feat(spiders): add a development mode

scrapling/spiders/cache.py

@@ -0,0 +1,79 @@
+from base64 import b64encode, b64decode
+from pathlib import Path
+
+import orjson
+import anyio
+from anyio import Path as AsyncPath
+
+from scrapling.core.utils import log
+from scrapling.core._types import Dict, Optional, Any
+from scrapling.engines.toolbelt.custom import Response
+
+
+class ResponseCacheManager:
+    """Caches HTTP responses to disk for replay during spider development."""
+
+    def __init__(self, cache_dir: str | Path):
+        self._cache_dir = AsyncPath(cache_dir)
+
+    def _cache_path(self, fingerprint: bytes) -> AsyncPath:
+        return self._cache_dir / f"{fingerprint.hex()}.json"
+
+    async def get(self, fingerprint: bytes) -> Optional[Response]:
+        path = self._cache_path(fingerprint)
+        if not await path.exists():
+            return None
+
+        try:
+            async with await anyio.open_file(path, "rb") as f:
+                data: Dict[str, Any] = orjson.loads(await f.read())
+
+            return Response(
+                url=data["url"],
+                content=b64decode(data["content"]),
+                status=data["status"],
+                reason=data["reason"],
+                encoding=data["encoding"],
+                cookies=data["cookies"],
+                headers=data["headers"],
+                request_headers=data["request_headers"],
+                method=data["method"],
+            )
+        except Exception as e:
+            log.warning(f"Failed to read cached response for {fingerprint.hex()}: {e}")
+            return None
+
+    async def put(self, fingerprint: bytes, response: Response, method: str = "GET") -> None:
+        await self._cache_dir.mkdir(parents=True, exist_ok=True)
+        temp_path = self._cache_path(fingerprint).with_suffix(".tmp")
+
+        try:
+            serialized = orjson.dumps(
+                {
+                    "url": response.url,
+                    "content": b64encode(response.body).decode("ascii"),
+                    "status": response.status,
+                    "reason": response.reason,
+                    "encoding": response.encoding,
+                    "cookies": dict(response.cookies) if isinstance(response.cookies, dict) else {},
+                    "headers": dict(response.headers),
+                    "request_headers": dict(response.request_headers),
+                    "method": method,
+                }
+            )
+            async with await anyio.open_file(temp_path, "wb") as f:
+                await f.write(serialized)
+
+            await temp_path.rename(self._cache_path(fingerprint))
+        except Exception as e:
+            if await temp_path.exists():
+                await temp_path.unlink()
+            log.warning(f"Failed to cache response for {fingerprint.hex()}: {e}")
+
+    async def clear(self) -> None:
+        if not await self._cache_dir.exists():
+            return
+        async for entry in self._cache_dir.iterdir():
+            if entry.suffix == ".json":
+                await entry.unlink()
+        log.info(f"Cleared response cache at {self._cache_dir}")

scrapling/spiders/engine.py

@@ -13,6 +13,7 @@ from scrapling.spiders.session import SessionManager
 from scrapling.spiders.request import Request, Response
 from scrapling.spiders.robotstxt import RobotsTxtManager
 from scrapling.spiders.result import CrawlStats, ItemList
+from scrapling.spiders.cache import ResponseCacheManager
 from scrapling.spiders.checkpoint import CheckpointManager, CheckpointData
 from scrapling.core._types import Dict, Union, Optional, TYPE_CHECKING, Any, AsyncGenerator
 
@@ -52,6 +53,13 @@ class CrawlerEngine:
         else:
             self._robots_manager = None
 
+        if self.spider.development_mode:
+            cache_dir = self.spider.development_cache_dir or f".scrapling_cache/{self.spider.name}"
+            self._cache_manager: Optional[ResponseCacheManager] = ResponseCacheManager(cache_dir)
+            log.warning("Development mode enabled -- responses will be cached to disk and replayed on subsequent runs")
+        else:
+            self._cache_manager = None
+
         self._global_limiter = CapacityLimiter(spider.concurrent_requests)
         self._domain_limiters: dict[str, CapacityLimiter] = {}
         self._allowed_domains: set[str] = spider.allowed_domains or set()
@@ -130,57 +138,8 @@ class CrawlerEngine:
         if not request.sid:
             request.sid = self.session_manager.default_session_id
 
-    async def _process_request(self, request: Request) -> None:
-        """Download and process a single request."""
-        if self._robots_manager:
-            can_fetch = await self._robots_manager.can_fetch(request.url, request.sid)
-            if not can_fetch:
-                self.stats.robots_disallowed_count += 1
-                log.info(f"Request disallowed by robots.txt: {request.url}")
-                return
-            delay = await self._get_domain_delay(request)
-        else:
-            delay = self.spider.download_delay
-
-        async with self._rate_limiter(request.domain):
-            if delay:
-                await anyio.sleep(delay)
-
-            if request._session_kwargs.get("proxy"):
-                self.stats.proxies.append(request._session_kwargs["proxy"])
-            if request._session_kwargs.get("proxies"):
-                self.stats.proxies.append(dict(request._session_kwargs["proxies"]))
-            try:
-                response = await self.session_manager.fetch(request)
-                self.stats.increment_requests_count(request.sid or self.session_manager.default_session_id)
-                self.stats.increment_response_bytes(request.domain, len(response.body))
-                self.stats.increment_status(response.status)
-
-            except Exception as e:
-                self.stats.failed_requests_count += 1
-                await self.spider.on_error(request, e)
-                return
-
-        if await self.spider.is_blocked(response):
-            self.stats.blocked_requests_count += 1
-            if request._retry_count < self.spider.max_blocked_retries:
-                retry_request = request.copy()
-                retry_request._retry_count += 1
-                retry_request.priority -= 1  # Don't retry immediately
-                retry_request.dont_filter = True
-                retry_request._session_kwargs.pop("proxy", None)
-                retry_request._session_kwargs.pop("proxies", None)
-
-                new_request = await self.spider.retry_blocked_request(retry_request, response)
-                self._normalize_request(new_request)
-                await self.scheduler.enqueue(new_request)
-                log.info(
-                    f"Scheduled blocked request for retry ({retry_request._retry_count}/{self.spider.max_blocked_retries}): {request.url}"
-                )
-            else:
-                log.warning(f"Max retries exceeded for blocked request: {request.url}")
-            return
-
+    async def _run_callbacks(self, request: Request, response: Response) -> None:
+        """Dispatch response to the request's callback and process yielded items/requests."""
         callback = request.callback if request.callback else self.spider.parse
         try:
             async for result in callback(response):
@@ -210,6 +169,75 @@ class CrawlerEngine:
             log.error(msg, exc_info=e)
             await self.spider.on_error(request, e)
 
+    async def _process_request(self, request: Request) -> None:
+        """Download and process a single request."""
+        if self._robots_manager:
+            can_fetch = await self._robots_manager.can_fetch(request.url, request.sid)
+            if not can_fetch:
+                self.stats.robots_disallowed_count += 1
+                log.info(f"Request disallowed by robots.txt: {request.url}")
+                return
+            delay = await self._get_domain_delay(request)
+        else:
+            delay = self.spider.download_delay
+
+        if self._cache_manager and request._fp is not None:
+            cached = await self._cache_manager.get(request._fp)
+            if cached is not None:
+                cached.request = request
+                self.stats.cache_hits += 1
+                self.stats.increment_requests_count(request.sid or self.session_manager.default_session_id)
+                self.stats.increment_response_bytes(request.domain, len(cached.body))
+                self.stats.increment_status(cached.status)
+                log.debug(f"Cache hit: {request.url}")
+                await self._run_callbacks(request, cached)
+                return
+
+        async with self._rate_limiter(request.domain):
+            if delay:
+                await anyio.sleep(delay)
+
+            if request._session_kwargs.get("proxy"):
+                self.stats.proxies.append(request._session_kwargs["proxy"])
+            if request._session_kwargs.get("proxies"):
+                self.stats.proxies.append(dict(request._session_kwargs["proxies"]))
+            try:
+                response = await self.session_manager.fetch(request)
+                self.stats.increment_requests_count(request.sid or self.session_manager.default_session_id)
+                self.stats.increment_response_bytes(request.domain, len(response.body))
+                self.stats.increment_status(response.status)
+
+            except Exception as e:
+                self.stats.failed_requests_count += 1
+                await self.spider.on_error(request, e)
+                return
+
+        if self._cache_manager and request._fp is not None:
+            self.stats.cache_misses += 1
+            await self._cache_manager.put(request._fp, response, request._session_kwargs.get("method", "GET"))
+
+        if await self.spider.is_blocked(response):
+            self.stats.blocked_requests_count += 1
+            if request._retry_count < self.spider.max_blocked_retries:
+                retry_request = request.copy()
+                retry_request._retry_count += 1
+                retry_request.priority -= 1  # Don't retry immediately
+                retry_request.dont_filter = True
+                retry_request._session_kwargs.pop("proxy", None)
+                retry_request._session_kwargs.pop("proxies", None)
+
+                new_request = await self.spider.retry_blocked_request(retry_request, response)
+                self._normalize_request(new_request)
+                await self.scheduler.enqueue(new_request)
+                log.info(
+                    f"Scheduled blocked request for retry ({retry_request._retry_count}/{self.spider.max_blocked_retries}): {request.url}"
+                )
+            else:
+                log.warning(f"Max retries exceeded for blocked request: {request.url}")
+            return
+
+        await self._run_callbacks(request, response)
+
     async def _task_wrapper(self, request: Request) -> None:
         """Wrapper to track active task count."""
         try:
@@ -330,11 +358,7 @@ class CrawlerEngine:
                     while self._running:
                         if self._pause_requested:
                             if self._active_tasks == 0 or self._force_stop:
-                                # Save checkpoint BEFORE cancelling the scope.
-                                # cancel_scope.cancel() makes all subsequent awaits
-                                # raise Cancelled, which would abort the checkpoint
-                                # write and leave self.paused=False — causing the
-                                # finally block to DELETE the previous checkpoint.
+                                # Save checkpoint before canceling to avoid data loss
                                 if self._checkpoint_system_enabled:
                                     await self._save_checkpoint()
                                     self.paused = True

scrapling/spiders/result.py

@@ -48,6 +48,8 @@ class CrawlStats:
     failed_requests_count: int = 0
     offsite_requests_count: int = 0
     robots_disallowed_count: int = 0
+    cache_hits: int = 0
+    cache_misses: int = 0
     response_bytes: int = 0
     items_scraped: int = 0
     items_dropped: int = 0
@@ -97,6 +99,8 @@ class CrawlStats:
             "failed_requests_count": self.failed_requests_count,
             "offsite_requests_count": self.offsite_requests_count,
             "robots_disallowed_count": self.robots_disallowed_count,
+            "cache_hits": self.cache_hits,
+            "cache_misses": self.cache_misses,
             "blocked_requests_count": self.blocked_requests_count,
             "response_status_count": self.response_status_count,
             "response_bytes": self.response_bytes,

scrapling/spiders/spider.py

@@ -75,6 +75,10 @@ class Spider(ABC):
     # Robots.txt compliance
     robots_txt_obey: bool = False
 
+    # Development mode
+    development_mode: bool = False
+    development_cache_dir: Optional[str] = None
+
     # Concurrency settings
     concurrent_requests: int = 4
     concurrent_requests_per_domain: int = 0

tests/spiders/test_cache.py

@@ -0,0 +1,228 @@
+"""Tests for the ResponseCacheManager and development_mode integration."""
+
+import tempfile
+from pathlib import Path
+
+import anyio
+import pytest
+
+from scrapling.spiders.cache import ResponseCacheManager
+from scrapling.spiders.engine import CrawlerEngine
+from scrapling.spiders.request import Request
+from scrapling.spiders.session import SessionManager
+from scrapling.engines.toolbelt.custom import Response
+from scrapling.core._types import Any, Dict, Set, AsyncGenerator
+
+
+def _make_response(url: str = "https://example.com", body: bytes = b"<html>hello</html>", status: int = 200) -> Response:
+    return Response(
+        url=url,
+        content=body,
+        status=status,
+        reason="OK",
+        encoding="utf-8",
+        cookies={},
+        headers={"content-type": "text/html"},
+        request_headers={"user-agent": "test"},
+        method="GET",
+    )
+
+
+class TestResponseCacheManager:
+
+    @pytest.mark.anyio
+    async def test_put_get_roundtrip(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            cache = ResponseCacheManager(tmpdir)
+            fp = b"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14"
+            original = _make_response(body=b"<html>test content</html>")
+
+            await cache.put(fp, original, "GET")
+            restored = await cache.get(fp)
+
+            assert restored is not None
+            assert restored.url == original.url
+            assert restored.body == original.body
+            assert restored.status == original.status
+            assert restored.reason == original.reason
+            assert restored.encoding == original.encoding
+            assert dict(restored.headers) == dict(original.headers)
+            assert dict(restored.request_headers) == dict(original.request_headers)
+
+    @pytest.mark.anyio
+    async def test_get_cache_miss(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            cache = ResponseCacheManager(tmpdir)
+            result = await cache.get(b"\x00" * 20)
+            assert result is None
+
+    @pytest.mark.anyio
+    async def test_get_corrupt_file(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            cache = ResponseCacheManager(tmpdir)
+            fp = b"\xaa" * 20
+            corrupt_path = Path(tmpdir) / f"{fp.hex()}.json"
+            corrupt_path.write_text("not valid json{{{")
+
+            result = await cache.get(fp)
+            assert result is None
+
+    @pytest.mark.anyio
+    async def test_clear(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            cache = ResponseCacheManager(tmpdir)
+            fp1 = b"\x01" * 20
+            fp2 = b"\x02" * 20
+
+            await cache.put(fp1, _make_response(url="https://a.com"), "GET")
+            await cache.put(fp2, _make_response(url="https://b.com"), "GET")
+
+            assert await cache.get(fp1) is not None
+            assert await cache.get(fp2) is not None
+
+            await cache.clear()
+
+            assert await cache.get(fp1) is None
+            assert await cache.get(fp2) is None
+
+    @pytest.mark.anyio
+    async def test_creates_cache_dir(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            nested = Path(tmpdir) / "sub" / "dir"
+            cache = ResponseCacheManager(str(nested))
+            await cache.put(b"\x03" * 20, _make_response(), "GET")
+            assert nested.exists()
+
+    @pytest.mark.anyio
+    async def test_preserves_binary_body(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            cache = ResponseCacheManager(tmpdir)
+            fp = b"\x04" * 20
+            binary_body = bytes(range(256))
+            await cache.put(fp, _make_response(body=binary_body), "GET")
+            restored = await cache.get(fp)
+            assert restored is not None
+            assert restored.body == binary_body
+
+
+# ---------------------------------------------------------------------------
+# Integration tests
+# ---------------------------------------------------------------------------
+
+
+class MockSession:
+    def __init__(self):
+        self._is_alive = False
+        self.fetch_count = 0
+
+    async def __aenter__(self):
+        self._is_alive = True
+        return self
+
+    async def __aexit__(self, *args):
+        self._is_alive = False
+
+    async def fetch(self, url: str, **kwargs):
+        self.fetch_count += 1
+        return _make_response(url=url, body=b"<html>fetched</html>")
+
+
+class _LogCounterStub:
+    def get_counts(self) -> Dict[str, int]:
+        return {"debug": 0, "info": 0, "warning": 0, "error": 0, "critical": 0}
+
+
+class MockSpider:
+    def __init__(self, cache_dir: str):
+        self.concurrent_requests = 4
+        self.concurrent_requests_per_domain = 0
+        self.download_delay = 0.0
+        self.max_blocked_retries = 3
+        self.allowed_domains: Set[str] = set()
+        self.fp_include_kwargs = False
+        self.fp_include_headers = False
+        self.fp_keep_fragments = False
+        self.robots_txt_obey = False
+        self.development_mode = True
+        self.development_cache_dir = cache_dir
+        self.start_urls: list[str] = []
+        self.name = "test_cache_spider"
+        self._log_counter = _LogCounterStub()
+        self.scraped_items: list[dict] = []
+
+    async def parse(self, response) -> AsyncGenerator[Dict[str, Any] | Request | None, None]:
+        yield {"url": str(response)}
+
+    async def on_start(self, resuming: bool = False) -> None:
+        pass
+
+    async def on_close(self) -> None:
+        pass
+
+    async def on_error(self, request: Request, error: Exception) -> None:
+        pass
+
+    async def on_scraped_item(self, item: Dict[str, Any]) -> Dict[str, Any] | None:
+        self.scraped_items.append(item)
+        return item
+
+    async def is_blocked(self, response) -> bool:
+        return False
+
+    async def retry_blocked_request(self, request: Request, response) -> Request:
+        return request
+
+    async def start_requests(self) -> AsyncGenerator[Request, None]:
+        yield Request("https://example.com/page1", sid="default")
+
+
+class TestDevelopmentModeIntegration:
+
+    @pytest.mark.anyio
+    async def test_first_run_fetches_and_caches(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            session = MockSession()
+            spider = MockSpider(cache_dir=tmpdir)
+            sm = SessionManager()
+            sm.add("default", session)
+            engine = CrawlerEngine(spider, sm)
+
+            await engine.crawl()
+
+            assert session.fetch_count == 1
+            assert engine.stats.cache_misses == 1
+            assert engine.stats.cache_hits == 0
+            assert engine.stats.items_scraped == 1
+
+    @pytest.mark.anyio
+    async def test_second_run_uses_cache(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            session = MockSession()
+            spider = MockSpider(cache_dir=tmpdir)
+            sm = SessionManager()
+            sm.add("default", session)
+            engine = CrawlerEngine(spider, sm)
+
+            await engine.crawl()
+            assert session.fetch_count == 1
+
+            session2 = MockSession()
+            spider2 = MockSpider(cache_dir=tmpdir)
+            sm2 = SessionManager()
+            sm2.add("default", session2)
+            engine2 = CrawlerEngine(spider2, sm2)
+
+            await engine2.crawl()
+            assert session2.fetch_count == 0
+            assert engine2.stats.cache_hits == 1
+            assert engine2.stats.cache_misses == 0
+            assert engine2.stats.items_scraped == 1
+
+    @pytest.mark.anyio
+    async def test_disabled_by_default(self):
+        spider = MockSpider(cache_dir="unused")
+        spider.development_mode = False
+        sm = SessionManager()
+        sm.add("default", MockSession())
+        engine = CrawlerEngine(spider, sm)
+        assert engine._cache_manager is None

tests/spiders/test_engine.py

@@ -98,6 +98,8 @@ class MockSpider:
         self.fp_keep_fragments = fp_keep_fragments
         self.name = "test_spider"
         self.robots_txt_obey = robots_txt_obey
+        self.development_mode = False
+        self.development_cache_dir = None
         self.start_urls = start_urls or []
 
         # Tracking lists

tests/spiders/test_force_stop_checkpoint.py

@@ -76,6 +76,8 @@ class SlowSpider:
         self.fp_include_headers = False
         self.fp_keep_fragments = False
         self.robots_txt_obey = False
+        self.development_mode = False
+        self.development_cache_dir = None
         self.start_urls = []
         self.name = "slow_spider"
         self._log_counter = _LogCounterStub()