测量CompletableFuture链中的单个执行时间

Question

我有几个异步 api 调用组合在一起形成一个完整的 futures 链。链的每个部分都取决于前一阶段，即如果前一个调用返回非空数据，则我们跳过下一个调用。

我不仅想测量整个链执行所花费的总时间，还想单独测量每个 api 调用。

像下面的代码片段那样测量时间是否正确，或者有更好的方法来做到这一点，例如扩展

CompletableFuture

类？

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;

public class CompletableFutureChainExample {

public static void main(String[] args) {
    // Record the start time
    long startTime = System.nanoTime();

    CompletableFuture<String> futureChain = CompletableFuture.supplyAsync(() -> api1Call())
            .thenCompose(result -> {
                long api2StartTime = System.nanoTime();
                if (api1Call.isEmpty()) {
                    CompletableFuture<String> api2Call = api2Call(result);
                } else { 
                    return CompletableFuture.completedFuture(api1Call);
                }
                long api2ElapsedTime = (System.nanoTime() - api2StartTime) / 1_000_000; // Convert to milliseconds
                System.out.println("Api 2 Elapsed Time: " + api2ElapsedTime + " milliseconds");
                return api2Result;
            })
            .thenCompose(result -> {
                long api3StartTime = System.nanoTime();
                if (api2Call.isEmpty()) {
                    CompletableFuture<String> api3Call = api3Call(result);
                } else { 
                    return CompletableFuture.completedFuture(api2Call);
                }
                long api3ElapsedTime = (System.nanoTime() - api3StartTime) / 1_000_000; // Convert to milliseconds
                System.out.println("Api 3 Elapsed Time: " + api3ElapsedTime + " milliseconds");
                return api3Result;
            })
            .thenApply(result -> finalMapping(result));

    // Wait for the last CompletableFuture in the chain to complete
    try {
        String finalResult = futureChain.get();
        // Calculate the total elapsed time
        long totalElapsedTime = (System.nanoTime() - startTime) / 1_000_000; // Convert to milliseconds
        System.out.println("Final Result: " + finalResult);
        System.out.println("Total Elapsed Time: " + totalElapsedTime + " milliseconds");
    } catch (InterruptedException | ExecutionException e) {
        e.printStackTrace();
    }
}

private static CompletableFuture<String> api1Call(String input) {
    // some time-consuming computation
    return CompletableFuture.completedFuture(“whatever1”);
}

private static CompletableFuture<String> api2Call(String input) {
    // some time-consuming computation
    return CompletableFuture.completedFuture(“whatever2”);
}

private static CompletableFuture<String> api3Call(String input) {
    // some time-consuming computation
    return CompletableFuture.completedFuture(“whatever3”);
}
private static CompletableFuture<String> finalMapping(String input) {
    // mapping
    return CompletableFuture.completedFuture(“whateverFinal”);
}

}