with shared memory

rktwebview_qt/shmqueue.cpp

@@ -0,0 +1,106 @@
+#include "shmqueue.h"
+
+ShmQueue::ShmQueue(Shm *shm, ShmSlot slot, bool owner)
+{
+    _shm = shm;
+    _owner = owner;
+
+    if (owner) {
+        ShmPlace queue_place = shm->alloc(sizeof(ShmQueueStart));
+        shm->setSlot(slot, queue_place);
+        ref(shm, queue_place, &_queue);
+        _queue->first = SHM_NULL;
+        _queue->last = SHM_NULL;
+        _queue->count = 0;
+    } else {
+        ShmPlace queue_start = shm->slot(slot);
+        ref(shm, queue_start, &_queue);
+    }
+
+    char buf[1024];
+    sprintf(buf, "sem_%s_%d", shm->name(), slot);
+    _queue_sem = shm->sem(buf, owner);
+}
+
+ShmQueue::~ShmQueue()
+{
+    if (_owner) {
+        cleanup();
+    }
+}
+
+void ShmQueue::cleanup()
+{
+    // does currently nothing
+    delete _queue_sem;
+}
+
+int ShmQueue::depth()
+{
+    _shm->lock();
+    int d = _queue->count;
+    _shm->unlock();
+    return d;
+}
+
+void ShmQueue::enqueue(int cmd, const QString &json_data)
+{
+    QByteArray b(json_data.toUtf8());
+
+    int str_place = _shm->alloc(b.size() + 1);
+    char *s;
+    ref(_shm, str_place, &s);
+    memcpy(s, b.constData(), b.size());
+    s[b.size()] = '\0';
+
+    int item_place = _shm->alloc(sizeof(ShmQueueItem));
+    ShmQueueItem *item;
+    ref(_shm, item_place, &item);
+    item->cmd = cmd;
+    item->data_place = str_place;
+    item->prev = _queue->last;
+    item->next = SHM_NULL;
+
+    _shm->lock();
+    _queue->last = item_place;
+    if (_queue->first == SHM_NULL) {
+        _queue->first = _queue->last;
+    }
+    _queue->count += 1;
+    _shm->unlock();
+    _queue_sem->post();
+}
+
+bool ShmQueue::dequeue(int &cmd, QString &json_data, bool wait)
+{
+    if (wait) {
+        _queue_sem->wait();
+    } else {
+        if (!_queue_sem->trywait()) {
+            return false;
+        }
+    }
+    _shm->lock();
+
+    ShmPlace item_place = _queue->first;
+    ShmQueueItem *item;
+    ref(_shm, item_place, &item);
+    _queue->first = item->next;
+    if (_queue->first == SHM_NULL) {
+        _queue->last = SHM_NULL;
+    }
+    _queue->count -= 1;
+
+    _shm->unlock();
+
+    ShmPlace data_place = item->data_place;
+    char *data;
+    ref(_shm, data_place, &data);
+    json_data = QString::fromUtf8(data, strlen(data));
+
+    _shm->free(data_place);
+    cmd = item->cmd;
+
+    _shm->free(item_place);
+    return true;
+}