Introduction to the retrospective version of the JSR 166 framework in the Java class library
The JSR 166 framework is a very important part of the Java class library.This framework provides a set of tools and classes for concurrent programming, so that developers can easily handle multi -threaded and concurrent problems.However, although the framework is very powerful and practical, there may be some problems in certain circumstances.
To solve these problems, the JSR 166 framework introduced the concept of retrospective version.The so -called retrospective version means that when an operation fails, it can roll back to the previous state, so that the application can return to a consistent state.This retrospective mechanism allows the program to maintain consistency in the concurrent environment and avoid inconsistent data caused by multi -threaded competition.
The following is an example code that uses the retrospective version to illustrate its usage and role:
import java.util.concurrent.atomic.AtomicInteger;
public class BackoffExample {
private AtomicInteger counter = new AtomicInteger(0);
public void increment() {
int backoffCount = 0;
while (true) {
int currentValue = counter.get();
int newValue = currentValue + 1;
if (counter.compareAndSet(currentValue, newValue)) {
System.out.println("Successfully incremented value to: " + newValue);
break;
} else {
backoffCount++;
// Use the retrospective version for retreat operation
Backoff.backoff(backoffCount);
}
}
}
public static void main(String[] args) {
BackoffExample example = new BackoffExample();
for (int i = 0; i < 10; i++) {
new Thread(() -> example.increment()).start();
}
}
}
class Backoff {
private static final int MIN_DELAY = 100;
private static final int MAX_DELAY = 1000;
public static void backoff(int backoffCount) {
int delay = Math.min((1 << backoffCount) * MIN_DELAY, MAX_DELAY);
try {
Thread.sleep(delay);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
In the above example, the `Backoffexample` class implements a self -increase method using a retrospective version,` Increment`.In this method, the `AtomicInteger` class is used to ensure atomic operations and retreat when the operation fails.The retreat operation is implemented by the `Backoff` class. Calculate the waiting time of waiting based on the number of retreats, and use the` Thread.sleep` method to suspend the current thread.
By using the retrospective version, we can ensure that the operation of shared resources in the concurrent environment is safe and consistent.When each thread is operated, if it fails, it will go back and try to re -operate until it succeeds.
In summary, the retrospective version is a mechanism to solve the problem of concurrent problems in the JSR 166 framework.It provides a way to ensure the consistency of shared resource, which can effectively handle the problem of inconsistent data caused by multi -threaded competition.In practical applications, we can flexibly use the retrospective version to improve the concurrent performance and stability according to specific needs and scenes.
