* the device. Items in this record are "local" to the Job and
* do not affect other Jobs. Note, a job can have multiple
* DCRs open, each pointing to a different device.
+ * Normally, there is only one JCR thread per DCR. However, the
+ * big and important exception to this is when a Job is being
+ * canceled. At that time, there may be two threads using the
+ * same DCR. Consequently, when creating/attaching/detaching
+ * and freeing the DCR we must lock it (m_mutex).
*/
class DCR {
private:
public:
dlink dev_link; /* link to attach to dev */
JCR *jcr; /* pointer to JCR */
+ pthread_mutex_t m_mutex; /* access control */
DEVICE * volatile dev; /* pointer to device */
DEVRES *device; /* pointer to device resource */
DEV_BLOCK *block; /* pointer to block */