od-database/task.py
2018-06-26 20:25:28 -04:00

238 lines
8.2 KiB
Python

from apscheduler.schedulers.background import BackgroundScheduler
from search.search import ElasticSearchEngine
from crawl_server.database import Task, TaskResult
import requests
from requests.exceptions import ConnectionError, ReadTimeout
import json
import database
from concurrent.futures import ThreadPoolExecutor
import urllib3
urllib3.disable_warnings()
class CrawlServer:
def __init__(self, url, name, slots, token, server_id=None):
self.url = url
self.name = name
self.slots = slots
self.used_slots = 0
self.token = token
self.id = server_id
def _generate_headers(self):
return {
"Content-Type": "application/json",
"Authorization": "Token " + self.token,
}
def queue_task(self, task: Task) -> bool:
print("Sending task to crawl server " + self.url)
try:
payload = json.dumps(task.to_json())
r = requests.post(self.url + "/task/put", headers=self._generate_headers(), data=payload, verify=False,
timeout=5)
print(r) # TODO: If the task could not be added, fallback to another server
return r.status_code == 200
except (ConnectionError, ReadTimeout):
return False
def pop_completed_tasks(self) -> list:
try:
r = requests.get(self.url + "/task/completed", headers=self._generate_headers(), verify=False, timeout=5)
if r.status_code != 200:
print("Problem while fetching completed tasks for '" + self.name + "': " + str(r.status_code))
print(r.text)
return []
return [
TaskResult(r["status_code"], r["file_count"], r["start_time"], r["end_time"], r["website_id"])
for r in json.loads(r.text)]
except (ConnectionError, ReadTimeout):
print("Crawl server cannot be reached @ " + self.url)
return []
def fetch_queued_tasks(self):
try:
r = requests.get(self.url + "/task/", headers=self._generate_headers(), verify=False, timeout=5)
if r.status_code != 200:
print("Problem while fetching queued tasks for '" + self.name + "' " + str(r.status_code))
print(r.text)
return None
return [
Task(t["website_id"], t["url"], t["priority"], t["callback_type"], t["callback_args"])
for t in json.loads(r.text)
]
except (ConnectionError, ReadTimeout):
return None
def fetch_current_tasks(self):
try:
r = requests.get(self.url + "/task/current", headers=self._generate_headers(), verify=False, timeout=5)
if r.status_code != 200:
print("Problem while fetching current tasks for '" + self.name + "' " + str(r.status_code))
print(r.text)
return None
return [
Task(t["website_id"], t["url"], t["priority"], t["callback_type"], t["callback_args"])
for t in json.loads(r.text)
]
except (ConnectionError, ReadTimeout):
return None
def fetch_website_files(self, website_id) -> str:
try:
r = requests.get(self.url + "/file_list/" + str(website_id) + "/", stream=True,
headers=self._generate_headers(), verify=False)
if r.status_code != 200:
print("Problem while fetching website files for '" + self.name + "': " + str(r.status_code))
print(r.text)
return ""
for line in r.iter_lines(chunk_size=1024 * 256):
yield line
except (ConnectionError, ReadTimeout):
return ""
def free_website_files(self, website_id) -> bool:
try:
r = requests.get(self.url + "/file_list/" + str(website_id) + "/free", headers=self._generate_headers(),
verify=False)
return r.status_code == 200
except (ConnectionError, ReadTimeout) as e:
print(e)
return False
def pop_queued_tasks(self):
try:
r = requests.get(self.url + "/task/pop_all", headers=self._generate_headers(), verify=False)
if r.status_code != 200:
print("Problem while popping tasks for '" + self.name + "': " + str(r.status_code))
print(r.text)
return [
Task(t["website_id"], t["url"], t["priority"], t["callback_type"], t["callback_args"])
for t in json.loads(r.text)
]
except (ConnectionError, ReadTimeout):
return []
class TaskDispatcher:
def __init__(self):
scheduler = BackgroundScheduler()
scheduler.add_job(self.check_completed_tasks, "interval", seconds=10)
scheduler.start()
self.search = ElasticSearchEngine("od-database")
self.db = database.Database("db.sqlite3")
def check_completed_tasks(self):
for server in self.db.get_crawl_servers():
for task in server.pop_completed_tasks():
print("Completed task")
task.server_id = server.id
if task.file_count:
# All files are overwritten
self.search.delete_docs(task.website_id)
file_list = server.fetch_website_files(task.website_id)
self.search.import_json(file_list, task.website_id)
# File list is safe to delete once indexed
server.free_website_files(task.website_id)
# Update last_modified date for website
self.db.update_website_date_if_exists(task.website_id)
self.db.log_result(task)
def dispatch_task(self, task: Task):
self._get_available_crawl_server().queue_task(task)
def _get_available_crawl_server(self) -> CrawlServer:
queued_tasks_by_server = self._get_queued_tasks_by_server()
server_with_most_free_slots = None
most_free_slots = -10000
for server in queued_tasks_by_server:
free_slots = server.slots - len(queued_tasks_by_server[server])
if free_slots > most_free_slots:
server_with_most_free_slots = server
most_free_slots = free_slots
print("Dispatching task to '" +
server_with_most_free_slots.name + "' " +
str(most_free_slots) + " free out of " + str(server_with_most_free_slots.slots))
return server_with_most_free_slots
def get_queued_tasks(self):
queued_tasks_by_server = self._get_queued_tasks_by_server()
for queued_tasks in queued_tasks_by_server.values():
for task in queued_tasks:
yield task
def _get_queued_tasks_by_server(self) -> dict:
queued_tasks = dict()
pool = ThreadPoolExecutor(max_workers=10)
crawl_servers = self.db.get_crawl_servers()
responses = list(pool.map(lambda s: s.fetch_queued_tasks(), crawl_servers))
pool.shutdown()
for i, server in enumerate(crawl_servers):
if responses[i] is not None:
queued_tasks[server] = responses[i]
return queued_tasks
def get_current_tasks(self):
current_tasks_by_server = self._get_current_tasks_by_server()
for current_tasks in current_tasks_by_server.values():
for task in current_tasks:
yield task
def _get_current_tasks_by_server(self) -> dict:
current_tasks = dict()
pool = ThreadPoolExecutor(max_workers=10)
crawl_servers = self.db.get_crawl_servers()
responses = list(pool.map(lambda s: s.fetch_current_tasks(), crawl_servers))
pool.shutdown()
for i, server in enumerate(crawl_servers):
if responses[i] is not None:
current_tasks[server] = responses[i]
return current_tasks
def redispatch_queued(self) -> int:
counter = 0
for server in self.db.get_crawl_servers():
for task in server.pop_queued_tasks():
self.dispatch_task(task)
counter += 1
return counter