GOSU中的静态方法和线程安全

Question

I have below function in a .gs class, which gets called when accessing specific Claim information -

public static function testVisibility(claim : Claim) : boolean {
    if(claim.State == ClaimState.TC_OPEN){
        return true;
    }
    else{
        return false;
    }
}

My question -

a) If two users are accessing their respective Claims information, this function should get called twice - first time it should receive the Claim instance of first user, second time Claim instance of second user. If the accessing in simultaneous - will two copies of the same function be invoked? Should not be the case, as static function is only one copy. So, if it's one copy, how is thread safety ensured? Will the function be called one-after-another?

b) Like Java, does Gosu also use Heap to run the static functions?

Answer 1

It seems you are confusing a little about the definition here. Thread-safe is only a mechanism created to protect the integrity of data shared between threads. Therefore, your example function is thread-safe, no matter if it is static or not.

a) For the reason mentioned above, there would be no thread-safety problem here, because you are working with 2 different sets of data .

b) Provided that Gosu is built to run on JVM, and produce .class files, I believe for the most part (if not 100%, beside the syntax) it will behave like Java.

Answer 2

This is a cliche confusion when we start loving any programming language.

Consider 100 people accessing a web-application exactly at a particular point of time, here as per your doubt, the static variable/function will return/share the content value for all the 100 people. The fact is, data sharing won't happen here because for each server connection, each separate THREAD is created and the entire application works on that thread (called as one-thread-per-connection).

SO if have a static/global variable, that particular variable will work on 100 different threads, and content/data of each thread will be secure and cant be accessed from other threads(directly). This is how web applications works.

If we need to share some variables/Classes among threads, we have to make it singleton. Eg, For database connections, we don't need to create the connection all the time if already an established connection exists. In that case the connection class will be singleton.

Hope this make sense. :)

-Aravind