From 47bd9c0e96a66169df6dffead54612f6265bf9dd Mon Sep 17 00:00:00 2001
From: Vostretsov Nikita <whalebot.helmsman@gmail.com>
Date: Sun, 14 Jul 2019 22:31:02 +0500
Subject: [PATCH] move serialization/deserialization logic to downstream queues

---
 scrapy/core/scheduler.py |  8 +++-----
 scrapy/pqueues.py        | 33 +++++----------------------------
 scrapy/squeues.py        | 28 ++++++++++++++++++++++------
 3 files changed, 30 insertions(+), 39 deletions(-)

diff --git a/scrapy/core/scheduler.py b/scrapy/core/scheduler.py
index 975aede0c..473cff92e 100644
--- a/scrapy/core/scheduler.py
+++ b/scrapy/core/scheduler.py
@@ -148,12 +148,11 @@ class Scheduler(object):
     def _newdq(self, priority):
         """ Factory for creating disk queues. """
         path = join(self.dqdir, 'p%s' % (priority, ))
-        return self.dqclass(path)
+        return self.dqclass(self.crawler, path)
 
     def _mq(self):
         """ Create a new priority queue instance, with in-memory storage """
-        return create_instance(self.pqclass, None, self.crawler, self._newmq,
-                               serialize=False)
+        return create_instance(self.pqclass, None, self.crawler, self._newmq)
 
     def _dq(self):
         """ Create a new priority queue instance, with disk storage """
@@ -162,8 +161,7 @@ class Scheduler(object):
                             None,
                             self.crawler,
                             self._newdq,
-                            state,
-                            serialize=True)
+                            state)
         if q:
             logger.info("Resuming crawl (%(queuesize)d requests scheduled)",
                         {'queuesize': len(q)}, extra={'spider': self.spider})
diff --git a/scrapy/pqueues.py b/scrapy/pqueues.py
index 6ecd1b51a..454609470 100644
--- a/scrapy/pqueues.py
+++ b/scrapy/pqueues.py
@@ -91,29 +91,7 @@ class _SlotPriorityQueues(object):
 
 
 class ScrapyPriorityQueue(PriorityQueue):
-    """
-    PriorityQueue which works with scrapy.Request instances and
-    can optionally convert them to/from dicts before/after putting to a queue.
-    """
-    def __init__(self, crawler, qfactory, startprios=(), serialize=False):
-        super(ScrapyPriorityQueue, self).__init__(qfactory, startprios)
-        self.serialize = serialize
-        self.spider = crawler.spider
-
-    @classmethod
-    def from_crawler(cls, crawler, qfactory, startprios=(), serialize=False):
-        return cls(crawler, qfactory, startprios, serialize)
-
-    def push(self, request, priority=0):
-        if self.serialize:
-            request = request_to_dict(request, self.spider)
-        super(ScrapyPriorityQueue, self).push(request, priority)
-
-    def pop(self):
-        request = super(ScrapyPriorityQueue, self).pop()
-        if request and self.serialize:
-            request = request_from_dict(request, self.spider)
-        return request
+    pass
 
 
 class DownloaderInterface(object):
@@ -142,10 +120,10 @@ class DownloaderAwarePriorityQueue(object):
     """
 
     @classmethod
-    def from_crawler(cls, crawler, qfactory, slot_startprios=None, serialize=False):
-        return cls(crawler, qfactory, slot_startprios, serialize)
+    def from_crawler(cls, crawler, qfactory, slot_startprios=None):
+        return cls(crawler, qfactory, slot_startprios)
 
-    def __init__(self, crawler, qfactory, slot_startprios=None, serialize=False):
+    def __init__(self, crawler, qfactory, slot_startprios=None):
         if crawler.settings.getint('CONCURRENT_REQUESTS_PER_IP') != 0:
             raise ValueError('"%s" does not support CONCURRENT_REQUESTS_PER_IP'
                              % (self.__class__,))
@@ -164,9 +142,8 @@ class DownloaderAwarePriorityQueue(object):
             for slot, startprios in (slot_startprios or {}).items()}
 
         def pqfactory(startprios=()):
-            return ScrapyPriorityQueue(crawler, qfactory, startprios, serialize)
+            return ScrapyPriorityQueue(qfactory, startprios)
         self._slot_pqueues = _SlotPriorityQueues(pqfactory, slot_startprios)
-        self.serialize = serialize
         self._downloader_interface = DownloaderInterface(crawler)
 
     def pop(self):
diff --git a/scrapy/squeues.py b/scrapy/squeues.py
index 30cc926e5..9f78e17cc 100644
--- a/scrapy/squeues.py
+++ b/scrapy/squeues.py
@@ -7,19 +7,35 @@ from six.moves import cPickle as pickle
 
 from queuelib import queue
 
+from scrapy.utils.reqser import request_to_dict, request_from_dict
+
 
 def _serializable_queue(queue_class, serialize, deserialize):
 
     class SerializableQueue(queue_class):
 
-        def push(self, obj):
-            s = serialize(obj)
-            super(SerializableQueue, self).push(s)
+        def __init__(self, crawler, key):
+            self.spider = crawler.spider
+            super(SerializableQueue, self).__init__(key)
+
+        def push(self, request):
+            if serialize:
+                request = request_to_dict(request, self.spider)
+                request = serialize(request)
+
+            return super(SerializableQueue, self).push(request)
 
         def pop(self):
-            s = super(SerializableQueue, self).pop()
-            if s:
-                return deserialize(s)
+            request = super(SerializableQueue, self).pop()
+
+            if not request:
+                return None
+
+            if deserialize:
+                request = deserialize(request)
+                request = request_from_dict(request, self.spider)
+
+            return request
 
     return SerializableQueue