first bits of CV code

threads-cv/Makefile

@@ -0,0 +1,20 @@
+CC     := gcc
+CFLAGS := -Wall -Werror -I../include 
+
+SRCS   := join.c \
+	join_modular.c
+
+OBJS   := ${SRCS:c=o}
+PROGS  := ${SRCS:.c=}
+
+.PHONY: all
+all: ${PROGS}
+
+${PROGS} : % : %.o Makefile
+	${CC} $< -o $@ -pthread
+
+clean:
+	rm -f ${PROGS} ${OBJS}
+
+%.o: %.c Makefile
+	${CC} ${CFLAGS} -c $<

threads-cv/join.c

@@ -0,0 +1,31 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <pthread.h>
+#include "common.h"
+#include "common_threads.h"
+
+pthread_cond_t  c = PTHREAD_COND_INITIALIZER;
+pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
+int done = 0;
+
+void *child(void *arg) {
+    printf("child\n");
+    sleep(1);
+    Mutex_lock(&m);
+    done = 1;
+    Cond_signal(&c);
+    Mutex_unlock(&m);
+    return NULL;
+}
+int main(int argc, char *argv[]) {
+    pthread_t p;
+    printf("parent: begin\n");
+    Pthread_create(&p, NULL, child, NULL);
+    Mutex_lock(&m);
+    while (done == 0) 
+	Cond_wait(&c, &m); // releases lock when going to sleep
+    Mutex_unlock(&m);
+    printf("parent: end\n");
+    return 0;
+}
+

threads-cv/join_modular.c

@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <pthread.h>
+#include "common.h"
+#include "common_threads.h"
+
+//
+// Simple sync "object"
+//
+
+typedef struct {
+    pthread_cond_t c;
+    pthread_mutex_t m;
+    int done;
+} synchronizer_t;
+
+synchronizer_t s;
+
+void sync_init(synchronizer_t *s) {
+    s->done = 0;
+    Mutex_init(&s->m);
+    Cond_init(&s->c);
+}
+
+void sync_signal(synchronizer_t *s) {
+    Mutex_lock(&s->m);
+    s->done = 1;
+    Cond_signal(&s->c);
+    Mutex_unlock(&s->m);
+}
+
+void sync_wait(synchronizer_t *s) {
+    Mutex_lock(&s->m);
+    while (s->done == 0) 
+	Cond_wait(&s->c, &s->m); 
+    s->done = 0; // reset for next use
+    Mutex_unlock(&s->m);
+}
+
+
+//
+// Main threads
+//
+
+void *child(void *arg) {
+    printf("child\n");
+    sleep(1);
+    sync_signal(&s);
+    return NULL;
+}
+int main(int argc, char *argv[]) {
+    pthread_t p;
+    printf("parent: begin\n");
+    sync_init(&s);
+    Pthread_create(&p, NULL, child, NULL);
+    sync_wait(&s);
+    printf("parent: end\n");
+    return 0;
+}
+