<?php

/**
 * Copyright 2014-Present Couchbase, Inc.
 *
 * 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.
 */

declare(strict_types=1);

namespace Couchbase;

/**
 * Implements a no-op tracer which performs no work.  Note that to reduce the
 * performance impact of using this tracer, this class is not actually
 * used by the SDK, and simply acts as a placeholder which triggers a
 * native implementation to be used instead.
 */
class NoopTracer implements RequestTracer
{
    private static ?NoopTracer $instance = null;

    public function requestSpan(string $name, ?RequestSpan $parent = null, ?int $startTimestampNanoseconds = null): RequestSpan
    {
        return NoopSpan::getInstance();
    }

    public function close(): void
    {
    }

    public static function getInstance(): NoopTracer
    {
        if (self::$instance == null) {
            self::$instance = new NoopTracer();
        }
        return self::$instance;
    }
}
