Example: lr_user_data_point_instance

In the following example,lr_start_transaction_instance measures the duration a withdrawal from a bank server. Once the server API call is completed and returns a value to the status variable, the transaction instance is complete. Each successful instance of the transaction is accompanied by a data point instance that records the amount overdrawn with the transaction. This is achieved by passing the instance_id of the transaction to lr_user_data_point_instance.

int LIMIT=1000;
long instance_id;
int amount_overdrawn = get_amount_overdrawn(); /* Call to server API */
while (amount_overdrawn < LIMIT) {
    /* Notify that a transaction is starting */
    instance_id = lr_start_transaction_instance("withdraw", 0);
    status = bank_withdraw(500); /* Call to server API */
   /* End transaction with operation result - pass or fail */
    if (status == 0)
        /* Before ending the transaction, record the amount
        * overdrawn as a data point and associate it with 
        * the specific transaction instance by using the
        * instance's id */
        lr_user_data_point_instance("Amount Overdrawn",
            (double)amount_overdrawn, instance_id);
        lr_end_transaction_instance(instance_id, LR_PASS);
        lr_end_transaction_instance(instance_id, LR_FAIL);
    amount_overdrawn = get_amount_overdrawn();