scrapy/scrapy — pull request #74 by darkrho (2011-12-30 18:13:30+00:00)
Title: httpcache: keep stats of cache hit/miss/store.

Example final stats with httpcache/* counters:

```javascript
{'downloader/request_bytes': 2595,
'downloader/request_count': 7,
'downloader/request_method_count/GET': 7,
'downloader/response_bytes': 1203485,
'downloader/response_count': 7,
'downloader/response_status_count/200': 5,
'downloader/response_status_count/301': 2,
'finish_reason': 'shutdown',
'finish_time': datetime.datetime(2011, 12, 30, 18, 3, 43, 953507),
'httpcache/hit': 6,
'httpcache/miss': 1,
'httpcache/store': 7,
'request_depth_max': 3,
'scheduler/memory_enqueued': 656,
'start_time': datetime.datetime(2011, 12, 30, 18, 3, 15, 145445)}
```