Simple example of a "softlock" concurrent database

softlock.js

let softlock = require('softlock');
softlock.backoffAlgorithm('linear');
softlock.maxResets(4);
let query = softlock.query();

// Softlock is a concurrent database that emulates a locking mechanism using versioned keys.
// If a 'locked' key has been changed since the transaction started, then the transaction
// is rejected and the logic retried

query.lock(['a','b','c']);  // these keys are locked, but their values are not retrieved.
query.get('d', 'e', 'f');  // the keys to use for this transaction, all these are locked
query.peek('fff'); // these values are retrieved, but the keys are not locked.

while(!query.fail && await query.submit()){  // internally, submit may wait according to a backoff algorithm.
   // query.ready, indicates we are ready to start the transaction.
   // note that the transaction logic may need to be re-run on new values, if the transaction was rejected.
   if(query.ready){
     let a = query.values['a'];
     let r = query.revisions['a'];
     console.log(`The current revision for key 'a' is ${r}`);
     query.set('a', a+1);
   }
}
console.log(query.success? "Query succeeded." : "Query failed.");
if(query.fail){
   console.log("Query failed");
}
query.get('b')