README.md

Condition Store

This project sets up an SQLite database as a backing store for script conditions.

What this means in practice is that you can have a logger operate at an INFO level:

package com.example;

import echopraxia.simple.Logger;
import echopraxia.simple.LoggerFactory;

public class App {
  private static final Logger logger = LoggerFactory.getLogger();

  public static void main(String[] args) throws InterruptedException {
    while (true) {
      logger.info("logging only if sqlite condition reached");
      Thread.sleep(1000L);
    }
  }

}

and attach a condition using a filter

public class SqliteConditionFilter implements CoreLoggerFilter {
  private final JdbcConditionStore conditionStore;

  public SqliteConditionFilter() {
    try {
      // https://github.com/xerial/sqlite-jdbc#how-to-specify-database-files
      // Need to specify files as sqlite / postgresql etc
      final ResourceBundle bundle = ResourceBundle.getBundle("echopraxia.sqlite");
      final String jdbcUrl = "jdbc:sqlite:conditions.db";

      conditionStore =
        new JdbcConditionStore(
          true,
          jdbcUrl,
          bundle,
          (name, e) -> {
            e.printStackTrace();
          });

      conditionStore.runDDL(bundle);
    } catch (SQLException e) {
      throw new ScriptException(e);
    }
  }

  @Override
  public CoreLogger apply(CoreLogger coreLogger) {
    final Condition condition = conditionStore.create(coreLogger.getName());
    return coreLogger.withCondition(condition);
  }
}

Then if you go into the conditions.db database and change the script field from the default, it will be picked up and run by the logger automatically.

Because sqlite can be replicated across multiple instances, you can manage complex logging conditions for an entire service at once, without redeploying or bouncing your application.