Package velox.api.layer1.dynamichistory.metadata

Class MetadataType<T>

java.lang.Object

velox.api.layer1.dynamichistory.metadata.MetadataType<T>

Type Parameters:

T - type of the value returned by getMetadata when this token is used

Direct Known Subclasses:

MetadataType.FirstEventTimeType, MetadataType.LinearMetadataType

public abstract sealed class MetadataType<T>
extends Object
permits MetadataType.FirstEventTimeType, MetadataType.LinearMetadataType

Selects which piece of metadata to request from getMetadata.

Pass one of the tokens returned by the static methods of this class to getMetadata; the type of value you get back is determined by the token you pass. For example:

 FirstEventTime first = accessInterface.getMetadata(dataSource, instrumentInfo, MetadataType.firstEventTimeType())
     .toCompletableFuture()
     .orTimeout(5, TimeUnit.SECONDS)
     .join();
 

Available metadata:

• firstEventTimeType() — returns FirstEventTime, the timestamp of the earliest event available for the instrument. Or nothing if metadata is not available
• linearMetadataType() — returns Optional<LinearDataMetadata>, the catalog of linear data structures recorded for the instrument, or Optional.empty() if the server records none

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	MetadataType.FirstEventTimeType	Metadata token for FirstEventTime; obtain it from firstEventTimeType().
static final class	MetadataType.LinearMetadataType	Metadata token for LinearDataMetadata, obtain it from linearMetadataType()

Field Summary

Fields

Modifier and Type	Field	Description
final Class<T>	type	Type of the value returned by getMetadata for this token.

Method Summary

Modifier and Type	Method	Description
static MetadataType.FirstEventTimeType	firstEventTimeType()	Requests the time of the earliest available event for the instrument.
static MetadataType.LinearMetadataType	linearMetadataType()	Discovers which linear data structures (per-interval block series, e.g.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

type

public final Class<T> type

Type of the value returned by getMetadata for this token.

Method Details

toString

public String toString()

Overrides:

toString in class Object

firstEventTimeType

public static MetadataType.FirstEventTimeType firstEventTimeType()

Requests the time of the earliest available event for the instrument. Can return response or nothing if there is no metadata for the given instrument, in case there is no history for it, or the server was unavailable at the moment when the request was made. When passed to getMetadata, the returned stage:

• yields FirstEventTime.Found with the earliest event time, or FirstEventTime.HistoryNotAvailable if the instrument has no history;
• completes exceptionally (cause is RequestTimeoutException) if the request times out.
• completes exceptionally (cause is ServerNotAvailableException) if the server is unavailable.

NOTE: All listed exception are wrapped into CompletionException

Returns:

a token that makes getMetadata return a FirstEventTime

linearMetadataType

public static MetadataType.LinearMetadataType linearMetadataType()

Discovers which linear data structures (per-interval block series, e.g. zoom-out candles) the server has recorded for the given instrument, and — per interval — how many blocks are finalized and when the series starts. Use it to decide which structure and interval to request and which time range is worth requesting; the server translates time to block indices, so a consumer never computes indices itself.

When passed to getMetadata, the returned stage never blocks the calling thread and is guaranteed to complete: the fetch is bounded by the client's request timeouts plus a hard cap. It yields Optional.empty() when the server records no linear data for the instrument (re-checked periodically, since recording can start mid-session); a transient failure (server unreachable, timeout) completes the stage exceptionally and is not cached — the next call retries. The catalog is cached briefly, so block counts may lag the server by about a minute.

Returns:

a token that makes getMetadata return the per-alias catalog as an Optional<LinearDataMetadata>