Content of file CachingRestClientSupport.java.html
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml" lang="en"><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"/><link rel="stylesheet" href="../../jacoco-resources/report.css" type="text/css"/><link rel="shortcut icon" href="../../jacoco-resources/report.gif" type="image/gif"/><title>CachingRestClientSupport.java</title><link rel="stylesheet" href="../../jacoco-resources/prettify.css" type="text/css"/><script type="text/javascript" src="../../jacoco-resources/prettify.js"></script></head><body onload="window['PR_TAB_WIDTH']=4;prettyPrint()"><div class="breadcrumb" id="breadcrumb"><span class="info"><a href="../../jacoco-sessions.html" class="el_session">Sessions</a></span><a href="../../index.html" class="el_report">blueMarine II :: Model</a> > <a href="../index.html" class="el_bundle">it-tidalwave-bluemarine2-commons</a> > <a href="index.source.html" class="el_package">it.tidalwave.bluemarine2.rest</a> > <span class="el_source">CachingRestClientSupport.java</span></div><h1>CachingRestClientSupport.java</h1><pre class="source lang-java linenums">/*
* *********************************************************************************************************************
*
* blueMarine II: Semantic Media Centre
* http://tidalwave.it/projects/bluemarine2
*
* Copyright (C) 2015 - 2021 by Tidalwave s.a.s. (http://tidalwave.it)
*
* *********************************************************************************************************************
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*
* *********************************************************************************************************************
*
* git clone https://bitbucket.org/tidalwave/bluemarine2-src
* git clone https://github.com/tidalwave-it/bluemarine2-src
*
* *********************************************************************************************************************
*/
package it.tidalwave.bluemarine2.rest;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.PostConstruct;
import java.util.List;
import java.util.Optional;
import java.io.IOException;
import java.nio.file.Path;
import java.net.URI;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.web.client.ResponseErrorHandler;
import org.springframework.web.client.RestTemplate;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import static java.util.Collections.*;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.springframework.http.HttpHeaders.*;
/***********************************************************************************************************************
*
* @author Fabrizio Giudici
*
**********************************************************************************************************************/
<span class="nc" id="L57">@Slf4j</span>
public class CachingRestClientSupport
{
<span class="nc" id="L60"> public enum CacheMode</span>
{
/** Always use the network. */
<span class="nc" id="L63"> DONT_USE_CACHE</span>
{
@Override @Nonnull
public ResponseEntity<String> request (@Nonnull final CachingRestClientSupport api,
@Nonnull final String url)
throws IOException, InterruptedException
{
<span class="nc" id="L70"> return api.requestFromNetwork(url);</span>
}
},
/** Never use the network. */
<span class="nc" id="L74"> ONLY_USE_CACHE</span>
{
@Override @Nonnull
public ResponseEntity<String> request (@Nonnull final CachingRestClientSupport api,
@Nonnull final String url)
throws IOException
{
<span class="nc" id="L81"> return api.requestFromCache(url).get();</span>
}
},
/** First try the cache, then the network. */
<span class="nc" id="L85"> USE_CACHE</span>
{
@Override @Nonnull
public ResponseEntity<String> request (@Nonnull final CachingRestClientSupport api,
@Nonnull final String url)
throws IOException, InterruptedException
{
<span class="nc" id="L92"> return api.requestFromCacheAndThenNetwork(url);</span>
}
};
@Nonnull
public abstract ResponseEntity<String> request (@Nonnull CachingRestClientSupport api,
@Nonnull String url)
throws IOException, InterruptedException;
}
<span class="nc" id="L102"> private final RestTemplate restTemplate = new RestTemplate(); // FIXME: inject?</span>
<span class="nc" id="L104"> @Getter @Setter</span>
private CacheMode cacheMode = CacheMode.USE_CACHE;
<span class="nc" id="L107"> @Getter @Setter</span>
private Path cachePath;
<span class="nc" id="L110"> @Getter @Setter</span>
private String accept = "application/xml";
<span class="nc" id="L113"> @Getter @Setter</span>
private String userAgent = "blueMarine II (fabrizio.giudici@tidalwave.it)";
<span class="nc" id="L116"> @Getter @Setter</span>
private long throttleLimit;
<span class="nc" id="L119"> @Getter @Setter @Nonnegative</span>
private int maxRetry = 3;
<span class="nc" id="L122"> @Getter @Setter</span>
<span class="nc" id="L123"> private List<Integer> retryStatusCodes = List.of(503);</span>
<span class="nc" id="L125"> private long latestNetworkAccessTimestamp = 0;</span>
/*******************************************************************************************************************
*
*
*
******************************************************************************************************************/
<span class="nc" id="L132"> private static final ResponseErrorHandler IGNORE_HTTP_ERRORS = new ResponseErrorHandler()</span>
<span class="nc" id="L133"> {</span>
@Override
public boolean hasError (@Nonnull final ClientHttpResponse response)
throws IOException
{
<span class="nc" id="L138"> return false;</span>
}
@Override
public void handleError (@Nonnull final ClientHttpResponse response)
throws IOException
{
<span class="nc" id="L145"> }</span>
};
/*******************************************************************************************************************
*
*
*
******************************************************************************************************************/
<span class="nc" id="L153"> private final ClientHttpRequestInterceptor interceptor = (request, body, execution) -></span>
{
<span class="nc" id="L155"> final HttpHeaders headers = request.getHeaders();</span>
<span class="nc" id="L156"> headers.add(USER_AGENT, userAgent);</span>
<span class="nc" id="L157"> headers.add(ACCEPT, accept);</span>
<span class="nc" id="L158"> return execution.execute(request, body);</span>
};
/*******************************************************************************************************************
*
*
*
******************************************************************************************************************/
public CachingRestClientSupport()
<span class="nc" id="L167"> {</span>
<span class="nc" id="L168"> restTemplate.setInterceptors(singletonList(interceptor));</span>
<span class="nc" id="L169"> restTemplate.setErrorHandler(IGNORE_HTTP_ERRORS);</span>
<span class="nc" id="L170"> }</span>
/*******************************************************************************************************************
*
*
*
******************************************************************************************************************/
@PostConstruct
void initialize()
{
<span class="nc" id="L180"> }</span>
/*******************************************************************************************************************
*
* Performs a web request.
*
* @return the response
*
******************************************************************************************************************/
@Nonnull
protected ResponseEntity<String> request (@Nonnull final String url)
throws IOException, InterruptedException
{
<span class="nc" id="L193"> log.debug("request({})", url);</span>
<span class="nc" id="L194"> return cacheMode.request(this, url);</span>
}
/*******************************************************************************************************************
*
*
*
******************************************************************************************************************/
@Nonnull
private Optional<ResponseEntity<String>> requestFromCache (@Nonnull final String url)
throws IOException
{
<span class="nc" id="L206"> log.debug("requestFromCache({})", url);</span>
<span class="nc" id="L207"> return ResponseEntityIo.load(cachePath.resolve(fixedPath(url)));</span>
}
/*******************************************************************************************************************
*
*
*
******************************************************************************************************************/
@Nonnull
private synchronized ResponseEntity<String> requestFromNetwork (@Nonnull final String url)
throws IOException, InterruptedException
{
<span class="nc" id="L219"> log.debug("requestFromNetwork({})", url);</span>
<span class="nc" id="L220"> ResponseEntity<String> response = null;</span>
<span class="nc bnc" id="L222" title="All 2 branches missed."> for (int retry = 0; retry < maxRetry; retry++)</span>
{
<span class="nc" id="L224"> final long now = System.currentTimeMillis();</span>
<span class="nc" id="L225"> final long delta = now - latestNetworkAccessTimestamp;</span>
<span class="nc" id="L226"> final long toWait = Math.max(throttleLimit - delta, 0);</span>
<span class="nc bnc" id="L228" title="All 2 branches missed."> if (toWait > 0)</span>
{
<span class="nc" id="L230"> log.info(">>>> throttle limit: waiting for {} msec...", toWait);</span>
<span class="nc" id="L231"> Thread.sleep(toWait);</span>
}
<span class="nc" id="L234"> latestNetworkAccessTimestamp = now;</span>
<span class="nc" id="L235"> response = restTemplate.getForEntity(URI.create(url), String.class);</span>
<span class="nc" id="L236"> final int httpStatusCode = response.getStatusCodeValue();</span>
<span class="nc" id="L237"> log.debug(">>>> HTTP status code: {}", httpStatusCode);</span>
<span class="nc bnc" id="L239" title="All 2 branches missed."> if (!retryStatusCodes.contains(httpStatusCode))</span>
{
<span class="nc" id="L241"> break;</span>
}
<span class="nc" id="L244"> log.warn("HTTP status code: {} - retry #{}", httpStatusCode, retry + 1);</span>
}
// log.trace(">>>> response: {}", response);
<span class="nc" id="L248"> return response;</span>
}
/*******************************************************************************************************************
*
*
*
******************************************************************************************************************/
@Nonnull
private ResponseEntity<String> requestFromCacheAndThenNetwork (@Nonnull final String url)
throws IOException, InterruptedException
{
<span class="nc" id="L260"> log.debug("requestFromCacheAndThenNetwork({})", url);</span>
<span class="nc" id="L262"> return requestFromCache(url).orElseGet(() -></span>
{
try
{
<span class="nc" id="L266"> final ResponseEntity<String> response = requestFromNetwork(url);</span>
<span class="nc" id="L267"> final int httpStatusCode = response.getStatusCodeValue();</span>
<span class="nc bnc" id="L269" title="All 2 branches missed."> if (!retryStatusCodes.contains(httpStatusCode))</span>
{
<span class="nc" id="L271"> ResponseEntityIo.store(cachePath.resolve(fixedPath(url)), response, emptyList());</span>
}
<span class="nc" id="L274"> return response;</span>
}
<span class="nc" id="L276"> catch (IOException | InterruptedException e)</span>
{
<span class="nc" id="L278"> throw new RestException(e); // FIXME</span>
}
});
}
/*******************************************************************************************************************
*
*
******************************************************************************************************************/
@Nonnull
/* package */ static String fixedPath (@Nonnull final String url)
{
<span class="nc" id="L290"> String s = url.replace("://", "/");</span>
<span class="nc" id="L291"> int i = s.lastIndexOf('/');</span>
<span class="nc bnc" id="L293" title="All 2 branches missed."> if (i >= 0)</span>
{
<span class="nc" id="L295"> final String lastSegment = s.substring(i + 1);</span>
<span class="nc bnc" id="L297" title="All 2 branches missed."> if (lastSegment.length() > 255) // FIXME: and Mac OS X</span>
{
try
{
<span class="nc" id="L301"> final MessageDigest digestComputer = MessageDigest.getInstance("SHA1");</span>
<span class="nc" id="L302"> s = s.substring(0, i) + "/" + toString(digestComputer.digest(lastSegment.getBytes(UTF_8)));</span>
}
<span class="nc" id="L304"> catch (NoSuchAlgorithmException e)</span>
{
<span class="nc" id="L306"> throw new RuntimeException(e);</span>
<span class="nc" id="L307"> }</span>
}
}
<span class="nc" id="L311"> return s;</span>
}
/*******************************************************************************************************************
*
*
******************************************************************************************************************/
@Nonnull
private static String toString (@Nonnull final byte[] bytes)
{
<span class="nc" id="L321"> final StringBuilder builder = new StringBuilder();</span>
<span class="nc bnc" id="L323" title="All 2 branches missed."> for (final byte b : bytes)</span>
{
<span class="nc" id="L325"> final int value = b & 0xff;</span>
<span class="nc" id="L326"> builder.append(Integer.toHexString(value >>> 4)).append(Integer.toHexString(value & 0x0f));</span>
}
<span class="nc" id="L329"> return builder.toString();</span>
}
}
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