rework memory block management to be thread-safe and mostly lock-free.

pa_memblock is now an opaque structure. Access to its fields is now done
through various accessor functions in a thread-safe manner.

pa_memblock_acquire() and pa_memblock_release() are now used to access the
attached audio data. Why? To allow safe manipulation of the memory pointer
maintained by the memory block. Internally _acquire() and _release() maintain a
reference counter. Please do not confuse this reference counter whith the one
maintained by pa_memblock_ref()/_unref()!

As a side effect this patch removes all direct usages of AO_t and replaces it
with pa_atomic_xxx based code.

This stuff needs some serious testing love. Especially if threads are actively
used.



git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1404 fefdeb5f-60dc-0310-8127-8f9354f1896f

src/tests/flist-test.c

@@ -54,7 +54,7 @@ static void thread_func(void *data) {
     int b = 1;
 
     while (!quit) {
-        char *text, *t;
+        char *text;
 
         /* Allocate some memory, if possible take it from the flist */
         if (b && (text = pa_flist_pop(flist)))

src/tests/mcalign-test.c

@@ -59,24 +59,27 @@ int main(PA_GCC_UNUSED int argc, PA_GCC_UNUSED char *argv[]) {
             c.index = c.length = 0;
         }
 
-        assert(c.index < c.memblock->length);
+        assert(c.index < pa_memblock_get_length(c.memblock));
 
-        l = c.memblock->length - c.index;
+        l = pa_memblock_get_length(c.memblock) - c.index;
 
         l = l <= 1 ? l : rand() % (l-1) +1 ;
-        
-        if ((r = read(STDIN_FILENO, (uint8_t*) c.memblock->data + c.index, l)) <= 0) {
+
+        p = pa_memblock_acquire(c.memblock);
+        if ((r = read(STDIN_FILENO, (uint8_t*) p + c.index, l)) <= 0) {
+            pa_memblock_release(c.memblock);
             fprintf(stderr, "read() failed: %s\n", r < 0 ? strerror(errno) : "EOF");
             break;
         }
-
+        pa_memblock_release(c.memblock);
+            
         c.length = r;
         pa_mcalign_push(a, &c);
         fprintf(stderr, "Read %ld bytes\n", (long)r);
 
         c.index += r;
 
-        if (c.index >= c.memblock->length) {
+        if (c.index >= pa_memblock_get_length(c.memblock)) {
             pa_memblock_unref(c.memblock);
             pa_memchunk_reset(&c);
         }
@@ -87,7 +90,9 @@ int main(PA_GCC_UNUSED int argc, PA_GCC_UNUSED char *argv[]) {
             if (pa_mcalign_pop(a, &t) < 0)
                 break;
 
-            pa_loop_write(STDOUT_FILENO, (uint8_t*) t.memblock->data + t.index, t.length, NULL);
+            p = pa_memblock_acquire(t.memblock);
+            pa_loop_write(STDOUT_FILENO, (uint8_t*) p + t.index, t.length, NULL);
+            pa_memblock_release(t.memblock);
             fprintf(stderr, "Wrote %lu bytes.\n", (unsigned long) t.length);
 
             pa_memblock_unref(t.memblock);

src/tests/memblock-test.c

@@ -76,6 +76,7 @@ int main(int argc, char *argv[]) {
     pa_memblock* blocks[5];
     uint32_t id, shm_id;
     size_t offset, size;
+    char *x;
 
     const char txt[] = "This is a test!";
     
@@ -90,10 +91,17 @@ int main(int argc, char *argv[]) {
     assert(pool_a && pool_b && pool_c);
     
     blocks[0] = pa_memblock_new_fixed(pool_a, (void*) txt, sizeof(txt), 1);
+
     blocks[1] = pa_memblock_new(pool_a, sizeof(txt));
-    snprintf(blocks[1]->data, blocks[1]->length, "%s", txt);
+    x = pa_memblock_acquire(blocks[1]);
+    snprintf(x, pa_memblock_get_length(blocks[1]), "%s", txt);
+    pa_memblock_release(blocks[1]);
+    
     blocks[2] = pa_memblock_new_pool(pool_a, sizeof(txt));
-    snprintf(blocks[2]->data, blocks[2]->length, "%s", txt);
+    x = pa_memblock_acquire(blocks[2]);
+    snprintf(x, pa_memblock_get_length(blocks[2]), "%s", txt);
+    pa_memblock_release(blocks[1]);
+
     blocks[3] = pa_memblock_new_malloced(pool_a, pa_xstrdup(txt), sizeof(txt));
     blocks[4] = NULL;
 
@@ -130,14 +138,18 @@ int main(int argc, char *argv[]) {
         
         mb_c = pa_memimport_get(import_c, id, shm_id, offset, size);
         assert(mb_c);
-        printf("1 data=%s\n", (char*) mb_c->data);
+        x = pa_memblock_acquire(mb_c);
+        printf("1 data=%s\n", x);
+        pa_memblock_release(mb_c);
 
         print_stats(pool_a, "A");
         print_stats(pool_b, "B");
         print_stats(pool_c, "C");
         
         pa_memexport_free(export_b);
-        printf("2 data=%s\n", (char*) mb_c->data);
+        x = pa_memblock_acquire(mb_c);
+        printf("2 data=%s\n", x);
+        pa_memblock_release(mb_c);
         pa_memblock_unref(mb_c);
         
         pa_memimport_free(import_b);

src/tests/memblockq-test.c

@@ -131,8 +131,10 @@ int main(int argc, char *argv[]) {
         if (pa_memblockq_peek(bq, &out) < 0)
             break;
 
-        for (e = (char*) out.memblock->data + out.index, n = 0; n < out.length; n++)
+        p = pa_memblock_acquire(out.memblock);
+        for (e = (char*) p + out.index, n = 0; n < out.length; n++)
             printf("%c", *e);
+        pa_memblock_release(out.memblock);
 
         pa_memblock_unref(out.memblock);
         pa_memblockq_drop(bq, &out, out.length);