Use static variable storage for keys

Here is a patch that implements static variable storage for keys.

Interesting. I hadn't thought of that. So, a single key provider could return a different value within a page request—based on, for example, the node ID and/or a field name, or something else that's specific to that particular piece of data.

I did a rough Apache Benchmark comparison (1000 requests of 50 nodes with 20 encrypted fields) with the basic, default encryption method and the Drupal Private Key as the key provider and the difference with and without static variable storage was negligible. However, I'm writing a key provider plugin that retrieves a key from an external server, so it would be preferable to avoid making a lot of unnecessary external requests.

I can certainly use static variable storage within my specific key provider plugin, but I thought it could be useful generally in the Encryption module.

Presumably, the key provider plugin that is calling encrypt_get_key_from_key_provider would know if it could take advantage of static variable storage, so perhaps there could be a second argument to that function, $static, that is FALSE by default, so as not to break any existing implementations. If it's set to TRUE, the function would use the static variable, if it's available. I expect that the three key providers that are included with Encryption could use it.

Absolutely, I'll do that. Thanks, Greg.

I realize that the last paragraph in my previous post doesn't make sense. encrypt_get_key_from_key_provider isn't called by the plugin; it's the other way around. So either each key provider plugin can implement static variable storage on its own, or whether or not it should be used can be set in the plugin definition.

OK, the attached patch does the following:

• Adds a new parameter to the key provider plugin definition: 'static key', which defaults to TRUE
• Adds the new parameter (with the definition TRUE) to all three of the included key provider plugins
• Modifies the function that gets a key to store and retrieve a static variable for the key if the plugin allows it
• Adds information about the new plugin parameter to the help document for creating key provider plugins, with an explanation of when it's appropriate to set 'static key' to FALSE

Changing status.

Changing status.

Due to the addition of configurations, the previously submitted patch is no longer applicable. In order to determine if a key has already been retrieved, we need to use a unique hash of the provider name and settings to identify it. Here's a new patch that does that.

I made a slight modification, so here's a new patch.

This is committed.