software.amazon.event.ruler.Machine Maven / Gradle / Ivy

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package software.amazon.event.ruler;

/**
 *  Represents a state machine used to match name/value patterns to rules.
 *  The machine is thread safe. The concurrency strategy is:
 *  Multi-thread access assumed, single-thread update enforced by synchronized on
 *  addRule/deleteRule.
 *  ConcurrentHashMap and ConcurrentSkipListSet are used so that writer and readers can be in tables
 *  simultaneously. So all changes the writer made could be synced to and viable by all readers (in other threads).
 *  Though it may  generate a half-built rule to rulesForEvent() e.g. when a long rule is adding and
 *  in the middle of adding, some event is coming to query machine, it won't generate side impact with rulesForEvent
 *  because each step of routing will check next State and transition map before moving forward.
 */
public class Machine extends GenericMachine {

    @Deprecated
    public Machine() {
        super();
    }

    private Machine(GenericMachineConfiguration configuration) {
        super(configuration);
    }

    public static Builder builder() {
        return new Builder();
    }

    public static class Builder extends GenericMachine.Builder {

        Builder() {}

        @Override
        public Machine build() {
            return new Machine(buildConfig());
        }
    }
}