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Diffstat (limited to 'doc/development/polling.md')
-rw-r--r-- | doc/development/polling.md | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/doc/development/polling.md b/doc/development/polling.md index a7f2962acf0..4042b8aaa61 100644 --- a/doc/development/polling.md +++ b/doc/development/polling.md @@ -22,6 +22,9 @@ Instead you should use polling mechanism with ETag caching in Redis. ## How it works +![Cache miss](img/cache-miss.svg) +![Cache hit](img/cache-hit.svg) + 1. Whenever a resource changes we generate a random value and store it in Redis. 1. When a client makes a request we set the `ETag` response header to the value @@ -36,6 +39,12 @@ Instead you should use polling mechanism with ETag caching in Redis. 1. If the `If-None-Match` header does not match the current value in Redis we have to generate a new response, because the resource changed. +Do not use query parameters (for example `?scope=all`) for endpoints where you +want to enable ETag caching. The middleware takes into account only the request +path and ignores query parameters. All parameters should be included in the +request path. By doing this we avoid query parameter ordering problems and make +route matching easier. + For more information see: - [RFC 7232](https://tools.ietf.org/html/rfc7232) - [ETag proposal](https://gitlab.com/gitlab-org/gitlab-ce/issues/26926) |