Handle Hash Collison in Stripe Read Write lock

Question

We are using stripe lock for one of our implementation. We take readlock on some final constant and a writelock on key. We noticed that we ran into a deadlock because hash code of two different keys turned out to be same. And hence it is like upgrading a read lock to write lock and we ran into deadlock. Below is the code used by Stripe library to generate a hashcode. What is the best way to handle this deadlock?

Stripe code:

static int smear(int hashCode) 
{
    hashCode ^= hashCode >>> 20 ^ hashCode >>> 12;
    return hashCode ^ hashCode >>> 7 ^ hashCode >>> 4;
}

static final int indexFor(Object key) 
{
    int hash = smear(key.hashCode());
    int mask = ceilToPowerOfTwo(2003) -1;
    return hash & mask;
}

static int ceilToPowerOfTwo(int x) 
{
    return 1 << IntMath.log2(x, RoundingMode.CEILING);
}

public static void main(String[] args) {
    String publicKey = "$public";
    int hash = indexFor(publicKey );
    
    for(int i=0;i<1000;i++) {
        String key = "key"+i;
        if(indexFor(key) == hash) {
            System.out.println("Hash of "+key + " is same as hash of public");
        }
    }
}

Our Logic:

Take readLock on publicKey 
Take writeLock on key
release the write lock
release the read lock

Handle Hash Collison in Stripe Read Write lock

0 Answers0