Adding DOWNLOAD_MAXSIZE and DOWNLOAD_WARNSIZE

scrapy_zyte_api/handler.py

@@ -23,6 +23,27 @@
 logger = logging.getLogger(__name__)
 
 
+def _body_max_size_exceeded(
+    body_size: int,
+    warnsize: Optional[int],
+    maxsize: Optional[int],
+    request_url: str,
+) -> bool:
+    if warnsize and body_size > warnsize:
+        logger.warning(
+            f"Actual response size {body_size} larger than "
+            f"download warn size {warnsize} in request {request_url}."
+        )
+
+    if maxsize and body_size > maxsize:
+        logger.warning(
+            f"Dropping the response for {request_url}: actual response size "
+            f"{body_size} larger than download max size {maxsize}."
+        )
+        return True
+    return False
+
+
 def _truncate_str(obj, index, text, limit):
     if len(text) <= limit:
         return
@@ -92,6 +113,9 @@ def __init__(
                 f"({self._truncate_limit}) is invalid. It must be 0 or a "
                 f"positive integer."
             )
+        self._default_maxsize = settings.getint("DOWNLOAD_MAXSIZE")
+        self._default_warnsize = settings.getint("DOWNLOAD_WARNSIZE")
+
         crawler.signals.connect(self.engine_started, signal=signals.engine_started)
         self._crawler = crawler
         self._fallback_handler = None
@@ -231,7 +255,18 @@ async def _download_request(
         finally:
             self._update_stats(api_params)
 
-        return _process_response(api_response, request, self._cookie_jars)
+        process_response = _process_response(
+            api_response=api_response, request=request, cookie_jars=self._cookie_jars
+        )
+        if process_response and _body_max_size_exceeded(
+            len(process_response.body),
+            self._default_warnsize,
+            self._default_maxsize,
+            request.url,
+        ):
+            return None
+
+        return process_response
 
     def _process_request_error(self, request, error):
         detail = (error.parsed.data or {}).get("detail", error.message)

tests/test_handler.py

@@ -17,7 +17,11 @@
 from zyte_api.aio.retry import RetryFactory
 from zyte_api.constants import API_URL
 
-from scrapy_zyte_api.handler import ScrapyZyteAPIDownloadHandler
+from scrapy_zyte_api.handler import (
+    ScrapyZyteAPIDownloadHandler,
+    _body_max_size_exceeded,
+)
+from scrapy_zyte_api.responses import ZyteAPITextResponse
 from scrapy_zyte_api.utils import USER_AGENT
 
 from . import DEFAULT_CLIENT_CONCURRENCY, SETTINGS, SETTINGS_T, UNSET
@@ -557,3 +561,101 @@ async def test_fallback_setting():
     handler = get_download_handler(crawler, "https")
     assert isinstance(handler, ScrapyZyteAPIDownloadHandler)
     assert isinstance(handler._fallback_handler, HTTPDownloadHandler)
+
+
+@pytest.mark.parametrize(
+    "body_size, warnsize, maxsize, expected_result, expected_warnings",
+    [
+        # Warning only (exceeds warnsize but not maxsize)
+        (
+            1200,
+            1000,
+            1500,
+            False,
+            [
+                "Actual response size 1200 larger than download warn size 1000 in request http://example.com."
+            ],
+        ),
+        # Cancel download (exceeds both warnsize and maxsize)
+        (
+            1600,
+            1000,
+            1500,
+            True,
+            [
+                "Actual response size 1600 larger than download warn size 1000 in request http://example.com.",
+                "Dropping the response for http://example.com: actual response size 1600 larger than download max size 1500.",
+            ],
+        ),
+        # No limits - no warnings expected
+        (500, None, None, False, []),
+    ],
+)
+def test_body_max_size_exceeded(
+    body_size, warnsize, maxsize, expected_result, expected_warnings
+):
+    with mock.patch("scrapy_zyte_api.handler.logger") as logger:
+        result = _body_max_size_exceeded(
+            body_size=body_size,
+            warnsize=warnsize,
+            maxsize=maxsize,
+            request_url="http://example.com",
+        )
+
+    assert result == expected_result
+
+    if expected_warnings:
+        for call, expected_warning in zip(
+            logger.warning.call_args_list, expected_warnings
+        ):
+            assert call[0][0] == expected_warning
+    else:
+        logger.warning.assert_not_called()
+
+
+@ensureDeferred
+@pytest.mark.parametrize(
+    "body_size, warnsize, maxsize, expect_null",
+    [
+        (500, None, None, False),  # No limits, should return response
+        (
+            1500,
+            1000,
+            None,
+            False,
+        ),  # Exceeds warnsize, should log warning but return response
+        (2500, 1000, 2000, True),  # Exceeds maxsize, should return None
+        (500, 1000, 2000, False),  # Within limits, should return response
+        (
+            1500,
+            None,
+            1000,
+            True,
+        ),  # Exceeds maxsize with no warnsize, should return None
+    ],
+)
+async def test_download_request_limits(
+    body_size, warnsize, maxsize, expect_null, mockserver
+):
+    settings: SETTINGS_T = {"DOWNLOAD_WARNSIZE": warnsize, "DOWNLOAD_MAXSIZE": maxsize}
+    async with make_handler(settings, mockserver.urljoin("/")) as handler:
+        handler._session = mock.AsyncMock()
+        handler._session.get.return_value = mock.Mock(body=b"x" * body_size)
+
+        mock_api_response = mock.Mock(body=b"x" * body_size)
+
+        # Patch the `from_api_response` method of ZyteAPITextResponse only for the test
+        with mock.patch.object(
+            ZyteAPITextResponse, "from_api_response", return_value=mock_api_response
+        ):
+            with mock.patch(
+                "scrapy_zyte_api.responses._process_response",
+                return_value=mock_api_response,
+            ):
+                request = Request("https://example.com")
+                result = await handler._download_request({}, request, None)
+
+                if expect_null:
+                    assert result is None
+                else:
+                    assert result is not None