>From 04c6c10ec7d6f9b215141bee0ec7f8001891bcf1 Mon Sep 17 00:00:00 2001
From: Akira Yokosawa <akiyks@xxxxxxxxx>
Date: Sat, 11 Jan 2020 13:48:01 +0900
Subject: [PATCH 4/6] count: Promote code snippet in Quiz part of QQZ to listing
Current scheme of QQZ can't handle a snippet at the end of a Quiz
part due to the implied break-ability in front of the ending "square
mark".
QQZ 5.29 suffers from such a symptom.
Promote the snippet to a proper listing and rephrase the Quiz
and Answer part accordingly.
Also add WRITE_ONCE() and adjust indent in the snippet for
consistency with the right snippet.
Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
---
count/count.tex | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/count/count.tex b/count/count.tex
index 7cd8eceb..28a6602b 100644
--- a/count/count.tex
+++ b/count/count.tex
@@ -1398,24 +1398,29 @@ This is the \co{add_counter()} fastpath, and it does no atomic operations,
references only per-thread variables, and should not incur any cache misses.
\end{lineref}
+\begin{listing}[tbp]
+\begin{VerbatimL}[firstnumber=3]
+ if (counter + delta <= countermax) {
+ WRITE_ONCE(counter, counter + delta);
+ return 1;
+ }
+\end{VerbatimL}
+\caption{Intuitive Fastpath}
+\label{lst:count:Intuitive Fastpath}
+\end{listing}
+
\QuickQuiz{}
What is with the strange form of the condition on
line~\ref{ln:count:count_lim:add_sub_read:add:checklocal} of
Listing~\ref{lst:count:Simple Limit Counter Add, Subtract, and Read}?
- Why not the following more intuitive form of the fastpath?
-
-\begin{VerbatimN}[firstnumber=3]
-if (counter + delta <= countermax) {
- counter += delta;
- return 1;
-}
-\end{VerbatimN}
-\vspace{-9pt}
+ Why not the more intuitive form of the fastpath shown in
+ \cref{lst:count:Intuitive Fastpath}?
\QuickQuizAnswer{
Two words.
``Integer overflow.''
- Try the above formulation with \co{counter} equal to 10 and
+ Try the formulation in \cref{lst:count:Intuitive Fastpath}
+ with \co{counter} equal to~10 and
\co{delta} equal to \co{ULONG_MAX}.
Then try it again with the code shown in
Listing~\ref{lst:count:Simple Limit Counter Add, Subtract, and Read}.
--
2.17.1
