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Microsoft JDBC Driver for SQL Server. The Azure Key Vault feature in Microsoft JDBC Driver for SQL Server depends on Azure SDK for JAVA and Azure Active Directory Library For Java.

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/*
 * Microsoft JDBC Driver for SQL Server
 * 
 * Copyright(c) Microsoft Corporation All rights reserved.
 * 
 * This program is made available under the terms of the MIT License. See the LICENSE file in the project root for more information.
 */

package com.microsoft.sqlserver.jdbc;

import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;

/**
 * ActivityCorrelator provides the APIs to access the ActivityId in TLS
 */
final class ActivityCorrelator {

    private static Map ActivityIdTlsMap = new ConcurrentHashMap();
    
    static void cleanupActivityId() {
        //remove the ActivityId that belongs to this thread.
        long uniqueThreadId = Thread.currentThread().getId();

        if (ActivityIdTlsMap.containsKey(uniqueThreadId)) {
            ActivityIdTlsMap.remove(uniqueThreadId);
        }
    }

    // Get the current ActivityId in TLS
    static ActivityId getCurrent() {
        // get the value in TLS, not reference
        long uniqueThreadId = Thread.currentThread().getId();
        
        //Since the Id for each thread is unique, this assures that the below if statement is run only once per thread.
        if (!ActivityIdTlsMap.containsKey(uniqueThreadId)) {
            ActivityIdTlsMap.put(uniqueThreadId, new ActivityId());
        }
        
        return ActivityIdTlsMap.get(uniqueThreadId);
    }

    // Increment the Sequence number of the ActivityId in TLS
    // and return the ActivityId with new Sequence number
    static ActivityId getNext() {
        // Get the current ActivityId in TLS
        ActivityId activityId = getCurrent();

        // Increment the Sequence number
        activityId.Increment();

        return activityId;
    }

    static void setCurrentActivityIdSentFlag() {
        ActivityId activityId = getCurrent();
        activityId.setSentFlag();
    }
}

class ActivityId {
    private final UUID Id;
    private long Sequence;
    private boolean isSentToServer;

    ActivityId() {
        Id = UUID.randomUUID();
        Sequence = 0;
        isSentToServer = false;
    }

    UUID getId() {
        return Id;
    }

    long getSequence() {
        return Sequence;
    }

    void Increment() {
        if (Sequence < 0xffffffffl) // to get to 32-bit unsigned
        {
            ++Sequence;
        }
        else {
            Sequence = 0;
        }

        isSentToServer = false;
    }

    void setSentFlag() {
        isSentToServer = true;
    }

    boolean IsSentToServer() {
        return isSentToServer;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(Id.toString());
        sb.append("-");
        sb.append(Sequence);
        return sb.toString();
    }
}