@@ -13,57 +13,62 @@ two threads, one prints odd one prints even in order
1313pthread_mutex_t mtx;
1414pthread_cond_t cond;
1515
16- int seq = START_NUMBER;
17- 18- int thread_run;
16+ int seq;
17+ int run_thread;
1918
2019typedef struct range_s {
2120 int start;
2221 int end;
2322} range_t;
2423
2524int odd_print_one(const int start, const int end) {
26- 25+ int rc = 0;
26+ 2727 pthread_mutex_lock(&mtx);
2828
2929 // wait for cond to be singaled by using mtx and cond
30- while (thread_run = = 1) {
30+ while (run_thread ! = 1) {
3131 pthread_cond_wait(&cond, &mtx);
3232 }
3333 if (seq > end) {
34- pthread_mutex_unlock(&mtx);
35- return -1;
34+ rc = -1;
35+ } else {
36+ printf("%d ", seq);
37+ seq ++;
3638 }
37- printf("%d ", seq);
38- seq ++;
39- thread_run = 2;
39+ run_thread = 2;
40+ 4041 // siganl cond variable;
4142 pthread_cond_signal(&cond);
4243 pthread_mutex_unlock(&mtx);
4344
44- return 0 ;
45+ return rc ;
4546}
4647
48+ /* most of code is common with odd_print_one(), they can be
49+ incooperated as one function, for readability, I keep them
50+ separated here. */
4751int even_print_one(const int start, const int end) {
48- 52+ int rc = 0;
4953 pthread_mutex_lock(&mtx);
5054
5155 // wait for cond to be singaled by using mtx and cond
52- while (thread_run = = 2) {
56+ while (run_thread ! = 2) {
5357 pthread_cond_wait(&cond, &mtx);
5458 }
5559 if (seq > end) {
56- pthread_mutex_unlock(&mtx);
57- return -1;
60+ rc = -1;
61+ } else {
62+ printf("%d ", seq);
63+ seq ++;
5864 }
59- printf("%d ", seq);
60- seq ++;
61- thread_run = 1;
65+ run_thread = 1;
66+ 6267 // siganl cond variable
63- pthread_cond_signal(&cond);
6468 pthread_mutex_unlock(&mtx);
69+ pthread_cond_signal(&cond);
6570
66- return 0 ;
71+ return rc ;
6772}
6873
6974void *odd_printer(void *args) {
@@ -94,12 +99,13 @@ int main() {
9499 void *ret;
95100
96101 const range_t range = {START_NUMBER, END_NUMBER};
97- 102+ 103+ seq = range.start;
104+ run_thread = 1;
105+ 98106 pthread_mutex_init(&mtx, NULL);
99107 pthread_cond_init(&cond, NULL);
100108
101- thread_run = 1;
102- 103109 rc = pthread_create(&odd_thread, NULL, odd_printer, (void *)&range);
104110 if (rc != 0) {
105111 goto cu1;
@@ -112,9 +118,9 @@ int main() {
112118
113119 // clean up
114120 pthread_join(even_thread, &ret);
115- 116121cu0:
117- pthread_join(odd_thread, &ret);
122+ pthread_join(odd_thread, &ret);
123+ 118124cu1:
119125 printf("\n");
120126 pthread_mutex_destroy(&mtx);
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