test/testshm: Fix synchronization of msgput/msgwait IPC functions.

* test/testshm.h():
  Move (APR_INLINE) common msgput/msgwait() functions there.

* test/testshm.h(msgput, msgwait):
  Use atomics (cas) to prevent producer and consumer from writing to
  the same box.

* testshm.c, testshmconsumer.c, testshmproducer.c:
  Use common helpers.



git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1902267 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 65 insertions, 62 deletions

diff --git a/test/testshm.c b/test/testshm.c
index 738706906..12b6f3542 100644
--- a/test/testshm.c
+++ b/test/testshm.c
@@ -31,36 +31,6 @@
 
 #if APR_HAS_SHARED_MEMORY
 
-#if APR_HAS_FORK
-static int msgwait(int sleep_sec, int first_box, int last_box)
-{
-    int i;
-    int recvd = 0;
-    apr_time_t start = apr_time_now();
-    apr_interval_time_t sleep_duration = apr_time_from_sec(sleep_sec);
-    while (apr_time_now() - start < sleep_duration) {
-        for (i = first_box; i < last_box; i++) {
-            if (boxes[i].msgavail && !strcmp(boxes[i].msg, MSG)) {
-                recvd++;
-                boxes[i].msgavail = 0; /* reset back to 0 */
-                /* reset the msg field.  1024 is a magic number and it should
-                 * be a macro, but I am being lazy.
-                 */
-                memset(boxes[i].msg, 0, 1024);
-            }
-        }
-        apr_sleep(apr_time_make(0, 10000)); /* 10ms */
-    }
-    return recvd;
-}
-
-static void msgput(int boxnum, char *msg)
-{
-    apr_cpystrn(boxes[boxnum].msg, msg, strlen(msg) + 1);
-    boxes[boxnum].msgavail = 1;
-}
-#endif /* APR_HAS_FORK */
-
 static void test_anon_create(abts_case *tc, void *data)
 {
     apr_status_t rv;
@@ -102,6 +72,7 @@ static void test_shm_allocate(abts_case *tc, void *data)
 
     boxes = apr_shm_baseaddr_get(shm);
     ABTS_PTR_NOTNULL(tc, boxes);
+    memset(boxes, 0, SHARED_SIZE);
 
     rv = apr_shm_destroy(shm);
     APR_ASSERT_SUCCESS(tc, "Error destroying shared memory block", rv);
@@ -126,10 +97,13 @@ static void test_anon(abts_case *tc, void *data)
 
     boxes = apr_shm_baseaddr_get(shm);
     ABTS_PTR_NOTNULL(tc, boxes);
+    memset(boxes, 0, SHARED_SIZE);
 
     rv = apr_proc_fork(&proc, p);
     if (rv == APR_INCHILD) { /* child */
-        int num = msgwait(5, 0, N_BOXES);
+        int num = msgwait("anon_test", N_MESSAGES,
+                          5, /* wait for 5s */
+                          10 /* with 10ms spin delay */);
         /* exit with the number of messages received so that the parent
          * can check that all messages were received.
          */
@@ -142,8 +116,10 @@ static void test_anon(abts_case *tc, void *data)
             if ((i-=3) < 0) {
                 i += N_BOXES; /* start over at the top */
             }
-            msgput(i, MSG);
-            apr_sleep(apr_time_make(0, 10000));
+            if (!msgput("anon_test", i)) {
+                cnt--;
+            }
+            apr_sleep(apr_time_from_msec(10));
         }
     }
     else {
@@ -183,6 +159,7 @@ static void test_named(abts_case *tc, void *data)
 
     boxes = apr_shm_baseaddr_get(shm);
     ABTS_PTR_NOTNULL(tc, boxes);
+    memset(boxes, 0, SHARED_SIZE);
 
     rv = apr_procattr_create(&attr1, p);
     ABTS_PTR_NOTNULL(tc, attr1);
diff --git a/test/testshm.h b/test/testshm.h
index 5b24a9d42..4d4f0c5db 100644
--- a/test/testshm.h
+++ b/test/testshm.h
@@ -17,17 +17,67 @@
 #ifndef TESTSHM_H
 #define TESTSHM_H
 
+#include "apr.h"
+#include "apr_time.h"
+#include "apr_atomic.h"
+#include "apr_strings.h"
+
+#include <assert.h>
+
 typedef struct mbox {
     char msg[1024]; 
-    int msgavail; 
+    apr_uint32_t msgavail; 
 } mbox;
 mbox *boxes;
 
 #define N_BOXES 10
+#define N_MESSAGES 100
 #define SHARED_SIZE (apr_size_t)(N_BOXES * sizeof(mbox))
 #define SHARED_FILENAME "data/apr.testshm.shm"
-#define N_MESSAGES 100
 #define MSG "Sending a message"
 
-#endif
+#if APR_HAS_SHARED_MEMORY
 
+static APR_INLINE
+int msgwait(const char *msg, int count, int duration, int sleep_ms)
+{
+    int recvd = 0, i;
+    apr_time_t start = apr_time_now();
+    apr_interval_time_t sleep_duration = apr_time_from_sec(duration);
+    apr_interval_time_t sleep_delay = apr_time_from_msec(sleep_ms);
+    while (apr_time_now() - start < sleep_duration) {
+        for (i = 0; i < N_BOXES; i++) {
+            if (apr_atomic_cas32(&boxes[i].msgavail, 0, 1) == 1) {
+                if (msg) {
+                    assert(strcmp(boxes[i].msg, msg) == 0);
+                }
+                *boxes[i].msg = '\0';
+                if (++recvd == count) {
+                    return recvd;
+                }
+            }
+        }
+        apr_sleep(sleep_delay);
+    }
+    return recvd;
+}
+
+static APR_INLINE
+int msgput(const char *msg, int boxnum)
+{
+    if (apr_atomic_cas32(&boxes[boxnum].msgavail, -1, 0) != 0) {
+        return 0;
+    }
+    if (msg) {
+        apr_cpystrn(boxes[boxnum].msg, msg, sizeof(boxes[boxnum].msg));
+    }
+    else {
+        *boxes[boxnum].msg = '\0';
+    }
+    apr_atomic_set32(&boxes[boxnum].msgavail, 1);
+    return 1;
+}
+
+#endif /* APR_HAS_SHARED_MEMORY */
+
+#endif
diff --git a/test/testshmconsumer.c b/test/testshmconsumer.c
index 6a2a3c30d..bf70e728c 100644
--- a/test/testshmconsumer.c
+++ b/test/testshmconsumer.c
@@ -30,25 +30,6 @@
 
 #if APR_HAS_SHARED_MEMORY
 
-static int msgwait(int sleep_sec, int first_box, int last_box)
-{
-    int i;
-    int recvd = 0;
-    apr_time_t start = apr_time_now();
-    apr_interval_time_t sleep_duration = apr_time_from_sec(sleep_sec);
-    while (apr_time_now() - start < sleep_duration) {
-        for (i = first_box; i < last_box; i++) {
-            if (boxes[i].msgavail && !strcmp(boxes[i].msg, MSG)) {
-                recvd++;
-                boxes[i].msgavail = 0; /* reset back to 0 */
-                memset(boxes[i].msg, 0, 1024);
-            }
-        }
-        apr_sleep(apr_time_from_sec(1));
-    }
-    return recvd;
-}
-
 int main(void)
 {
     apr_status_t rv;
@@ -70,7 +51,7 @@ int main(void)
     boxes = apr_shm_baseaddr_get(shm);
 
     /* consume messages on all of the boxes */
-    recvd = msgwait(30, 0, N_BOXES); /* wait for 30 seconds for messages */
+    recvd = msgwait(MSG, N_MESSAGES, 30, 1);
 
     rv = apr_shm_detach(shm);
     if (rv != APR_SUCCESS) {
diff --git a/test/testshmproducer.c b/test/testshmproducer.c
index 58eb94fcd..eb61e76b9 100644
--- a/test/testshmproducer.c
+++ b/test/testshmproducer.c
@@ -29,11 +29,6 @@
 
 
 #if APR_HAS_SHARED_MEMORY
-static void msgput(int boxnum, char *msg)
-{
-    apr_cpystrn(boxes[boxnum].msg, msg, strlen(msg) + 1);
-    boxes[boxnum].msgavail = 1;
-}
 
 int main(void)
 {
@@ -63,7 +58,7 @@ int main(void)
      * are returning the right number.
      */
     for (i = N_BOXES - 1, sent = 0; i >= 0; i--, sent++) {
-        msgput(i, MSG);
+        msgput(MSG, i);
         apr_sleep(apr_time_from_sec(1));
     }