com.google.cloud.trace.core.RateLimitingTraceOptionsFactory.java Source code

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Here is the source code for com.google.cloud.trace.core.RateLimitingTraceOptionsFactory.java

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// Copyright 2016 Google Inc. All rights reserved.
//
// 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.google.cloud.trace.core;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.util.concurrent.RateLimiter;
import javax.annotation.concurrent.ThreadSafe;

/**
 * A factory for generating new trace options. In case of a new root {@link SpanContext}, the trace
 * option values are set based on a rate limiter which limits the number of enabled traces per
 * second. The new trace options' stack trace option is set to the provided value. No sampling
 * decision is made in case of trace options for a child {@link SpanContext}.
 *
 * <p>This class is unconditionally thread-safe.
 */
@ThreadSafe
public final class RateLimitingTraceOptionsFactory implements TraceOptionsFactory {

    private final RateLimiter rateLimiter;
    private final boolean stackTraceEnabled;

    /**
     * Creates a trace options factory that generates trace options based on a rate limiter which
     * limits the number of enabled traces according to the specified {@code samplingRate} and sets
     * the stack trace according to the specified {@code stackTraceEnabled} parameter.
     *
     * @param samplingRate a double that is the rate (unit 1/s) of generated trace options whose trace
     *     option is true.
     * @param stackTraceEnabled the value of the new trace options' stack trace option
     */
    public RateLimitingTraceOptionsFactory(double samplingRate, boolean stackTraceEnabled) {
        this(RateLimiter.create(samplingRate), stackTraceEnabled);
    }

    @VisibleForTesting
    RateLimitingTraceOptionsFactory(RateLimiter rateLimiter, boolean stackTraceEnabled) {
        this.rateLimiter = checkNotNull(rateLimiter);
        this.stackTraceEnabled = stackTraceEnabled;
    }

    @Override
    public TraceOptions create() {
        boolean traceEnabled = rateLimiter.tryAcquire();

        return new TraceOptions().overrideTraceEnabled(traceEnabled).overrideStackTraceEnabled(stackTraceEnabled);
    }

    @Override
    public TraceOptions create(TraceOptions traceOptions) {
        checkNotNull(traceOptions);

        return traceOptions;
    }
}