sc-read-fix.js

function fixed_read(db, key) { 
  var value = db.read(key);
  while (true) {
    // If we try to write the read value then we
    const written = db.updateWhen(key, {
      predicate: `x => x.ver==${value.ver}`,
      value: { ver: value.ver+1, val: value.val} 
    });
    if (!written.isConflict) {
      // either succeed and return the just written value
      return written.value;
    }
    // or fail and use a newer value and repeat the trick.
    value = written.conflict;
  }
}