121 lines
3.2 KiB
Java
121 lines
3.2 KiB
Java
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package eu.dnetlib.dhp.provision.update;
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import java.io.IOException;
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import java.util.Iterator;
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import java.util.List;
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import java.util.stream.Collectors;
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import org.apache.commons.io.IOUtils;
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import org.apache.http.client.methods.CloseableHttpResponse;
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import org.apache.http.client.methods.HttpPost;
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import org.apache.http.entity.StringEntity;
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import org.apache.http.impl.client.CloseableHttpClient;
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import org.apache.http.impl.client.HttpClients;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import com.jayway.jsonpath.JsonPath;
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import net.minidev.json.JSONArray;
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public class DataciteClientIterator implements Iterator<String> {
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static final String blobPath = "$.hits.hits[*]._source";
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static final String scrollIdPath = "$._scroll_id";
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String scrollId;
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List<String> buffer;
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final String esHost;
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final String esIndex;
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final ObjectMapper mapper = new ObjectMapper();
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public DataciteClientIterator(final String esHost, final String esIndex, long timestamp)
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throws IOException {
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this.esHost = esHost;
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this.esIndex = esIndex;
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// THIS FIX IS NECESSARY to avoid different timezone
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timestamp -= (60 * 60 * 2);
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final String body = getResponse(
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String.format("http://%s:9200/%s/_search?scroll=1m", esHost, esIndex),
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String
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.format(
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"{\"size\":1000, \"query\":{\"range\":{\"timestamp\":{\"gte\":%d}}}}", timestamp));
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scrollId = getJPathString(scrollIdPath, body);
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buffer = getBlobs(body);
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}
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public String getResponse(final String url, final String json) {
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CloseableHttpClient client = HttpClients.createDefault();
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try {
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HttpPost httpPost = new HttpPost(url);
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if (json != null) {
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StringEntity entity = new StringEntity(json);
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httpPost.setEntity(entity);
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httpPost.setHeader("Accept", "application/json");
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httpPost.setHeader("Content-type", "application/json");
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}
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CloseableHttpResponse response = client.execute(httpPost);
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return IOUtils.toString(response.getEntity().getContent());
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} catch (Throwable e) {
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throw new RuntimeException("Error on executing request ", e);
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} finally {
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try {
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client.close();
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} catch (IOException e) {
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throw new RuntimeException("Unable to close client ", e);
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}
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}
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}
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private String getJPathString(final String jsonPath, final String json) {
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try {
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Object o = JsonPath.read(json, jsonPath);
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if (o instanceof String)
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return (String) o;
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return null;
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} catch (Exception e) {
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return "";
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}
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}
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private List<String> getBlobs(final String body) {
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JSONArray array = JsonPath.read(body, blobPath);
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return array
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.stream()
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.map(
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o -> {
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try {
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return mapper.writeValueAsString(o);
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} catch (Throwable e) {
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throw new RuntimeException(e);
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}
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})
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.collect(Collectors.toList());
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}
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@Override
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public boolean hasNext() {
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return (buffer != null && !buffer.isEmpty());
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}
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@Override
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public String next() {
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final String nextItem = buffer.remove(0);
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if (buffer.isEmpty()) {
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final String json_param = String.format("{\"scroll_id\":\"%s\",\"scroll\" : \"1m\"}", scrollId);
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final String body = getResponse(String.format("http://%s:9200/_search/scroll", esHost), json_param);
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try {
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buffer = getBlobs(body);
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} catch (Throwable e) {
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System.out.println(body);
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}
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}
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return nextItem;
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}
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}
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