Add support for Cache-Control: stale-if-error

2 files changed, 9 insertions, 0 deletions

diff --git a/docs/user_guide/expiration.md b/docs/user_guide/expiration.md
index 767b220..d0465f1 100644
--- a/docs/user_guide/expiration.md
+++ b/docs/user_guide/expiration.md
@@ -108,6 +108,13 @@ you get a 500. You will then get the expired cache data instead:
 True, True
 ```
 
+Similar to the header `Cache-Control: stale-if-error`, you may also pass time value representing the
+maximum staleness you are willing to accept:
+```python
+# If there is an error on refresh, use a cached response if it expired 5 minutes ago or less
+session = CachedSession(stale_if_error=timedelta(minutes=5))
+```
+
 In addition to HTTP error codes, `stale_if_error` also applies to python exceptions (typically a
 {py:exc}`~requests.RequestException`). See `requests` documentation on
 [Errors and Exceptions](https://2.python-requests.org/en/master/user/quickstart/#errors-and-exceptions)
diff --git a/docs/user_guide/headers.md b/docs/user_guide/headers.md
index 9681d64..5d7c696 100644
--- a/docs/user_guide/headers.md
+++ b/docs/user_guide/headers.md
@@ -54,6 +54,8 @@ The following headers are currently supported:
 - `Cache-Control: no-store`: Skip reading from and writing to the cache
 - `Cache-Control: only-if-cached`: Only return results from the cache. If not cached, return a 504
   response instead of sending a new request. Note that this may return a stale response.
+- `Cache-Control: stale-if-error`: If an error occurs while refreshing a cached response, use it
+  if it expired by no more than this many seconds ago
 - `If-None-Match`: Automatically added for revalidation, if an `ETag` is available
 - `If-Modified-Since`: Automatically added for revalidation, if `Last-Modified` is available