Tanzu GemFire Distributed Types Java API Reference

DSnowflake (gemfire-distributed-types 1.0.0-build.2826.f2926f38 API)

All Superinterfaces:

DType
```
public interface DSnowflake
extends DType
```
DSnowflake is a cluster-unique ID generator based on the Twitter/X Snowflake design. Generated IDs are long primitive values and are k-ordered (roughly ordered). IDs are in the range from 0 to Long.MAX_VALUE.
The layout of IDs is as follows:
- timestamp (41 bits by default)
- machine ID (10 bits by default)
- sequence number (12 bits by default)
The layout can be adjusted by creating DSnowflakes with custom bit lengths for the machine ID and the sequence number.
The timestamp is stored relative to a specific epoch start which, by default, is 1 Jan, 2020 (DEFAULT_EPOCH_START).
The default bit sizes allow for generating 4096 (2^12) sequence IDs per millisecond. If that rate is exceeded, generation will block until the next millisecond.
The current implementation generates the default machine ID from the nanosecond timestamp on the system. Thus, DSnowflakes created on the same system, will have different machine IDs. If required, a custom machine ID can be provided.
A builder pattern is used to create custom DSnowflake instance:
```
 DSnowflake flake = DSnowflake.builder()
     .withEpochStart(1_000_000)
     .withMachineId(37)
     .withSequenceBits(15)
     .build();
 
```

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface DSnowflake.Builder
Builder used to create custom DSnowflakes.

Field Summary

Fields
Modifier and Type Field Description

static long DEFAULT_EPOCH_START
The default epoch start - 1 Jan, 2020

static int DEFAULT_MACHINE_BITS

static int DEFAULT_SEQUENCE_BITS

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`static DSnowflake.Builder`	`builder()`	Provides a Builder used to create customized DSnowflakes.
`default void`	`destroy()`	This is a no-op for DSnowflakes.
`long`	`nextId()`	Generate a new ID.
`long[]`	`parse(long sequence)`	Parse a sequence ID into its individual components based on the configured bit lengths.

Methods inherited from interface dev.gemfire.dtype.DType
getName

- Field Detail
  - DEFAULT_MACHINE_BITS
```
static final int DEFAULT_MACHINE_BITS
```
    See Also:
    
    Constant Field Values
  - DEFAULT_SEQUENCE_BITS
```
static final int DEFAULT_SEQUENCE_BITS
```
    See Also:
    
    Constant Field Values
  - DEFAULT_EPOCH_START
```
static final long DEFAULT_EPOCH_START
```
    The default epoch start - 1 Jan, 2020
    
    See Also:
    
    Constant Field Values
- Method Detail
  - nextId
```
long nextId()
```
    Generate a new ID.
    
    Returns:
    
    the next ID
  - parse
```
long[] parse(long sequence)
```
    Parse a sequence ID into its individual components based on the configured bit lengths. Note that the timestamp will be adjusted by the epoch start to reflect the 'correct' time.
    
    Parameters:
    
    sequence - the sequence ID to parse
    
    Returns:
    
    a long[3] array consisting of timestamp, machine ID and sequence number
  - destroy
```
default void destroy()
```
    This is a no-op for DSnowflakes. Since nothing is distributed or stored for this type, there are no additional resources to release.
    
    Specified by:
    
    destroy in interface DType
  - builder
```
static DSnowflake.Builder builder()
```
    Provides a Builder used to create customized DSnowflakes.
    
    Returns:
    
    a new Builder