com.yoho.core.trace.instrument.web.HttpServletRequestExtractor.java Source code

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Here is the source code for com.yoho.core.trace.instrument.web.HttpServletRequestExtractor.java

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/*
 * Copyright 2013-2016 the original author or authors.
 *
 * 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.
 */

package com.yoho.core.trace.instrument.web;

import java.util.Random;
import java.util.regex.Pattern;

import javax.servlet.http.HttpServletRequest;

import com.yoho.core.trace.Span;
import com.yoho.core.trace.SpanExtractor;
import org.springframework.util.StringUtils;
import org.springframework.web.util.UrlPathHelper;

/**
 * Creates a {@link Span.SpanBuilder} from {@link HttpServletRequest}
 *
 * @author Marcin Grzejszczak
 *
 * @since 1.0.0
 */
class HttpServletRequestExtractor implements SpanExtractor<HttpServletRequest> {

    private static final String HTTP_COMPONENT = "http";

    private final Random random;
    private final Pattern skipPattern;

    private UrlPathHelper urlPathHelper = new UrlPathHelper();

    public HttpServletRequestExtractor(Random random) {
        this.random = random;
        this.skipPattern = Pattern.compile(TraceInterceptor.DEFAULT_SKIP_PATTERN);
    }

    @Override
    public Span joinTrace(HttpServletRequest carrier) {
        if (carrier.getHeader(Span.TRACE_ID_NAME) == null) {
            // can't build a Span without trace id
            return null;
        }
        String uri = this.urlPathHelper.getPathWithinApplication(carrier);
        boolean skip = this.skipPattern.matcher(uri).matches()
                || Span.SPAN_NOT_SAMPLED.equals(carrier.getHeader(Span.SAMPLED_NAME));
        long traceId = Span.hexToId(carrier.getHeader(Span.TRACE_ID_NAME));
        long spanId = carrier.getHeader(Span.SPAN_ID_NAME) != null
                ? Span.hexToId(carrier.getHeader(Span.SPAN_ID_NAME))
                : this.random.nextLong();
        return buildParentSpan(carrier, uri, skip, traceId, spanId);
    }

    private Span buildParentSpan(HttpServletRequest carrier, String uri, boolean skip, long traceId, long spanId) {
        Span.SpanBuilder span = Span.builder().traceId(traceId).spanId(spanId);
        String processId = carrier.getHeader(Span.PROCESS_ID_NAME);
        String parentName = carrier.getHeader(Span.SPAN_NAME_NAME);
        if (StringUtils.hasText(parentName)) {
            span.name(parentName);
        } else {
            span.name(HTTP_COMPONENT + ":" + "/parent" + uri);
        }
        if (StringUtils.hasText(processId)) {
            span.processId(processId);
        }
        if (carrier.getHeader(Span.PARENT_ID_NAME) != null) {
            span.parent(Span.hexToId(carrier.getHeader(Span.PARENT_ID_NAME)));
        }
        span.remote(true);
        if (skip) {
            span.exportable(false);
        }
        return span.build();
    }
}