isInitialized & dataStore.isInitialized()

[t3hnar]

Hey guys,
I'm going through code in order to assess java client before adding is as dependency

I can see repeated pattern of two checks like:

if (!isInitialized()) { <-- first check
      if (dataStore.isInitialized()) { <-- second check
        evaluationLogger.warn("allFlagsState() was called before client initialized; using last known values from data store");
      } else {
        evaluationLogger.warn("allFlagsState() was called before client initialized; data store unavailable, returning no data");
        return builder.valid(false).build();
      }
    }

https://github.com/launchdarkly/java-server-sdk/blob/main/src/main/java/com/launchdarkly/sdk/server/LDClient.java#L341

however

public boolean isInitialized() {
    return dataSource.isInitialized();
  }

This should be either bug or I must be missing something. Could you please help?

[eli-darkly]

You didn't say why it looks like a bug to you, so I don't know whether you're missing something, but here's a summary of what the intention is:

• There are two components with different purposes, the "data store" (which is either a simple in-memory store or a database) and the "data source" (which manages the connection to LaunchDarkly for getting flags).
• LDClient.isInitialized() is intended to return true if the SDK has received flag data from LaunchDarkly at least once so far. That is the job of the data source component, so that's why it is delegating to dataSource.isInitialized().
• Even if the SDK has not received flag data from LaunchDarkly, there could still be old flag data present in the data store— specifically, if the data store is a database. If so, we can use that data to evaluate flags, even though we would prefer to have more up-to-date flag data. That's what is going on in the first block you quoted.

[eli-darkly]

So, the specific scenarios that that first block is there to handle are:

1. The SDK has not (yet) completed a successful initialization because it has not been able to connect to LaunchDarkly. But, when it calls dataStore.isInitialized(), it returns true, indicating that we are using a database and we detected some flag data already in the database (either from a previous run of the application, or put there by another process such as the Relay Proxy). So, we use that data, and we print a warning ("using last known values from data store").
2. Or, the SDK has not yet completed a successful initialization, and there is not already data in the data store. So we have no data, there is no way to evaluate flags, and we print a different warning ("data store unavailable").

[t3hnar]

ok makes sense, I was confused by similar naming [dataS]tore with [dataS]ource, and thought that those both are the same thing.

I'm closing the issue now.