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# Copyright 2018 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the 'License');
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an 'AS IS' BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# [START functions_tips_infinite_retries]
from datetime import datetime, timezone
# [END functions_tips_infinite_retries]
# [START functions_tips_gcp_apis]
import os
# [END functions_tips_gcp_apis]
# [START functions_tips_infinite_retries]
# The 'python-dateutil' package must be included in requirements.txt.
from dateutil import parser
# [END functions_tips_infinite_retries]
# [START functions_tips_retry]
from google.cloud import error_reporting
# [END functions_tips_retry]
# [START functions_tips_gcp_apis]
from google.cloud import pubsub_v1
# [END functions_tips_gcp_apis]
# [START functions_tips_connection_pooling]
import requests
# [END functions_tips_connection_pooling]
# Placeholder
def file_wide_computation():
return 1
# Placeholder
def function_specific_computation():
return 1
# [START functions_tips_lazy_globals]
# Always initialized (at cold-start)
non_lazy_global = file_wide_computation()
# Declared at cold-start, but only initialized if/when the function executes
lazy_global = None
def lazy_globals(request):
"""
HTTP Cloud Function that uses lazily-initialized globals.
Args:
request (flask.Request): The request object.
<http://flask.pocoo.org/docs/0.12/api/#flask.Request>
Returns:
The response text, or any set of values that can be turned into a
Response object using `make_response`
<http://flask.pocoo.org/docs/0.12/api/#flask.Flask.make_response>.
"""
global lazy_global, non_lazy_global
# This value is initialized only if (and when) the function is called
if not lazy_global:
lazy_global = function_specific_computation()
return 'Lazy: {}, non-lazy: {}.'.format(lazy_global, non_lazy_global)
# [END functions_tips_lazy_globals]
# [START functions_tips_connection_pooling]
# Create a global HTTP session (which provides connection pooling)
session = requests.Session()
def connection_pooling(request):
"""
HTTP Cloud Function that uses a connection pool to make HTTP requests.
Args:
request (flask.Request): The request object.
<http://flask.pocoo.org/docs/0.12/api/#flask.Request>
Returns:
The response text, or any set of values that can be turned into a
Response object using `make_response`
<http://flask.pocoo.org/docs/0.12/api/#flask.Flask.make_response>.
"""
# The URL to send the request to
url = 'http://example.com'
# Process the request
response = session.get(url)
response.raise_for_status()
return 'Success!'
# [END functions_tips_connection_pooling]
# [START functions_tips_gcp_apis]
# Create a global Pub/Sub client to avoid unneeded network activity
pubsub = pubsub_v1.PublisherClient()
def gcp_api_call(request):
"""
HTTP Cloud Function that uses a cached client library instance to
reduce the number of connections required per function invocation.
Args:
request (flask.Request): The request object.
Returns:
The response text, or any set of values that can be turned into a
Response object using `make_response`
<http://flask.pocoo.org/docs/0.12/api/#flask.Flask.make_response>.
"""
project = os.getenv('GCP_PROJECT')
request_json = request.get_json()
topic_name = request_json['topic']
topic_path = pubsub.topic_path(project, topic_name)
# Process the request
data = 'Test message'.encode('utf-8')
pubsub.publish(topic_path, data=data)
return '1 message published'
# [END functions_tips_gcp_apis]
# [START functions_tips_infinite_retries]
def avoid_infinite_retries(data, context):
"""Background Cloud Function that only executes within a certain
time period after the triggering event.
Args:
data (dict): The event payload.
context (google.cloud.functions.Context): The event metadata.
Returns:
None; output is written to Stackdriver Logging
"""
timestamp = context.timestamp
event_time = parser.parse(timestamp)
event_age = (datetime.now(timezone.utc) - event_time).total_seconds()
event_age_ms = event_age * 1000
# Ignore events that are too old
max_age_ms = 10000
if event_age_ms > max_age_ms:
print('Dropped {} (age {}ms)'.format(context.event_id, event_age_ms))
return 'Timeout'
# Do what the function is supposed to do
print('Processed {} (age {}ms)'.format(context.event_id, event_age_ms))
return
# [END functions_tips_infinite_retries]
# [START functions_tips_retry]
error_client = error_reporting.Client()
def retry_or_not(data, context):
"""Background Cloud Function that demonstrates how to toggle retries.
Args:
data (dict): The event payload.
context (google.cloud.functions.Context): The event metadata.
Returns:
None; output is written to Stackdriver Logging
"""
if data.data.get('retry'):
try_again = True
else:
try_again = False
try:
raise RuntimeError('I failed you')
except RuntimeError:
error_client.report_exception()
if try_again:
raise # Raise the exception and try again
else:
pass # Swallow the exception and don't retry
# [END functions_tips_retry]