[CASSANDRA-6881] Replace static singletons potentially using dependency injection

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Duplicate
• Assignee: Edward Capriolo
• Reporter: Edward Capriolo

Authors

Edward Capriolo

• Created: 18/Mar/14 14:38
• Updated: 16/Apr/19 09:31
• Resolved: 23/Feb/15 23:55

Description

I have noticed several places in the cassandra codebase where unit,functional, and end-to-end testing is made more difficult due to the pattern of using singleton objects with static initialization.

An example is StorageProxy

static final boolean OPTIMIZE_LOCAL_REQUESTS = true; // set to false to test messagingservice path on single node

There is no coverage for this. It turns out to be very difficult to test for a variety of reasons. Mostly that everything it interacts with is hidden behind other static singletons.

The goal here would be to remove static stuff, have have a context, (spring, guice, or do out own). For the majority of things stop accessing them through static singleton, instead pass the objects (DatabaseDescriptor, Storageproxy) around or get them from the context. I think this will make a clearer API and allow us to provide better coverage on features that cross cut the components. It will also provide us better isolation for things like triggers/ udfs/ as they wont be able to acquire references to things they should not be able to.

Issue Links

• duplicates: CASSANDRA-7837 Factor out static initialization / singletons
• is related to: CASSANDRA-6846 Provide standard interface for deep application server integration

Sub-Tasks

• ReadExecutors should not rely on static StorageProxy: Resolved