public interface FlakeIdGenerator extends IdGenerator
longprimitive values and are k-ordered (roughly ordered). IDs are in the range from
The IDs contain timestamp component and a node ID component, which is assigned when the member
joins the cluster. This allows the IDs to be ordered and unique without any coordination between
members, which makes the generator safe even in split-brain scenario (for caveats,
Timestamp component is in milliseconds since 1.1.2018, 0:00 UTC and has 41 bits. This caps the useful lifespan of the generator to little less than 70 years (until ~2088). The sequence component is 6 bits. If more than 64 IDs are requested in single millisecond, IDs will gracefully overflow to the next millisecond and uniqueness is guaranteed in this case. The implementation does not allow overflowing by more than 15 seconds, if IDs are requested at higher rate, the call will block. Note, however, that clients are able to generate even faster because each call goes to a different (random) member and the 64 IDs/ms limit is for single member.
|Modifier and Type||Method and Description|
Generates and returns a cluster-wide unique ID.
Operation on member is always local, if the member has valid node ID, otherwise it's remote. On
client, this method goes to a random member and gets a batch of IDs, which will then be returned
locally for limited time. The pre-fetch size and the validity time can be configured for
each client and member, see
here for member config and see
ClientConfig.addFlakeIdGeneratorConfig() for client config.
Note: Values returned from this method may be not strictly ordered.
HazelcastException- if node ID for all members in the cluster is out of valid range. See "Node ID overflow" in
class documentationfor more details.
UnsupportedOperationException- if the cluster version is below 3.10
@Deprecated boolean init(long id)
IdGeneratorinstance with the given ID.
The next generated ID will be 1 greater than the supplied ID.
Note for Flake ID Generator: This method does nothing and will simply tell if the next ID will be larger than the given ID. You don't need to call this method on cluster restart - uniqueness is preserved thanks to the timestamp component of the ID.
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