refactor: linkcheck: Separate thread manager feature from builder class

To reduce the complexity of the linkcheck builder, this separates
the thread manager feature from the builder class as
HyperlinkAvailabilityChecker.

CHANGES

@@ -23,7 +23,10 @@ Deprecated
 * ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.broken``
 * ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.good``
 * ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.redirected``
+* ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.rqueue``
 * ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.to_ignore``
+* ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.workers``
+* ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.wqueue``
 * ``sphinx.builders.linkcheck.node_line_or_0()``
 * ``sphinx.ext.autodoc.AttributeDocumenter.isinstanceattribute()``
 * ``sphinx.ext.autodoc.directive.DocumenterBridge.reporter``

doc/extdev/deprecated.rst

@@ -52,11 +52,26 @@ The following is a list of deprecated interfaces.
      - 5.0
      - N/A
 
+   * - ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.rqueue``
+     - 3.5
+     - 5.0
+     - N/A
+
    * - ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.to_ignore``
      - 3.5
      - 5.0
      - N/A
 
+   * - ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.workers``
+     - 3.5
+     - 5.0
+     - N/A
+
+   * - ``sphinx.builders.linkcheck.CheckExternalLinksBuilder.wqueue``
+     - 3.5
+     - 5.0
+     - N/A
+
    * - ``sphinx.builders.linkcheck.node_line_or_0()``
      - 3.5
      - 5.0

sphinx/builders/linkcheck.py

@@ -19,7 +19,7 @@ from email.utils import parsedate_to_datetime
 from html.parser import HTMLParser
 from os import path
 from threading import Thread
-from typing import Any, Dict, List, NamedTuple, Optional, Pattern, Set, Tuple, cast
+from typing import Any, Dict, Generator, List, NamedTuple, Optional, Pattern, Set, Tuple, cast
 from urllib.parse import unquote, urlparse
 
 from docutils import nodes
@@ -121,17 +121,8 @@ class CheckExternalLinksBuilder(DummyBuilder):
         socket.setdefaulttimeout(5.0)
 
         # create queues and worker threads
-        self.rate_limits = {}  # type: Dict[str, RateLimit]
-        self.wqueue = queue.PriorityQueue()  # type: queue.PriorityQueue
-        self.rqueue = queue.Queue()  # type: queue.Queue
-        self.workers = []  # type: List[Thread]
-        for i in range(self.config.linkcheck_workers):
-            thread = HyperlinkAvailabilityCheckWorker(self)
-            thread.start()
-            self.workers.append(thread)
-
-    def is_ignored_uri(self, uri: str) -> bool:
-        return any(pat.match(uri) for pat in self.to_ignore)
+        self._wqueue = queue.PriorityQueue()  # type: queue.PriorityQueue
+        self._rqueue = queue.Queue()  # type: queue.Queue
 
     @property
     def anchors_ignore(self) -> List[Pattern]:
@@ -202,7 +193,31 @@ class CheckExternalLinksBuilder(DummyBuilder):
             RemovedInSphinx50Warning,
             stacklevel=2,
         )
-        return HyperlinkAvailabilityCheckWorker(self).limit_rate(response)
+        return HyperlinkAvailabilityCheckWorker(self, None, None, {}).limit_rate(response)
+
+    def rqueue(self, response: Response) -> queue.Queue:
+        warnings.warn(
+            "%s.%s is deprecated." % (self.__class__.__name__, "rqueue"),
+            RemovedInSphinx50Warning,
+            stacklevel=2,
+        )
+        return self._rqueue
+
+    def workers(self, response: Response) -> List[Thread]:
+        warnings.warn(
+            "%s.%s is deprecated." % (self.__class__.__name__, "workers"),
+            RemovedInSphinx50Warning,
+            stacklevel=2,
+        )
+        return []
+
+    def wqueue(self, response: Response) -> queue.Queue:
+        warnings.warn(
+            "%s.%s is deprecated." % (self.__class__.__name__, "wqueue"),
+            RemovedInSphinx50Warning,
+            stacklevel=2,
+        )
+        return self._wqueue
 
     def process_result(self, result: Tuple[str, str, int, str, str, int]) -> None:
         uri, docname, lineno, status, info, code = result
@@ -268,49 +283,84 @@ class CheckExternalLinksBuilder(DummyBuilder):
         self.json_outfile.write('\n')
 
     def finish(self) -> None:
+        checker = HyperlinkAvailabilityChecker(self)
         logger.info('')
 
         with open(path.join(self.outdir, 'output.txt'), 'w') as self.txt_outfile,\
              open(path.join(self.outdir, 'output.json'), 'w') as self.json_outfile:
+            for result in checker.check(self.hyperlinks):
+                self.process_result(result)
+
+        if self._broken:
+            self.app.statuscode = 1
+
+
+class HyperlinkAvailabilityChecker:
+    def __init__(self, builder: CheckExternalLinksBuilder) -> None:
+        self.builder = builder
+        self.config = builder.config
+        self.rate_limits = {}  # type: Dict[str, RateLimit]
+        self.workers = []  # type: List[Thread]
+
+        self.to_ignore = [re.compile(x) for x in self.config.linkcheck_ignore]
+
+        if builder:
+            self.rqueue = builder._rqueue
+            self.wqueue = builder._wqueue
+        else:
+            self.rqueue = queue.Queue()
+            self.wqueue = queue.PriorityQueue()
+
+    def invoke_threads(self) -> None:
+        for i in range(self.config.linkcheck_workers):
+            thread = HyperlinkAvailabilityCheckWorker(self.builder, self.rqueue, self.wqueue,
+                                                      self.rate_limits)
+            thread.start()
+            self.workers.append(thread)
+
+    def shutdown_threads(self) -> None:
+        self.wqueue.join()
+        for worker in self.workers:
+            self.wqueue.put((CHECK_IMMEDIATELY, None, None, None), False)
+
+    def check(self, hyperlinks: Dict[str, Hyperlink]) -> Generator[CheckResult, None, None]:
+        self.invoke_threads()
+
         total_links = 0
-            for hyperlink in self.hyperlinks.values():
+        for hyperlink in hyperlinks.values():
             if self.is_ignored_uri(hyperlink.uri):
-                    self.process_result(
-                        CheckResult(hyperlink.uri, hyperlink.docname, hyperlink.lineno,
-                                    'ignored', '', 0))
+                yield CheckResult(hyperlink.uri, hyperlink.docname, hyperlink.lineno,
+                                  'ignored', '', 0)
             else:
                 self.wqueue.put(hyperlink, False)
                 total_links += 1
 
         done = 0
         while done < total_links:
-                self.process_result(self.rqueue.get())
+            yield self.rqueue.get()
             done += 1
 
-        if self._broken:
-            self.app.statuscode = 1
+        self.shutdown_threads()
 
-        self.wqueue.join()
-        # Shutdown threads.
-        for worker in self.workers:
-            self.wqueue.put((CHECK_IMMEDIATELY, None, None, None), False)
+    def is_ignored_uri(self, uri: str) -> bool:
+        return any(pat.match(uri) for pat in self.to_ignore)
 
 
 class HyperlinkAvailabilityCheckWorker(Thread):
     """A worker class for checking the availability of hyperlinks."""
 
-    def __init__(self, builder: CheckExternalLinksBuilder) -> None:
+    def __init__(self, builder: CheckExternalLinksBuilder, rqueue: queue.Queue,
+                 wqueue: queue.Queue, rate_limits: Dict[str, RateLimit]) -> None:
         self.config = builder.config
         self.env = builder.env
-        self.rate_limits = builder.rate_limits
-        self.rqueue = builder.rqueue
-        self.wqueue = builder.wqueue
+        self.rate_limits = rate_limits
+        self.rqueue = rqueue
+        self.wqueue = wqueue
 
         self.anchors_ignore = [re.compile(x)
                                for x in self.config.linkcheck_anchors_ignore]
         self.auth = [(re.compile(pattern), auth_info) for pattern, auth_info
                      in self.config.linkcheck_auth]
-        self.to_ignore = [re.compile(x) for x in self.config.linkcheck_ignore]
 
         self._good = builder._good
         self._broken = builder._broken

tests/test_build_linkcheck.py

@@ -21,7 +21,7 @@ from unittest import mock
 import pytest
 import requests
 
-from sphinx.builders.linkcheck import (CheckExternalLinksBuilder,
+from sphinx.builders.linkcheck import (CheckExternalLinksBuilder, HyperlinkAvailabilityChecker,
                                        HyperlinkAvailabilityCheckWorker, RateLimit)
 from sphinx.util.console import strip_colors
 
@@ -536,10 +536,12 @@ class FakeResponse:
 
 
 def test_limit_rate_default_sleep(app):
-    checker = CheckExternalLinksBuilder(app)
-    checker.init()
+    builder = CheckExternalLinksBuilder(app)
+    builder.init()
+    checker = HyperlinkAvailabilityChecker(builder)
     checker.rate_limits = {}
-    worker = HyperlinkAvailabilityCheckWorker(checker)
+    worker = HyperlinkAvailabilityCheckWorker(builder, checker.rqueue, checker.wqueue,
+                                              checker.rate_limits)
     with mock.patch('time.time', return_value=0.0):
         next_check = worker.limit_rate(FakeResponse())
     assert next_check == 60.0
@@ -547,40 +549,48 @@ def test_limit_rate_default_sleep(app):
 
 def test_limit_rate_user_max_delay(app):
     app.config.linkcheck_rate_limit_timeout = 0.0
-    checker = CheckExternalLinksBuilder(app)
-    checker.init()
+    builder = CheckExternalLinksBuilder(app)
+    builder.init()
+    checker = HyperlinkAvailabilityChecker(builder)
     checker.rate_limits = {}
-    worker = HyperlinkAvailabilityCheckWorker(checker)
+    worker = HyperlinkAvailabilityCheckWorker(builder, checker.rqueue, checker.wqueue,
+                                              checker.rate_limits)
     next_check = worker.limit_rate(FakeResponse())
     assert next_check is None
 
 
 def test_limit_rate_doubles_previous_wait_time(app):
-    checker = CheckExternalLinksBuilder(app)
-    checker.init()
+    builder = CheckExternalLinksBuilder(app)
+    builder.init()
+    checker = HyperlinkAvailabilityChecker(builder)
     checker.rate_limits = {"localhost": RateLimit(60.0, 0.0)}
-    worker = HyperlinkAvailabilityCheckWorker(checker)
+    worker = HyperlinkAvailabilityCheckWorker(builder, checker.rqueue, checker.wqueue,
+                                              checker.rate_limits)
     with mock.patch('time.time', return_value=0.0):
         next_check = worker.limit_rate(FakeResponse())
     assert next_check == 120.0
 
 
 def test_limit_rate_clips_wait_time_to_max_time(app):
-    checker = CheckExternalLinksBuilder(app)
-    checker.init()
     app.config.linkcheck_rate_limit_timeout = 90.0
+    builder = CheckExternalLinksBuilder(app)
+    builder.init()
+    checker = HyperlinkAvailabilityChecker(builder)
     checker.rate_limits = {"localhost": RateLimit(60.0, 0.0)}
-    worker = HyperlinkAvailabilityCheckWorker(checker)
+    worker = HyperlinkAvailabilityCheckWorker(builder, checker.rqueue, checker.wqueue,
+                                              checker.rate_limits)
     with mock.patch('time.time', return_value=0.0):
         next_check = worker.limit_rate(FakeResponse())
     assert next_check == 90.0
 
 
 def test_limit_rate_bails_out_after_waiting_max_time(app):
-    checker = CheckExternalLinksBuilder(app)
-    checker.init()
     app.config.linkcheck_rate_limit_timeout = 90.0
+    builder = CheckExternalLinksBuilder(app)
+    builder.init()
+    checker = HyperlinkAvailabilityChecker(builder)
     checker.rate_limits = {"localhost": RateLimit(90.0, 0.0)}
-    worker = HyperlinkAvailabilityCheckWorker(checker)
+    worker = HyperlinkAvailabilityCheckWorker(builder, checker.rqueue, checker.wqueue,
+                                              checker.rate_limits)
     next_check = worker.limit_rate(FakeResponse())
     assert next_check is None