker_pool on forked processes.
"""
self._worker_pool = workerpool.WorkerPool(10, self.synchronize_segment)
self._worker_pool.start()
def shutdown(self):
"""
Shutdown worker_pool
"""
self._worker_pool.stop()
def _fetch_until(self, segment_name, fetch_options, till=None):
"""
Hit endpoint, update storage and return when since==till.
:param segment_name: Name of the segment to update.
:type segment_name: str
:param fetch_options Fetch options for getting segment definitions.
:type fetch_options splitio.api.FetchOptions
:param till: Passed till from Streaming.
:type till: int
:return: last change number
:rtype: int
"""
while True: # Fetch until since==till
change_number = self._segment_storage.get_change_number(segment_name)
if change_number is None:
change_number = -1
if till is not None and till < change_number:
# the passed till is less than change_number, no need to perform updates
return change_number
try:
segment_changes = self._api.fetch_segment(segment_name, change_number,
fetch_options)
except APIException as exc:
_LOGGER.error('Exception raised while fetching segment %s', segment_name)
_LOGGER.debug('Exception information: ', exc_info=True)
raise exc
if change_number == -1: # first time fetching the segment
new_segment = segments.from_raw(segment_changes)
self._segment_storage.put(new_segment)
else:
self._segment_storage.update(
segment_name,
segment_changes['added'],
segment_changes['removed'],
segment_changes['till']
)
if segment_changes['till'] == segment_changes['since']:
return segment_changes['till']
def _attempt_segment_sync(self, segment_name, fetch_options, till=None):
"""
Hit endpoint, update storage and return True if sync is complete.
:param segment_name: Name of the segment to update.
:type segment_name: str
:param fetch_options Fetch options for getting split definitions.
:type fetch_options splitio.api.FetchOptions
:param till: Passed till from Streaming.
:type till: int
:return: Flags to check if it should perform bypass or operation ended
:rtype: bool, int, int
"""
self._backoff.reset()
remaining_attempts = _ON_DEMAND_FETCH_BACKOFF_MAX_RETRIES
while True:
remaining_attempts -= 1
change_number = self._fetch_until(segment_name, fetch_options, till)
if till is None or till <= change_number:
return True, remaining_attempts, change_number
elif remaining_attempts <= 0:
return False, remaining_attempts, change_number
how_long = self._backoff.get()
time.sleep(how_long)
def synchronize_segment(self, segment_name, till=None):
"""
Update a segment from queue
:param segment_name: Name of the segment to update.
:type segment_name: str
:param till: ChangeNumber received.
:type till: int
:return: True if no error occurs. False otherwise.
:rtype: bool
"""
fetch_options = FetchOptions(True) # Set Cache-Control to no-cache
successful_sync, remaining_attempts, change_number = self._attempt_segment_sync(segment_name, fetch_options, till)
attempts = _ON_DEMAND_FETCH_BACKOFF_MAX_RETRIES - remaining_attempts
if successful_sync: # succedeed sync
_LOGGER.debug('Refresh completed in %d attempts.', attempts)
return True
with_cdn_bypass = FetchOptions(True, change_number) # Set flag for bypassing CDN
without_cdn_successful_sync, remaining_attempts, change_number = self._attempt_segment_sync(segment_name, with_cdn_bypass, till)
without_cdn_attempts = _ON_DEMAND_FETCH_BACKOFF_MAX_RETRIES - remaining_attempts
if without_cdn_successful_sync:
_LOGGER.debug('Refresh completed bypassing the CDN in %d attempts.',
without_cdn_attempts)
return True
_LOGGER.debug('No changes fetched after %d attempts with CDN bypassed.',
without_cdn_attempts)
return False
def synchronize_segments(self, segment_names = None, dont_wait = False):
"""
Submit all current segments and wait for them to finish depend on dont_wait flag, then set the ready flag.
:param segment_names: Optional, array of segment names to update.
:type segment_name: {str}
:param dont_wait: Optional, instruct the function to not wait for task completion
:type segment_name: boolean
:return: True if no error occurs or dont_wait flag is True. False otherwise.
:rtype: bool
"""
if segment_names is None:
segment_names = self._split_storage.get_segment_names()
for segment_name in segment_names:
self._worker_pool.submit_work(segment_name)
if (dont_wait):
return True
return not self._worker_pool.wait_for_completion()
def segment_exist_in_storage(self, segment_name):
"""
Check if a segment exists in the storage
:param segment_name: Name of the segment
:type segment_name: str
:return: True if segment exist. False otherwise.
:rtype: bool
"""
return self._segment_storage.get(segment_name) != None
class LocalSegmentSynchronizer(object):
"""Localhost mode segment synchronizer."""
_DEFAULT_SEGMENT_TILL = -1
def __init__(self, segment_folder, split_storage, segment_storage):
"""
Class constructor.
:param segment_folder: patch to the segment folder
:type segment_folder: str
:param split_storage: Split Storage.
:type split_storage: splitio.storage.InMemorySplitStorage
:param segment_storage: Segment storage reference.
:type segment_storage: splitio.storage.SegmentStorage
"""
self._segment_folder = segment_folder
self._split_storage = split_storage
self._segment_storage = segment_storage
self._segment_sha = {}
def synchronize_segments(self, segment_names = None):
"""
Loop through given segment names and synchronize each one.
:param segment_names: Optional, array of segment names to update.
:type segment_name: {str}
:return: True if no error occurs. False otherwise.
:rtype: bool
"""
_LOGGER.info('Synchronizing segments now.')
if segment_names is None:
segment_names = self._split_storage.get_segment_names()
return_flag = True
for segment_name in segment_names:
if not self.synchronize_segment(segment_name):
return_flag = False
return return_flag
def synchronize_segment(self, segment_name, till=None):
"""
Update a segment from queue
:param segment_name: Name of the segment to update.
:type segment_name: str
:param till: ChangeNumber received.
:type till: int
:return: True if no error occurs. False otherwise.
:rtype: bool
"""
try:
fetched = self._read_segment_from_json_file(segment_name)
fetched_sha = util._get_sha(json.dumps(fetched))
if not self.segment_exist_in_storage(segment_name):
self._segment_sha[segment_name] = fetched_sha
self._segment_storage.put(segments.from_raw(fetched))
_LOGGER.debug("segment %s is added to storage", segment_name)
return True
if fetched_sha == self._segment_sha[segment_name]:
return True
self._segment_sha[segment_name] = fetched_sha
if self._segment_storage.get_change_number(segment_name) > fetched['till'] and fetched['till'] != self._DEFAULT_SEGMENT_TILL:
return True
self._segment_storage.update(segment_name, fetched['added'], fetched['removed'], fetched['till'])
_LOGGER.debug("segment %s is updated", segment_name)
except Exception as e:
_LOGGER.error("Could not fetch segment: %s \n" + str(e), segment_name)
return False
return True
def _read_segment_from_json_file(self, filename):
"""
Parse a segment and store in segment storage.
:param filename: Path of the file containing split
:type filename: str.
:return: Sanitized segment structure
:rtype: Dict
"""
try:
with open(os.path.join(self._segment_folder, "%s.json" % filename), 'r') as flo:
parsed = json.load(flo)
santitized_segment = self._sanitize_segment(parsed)
return santitized_segment
except Exception as exc:
raise ValueError("Error parsing file %s. Make sure it's readable." % filename) from exc
def _sanitize_segment(self, parsed):
"""
Sanitize json elements.
:param parsed: segment dict
:type parsed: Dict
:return: sanitized segment structure dict
:rtype: Dict
"""
if 'name' not in parsed or parsed['name'] is None:
_LOGGER.warning("Segment does not have [name] element, skipping")
raise Exception("Segment does not have [name] element")
if parsed['name'].strip() == '':
_LOGGER.warning("Segment [name] element is blank, skipping")
raise Exception("Segment [name] element is blank")
for element in [('till', -1, -1, None, None, [0]),
('added', [], None, None, None, None),
('removed', [], None, None, None, None)
]:
parsed = util._sanitize_object_element(parsed, 'segment', element[0], element[1], lower_value=element[2], upper_value=element[3], in_list=None, not_in_list=element[5])
parsed = util._sanitize_object_element(parsed, 'segment', 'since', parsed['till'], -1, parsed['till'], None, [0])
return parsed
def segment_exist_in_storage(self, segment_name):
"""
Check if a segment exists in the storage
:param segment_name: Name of the segment
:type segment_name: str
:return: True if segment exist. False otherwise.
:rtype: bool
"""
return self._segment_storage.get(segment_name) != None