util.js

// Copyright The OpenTelemetry 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.

const {TraceContextFormat} = require('@opencensus/propagation-tracecontext');
const traceContext = new TraceContextFormat();

/**
 * fields represent variables that can be made optional for commenter output
 */ 
exports.fields = {
    CLIENT_TIMEZONE: "client_timezone",
    DB_DRIVER: "db_driver",
    ROUTE: "route",
    TRACE_STATE: "tracestate",
    TRACE_PARENT: "traceparent"
};

/**
 * Inspects the provided sql statement for existing comments.
 * 
 * @param {String} sql The SQL string to inspect
 * @return {Boolean} true if a comment exists, false otherwise
 */
exports.hasComment = (sql) => {

    if (!sql)
        return false;

    // See https://docs.oracle.com/cd/B12037_01/server.101/b10759/sql_elements006.htm
    // for how to detect comments.
    const indexOpeningDashDashComment = sql.indexOf('--');
    if (indexOpeningDashDashComment >= 0)
        return true;

    const indexOpeningSlashComment = sql.indexOf('/*');
    if (indexOpeningSlashComment < 0)
        return false;

    // Check if it is a well formed comment.
    const indexClosingSlashComment = sql.indexOf('*/');
    
    /* c8 ignore next */
    return indexOpeningSlashComment < indexClosingSlashComment;
}

const latestSpan = (span) => {

    if (!span || !span.isRootSpan())
        return span;
    
    // Otherwise if it is a root span, we'll try to grab its last child.
    const children = span.spans;
    if (children.length < 1)
        return span;

    /* c8 ignore next */
    return children[children.length - 1];
}

/**
 * Adds the required fields from span to dst for tracepropagation, ensuring
 * comformance with any system that uses W3C Distributed Tracing context to propagate traces.
 * In addition to adding a traceparent field, a tracestate is also added to dst
 * 
 * @param {Object} span The span object if tracing is active
 * @param {Object} dst The destination object to add trace propagation fields
 * @return {void}
 */
exports.toW3CTraceContext = (span, dst) => {
    // TODO: check if tracer.currentRootSpan can be null/undefined when tracer is active
    const curSpan = latestSpan(span);
    if (!curSpan)
        return dst;

    const spanContext = curSpan.spanContext || {};
    if (!(spanContext.traceId && spanContext.spanId))
        return dst;

    const setHeader = {
        setHeader: (key, value) => {
            dst[key] = value;
        }
    };
    traceContext.inject(setHeader, curSpan.spanContext);
    return dst;
}