com.google.api.gax.retrying.StreamResumptionStrategy Maven / Gradle / Ivy
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* Copyright 2018 Google LLC
*
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*
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package com.google.api.gax.retrying;
import com.google.api.core.BetaApi;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
/**
* This is part of the server streaming retry api. Its implementers are responsible for tracking the
* progress of the stream and calculating a request to resume it in case of an error.
*
* Implementations don't have to be threadsafe because all of the calls will be serialized.
*/
@BetaApi("The surface for streaming is not stable yet and may change in the future.")
public interface StreamResumptionStrategy {
/** Creates a new instance of this StreamResumptionStrategy without accumulated state */
@Nonnull
StreamResumptionStrategy createNew();
/**
* Called by the {@code ServerStreamingAttemptCallable} when a response has been successfully
* received. This method accomplishes two goals:
*
*
* - It allows the strategy implementation to update its internal state so that it can compose
* the resume request
*
- It allows the strategy to alter the incoming responses to adjust for after resume. For
* example, if the responses are numbered sequentially from the start of the stream, upon
* resume, the strategy could rewrite the messages to continue the sequence from where it
* left off. Please note that all messages (even for the first attempt) will be passed
* through this method.
*
*/
@Nonnull
ResponseT processResponse(ResponseT response);
/**
* Called when a stream needs to be restarted, the implementation should generate a request that
* will yield a new stream whose first response would come right after the last response received
* by processResponse.
*
* @return A request that can be used to resume the stream.
*/
@Nullable
RequestT getResumeRequest(RequestT originalRequest);
/** If a resume request can be created. */
boolean canResume();
}