Commit 4f15fbbb authored by Sean McGivern's avatar Sean McGivern

Merge branch 'docs-request-cache' into 'master'

Add docs for RequestCache

Closes #48094

See merge request gitlab-org/gitlab-ce!20064
parents 348ad22d d5c7fe29
......@@ -135,3 +135,44 @@ We developed a number of utilities to ease development.
Find.new.clear_memoization(:result)
```
## [`RequestCache`](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/gitlab/cache/request_cache.rb)
This module provides a simple way to cache values in RequestStore,
and the cache key would be based on the class name, method name,
optionally customized instance level values, optionally customized
method level values, and optional method arguments.
A simple example that only uses the instance level customised values:
``` ruby
class UserAccess
extend Gitlab::Cache::RequestCache
request_cache_key do
[user&.id, project&.id]
end
request_cache def can_push_to_branch?(ref)
# ...
end
end
```
This way, the result of `can_push_to_branch?` would be cached in
`RequestStore.store` based on the cache key. If `RequestStore` is not
currently active, then it would be stored in a hash saved in an
instance variable, so the cache logic would be the same.
We can also set different strategies for different methods:
``` ruby
class Commit
extend Gitlab::Cache::RequestCache
def author
User.find_by_any_email(author_email.downcase)
end
request_cache(:author) { author_email.downcase }
end
```
module Gitlab
module Cache
# This module provides a simple way to cache values in RequestStore,
# and the cache key would be based on the class name, method name,
# optionally customized instance level values, optionally customized
# method level values, and optional method arguments.
#
# A simple example:
#
# class UserAccess
# extend Gitlab::Cache::RequestCache
#
# request_cache_key do
# [user&.id, project&.id]
# end
#
# request_cache def can_push_to_branch?(ref)
# # ...
# end
# end
#
# This way, the result of `can_push_to_branch?` would be cached in
# `RequestStore.store` based on the cache key. If RequestStore is not
# currently active, then it would be stored in a hash saved in an
# instance variable, so the cache logic would be the same.
# Here's another example using customized method level values:
#
# class Commit
# extend Gitlab::Cache::RequestCache
#
# def author
# User.find_by_any_email(author_email.downcase)
# end
# request_cache(:author) { author_email.downcase }
# end
#
# So that we could have different strategies for different methods
#
# See https://docs.gitlab.com/ee/development/utilities.html#requestcache
module RequestCache
def self.extended(klass)
return if klass < self
......
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