我在1.5.X中阅读了SpringBoot源代码，但是在类var str1 = '10,00 €';
var str2 = '12.22 $';
function getCurrencySymbol(str) {
//replace all numbers, spaces, commas, and periods with an empty string
//we should only be left with the currency symbols
return str.replace(/[\d\., ]/g, '');
}
console.log(getCurrencySymbol(str1));
console.log(getCurrencySymbol(str2));中发现了一个问题，它是SpringApplicationBuilder方法代码：
run您看到的 /**
* Create an application context (and its parent if specified) with the command line
* args provided. The parent is run first with the same arguments if has not yet been
* started.
* @param args the command line arguments
* @return an application context created from the current state
*/
public ConfigurableApplicationContext run(String... args) {
if (this.running.get()) {
// If already created we just return the existing context
return this.context;
}
configureAsChildIfNecessary(args);
if (this.running.compareAndSet(false, true)) {
synchronized (this.running) {
// If not already running copy the sources over and then run.
this.context = build().run(args);
}
}
return this.context;
}
方法使用AtomicBoolean字段run来保持线程安全，compareAndSet不是线程安全的吗？为什么要使用同步的？
runningif (this.running.compareAndSet(false, true)) {
synchronized (this.running) {
// thread safe
}
}
在if (this.running.compareAndSet(false, true)) {
// not thread safe ?
}
中这是什么意思？