added API for dynamic polls;

include/sntl/pth_queue.h

@@ -9,7 +9,7 @@
 /**
  * @file pth_queue.h
  * @author Alexander Vdolainen
- * @date 4 Nov 2013
+ * @date 4 Nov 2013, 20 Dec 2014 (dynamic polls)
  * @brief queue implementation for threads intercommunication
  *
  */
@@ -19,9 +19,15 @@
 
 #include <pthread.h>
 
-#define SYS_MSG  0x0f0affee
+/* possible message types, ones with POLL_ prefix valid on for pth_dqtpoll_* */
-#define USR_MSG  0x0afeeffe
+#define SYS_MSG        0x0f0affee
-#define NIL_MSG  0x0
+#define USR_MSG        0x0afeeffe
+#define POLL_DECREASE  0x0afafafe
+#define POLL_INCREASE  0x0afaffff
+#define NIL_MSG        0x0
+
+/* max amount of threads within the poll */
+#define MAX_POLL_VALUE  32
 
 typedef struct pth_msg_s {
   void *data;           /** < message payload */
@@ -54,4 +60,50 @@ unsigned int pth_queue_length(pth_queue_t *queue);
 int pth_queue_destroy(pth_queue_t *queue, int freedata,
                       void (*free_msg)(void *));
 
+/* dynamic queue thread poll ... bbrrr .... ok, ok with beer
+ * Dynamic queue thread poll is a queue like pth_queue,
+ * but also it has itäs own mamagement for threads - that's
+ * why dynamic.
+ * Ideally, the model is trying to achieve the following:
+ * 1. one thread in queue while no or very small amount of jobs in the queue
+ * 2. grow until max threads is reached while too many requests
+ * 3. gently slide down volume of threads after job heat
+ * 4. minimal additional drawbacks (i hate something periodically running,
+ * it's bad practice)
+ * The model is quite simple, we should make spurious wakeups equal to zero,
+ * if no - decrease poll value, and, if we don't have thread available -
+ * create it.
+ */
+typedef struct pth_dqtpoll_s {
+  pth_queue_t *queue; /** < Job queue */
+  pthread_t *poll; /** < Thread descriptors */
+  int (*jobdata_callback)(void *); /** < Callback to have a deal with data */
+  int flags; /** < Flags */
+  pthread_rwlock_t stats_lock; /** < rwlock for stats data */
+  unsigned long spurious_wakeups; /** < amount of spurios wakeups */
+  int poll_value; /** < value of the poll (totally) */
+  int sleep_value; /** < value of the sleeping threads */
+} pth_dqtpoll_t;
+
+/* flags for poll */
+#define DQTPOLL_RUNNING    (1 << 1) /* poll is running */
+#define DQTPOLL_DEADSTAGE  (1 << 2) /* poll in the stage of destroy */
+
+/* init poll, structure must be allocated */
+int pth_dqtpoll_init(pth_dqtpoll_t*, int (*jobdata_callback)(void *));
+
+/* run poll: poll */
+int pth_dqtpoll_run(pth_dqtpoll_t*);
+
+/* add the job to the queue: poll, job data, message type  */
+int pth_dqtpoll_add(pth_dqtpoll_t*, void*, unsigned int);
+
+/* destroy the poll: poll, force flag
+ * if force flag is set (!= 0), give up
+ * about jobs, if no, do the job, but don't
+ * accept the new ones, and destroy all poll
+ * with last thread.
+ */
+int pth_dqtpoll_destroy(pth_dqtpoll_t*, int);
+
 #endif /* __PTH_QUEUE_H__ */