Buffered AsyncClientHttpResponses [SPR-13657]

[spring-projects-issues]

Jakub Narloch opened SPR-13657 and commented

After preparing the PoC for #16971, in order to fully facilitate the interceptors functionality would require to add buffering to the AsyncClientHttpResponse so that use cases like logging and body rewriting could be implemented on top of that.

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Affects: 4.2.3

Issue Links:

• Support of client interceptors in Spring's AsyncRestTemplate [SPR-12538] #16971 Support of client interceptors in Spring's AsyncRestTemplate

[spring-projects-issues]

Rossen Stoyanchev commented

#915

[spring-projects-issues]

Vijendra Kumar Kulhade commented

I would be happy to work on it. If it is still pending.

[spring-projects-issues]

Vijendra Kumar Kulhade commented

I saw the changes done for this pull request. I tried using them with [AsyncRestTemplate]. [BufferingAsyncClientHttpRequestFactory] is only implementing [AsyncClientHttpRequestFactory] and [AsyncRestTemplate] constructor takes [ClientHttpRequestFactory] also. It is breaking during auto-wiring. I wrote another version which is extending BufferingClientHttpRequestFactory and works fine as a decorator. Please guide if I am doing it right.
Below is the code

public class BufferingAsyncClientHttpRequestFactory extends BufferingClientHttpRequestFactory
		implements AsyncClientHttpRequestFactory {

	private final AsyncClientHttpRequestFactory requestFactory;
	/**
	 * Create a buffering wrapper for the given {@link ClientHttpRequestFactory}.
	 * @param requestFactory the target request factory to wrap
	 */
	public BufferingAsyncClientHttpRequestFactory(AsyncClientHttpRequestFactory requestFactory) {
		super((ClientHttpRequestFactory) requestFactory);
		this.requestFactory=requestFactory;
	}


	/**
	 * Indicates whether the request/response exchange for the given URI and method
	 * should be buffered in memory.
	 * <p>The default implementation returns {@code true} for all URIs and methods.
	 * Subclasses can override this method to change this behavior.
	 * @param uri the URI
	 * @param httpMethod the method
	 * @return {@code true} if the exchange should be buffered; {@code false} otherwise
	 */

	@Override
	public AsyncClientHttpRequest createAsyncRequest(URI uri, HttpMethod httpMethod) throws IOException {
		AsyncClientHttpRequest request = requestFactory.createAsyncRequest(uri, httpMethod);
		if (shouldBuffer(uri, httpMethod)) {
			return new BufferingAsyncClientHttpRequestWrapper(request);
		}
		else {
			return request;
		}
	}

	protected boolean shouldBuffer(URI uri, HttpMethod httpMethod) {
		return true;
	}


}

BufferingAsyncClientHttpRequestWrapper.java

public class BufferingAsyncClientHttpRequestWrapper extends AbstractBufferingAsyncClientHttpRequest {

    private final AsyncClientHttpRequest request;

    public BufferingAsyncClientHttpRequestWrapper(AsyncClientHttpRequest asyncClientHttpRequest){
        this.request=asyncClientHttpRequest;
    }

    @Override
    public HttpMethod getMethod() {
        return this.request.getMethod();
    }

    @Override
    public URI getURI() {
        return this.request.getURI();
    }

    @Override
    protected ListenableFuture<ClientHttpResponse> executeInternal(HttpHeaders headers, byte[] bufferedOutput) throws IOException {
        this.request.getHeaders().putAll(headers);
        if(bufferedOutput.length>0){
            StreamUtils.copy(bufferedOutput,this.request.getBody());
        }
        ListenableFuture<ClientHttpResponse> futureResponse = this.request.executeAsync();
        ListenableFutureAdapter<ClientHttpResponse,ClientHttpResponse> bufferedResponse =
                new ListenableFutureAdapter<ClientHttpResponse, ClientHttpResponse>(futureResponse) {
                    @Override
                    protected ClientHttpResponse adapt(ClientHttpResponse adapteeResult) throws ExecutionException {
                        return new BufferingClientHttpResponseWrapper(adapteeResult);
                    }
                };
        return bufferedResponse;
    }
}

[spring-projects-issues]

Rossen Stoyanchev commented

Jakub Narloch my sincere apologies for not getting to your PR. Given where we are, with AsyncRestTemplate deprecated in 5.0, and 4.3.x mostly picking up backports, I have to resolve this without fixing it. If you're on 5.0 simply use the WebClient where caching the content is straight forward (i.e. through operators on Flux and Mono).