@Nullable
	final T blockingGet(long timeout, TimeUnit unit) {
		if (Schedulers.isInNonBlockingThread()) {
			throw new IllegalStateException("block()/blockFirst()/blockLast() are blocking, which is not supported in thread " + Thread.currentThread().getName());
		}
		if (getCount() != 0) {
			try {
				if (!await(timeout, unit)) {
					dispose();
					throw new IllegalStateException("Timeout on blocking read for " + timeout + " " + unit);
				}
			}
			catch (InterruptedException ex) {
				dispose();
				RuntimeException re = Exceptions.propagate(ex);
				//this is ok, as re is always a new non-singleton instance
				re.addSuppressed(new Exception("#block has been interrupted"));
				throw re;
			}
		}

		Throwable e = error;
		if (e != null) {
			RuntimeException re = Exceptions.propagate(e);
			//this is ok, as re is always a new non-singleton instance
			re.addSuppressed(new Exception("#block terminated with an error"));
			throw re;
		}
		return value;
	}
@ Nullable final T blockingGet ( long timeout , TimeUnit unit ) { if ( Schedulers . isInNonBlockingThread ( ) ) { throw new IllegalStateException ( "block()/blockFirst()/blockLast() are blocking, which is not supported in thread " + Thread . currentThread ( ) . getName ( ) ) ; } if ( getCount ( ) != 0 ) { try { if ( ! await ( timeout , unit ) ) { dispose ( ) ; throw new IllegalStateException ( "Timeout on blocking read for " + timeout + " " + unit ) ; } } catch ( InterruptedException ex ) { dispose ( ) ; RuntimeException re = Exceptions . propagate ( ex ) ; re . addSuppressed ( new Exception ( "#block has been interrupted" ) ) ; throw re ; } } Throwable e = error ; if ( e != null ) { RuntimeException re = Exceptions . propagate ( e ) ; re . addSuppressed ( new Exception ( "#block terminated with an error" ) ) ; throw re ; } return value ; }
Block until the first value arrives and return it, otherwise
return null for an empty source and rethrow any exception.

@param timeout the timeout to wait
@param unit the time unit

@return the first value or null if the source is empty