com.google.cloud.bigquery.connector.common

Class StreamCombiningIterator

java.lang.Object

com.google.cloud.bigquery.connector.common.StreamCombiningIterator

All Implemented Interfaces:

Iterator<com.google.cloud.bigquery.storage.v1.ReadRowsResponse>

public class StreamCombiningIterator
extends Object
implements Iterator<com.google.cloud.bigquery.storage.v1.ReadRowsResponse>

An iterator that combines one or more ReadRows requests into a single iterator. Ordering of messages is not guaranteed from the streams.

This is adapted from ServerStream in gax. In comparison toServerStream, this implementation also buffers more a configured number of responses instead of a single one. For connections with high latency between client and server this can processing costs. It also allows combining one or more ReadRows calls into single iterator to potentially increase perceived client throughput if that becomes a bottleneck for processing.

Method Summary

Modifier and Type	Method and Description
void	cancel()
boolean	hasNext() Checks if the stream has been fully consumed or cancelled.
com.google.cloud.bigquery.storage.v1.ReadRowsResponse	next() Consumes the next response and asynchronously request the next response from the observer.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Method Detail

next

public com.google.cloud.bigquery.storage.v1.ReadRowsResponse next()

Consumes the next response and asynchronously request the next response from the observer.

Specified by:

next in interface Iterator<com.google.cloud.bigquery.storage.v1.ReadRowsResponse>

Returns:

The next response.

Throws:

NoSuchElementException - If the stream has been consumed or cancelled.

hasNext

public boolean hasNext()

Checks if the stream has been fully consumed or cancelled. This method will block until the observer enqueues another event (response or completion event). If the observer encountered an error, this method will propagate the error and put itself into an error where it will always return the same error.

Specified by:

hasNext in interface Iterator<com.google.cloud.bigquery.storage.v1.ReadRowsResponse>

Returns:

true If iterator has more responses.

cancel

public void cancel()