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<b>Warning</b>:  session_start(): open(/var/lib/php/sessions/sess_rj4ahv54smvt1tjk9ms5uq6t2o, O_RDWR) failed: No space left on device (28) in <b>/var/www/tb-usercake/models/config.php</b> on line <b>51</b><br />
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<b>Warning</b>:  session_start(): Failed to read session data: files (path: /var/lib/php/sessions) in <b>/var/www/tb-usercake/models/config.php</b> on line <b>51</b><br />
sclass WaitForStableValue<A> {
  long period;
  A value;
  long valueSince;
  
  *() {}
  *(long *period) {}
  *(double seconds) { period = toMS(seconds); }
  
  synchronized A set(A a) {
    if (neq(a, value)) {
      value = a;
      valueSince = sysNow();
    }
    ret get();
  }
  
  synchronized A get() {
    ret valueSince != 0 && sysNow() >= valueSince+period ? value : null;
  }
  
  public bool has() { ret get() != null; }
}