Add XContentHelper.childBytes() method (#54287)
We have a number of places where we want to read a fairly complex object from XContent, but aren't interested in its contents; for example, mappings are often serialized and deserialized between several objects before they are actually built into a MappingMetaData object. This means that potentially large maps of maps are constructed several times, only to immediately be re-serialized again. This commit adds a new helper method to XContentHelper that reads the children of an xcontent object directly to a BytesReference, serialized via the same xcontenttype as the parent parser, avoiding the construction of intermediary maps or lists.
This commit is contained in:
Alan Woodward
parent
d9d11f6d16
commit
461f1307d6
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@ -384,4 +384,23 @@ public class XContentHelper {
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BytesRef br = bytes.toBytesRef();
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BytesRef br = bytes.toBytesRef();
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return XContentFactory.xContentType(br.bytes, br.offset, br.length);
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return XContentFactory.xContentType(br.bytes, br.offset, br.length);
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}
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}
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/**
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* Returns the contents of an object as an unparsed BytesReference
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*
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* This is useful for things like mappings where we're copying bytes around but don't
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* actually need to parse their contents, and so avoids building large maps of maps
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* unnecessarily
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*/
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public static BytesReference childBytes(XContentParser parser) throws IOException {
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if (parser.currentToken() != XContentParser.Token.START_OBJECT) {
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if (parser.nextToken() != XContentParser.Token.START_OBJECT) {
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throw new XContentParseException(parser.getTokenLocation(),
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"Expected [START_OBJECT] but got [" + parser.currentToken() + "]");
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}
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}
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XContentBuilder builder = XContentBuilder.builder(parser.contentType().xContent());
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builder.copyCurrentStructure(parser);
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return BytesReference.bytes(builder);
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}
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}
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}
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@ -20,10 +20,12 @@
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package org.elasticsearch.common.xcontent.support;
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package org.elasticsearch.common.xcontent.support;
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import org.elasticsearch.common.bytes.BytesReference;
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import org.elasticsearch.common.bytes.BytesReference;
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import org.elasticsearch.common.compress.CompressedXContent;
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import org.elasticsearch.common.xcontent.DeprecationHandler;
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import org.elasticsearch.common.xcontent.DeprecationHandler;
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import org.elasticsearch.common.xcontent.NamedXContentRegistry;
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import org.elasticsearch.common.xcontent.NamedXContentRegistry;
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import org.elasticsearch.common.xcontent.ToXContent;
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import org.elasticsearch.common.xcontent.ToXContent;
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import org.elasticsearch.common.xcontent.ToXContentObject;
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import org.elasticsearch.common.xcontent.ToXContentObject;
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import org.elasticsearch.common.xcontent.XContentBuilder;
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import org.elasticsearch.common.xcontent.XContentHelper;
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import org.elasticsearch.common.xcontent.XContentHelper;
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import org.elasticsearch.common.xcontent.XContentParser;
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import org.elasticsearch.common.xcontent.XContentParser;
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import org.elasticsearch.common.xcontent.XContentType;
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import org.elasticsearch.common.xcontent.XContentType;
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@ -105,4 +107,127 @@ public class XContentHelperTests extends ESTestCase {
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}
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}
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}
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}
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}
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}
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public void testChildBytes() throws IOException {
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for (XContentType xContentType : XContentType.values()) {
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XContentBuilder builder = XContentBuilder.builder(xContentType.xContent());
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builder.startObject().startObject("level1");
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builder.startObject("level2")
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.startObject("object").field("text", "string").field("number", 10).endObject()
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.startObject("object2").field("boolean", true).nullField("null")
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.startArray("array_of_strings").value("string1").value("string2").endArray().endObject().endObject();
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builder.field("field", "value");
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builder.endObject().endObject();
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BytesReference input = BytesReference.bytes(builder);
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BytesReference bytes;
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try (XContentParser parser = xContentType.xContent()
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.createParser(NamedXContentRegistry.EMPTY, DeprecationHandler.THROW_UNSUPPORTED_OPERATION, input.streamInput())) {
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("level2", parser.currentName());
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// Extract everything under 'level2' as a bytestream
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bytes = XContentHelper.childBytes(parser);
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("field", parser.currentName());
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}
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// now parse the contents of 'level2'
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try (XContentParser parser = xContentType.xContent()
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.createParser(NamedXContentRegistry.EMPTY, DeprecationHandler.THROW_UNSUPPORTED_OPERATION, bytes.streamInput())) {
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("object", parser.currentName());
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("text", parser.currentName());
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assertEquals(XContentParser.Token.VALUE_STRING, parser.nextToken());
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assertEquals("string", parser.text());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("number", parser.currentName());
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assertEquals(XContentParser.Token.VALUE_NUMBER, parser.nextToken());
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assertEquals(10, parser.numberValue());
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assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("object2", parser.currentName());
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("boolean", parser.currentName());
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assertEquals(XContentParser.Token.VALUE_BOOLEAN, parser.nextToken());
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assertTrue(parser.booleanValue());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("null", parser.currentName());
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assertEquals(XContentParser.Token.VALUE_NULL, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("array_of_strings", parser.currentName());
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assertEquals(XContentParser.Token.START_ARRAY, parser.nextToken());
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assertEquals(XContentParser.Token.VALUE_STRING, parser.nextToken());
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assertEquals("string1", parser.text());
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assertEquals(XContentParser.Token.VALUE_STRING, parser.nextToken());
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assertEquals("string2", parser.text());
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assertEquals(XContentParser.Token.END_ARRAY, parser.nextToken());
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assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
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assertNull(parser.nextToken());
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}
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}
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}
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public void testEmbeddedObject() throws IOException {
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// Need to test this separately as XContentType.JSON never produces VALUE_EMBEDDED_OBJECT
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XContentBuilder builder = XContentBuilder.builder(XContentType.CBOR.xContent());
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builder.startObject().startObject("root");
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CompressedXContent embedded = new CompressedXContent("{\"field\":\"value\"}");
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builder.field("bytes", embedded.compressed());
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builder.endObject().endObject();
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BytesReference bytes = BytesReference.bytes(builder);
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BytesReference inner;
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try (XContentParser parser = XContentType.CBOR.xContent().createParser(
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NamedXContentRegistry.EMPTY, DeprecationHandler.THROW_UNSUPPORTED_OPERATION, bytes.streamInput())) {
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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inner = XContentHelper.childBytes(parser);
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assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
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assertNull(parser.nextToken());
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}
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try (XContentParser parser = XContentType.CBOR.xContent().createParser(
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NamedXContentRegistry.EMPTY, DeprecationHandler.THROW_UNSUPPORTED_OPERATION, inner.streamInput())) {
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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assertEquals("bytes", parser.currentName());
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assertEquals(XContentParser.Token.VALUE_EMBEDDED_OBJECT, parser.nextToken());
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assertEquals(embedded, new CompressedXContent(parser.binaryValue()));
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assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
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assertNull(parser.nextToken());
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}
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}
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public void testEmptyChildBytes() throws IOException {
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String inputJson = "{ \"mappings\" : {} }";
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try (XContentParser parser = XContentType.JSON.xContent()
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.createParser(NamedXContentRegistry.EMPTY, DeprecationHandler.THROW_UNSUPPORTED_OPERATION, inputJson)) {
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assertEquals(XContentParser.Token.START_OBJECT, parser.nextToken());
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assertEquals(XContentParser.Token.FIELD_NAME, parser.nextToken());
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BytesReference bytes = XContentHelper.childBytes(parser);
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assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
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assertNull(parser.nextToken());
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assertEquals("{}", bytes.utf8ToString());
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}
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}
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}
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}
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