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"""Additional handlers that are used as the base classes of the buildlogger handler."""
from __future__ import absolute_import
import json
import logging
import sys
import threading
import warnings
import requests
import requests.adapters
import requests.auth
try:
import requests.packages.urllib3.exceptions as urllib3_exceptions
except ImportError:
# Versions of the requests package prior to 1.2.0 did not vendor the urllib3 package.
urllib3_exceptions = None
import urllib3.util.retry as urllib3_retry
from . import flush
from .. import utils
_TIMEOUT_SECS = 10
class BufferedHandler(logging.Handler):
"""A handler class that buffers logging records in memory.
Whenever each record is added to the buffer, a check is made to see if the buffer
should be flushed. If it should, then flush() is expected to do what's needed.
"""
def __init__(self, capacity, interval_secs):
"""Initialize the handler with the buffer size and timeout.
These values determine when the buffer is flushed regardless.
"""
logging.Handler.__init__(self)
if not isinstance(capacity, int):
raise TypeError("capacity must be an integer")
elif capacity <= 0:
raise ValueError("capacity must be a positive integer")
if not isinstance(interval_secs, (int, float)):
raise TypeError("interval_secs must be a number")
elif interval_secs <= 0.0:
raise ValueError("interval_secs must be a positive number")
self.capacity = capacity
self.interval_secs = interval_secs
# self.__emit_lock prohibits concurrent access to 'self.__emit_buffer',
# 'self.__flush_event', and self.__flush_scheduled_by_emit.
self.__emit_lock = threading.Lock()
self.__emit_buffer = []
self.__flush_event = None # A handle to the event that calls self.flush().
self.__flush_scheduled_by_emit = False
self.__close_called = False
self.__flush_lock = threading.Lock() # Serializes callers of self.flush().
# We override createLock(), acquire(), and release() to be no-ops since emit(), flush(), and
# close() serialize accesses to 'self.__emit_buffer' in a more granular way via
# 'self.__emit_lock'.
def createLock(self):
"""Create lock."""
pass
def acquire(self):
"""Acquire."""
pass
def release(self):
"""Release."""
pass
def process_record(self, record): # pylint: disable=no-self-use
"""Apply a transformation to the record before it gets added to the buffer.
The default implementation returns 'record' unmodified.
"""
return record
def emit(self, record):
"""Emit a record.
Append the record to the buffer after it has been transformed by
process_record(). If the length of the buffer is greater than or
equal to its capacity, then the flush() event is rescheduled to
immediately process the buffer.
"""
processed_record = self.process_record(record)
with self.__emit_lock:
self.__emit_buffer.append(processed_record)
if self.__flush_event is None:
# Now that we've added our first record to the buffer, we schedule a call to flush()
# to occur 'self.interval_secs' seconds from now. 'self.__flush_event' should never
# be None after this point.
self.__flush_event = flush.flush_after(self, delay=self.interval_secs)
if not self.__flush_scheduled_by_emit and len(self.__emit_buffer) >= self.capacity:
# Attempt to flush the buffer early if we haven't already done so. We don't bother
# calling flush.cancel() and flush.flush_after() when 'self.__flush_event' is
# already scheduled to happen as soon as possible to avoid introducing unnecessary
# delays in emit().
if flush.cancel(self.__flush_event):
self.__flush_event = flush.flush_after(self, delay=0.0)
self.__flush_scheduled_by_emit = True
def flush(self):
"""Ensure all logging output has been flushed."""
self.__flush(close_called=False)
with self.__emit_lock:
if self.__flush_event is not None and not self.__close_called:
# We cancel 'self.__flush_event' in case flush() was called by someone other than
# the flush thread to avoid having multiple flush() events scheduled.
flush.cancel(self.__flush_event)
self.__flush_event = flush.flush_after(self, delay=self.interval_secs)
self.__flush_scheduled_by_emit = False
def __flush(self, close_called):
"""Ensure all logging output has been flushed."""
with self.__emit_lock:
buf = self.__emit_buffer
self.__emit_buffer = []
# The buffer 'buf' is flushed without holding 'self.__emit_lock' to avoid causing callers of
# self.emit() to block behind the completion of a potentially long-running flush operation.
if buf:
with self.__flush_lock:
self._flush_buffer_with_lock(buf, close_called)
def _flush_buffer_with_lock(self, buf, close_called):
"""Ensure all logging output has been flushed."""
raise NotImplementedError("_flush_buffer_with_lock must be implemented by BufferedHandler"
" subclasses")
def close(self):
"""Flush the buffer and tidies up any resources used by this handler."""
with self.__emit_lock:
self.__close_called = True
if self.__flush_event is not None:
flush.cancel(self.__flush_event)
self.__flush(close_called=True)
logging.Handler.close(self)
class HTTPHandler(object):
"""A class which sends data to a web server using POST requests."""
def __init__(self, url_root, username, password, should_retry=False):
"""Initialize the handler with the necessary authentication credentials."""
self.auth_handler = requests.auth.HTTPBasicAuth(username, password)
self.session = requests.Session()
if should_retry:
retry_status = [500, 502, 503, 504] # Retry for these statuses.
retry = urllib3_retry.Retry(
backoff_factor=0.1, # Enable backoff starting at 0.1s.
method_whitelist=False, # Support all HTTP verbs.
status_forcelist=retry_status)
adapter = requests.adapters.HTTPAdapter(max_retries=retry)
self.session.mount('http://', adapter)
self.session.mount('https://', adapter)
self.url_root = url_root
def _make_url(self, endpoint):
return "%s/%s/" % (self.url_root.rstrip("/"), endpoint.strip("/"))
def post(self, endpoint, data=None, headers=None, timeout_secs=_TIMEOUT_SECS):
"""Send a POST request to the specified endpoint with the supplied data.
Return the response, either as a string or a JSON object based
on the content type.
"""
data = utils.default_if_none(data, [])
data = json.dumps(data, encoding="utf-8")
headers = utils.default_if_none(headers, {})
headers["Content-Type"] = "application/json; charset=utf-8"
url = self._make_url(endpoint)
# Versions of Python earlier than 2.7.9 do not support certificate validation. So we
# disable certificate validation for older Python versions.
should_validate_certificates = sys.version_info >= (2, 7, 9)
with warnings.catch_warnings():
if urllib3_exceptions is not None and not should_validate_certificates:
try:
warnings.simplefilter("ignore", urllib3_exceptions.InsecurePlatformWarning)
except AttributeError:
# Versions of urllib3 prior to 1.10.3 didn't define InsecurePlatformWarning.
# Versions of requests prior to 2.6.0 didn't have a vendored copy of urllib3
# that defined InsecurePlatformWarning.
pass
try:
warnings.simplefilter("ignore", urllib3_exceptions.InsecureRequestWarning)
except AttributeError:
# Versions of urllib3 prior to 1.9 didn't define InsecureRequestWarning.
# Versions of requests prior to 2.4.0 didn't have a vendored copy of urllib3
# that defined InsecureRequestWarning.
pass
response = self.session.post(url, data=data, headers=headers, timeout=timeout_secs,
auth=self.auth_handler,
verify=should_validate_certificates)
response.raise_for_status()
if not response.encoding:
response.encoding = "utf-8"
headers = response.headers
if headers["Content-Type"].startswith("application/json"):
return response.json()
return response.text
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