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In Rails 4 if I'm doing work related to caching then first I need
to turn caching "on" by opening file config/environments/development.rb
and changing following line.
1
2config.action_controller.perform_caching = false
3
After changing the value from false
to true
, I need to restart the
server.
This means that if I am testing caching behavior locally then every time I turn caching "on" or "off" I need to restart the server.
Rails 5 has introduced a new command to create development cache and help us test how caching behaves in development mode. Here is the issue and here is the pull request.
1$ rails dev:cache
2Development mode is now being cached.
Execution of the above command creates file caching-dev.txt
in tmp
directory.
In Rails 5 when a brand new Rails app is created then
config/environments/development.rb
file will have the following
snippet of code.
1
2if Rails.root.join('tmp/caching-dev.txt').exist?
3 config.action_controller.perform_caching = true
4 config.static_cache_control = "public, max-age=172800"
5 config.cache_store = :mem_cache_store
6else
7 config.action_controller.perform_caching = false
8 config.cache_store = :null_store
9end
10
In the above code we are checking if the file tmp/caching-dev.txt
is present and then use :mem_cache_store
to enable caching only if the file is found.
Also, here is a snippet from the dev cache source code.
1
2def dev_cache
3 if File.exist? 'tmp/caching-dev.txt'
4 File.delete 'tmp/caching-dev.txt'
5 puts 'Development mode is no longer being cached.'
6 else
7 FileUtils.touch 'tmp/caching-dev.txt'
8 puts 'Development mode is now being cached.'
9 end
10
11 FileUtils.touch 'tmp/restart.txt'
12end
13
The advantage is that we do not need to restart the
server manually if we want to turn caching "on" or "off".
It is internally taken care by the dev_cache
method
that is executed when rails dev:cache
is executed.
You can see in the source code that tmp/restart.txt
is being touched.
Please note that this feature is not supported by unicorn, thin and
webrick. My guess is that DHH wants this feature because his team uses
pow and pow restarts when tmp/restart.txt
is touched.
He also created an issue for
spring to watch tmp/restart.txt
long time
back.
Execute the same command that was used to enable caching. If caching was previously enabled then it will be turned "off" now.
1
2$ rails dev:cache
3Development mode is no longer being cached.
4