>From 4bf3961a5c8501a9983a196119038b74cff7a18d Mon Sep 17 00:00:00 2001
From: Akira Yokosawa <akiyks@xxxxxxxxx>
Date: Sun, 14 Oct 2018 16:23:34 +0900
Subject: [PATCH 3/7] toolsoftrade: Employ new scheme for snippets of lock.c
NOTE: Several "if" statements, which are too wide for 2c layout,
are divided into a statement to get error code and a simple "if"
statement.
Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
---
CodeSamples/toolsoftrade/lock.c | 76 +++++++++--------
toolsoftrade/toolsoftrade.tex | 175 +++++++++++-----------------------------
2 files changed, 89 insertions(+), 162 deletions(-)
diff --git a/CodeSamples/toolsoftrade/lock.c b/CodeSamples/toolsoftrade/lock.c
index 6bb3c23..7b56c0f 100644
--- a/CodeSamples/toolsoftrade/lock.c
+++ b/CodeSamples/toolsoftrade/lock.c
@@ -26,62 +26,64 @@
#include <errno.h>
#include "../api.h"
-pthread_mutex_t lock_a = PTHREAD_MUTEX_INITIALIZER;
-pthread_mutex_t lock_b = PTHREAD_MUTEX_INITIALIZER;
+//\begin{snippet}[labelbase=ln:toolsoftrade:lock:reader_writer,commandchars=\$\[\]]
+pthread_mutex_t lock_a = PTHREAD_MUTEX_INITIALIZER; //\lnlbl{lock_a}
+pthread_mutex_t lock_b = PTHREAD_MUTEX_INITIALIZER; //\lnlbl{lock_b}
-int x = 0;
+int x = 0; //\lnlbl{x}
-void *lock_reader(void *arg)
+void *lock_reader(void *arg) //\lnlbl{reader:b}
{
int en;
int i;
int newx = -1;
int oldx = -1;
- pthread_mutex_t *pmlp = (pthread_mutex_t *)arg;
+ pthread_mutex_t *pmlp = (pthread_mutex_t *)arg; //\lnlbl{reader:cast}
- if ((en = pthread_mutex_lock(pmlp)) != 0) {
+ if ((en = pthread_mutex_lock(pmlp)) != 0) { //\lnlbl{reader:acq:b}
fprintf(stderr, "lock_reader:pthread_mutex_lock: %s\n",
strerror(en));
exit(EXIT_FAILURE);
- }
- for (i = 0; i < 100; i++) {
- newx = READ_ONCE(x);
+ } //\lnlbl{reader:acq:e}
+ for (i = 0; i < 100; i++) { //\lnlbl{reader:loop:b}
+ newx = READ_ONCE(x); //\lnlbl{reader:read_x}
if (newx != oldx) {
printf("lock_reader(): x = %d\n", newx);
}
oldx = newx;
- poll(NULL, 0, 1);
- }
- if ((en = pthread_mutex_unlock(pmlp)) != 0) {
+ poll(NULL, 0, 1); //\lnlbl{reader:sleep}
+ } //\lnlbl{reader:loop:e}
+ if ((en = pthread_mutex_unlock(pmlp)) != 0) { //\lnlbl{reader:rel:b}
fprintf(stderr, "lock_reader:pthread_mutex_lock: %s\n",
strerror(en));
exit(EXIT_FAILURE);
- }
- return NULL;
-}
+ } //\lnlbl{reader:rel:e}
+ return NULL; //\lnlbl{reader:return}
+} //\lnlbl{reader:e}
-void *lock_writer(void *arg)
+void *lock_writer(void *arg) //\lnlbl{writer:b}
{
int en;
int i;
- pthread_mutex_t *pmlp = (pthread_mutex_t *)arg;
+ pthread_mutex_t *pmlp = (pthread_mutex_t *)arg; //\lnlbl{writer:cast}
- if ((en = pthread_mutex_lock(pmlp)) != 0) {
+ if ((en = pthread_mutex_lock(pmlp)) != 0) { //\lnlbl{writer:acq:b}
fprintf(stderr, "lock_writer:pthread_mutex_lock: %s\n",
strerror(en));
exit(EXIT_FAILURE);
- }
- for (i = 0; i < 3; i++) {
- WRITE_ONCE(x, READ_ONCE(x) + 1);
+ } //\lnlbl{writer:acq:e}
+ for (i = 0; i < 3; i++) { //\lnlbl{writer:loop:b}
+ WRITE_ONCE(x, READ_ONCE(x) + 1); //\lnlbl{writer:inc}
poll(NULL, 0, 5);
- }
- if ((en = pthread_mutex_unlock(pmlp)) != 0) {
+ } //\lnlbl{writer:loop:e}
+ if ((en = pthread_mutex_unlock(pmlp)) != 0) { //\lnlbl{writer:rel:b}
fprintf(stderr, "lock_writer:pthread_mutex_lock: %s\n",
strerror(en));
exit(EXIT_FAILURE);
- }
+ } //\lnlbl{writer:rel:e}
return NULL;
-}
+} //\lnlbl{writer:e}
+//\end{snippet}
int main(int argc, char *argv[])
{
@@ -90,31 +92,38 @@ int main(int argc, char *argv[])
pthread_t tid2;
void *vp;
+//\begin{snippet}[labelbase=ln:toolsoftrade:lock:same_lock,commandchars=\$\[\]]
printf("Creating two threads using same lock:\n");
- if ((en = pthread_create(&tid1, NULL, lock_reader, &lock_a)) != 0) {
+ en = pthread_create(&tid1, NULL, lock_reader, &lock_a); //\lnlbl{cr:reader:b}
+ if (en != 0) {
fprintf(stderr, "pthread_create: %s\n", strerror(en));
exit(EXIT_FAILURE);
- }
- if ((en = pthread_create(&tid2, NULL, lock_writer, &lock_a)) != 0) {
+ } //\lnlbl{cr:reader:e}
+ en = pthread_create(&tid2, NULL, lock_writer, &lock_a); //\lnlbl{cr:writer:b}
+ if (en != 0) {
fprintf(stderr, "pthread_create: %s\n", strerror(en));
exit(EXIT_FAILURE);
- }
- if ((en = pthread_join(tid1, &vp)) != 0) {
+ } //\lnlbl{cr:writer:e}
+ if ((en = pthread_join(tid1, &vp)) != 0) { //\lnlbl{wait:b}
fprintf(stderr, "pthread_join: %s\n", strerror(en));
exit(EXIT_FAILURE);
}
if ((en = pthread_join(tid2, &vp)) != 0) {
fprintf(stderr, "pthread_join: %s\n", strerror(en));
exit(EXIT_FAILURE);
- }
+ } //\lnlbl{wait:e}
+//\end{snippet}
+//\begin{snippet}[labelbase=ln:toolsoftrade:lock:diff_lock,commandchars=\$\[\]]
printf("Creating two threads w/different locks:\n");
x = 0;
- if ((en = pthread_create(&tid1, NULL, lock_reader, &lock_a)) != 0) {
+ en = pthread_create(&tid1, NULL, lock_reader, &lock_a);
+ if (en != 0) {
fprintf(stderr, "pthread_create: %s\n", strerror(en));
exit(EXIT_FAILURE);
}
- if ((en = pthread_create(&tid2, NULL, lock_writer, &lock_b)) != 0) {
+ en = pthread_create(&tid2, NULL, lock_writer, &lock_b);
+ if (en != 0) {
fprintf(stderr, "pthread_create: %s\n", strerror(en));
exit(EXIT_FAILURE);
}
@@ -126,6 +135,7 @@ int main(int argc, char *argv[])
fprintf(stderr, "pthread_join: %s\n", strerror(en));
exit(EXIT_FAILURE);
}
+//\end{snippet}
return EXIT_SUCCESS;
}
diff --git a/toolsoftrade/toolsoftrade.tex b/toolsoftrade/toolsoftrade.tex
index 601829c..e699b6e 100644
--- a/toolsoftrade/toolsoftrade.tex
+++ b/toolsoftrade/toolsoftrade.tex
@@ -460,82 +460,32 @@ lock~\cite{Hoare74}.
} \QuickQuizEnd
\begin{listing}[tbp]
-{ \scriptsize
-\begin{verbbox}
- 1 pthread_mutex_t lock_a = PTHREAD_MUTEX_INITIALIZER;
- 2 pthread_mutex_t lock_b = PTHREAD_MUTEX_INITIALIZER;
- 3 int x = 0;
- 4
- 5 void *lock_reader(void *arg)
- 6 {
- 7 int i;
- 8 int newx = -1;
- 9 int oldx = -1;
- 10 pthread_mutex_t *pmlp = (pthread_mutex_t *)arg;
- 11
- 12 if (pthread_mutex_lock(pmlp) != 0) {
- 13 perror("lock_reader:pthread_mutex_lock");
- 14 exit(EXIT_FAILURE);
- 15 }
- 16 for (i = 0; i < 100; i++) {
- 17 newx = READ_ONCE(x);
- 18 if (newx != oldx) {
- 19 printf("lock_reader(): x = %d\n", newx);
- 20 }
- 21 oldx = newx;
- 22 poll(NULL, 0, 1);
- 23 }
- 24 if (pthread_mutex_unlock(pmlp) != 0) {
- 25 perror("lock_reader:pthread_mutex_unlock");
- 26 exit(EXIT_FAILURE);
- 27 }
- 28 return NULL;
- 29 }
- 30
- 31 void *lock_writer(void *arg)
- 32 {
- 33 int i;
- 34 pthread_mutex_t *pmlp = (pthread_mutex_t *)arg;
- 35
- 36 if (pthread_mutex_lock(pmlp) != 0) {
- 37 perror("lock_writer:pthread_mutex_lock");
- 38 exit(EXIT_FAILURE);
- 39 }
- 40 for (i = 0; i < 3; i++) {
- 41 WRITE_ONCE(x, READ_ONCE(x) + 1);
- 42 poll(NULL, 0, 5);
- 43 }
- 44 if (pthread_mutex_unlock(pmlp) != 0) {
- 45 perror("lock_writer:pthread_mutex_unlock");
- 46 exit(EXIT_FAILURE);
- 47 }
- 48 return NULL;
- 49 }
-\end{verbbox}
-}
-\centering
-\theverbbox
+\input{CodeSamples/toolsoftrade/lock@reader_writer.fcv}
\caption{Demonstration of Exclusive Locks}
\label{lst:toolsoftrade:Demonstration of Exclusive Locks}
\end{listing}
+\begin{lineref}[ln:toolsoftrade:lock:reader_writer]
This exclusive-locking property is demonstrated using the code shown in
Listing~\ref{lst:toolsoftrade:Demonstration of Exclusive Locks}
(\path{lock.c}).
-Line~1 defines and initializes a POSIX lock named \co{lock_a}, while
-line~2 similarly defines and initializes a lock named \co{lock_b}.
-Line~3 defines and initializes a shared variable~\co{x}.
+Line~\lnref{lock_a} defines and initializes a POSIX lock named \co{lock_a}, while
+line~\lnref{lock_b} similarly defines and initializes a lock named \co{lock_b}.
+Line~\lnref{x} defines and initializes a shared variable~\co{x}.
+\end{lineref}
-Lines~5-28 defines a function \co{lock_reader()} which repeatedly
+\begin{lineref}[ln:toolsoftrade:lock:reader_writer:reader]
+Lines~\lnref{b}-\lnref{e} defines a function \co{lock_reader()} which repeatedly
reads the shared variable \co{x} while holding
the lock specified by \co{arg}.
-Line~10 casts \co{arg} to a pointer to a \co{pthread_mutex_t}, as
+Line~\lnref{cast} casts \co{arg} to a pointer to a \co{pthread_mutex_t}, as
required by the \co{pthread_mutex_lock()} and \co{pthread_mutex_unlock()}
primitives.
+\end{lineref}
\QuickQuiz{}
Why not simply make the argument to \co{lock_reader()}
- on line~5 of
+ on line~\ref{ln:toolsoftrade:lock:reader_writer:reader:b} of
Listing~\ref{lst:toolsoftrade:Demonstration of Exclusive Locks}
be a pointer to a \co{pthread_mutex_t}?
\QuickQuizAnswer{
@@ -547,9 +497,12 @@ primitives.
} \QuickQuizEnd
\QuickQuiz{}
- What is the \co{READ_ONCE()} on lines~17 and~41 and the
- \co{WRITE_ONCE()} on line~41 of
+ \begin{lineref}[ln:toolsoftrade:lock:reader_writer]
+ What is the \co{READ_ONCE()} on
+ lines~\lnref{reader:read_x} and~\lnref{writer:inc} and the
+ \co{WRITE_ONCE()} on line~\lnref{writer:inc} of
Listing~\ref{lst:toolsoftrade:Demonstration of Exclusive Locks}?
+ \end{lineref}
\QuickQuizAnswer{
These macros constrain the compiler so as to prevent it from
carrying out optimizations that would be problematic for concurrently
@@ -569,16 +522,21 @@ primitives.
Chapter~\ref{chp:Advanced Synchronization: Memory Ordering}.
} \QuickQuizEnd
-Lines~12-15 acquire the specified \co{pthread_mutex_t}, checking
+\begin{lineref}[ln:toolsoftrade:lock:reader_writer:reader]
+Lines~\lnref{acq:b}-\lnref{acq:e} acquire the specified
+\co{pthread_mutex_t}, checking
for errors and exiting the program if any occur.
-Lines~16-23 repeatedly check the value of \co{x}, printing the new value
+Lines~\lnref{loop:b}-\lnref{loop:e} repeatedly check the value of \co{x},
+printing the new value
each time that it changes.
-Line~22 sleeps for one millisecond, which allows this demonstration
+Line~\lnref{sleep} sleeps for one millisecond, which allows this demonstration
to run nicely on a uniprocessor machine.
-Lines~24-27 release the \co{pthread_mutex_t}, again checking for
+Lines~\lnref{rel:b}-\lnref{rel:e} release the \co{pthread_mutex_t},
+again checking for
errors and exiting the program if any occur.
-Finally, line~28 returns \co{NULL}, again to match the function type
+Finally, line~\lnref{return} returns \co{NULL}, again to match the function type
required by \co{pthread_create()}.
+\end{lineref}
\QuickQuiz{}
Writing four lines of code for each acquisition and release
@@ -593,55 +551,39 @@ required by \co{pthread_create()}.
\co{spin_lock()} and \co{spin_unlock()} APIs.
} \QuickQuizEnd
-Lines~31-49 of
+\begin{lineref}[ln:toolsoftrade:lock:reader_writer:writer]
+Lines~\lnref{b}-\lnref{e} of
Listing~\ref{lst:toolsoftrade:Demonstration of Exclusive Locks}
shows \co{lock_writer()}, which
periodically update the shared variable \co{x} while holding the
specified \co{pthread_mutex_t}.
-As with \co{lock_reader()}, line~34 casts \co{arg} to a pointer
-to \co{pthread_mutex_t}, lines~36-39 acquires the specified lock,
-and lines~44-47 releases it.
-While holding the lock, lines~40-43 increment the shared variable \co{x},
+As with \co{lock_reader()}, line~\lnref{cast} casts \co{arg} to a pointer
+to \co{pthread_mutex_t},
+lines~\lnref{acq:b}-\lnref{acq:e} acquires the specified lock,
+and lines~\lnref{rel:b}-\lnref{rel:e} releases it.
+While holding the lock, lines~\lnref{loop:b}-\lnref{loop:e}
+increment the shared variable \co{x},
sleeping for five milliseconds between each increment.
-Finally, lines~44-47 release the lock.
+Finally, lines~\lnref{rel:b}-\lnref{rel:e} release the lock.
+\end{lineref}
\begin{listing}[tbp]
-{ \scriptsize
-\begin{verbbox}
- 1 printf("Creating two threads using same lock:\n");
- 2 if (pthread_create(&tid1, NULL,
- 3 lock_reader, &lock_a) != 0) {
- 4 perror("pthread_create");
- 5 exit(EXIT_FAILURE);
- 6 }
- 7 if (pthread_create(&tid2, NULL,
- 8 lock_writer, &lock_a) != 0) {
- 9 perror("pthread_create");
- 10 exit(EXIT_FAILURE);
- 11 }
- 12 if (pthread_join(tid1, &vp) != 0) {
- 13 perror("pthread_join");
- 14 exit(EXIT_FAILURE);
- 15 }
- 16 if (pthread_join(tid2, &vp) != 0) {
- 17 perror("pthread_join");
- 18 exit(EXIT_FAILURE);
- 19 }
-\end{verbbox}
-}
-\centering
-\theverbbox
+\input{CodeSamples/toolsoftrade/lock@same_lock.fcv}
\caption{Demonstration of Same Exclusive Lock}
\label{lst:toolsoftrade:Demonstration of Same Exclusive Lock}
\end{listing}
+\begin{lineref}[ln:toolsoftrade:lock:same_lock]
Listing~\ref{lst:toolsoftrade:Demonstration of Same Exclusive Lock}
shows a code fragment that runs \co{lock_reader()} and
\co{lock_writer()} as threads using the same lock, namely, \co{lock_a}.
-Lines~2-6 create a thread running \co{lock_reader()}, and then
-Lines~7-11 create a thread running \co{lock_writer()}.
-Lines~12-19 wait for both threads to complete.
+Lines~\lnref{cr:reader:b}-\lnref{cr:reader:e} create a thread
+running \co{lock_reader()}, and then
+Lines~\lnref{cr:writer:b}-\lnref{cr:writer:e} create a thread
+running \co{lock_writer()}.
+Lines~\lnref{wait:b}-\lnref{wait:e} wait for both threads to complete.
The output of this code fragment is as follows:
+\end{lineref}
\begin{VerbatimU}
Creating two threads using same lock:
@@ -672,32 +614,7 @@ by \co{lock_writer()} while holding the lock.
} \QuickQuizEnd
\begin{listing}[tbp]
-{ \scriptsize
-\begin{verbbox}
- 1 printf("Creating two threads w/different locks:\n");
- 2 x = 0;
- 3 if (pthread_create(&tid1, NULL,
- 4 lock_reader, &lock_a) != 0) {
- 5 perror("pthread_create");
- 6 exit(EXIT_FAILURE);
- 7 }
- 8 if (pthread_create(&tid2, NULL,
- 9 lock_writer, &lock_b) != 0) {
- 10 perror("pthread_create");
- 11 exit(EXIT_FAILURE);
- 12 }
- 13 if (pthread_join(tid1, &vp) != 0) {
- 14 perror("pthread_join");
- 15 exit(EXIT_FAILURE);
- 16 }
- 17 if (pthread_join(tid2, &vp) != 0) {
- 18 perror("pthread_join");
- 19 exit(EXIT_FAILURE);
- 20 }
-\end{verbbox}
-}
-\centering
-\theverbbox
+\input{CodeSamples/toolsoftrade/lock@diff_lock.fcv}
\caption{Demonstration of Different Exclusive Locks}
\label{lst:toolsoftrade:Demonstration of Different Exclusive Locks}
\end{listing}
@@ -761,7 +678,7 @@ values of \co{x} stored by \co{lock_writer()}.
so why does it need to be initialized in
Listing~\ref{lst:toolsoftrade:Demonstration of Different Exclusive Locks}?
\QuickQuizAnswer{
- See line~3 of
+ See line~\ref{ln:toolsoftrade:lock:reader_writer:x} of
Listing~\ref{lst:toolsoftrade:Demonstration of Exclusive Locks}.
Because the code in
Listing~\ref{lst:toolsoftrade:Demonstration of Same Exclusive Lock}
--
2.7.4
