#!/usr/bin/env python
# vim: set sw=4 et:

import logging
import json
import time
import threading
import kombu
import socket
from brozzler.browser import BrowserPool, BrowsingException
import brozzler
import urlcanon

class AmqpBrowserController:
    """
    Consumes amqp messages representing requests to browse urls, from the
    specified amqp queue (default: "urls") on the specified amqp exchange
    (default: "umbra"). Incoming amqp message is a json object with 3
    attributes:

      {
        "clientId": "umbra.client.123",
        "url": "http://example.com/my_fancy_page",
        "behaviorParameters": {"some":"parameter","another":"thing"},
        "metadata": {"arbitrary":"fields", "etc":4}
      }

    "url" is the url to browse.

    "clientId" uniquely identifies the client of umbra. Umbra uses the clientId
    as the amqp routing key, to direct information via amqp back to the client.
    It sends this information on the same specified amqp exchange (default:
    "umbra").

    "behaviorParameters" are used to populate the javascript behavior template.

    Each url requested in the browser is published to amqp this way. The
    outgoing amqp message is a json object:

      {
        "url": "http://example.com/images/embedded_thing.jpg",
        "method": "GET",
        "headers": {"User-Agent": "...", "Accept": "...", ...},
        "parentUrl": "http://example.com/my_fancy_page",
        "parentUrlMetadata": {"arbitrary":"fields", "etc":4, ...}
      }

    POST requests have an additional field, postData.
    """

    logger = logging.getLogger(__module__ + "." + __qualname__)

    def __init__(self, amqp_url='amqp://guest:guest@localhost:5672/%2f',
            chrome_exe='chromium-browser', max_active_browsers=1,
            queue_name='urls', exchange_name='umbra', routing_key='urls'):
        self.amqp_url = amqp_url
        self.queue_name = queue_name
        self.exchange_name = exchange_name
        self.routing_key = routing_key
        self.max_active_browsers = max_active_browsers

        self._browser_pool = BrowserPool(
                size=max_active_browsers, chrome_exe=chrome_exe,
                ignore_cert_errors=True)

    def start(self):
        self._browsing_threads = set()
        self._browsing_threads_lock = threading.Lock()

        self._exchange = kombu.Exchange(name=self.exchange_name, type='direct',
                durable=True)

        self._reconnect_requested = False

        self._producer = None
        self._producer_lock = threading.Lock()
        with self._producer_lock:
            self._producer_conn = kombu.Connection(self.amqp_url)
            self._producer = self._producer_conn.Producer(serializer='json')

        self._consumer_thread = threading.Thread(target=self._consume_amqp, name='AmqpConsumerThread')
        self._consumer_stop = threading.Event()
        self._consumer_thread.start()

    def shutdown(self):
        self.logger.info("shutting down amqp consumer {}".format(self.amqp_url))
        self._consumer_stop.set()
        self._consumer_thread.join()

    def shutdown_now(self):
        self.logger.info("shutting down amqp consumer %s", self.amqp_url)
        self._consumer_stop.set()
        with self._browsing_threads_lock:
            for th in self._browsing_threads:
                if th.is_alive():
                    brozzler.thread_raise(th, brozzler.ShutdownRequested)
        # self._browser_pool.shutdown_now()
        self._consumer_thread.join()

    def reconnect(self, *args, **kwargs):
        self._reconnect_requested = True
        self._browser_pool.shutdown_now()

    def _wait_for_and_browse_urls(self, conn, consumer, timeout):
        start = time.time()
        browser = None

        while not self._consumer_stop.is_set() and time.time() - start < timeout and not self._reconnect_requested:
            try:
                browser = self._browser_pool.acquire() # raises KeyError if none available

                def callback(body, message):
                    try:
                        client_id = body.get('clientId')
                        url = body['url']
                        metadata = body.get('metadata')
                        behavior_parameters = body.get('behaviorParameters')
                        username = body.get('username')
                        password = body.get('password')
                    except:
                        self.logger.error("unable to decipher message %s",
                                          message, exc_info=True)
                        self.logger.error("discarding bad message")
                        message.reject()
                        browser.stop()
                        self._browser_pool.release(browser)
                        return
                    self._start_browsing_page(
                            browser, message, client_id, url, metadata,
                            behavior_parameters, username, password)

                consumer.callbacks = [callback]

                while True:
                    try:
                        conn.drain_events(timeout=0.5)
                        break # out of "while True" to acquire another browser
                    except socket.timeout:
                        pass
                    except socket.error:
                        self.logger.error("problem consuming messages from AMQP, will try reconnecting after active browsing finishes", exc_info=True)
                        self._reconnect_requested = True

                    if self._consumer_stop.is_set() or time.time() - start >= timeout or self._reconnect_requested:
                        browser.stop()
                        self._browser_pool.release(browser)
                        break

            except brozzler.browser.NoBrowsersAvailable:
                # no browsers available
                time.sleep(0.5)
            except:
                self.logger.critical("problem with browser initialization", exc_info=True)
                time.sleep(0.5)
            finally:
                consumer.callbacks = None

    def _wait_for_active_browsers(self):
        self.logger.info("waiting for browsing threads to finish")
        while True:
            with self._browsing_threads_lock:
                if len(self._browsing_threads) == 0:
                    break
            time.sleep(0.5)
        self.logger.info("active browsing threads finished")

    def _consume_amqp(self):
        # XXX https://webarchive.jira.com/browse/ARI-3811
        # After running for some amount of time (3 weeks in the latest case),
        # consumer looks normal but doesn't consume any messages. Not clear if
        # it's hanging in drain_events() or not. As a temporary measure for
        # mitigation (if it works) or debugging (if it doesn't work), close and
        # reopen the connection every 2.5 hours
        RECONNECT_AFTER_SECONDS = 150 * 60

        url_queue = kombu.Queue(self.queue_name, exchange=self._exchange, routing_key=self.routing_key)

        while not self._consumer_stop.is_set():
            try:
                self.logger.info("connecting to amqp exchange={} at {}".format(self._exchange.name, self.amqp_url))
                self._reconnect_requested = False
                with kombu.Connection(self.amqp_url) as conn:
                    conn.default_channel.basic_qos(
                            prefetch_count=self.max_active_browsers,
                            prefetch_size=0, a_global=False)
                    with conn.Consumer(url_queue) as consumer:
                        self._wait_for_and_browse_urls(
                                conn, consumer, timeout=RECONNECT_AFTER_SECONDS)

                    # need to wait for browsers to finish here, before closing
                    # the amqp connection,  because they use it to do
                    # message.ack() after they finish browsing a page
                    self._wait_for_active_browsers()
            except BaseException as e:
                self.logger.error("caught exception {}".format(e), exc_info=True)
                time.sleep(0.5)
                self.logger.error("attempting to reopen amqp connection")

    def _start_browsing_page(
            self, browser, message, client_id, url, parent_url_metadata,
            behavior_parameters=None, username=None, password=<PASSWORD>):
        def on_response(chrome_msg):
            if (chrome_msg['params']['response']['url'].lower().startswith('data:')
                    or chrome_msg['params']['response']['fromDiskCache']):
                return

            request_headers = chrome_msg['params']['response'].get('requestHeaders', {})
            payload = {
                'url': chrome_msg['params']['response']['url'],
                'headers': request_headers,
                'parentUrl': url,
                'parentUrlMetadata': parent_url_metadata,
            }

            if ':method' in request_headers:
                # happens when http transaction is http 2.0
                payload['method'] = request_headers[':method']
            elif 'requestHeadersText' in chrome_msg['params']['response']:
                req = chrome_msg['params']['response']['requestHeadersText']
                payload['method'] = req[:req.index(' ')]
            else:
                self.logger.warn('unable to identify http method (assuming GET) chrome_msg=%s',
                                 chrome_msg)
                payload['method'] = 'GET'

            self.logger.debug(
                    'sending to amqp exchange=%s routing_key=%s payload=%s',
                    self.exchange_name, client_id, payload)
            with self._producer_lock:
                publish = self._producer_conn.ensure(self._producer,
                                                     self._producer.publish)
                publish(payload, exchange=self._exchange, routing_key=client_id)

        def post_outlinks(outlinks=None):
            def prune_outlinks(dirty_links, block_list=None):
                '''
                Filter for valid schemes, remove URL fragments, and drop any other designated URLs from the list.
                '''
                links = set()
                dirty_links = set(dirty_links)

                self.logger.info('Pruning links...')
                for link in dirty_links:
                    link = urlcanon.parse_url(link)

                    if link.scheme in (b'http', b'https', b'ftp'):
                        urlcanon.canon.remove_fragment(link)
                        link = str(link).strip()
                        links.add(link)

                self.logger.info('Pruning complete.')

                # Need to remove after link fragments have been removed to prevent duplication.
                self.logger.info('Removing Links: %s', ', '.join(block_list))
                links = links.difference(block_list)

                return links

            outlinks = prune_outlinks(outlinks, {url})

            self.logger.info('Posting Outlinks:\n\t%s', '\n\t'.join(sorted(outlinks)))

            for link in outlinks:
                 #  Each of these payload fields are required by AMQPUrlReceiver.java
                 #+ in Heritrix.
                 payload = {
                    'url': link,
                    'headers': {},
                    'parentUrl': url,
                    'parentUrlMetadata': parent_url_metadata,
                    'method': 'GET',
                 }
                 self.logger.debug(
                            'sending outlink to amqp exchange=%s routing_key=%s payload=%s',
                            self.exchange_name, client_id, payload)
                 with self._producer_lock:
                     publish = self._producer_conn.ensure(self._producer,
                                                          self._producer.publish)
                     publish(payload, exchange=self._exchange, routing_key=client_id)

        def browse_page_sync():
            self.logger.info(
                    'browser=%s client_id=%s url=%s behavior_parameters=%s',
                    browser, client_id, url, behavior_parameters)
            try:
                browser.start()
                final_page_url, outlinks = browser.browse_page(
                        url, on_response=on_response,
                        behavior_parameters=behavior_parameters,
                        username=username, password=password)

                # Temporarily commenting out for https://webarchive.jira.com/browse/AITFIVE-1295
                #post_outlinks(outlinks)

                message.ack()
            except brozzler.PageInterstitialShown as e:
                self.logger.info("page interstitial shown, likely unsupported http auth, for url {} - {}".format(url, e))
                message.reject()
            except brozzler.ShutdownRequested as e:
                self.logger.info("browsing did not complete normally, requeuing url {} - {}".format(url, e))
                message.requeue()  # republish?
            except BrowsingException as e:
                self.logger.warn("browsing did not complete normally, republishing url {} - {}".format(url, e))
                republish_amqp(self, message)
            except:
                self.logger.critical("problem browsing page, republishing url {}, may have lost browser process".format(url), exc_info=True)
                republish_amqp(self, message)
            finally:
                browser.stop()
                self._browser_pool.release(browser)

        def republish_amqp(self, message):
            # republish on exception, not requeue!
            payload = json.loads(to_str(message.body))
            message.ack()
            max_retries = 5
            if 'metadata' in payload:
                if not 'retries' in payload['metadata']:
                    payload['metadata']['retries'] = 1
                else:
                    if payload['metadata']['retries'] >= max_retries:
                        return
                    payload['metadata']['retries'] += 1
            self.logger.debug(
                       're-publishing url to amqp exchange=%s routing_key=%s payload=%s',
                       self.exchange_name, self.routing_key, payload)
            with self._producer_lock:
                publish = self._producer_conn.ensure(self._producer,
                                                     self._producer.publish)
                publish(payload, exchange=self._exchange, routing_key=self.routing_key)

        def to_str(bytes_or_str):
            if isinstance(bytes_or_str, bytes):
                value = bytes_or_str.decode() # uses 'utf-8' for encoding
            else:
                value = bytes_or_str
            return value # Instance of str

        def browse_thread_run_then_cleanup():
            browse_page_sync()
            self.logger.info(
                    'removing thread %s from self._browsing_threads',
                    threading.current_thread())
            with self._browsing_threads_lock:
                self._browsing_threads.remove(threading.current_thread())

        thread_name = "BrowsingThread:%s" % browser.chrome.port
        th = threading.Thread(target=browse_thread_run_then_cleanup, name=thread_name)
        self.logger.info('adding thread %s to self._browsing_threads', th)
        with self._browsing_threads_lock:
            self._browsing_threads.add(th)
        th.start()


#!/usr/bin/env python
# vim: set sw=4 et:

import logging
import json
import time
import threading
import kombu
import socket
from brozzler.browser import BrowserPool, BrowsingException
import brozzler
import urlcanon

class AmqpBrowserController:
    """
    Consumes amqp messages representing requests to browse urls, from the
    specified amqp queue (default: "urls") on the specified amqp exchange
    (default: "umbra"). Incoming amqp message is a json object with 3
    attributes:

      {
        "clientId": "umbra.client.123",
        "url": "http://example.com/my_fancy_page",
        "behaviorParameters": {"some":"parameter","another":"thing"},
        "metadata": {"arbitrary":"fields", "etc":4}
      }

    "url" is the url to browse.

    "clientId" uniquely identifies the client of umbra. Umbra uses the clientId
    as the amqp routing key, to direct information via amqp back to the client.
    It sends this information on the same specified amqp exchange (default:
    "umbra").

    "behaviorParameters" are used to populate the javascript behavior template.

    Each url requested in the browser is published to amqp this way. The
    outgoing amqp message is a json object:

      {
        "url": "http://example.com/images/embedded_thing.jpg",
        "method": "GET",
        "headers": {"User-Agent": "...", "Accept": "...", ...},
        "parentUrl": "http://example.com/my_fancy_page",
        "parentUrlMetadata": {"arbitrary":"fields", "etc":4, ...}
      }

    POST requests have an additional field, postData.
    """

    logger = logging.getLogger(__module__ + "." + __qualname__)

    def __init__(self, amqp_url='amqp://guest:guest@localhost:5672/%2f',
            chrome_exe='chromium-browser', max_active_browsers=1,
            queue_name='urls', exchange_name='umbra', routing_key='urls'):
        self.amqp_url = amqp_url
        self.queue_name = queue_name
        self.exchange_name = exchange_name
        self.routing_key = routing_key
        self.max_active_browsers = max_active_browsers

        self._browser_pool = BrowserPool(
                size=max_active_browsers, chrome_exe=chrome_exe,
                ignore_cert_errors=True)

    def start(self):
        self._browsing_threads = set()
        self._browsing_threads_lock = threading.Lock()

        self._exchange = kombu.Exchange(name=self.exchange_name, type='direct',
                durable=True)

        self._reconnect_requested = False

        self._producer = None
        self._producer_lock = threading.Lock()
        with self._producer_lock:
            self._producer_conn = kombu.Connection(self.amqp_url)
            self._producer = self._producer_conn.Producer(serializer='json')

        self._consumer_thread = threading.Thread(target=self._consume_amqp, name='AmqpConsumerThread')
        self._consumer_stop = threading.Event()
        self._consumer_thread.start()

    def shutdown(self):
        self.logger.info("shutting down amqp consumer {}".format(self.amqp_url))
        self._consumer_stop.set()
        self._consumer_thread.join()

    def shutdown_now(self):
        self.logger.info("shutting down amqp consumer %s", self.amqp_url)
        self._consumer_stop.set()
        with self._browsing_threads_lock:
            for th in self._browsing_threads:
                if th.is_alive():
                    brozzler.thread_raise(th, brozzler.ShutdownRequested)
        # self._browser_pool.shutdown_now()
        self._consumer_thread.join()

    def reconnect(self, *args, **kwargs):
        self._reconnect_requested = True
        self._browser_pool.shutdown_now()

    def _wait_for_and_browse_urls(self, conn, consumer, timeout):
        start = time.time()
        browser = None

        while not self._consumer_stop.is_set() and time.time() - start < timeout and not self._reconnect_requested:
            try:
                browser = self._browser_pool.acquire() # raises KeyError if none available

                def callback(body, message):
                    try:
                        client_id = body.get('clientId')
                        url = body['url']
                        metadata = body.get('metadata')
                        behavior_parameters = body.get('behaviorParameters')
                        username = body.get('username')
                        password = body.get('password')
                    except:
                        self.logger.error("unable to decipher message %s",
                                          message, exc_info=True)
                        self.logger.error("discarding bad message")
                        message.reject()
                        browser.stop()
                        self._browser_pool.release(browser)
                        return
                    self._start_browsing_page(
                            browser, message, client_id, url, metadata,
                            behavior_parameters, username, password)

                consumer.callbacks = [callback]

                while True:
                    try:
                        conn.drain_events(timeout=0.5)
                        break # out of "while True" to acquire another browser
                    except socket.timeout:
                        pass
                    except socket.error:
                        self.logger.error("problem consuming messages from AMQP, will try reconnecting after active browsing finishes", exc_info=True)
                        self._reconnect_requested = True

                    if self._consumer_stop.is_set() or time.time() - start >= timeout or self._reconnect_requested:
                        browser.stop()
                        self._browser_pool.release(browser)
                        break

            except brozzler.browser.NoBrowsersAvailable:
                # no browsers available
                time.sleep(0.5)
            except:
                self.logger.critical("problem with browser initialization", exc_info=True)
                time.sleep(0.5)
            finally:
                consumer.callbacks = None

    def _wait_for_active_browsers(self):
        self.logger.info("waiting for browsing threads to finish")
        while True:
            with self._browsing_threads_lock:
                if len(self._browsing_threads) == 0:
                    break
            time.sleep(0.5)
        self.logger.info("active browsing threads finished")

    def _consume_amqp(self):
        # XXX https://webarchive.jira.com/browse/ARI-3811
        # After running for some amount of time (3 weeks in the latest case),
        # consumer looks normal but doesn't consume any messages. Not clear if
        # it's hanging in drain_events() or not. As a temporary measure for
        # mitigation (if it works) or debugging (if it doesn't work), close and
        # reopen the connection every 2.5 hours
        RECONNECT_AFTER_SECONDS = 150 * 60

        url_queue = kombu.Queue(self.queue_name, exchange=self._exchange, routing_key=self.routing_key)

        while not self._consumer_stop.is_set():
            try:
                self.logger.info("connecting to amqp exchange={} at {}".format(self._exchange.name, self.amqp_url))
                self._reconnect_requested = False
                with kombu.Connection(self.amqp_url) as conn:
                    conn.default_channel.basic_qos(
                            prefetch_count=self.max_active_browsers,
                            prefetch_size=0, a_global=False)
                    with conn.Consumer(url_queue) as consumer:
                        self._wait_for_and_browse_urls(
                                conn, consumer, timeout=RECONNECT_AFTER_SECONDS)

                    # need to wait for browsers to finish here, before closing
                    # the amqp connection,  because they use it to do
                    # message.ack() after they finish browsing a page
                    self._wait_for_active_browsers()
            except BaseException as e:
                self.logger.error("caught exception {}".format(e), exc_info=True)
                time.sleep(0.5)
                self.logger.error("attempting to reopen amqp connection")

    def _start_browsing_page(
            self, browser, message, client_id, url, parent_url_metadata,
            behavior_parameters=None, username=None, password=<PASSWORD>):
        def on_response(chrome_msg):
            if (chrome_msg['params']['response']['url'].lower().startswith('data:')
                    or chrome_msg['params']['response']['fromDiskCache']):
                return

            request_headers = chrome_msg['params']['response'].get('requestHeaders', {})
            payload = {
                'url': chrome_msg['params']['response']['url'],
                'headers': request_headers,
                'parentUrl': url,
                'parentUrlMetadata': parent_url_metadata,
            }

            if ':method' in request_headers:
                # happens when http transaction is http 2.0
                payload['method'] = request_headers[':method']
            elif 'requestHeadersText' in chrome_msg['params']['response']:
                req = chrome_msg['params']['response']['requestHeadersText']
                payload['method'] = req[:req.index(' ')]
            else:
                self.logger.warn('unable to identify http method (assuming GET) chrome_msg=%s',
                                 chrome_msg)
                payload['method'] = 'GET'

            self.logger.debug(
                    'sending to amqp exchange=%s routing_key=%s payload=%s',
                    self.exchange_name, client_id, payload)
            with self._producer_lock:
                publish = self._producer_conn.ensure(self._producer,
                                                     self._producer.publish)
                publish(payload, exchange=self._exchange, routing_key=client_id)

        def post_outlinks(outlinks=None):
            def prune_outlinks(dirty_links, block_list=None):
                '''
                Filter for valid schemes, remove URL fragments, and drop any other designated URLs from the list.
                '''
                links = set()
                dirty_links = set(dirty_links)

                self.logger.info('Pruning links...')
                for link in dirty_links:
                    link = urlcanon.parse_url(link)

                    if link.scheme in (b'http', b'https', b'ftp'):
                        urlcanon.canon.remove_fragment(link)
                        link = str(link).strip()
                        links.add(link)

                self.logger.info('Pruning complete.')

                # Need to remove after link fragments have been removed to prevent duplication.
                self.logger.info('Removing Links: %s', ', '.join(block_list))
                links = links.difference(block_list)

                return links

            outlinks = prune_outlinks(outlinks, {url})

            self.logger.info('Posting Outlinks:\n\t%s', '\n\t'.join(sorted(outlinks)))

            for link in outlinks:
                 #  Each of these payload fields are required by AMQPUrlReceiver.java
                 #+ in Heritrix.
                 payload = {
                    'url': link,
                    'headers': {},
                    'parentUrl': url,
                    'parentUrlMetadata': parent_url_metadata,
                    'method': 'GET',
                 }
                 self.logger.debug(
                            'sending outlink to amqp exchange=%s routing_key=%s payload=%s',
                            self.exchange_name, client_id, payload)
                 with self._producer_lock:
                     publish = self._producer_conn.ensure(self._producer,
                                                          self._producer.publish)
                     publish(payload, exchange=self._exchange, routing_key=client_id)

        def browse_page_sync():
            self.logger.info(
                    'browser=%s client_id=%s url=%s behavior_parameters=%s',
                    browser, client_id, url, behavior_parameters)
            try:
                browser.start()
                final_page_url, outlinks = browser.browse_page(
                        url, on_response=on_response,
                        behavior_parameters=behavior_parameters,
                        username=username, password=password)

                # Temporarily commenting out for https://webarchive.jira.com/browse/AITFIVE-1295
                #post_outlinks(outlinks)

                message.ack()
            except brozzler.PageInterstitialShown as e:
                self.logger.info("page interstitial shown, likely unsupported http auth, for url {} - {}".format(url, e))
                message.reject()
            except brozzler.ShutdownRequested as e:
                self.logger.info("browsing did not complete normally, requeuing url {} - {}".format(url, e))
                message.requeue()  # republish?
            except BrowsingException as e:
                self.logger.warn("browsing did not complete normally, republishing url {} - {}".format(url, e))
                republish_amqp(self, message)
            except:
                self.logger.critical("problem browsing page, republishing url {}, may have lost browser process".format(url), exc_info=True)
                republish_amqp(self, message)
            finally:
                browser.stop()
                self._browser_pool.release(browser)

        def republish_amqp(self, message):
            # republish on exception, not requeue!
            payload = json.loads(to_str(message.body))
            message.ack()
            max_retries = 5
            if 'metadata' in payload:
                if not 'retries' in payload['metadata']:
                    payload['metadata']['retries'] = 1
                else:
                    if payload['metadata']['retries'] >= max_retries:
                        return
                    payload['metadata']['retries'] += 1
            self.logger.debug(
                       're-publishing url to amqp exchange=%s routing_key=%s payload=%s',
                       self.exchange_name, self.routing_key, payload)
            with self._producer_lock:
                publish = self._producer_conn.ensure(self._producer,
                                                     self._producer.publish)
                publish(payload, exchange=self._exchange, routing_key=self.routing_key)

        def to_str(bytes_or_str):
            if isinstance(bytes_or_str, bytes):
                value = bytes_or_str.decode() # uses 'utf-8' for encoding
            else:
                value = bytes_or_str
            return value # Instance of str

        def browse_thread_run_then_cleanup():
            browse_page_sync()
            self.logger.info(
                    'removing thread %s from self._browsing_threads',
                    threading.current_thread())
            with self._browsing_threads_lock:
                self._browsing_threads.remove(threading.current_thread())

        thread_name = "BrowsingThread:%s" % browser.chrome.port
        th = threading.Thread(target=browse_thread_run_then_cleanup, name=thread_name)
        self.logger.info('adding thread %s to self._browsing_threads', th)
        with self._browsing_threads_lock:
            self._browsing_threads.add(th)
        th.start()


#!/usr/bin/env python # vim: set sw=4 et: Consumes amqp messages representing requests to browse urls, from the     specified amqp queue (default: "urls") on the specified amqp exchange     (default: "umbra"). Incoming amqp message is a json object with 3     attributes:        {         "clientId": "umbra.client.123",         "url": "http://example.com/my_fancy_page",         "behaviorParameters": {"some":"parameter","another":"thing"},         "metadata": {"arbitrary":"fields", "etc":4}       }      "url" is the url to browse.      "clientId" uniquely identifies the client of umbra. Umbra uses the clientId     as the amqp routing key, to direct information via amqp back to the client.     It sends this information on the same specified amqp exchange (default:     "umbra").      "behaviorParameters" are used to populate the javascript behavior template.      Each url requested in the browser is published to amqp this way. The     outgoing amqp message is a json object:        {         "url": "http://example.com/images/embedded_thing.jpg",         "method": "GET",         "headers": {"User-Agent": "...", "Accept": "...", ...},         "parentUrl": "http://example.com/my_fancy_page",         "parentUrlMetadata": {"arbitrary":"fields", "etc":4, ...}       }      POST requests have an additional field, postData. # self._browser_pool.shutdown_now() # raises KeyError if none available # out of "while True" to acquire another browser # no browsers available # XXX https://webarchive.jira.com/browse/ARI-3811 # After running for some amount of time (3 weeks in the latest case), # consumer looks normal but doesn't consume any messages. Not clear if # it's hanging in drain_events() or not. As a temporary measure for # mitigation (if it works) or debugging (if it doesn't work), close and # reopen the connection every 2.5 hours # need to wait for browsers to finish here, before closing # the amqp connection,  because they use it to do # message.ack() after they finish browsing a page # happens when http transaction is http 2.0 Filter for valid schemes, remove URL fragments, and drop any other designated URLs from the list. # Need to remove after link fragments have been removed to prevent duplication. #  Each of these payload fields are required by AMQPUrlReceiver.java #+ in Heritrix. # Temporarily commenting out for https://webarchive.jira.com/browse/AITFIVE-1295 #post_outlinks(outlinks) # republish? # republish on exception, not requeue! # uses 'utf-8' for encoding # Instance of str