Timerlib Integrated with Wheel Timer

WheelTimer/libtimer/WheelTimer.c

@@ -5,10 +5,7 @@
 #include <unistd.h>
 #include <time.h>
 #include <assert.h>
-
-#define TH_JOINABLE	1
-#define TH_DETACHED	0
-
+#include "timerlib.h"
 
 int
 insert_wt_elem_in_slot(void *data1, void *data2){
@@ -25,25 +22,6 @@ insert_wt_elem_in_slot(void *data1, void *data2){
    return 0;
 }
 
-wheel_timer_t*
-init_wheel_timer(int wheel_size, int clock_tic_interval){
-	wheel_timer_t *wt = calloc(1, sizeof(wheel_timer_t) + 
-				(wheel_size * sizeof(slotlist_t)));
-
-	wt->clock_tic_interval = clock_tic_interval;
-	wt->wheel_size = wheel_size;
-
-    memset(&(wt->wheel_thread), 0, sizeof(wheel_timer_t));
-
-	int i = 0;
-	for(; i < wheel_size; i++){
-        init_glthread(WT_SLOTLIST_HEAD(wt, i));
-        pthread_mutex_init(WT_SLOTLIST_MUTEX(wt, i), NULL);
-    }
-    wt->no_of_wt_elem = 0;
-	return wt;
-}
-
 static void
 process_wt_reschedule_slotlist(wheel_timer_t *wt){
 
@@ -100,65 +78,86 @@ process_wt_reschedule_slotlist(wheel_timer_t *wt){
     WT_UNLOCK_SLOT_LIST(WT_GET_RESCHD_SLOTLIST(wt));
 }
 
-
-static void *
-wheel_fn(void *arg){
+static void
+wheel_fn(Timer_t *timer, void *arg){
 
 	wheel_timer_t *wt = (wheel_timer_t *)arg;
 	wheel_timer_elem_t *wt_elem = NULL;
 	int absolute_slot_no = 0, i =0;
-    slotlist_t *slot_list = NULL;
+	slotlist_t *slot_list = NULL;
 	glthread_t *curr;
 
-	while(1){
-        
-        wt->current_clock_tic++;
-        if(wt->current_clock_tic == wt->wheel_size){
-            wt->current_clock_tic = 0;
-            wt->current_cycle_no++;
-        }
-
-		sleep(wt->clock_tic_interval);
-
-		slot_list = WT_SLOTLIST(wt, wt->current_clock_tic);
-		absolute_slot_no = GET_WT_CURRENT_ABS_SLOT_NO(wt);
-
-		 ITERATE_GLTHREAD_BEGIN(&slot_list->slots, curr){
-
-            wt_elem = glthread_to_wt_elem(curr);
-           
-            /*Check if R == r*/
-			if(wt->current_cycle_no == wt_elem->execute_cycle_no){
-                /*Invoke the application event through fn pointer as below*/
-				wt_elem->app_callback(wt_elem->arg, wt_elem->arg_size);
-
-                /* After invocation, check if the event needs to be rescheduled again
-                 * in future*/
-				if(wt_elem->is_recurrence){
-
-                    /*relocate Or reschedule to the next slot*/
-					int next_abs_slot_no  = absolute_slot_no + 
-                            (wt_elem->time_interval/wt->clock_tic_interval);
-					int next_cycle_no     = next_abs_slot_no / wt->wheel_size;
-					int next_slot_no      = next_abs_slot_no % wt->wheel_size;
-					wt_elem->execute_cycle_no 	 = next_cycle_no;
-                    remove_glthread(&wt_elem->glue);
-					glthread_priority_insert(WT_SLOTLIST_HEAD(wt, next_slot_no), &wt_elem->glue, 
-                                    insert_wt_elem_in_slot, 
-                                    (unsigned long)&((wheel_timer_elem_t *)0)->glue);
-                    wt_elem->slotlist_head = WT_SLOTLIST(wt, next_slot_no);
-                    wt_elem->slot_no = next_slot_no;
-                    wt_elem->N_scheduled++;
-				}
-			}
-            else
-                break;
-        } ITERATE_GLTHREAD_END(slot_list, curr)
-        process_wt_reschedule_slotlist(wt);
+	wt->current_clock_tic++;
+	if(wt->current_clock_tic == wt->wheel_size){
+		wt->current_clock_tic = 0;
+		wt->current_cycle_no++;
 	}
-	return NULL;
+
+	slot_list = WT_SLOTLIST(wt, wt->current_clock_tic);
+	absolute_slot_no = GET_WT_CURRENT_ABS_SLOT_NO(wt);
+
+	ITERATE_GLTHREAD_BEGIN(&slot_list->slots, curr){
+
+		wt_elem = glthread_to_wt_elem(curr);
+
+		/*Check if R == r*/
+		if(wt->current_cycle_no == wt_elem->execute_cycle_no){
+			/*Invoke the application event through fn pointer as below*/
+			wt_elem->app_callback(wt_elem->arg, wt_elem->arg_size);
+
+			/* After invocation, check if the event needs to be rescheduled again
+			 * in future*/
+			if(wt_elem->is_recurrence){
+
+				/*relocate Or reschedule to the next slot*/
+				int next_abs_slot_no  = absolute_slot_no + 
+					(wt_elem->time_interval/wt->clock_tic_interval);
+				int next_cycle_no     = next_abs_slot_no / wt->wheel_size;
+				int next_slot_no      = next_abs_slot_no % wt->wheel_size;
+				wt_elem->execute_cycle_no 	 = next_cycle_no;
+				remove_glthread(&wt_elem->glue);
+				glthread_priority_insert(WT_SLOTLIST_HEAD(wt, next_slot_no), &wt_elem->glue, 
+						insert_wt_elem_in_slot, 
+						(unsigned long)&((wheel_timer_elem_t *)0)->glue);
+				wt_elem->slotlist_head = WT_SLOTLIST(wt, next_slot_no);
+				wt_elem->slot_no = next_slot_no;
+				wt_elem->N_scheduled++;
+			}
+		}
+		else
+			break;
+	} ITERATE_GLTHREAD_END(slot_list, curr)
+	process_wt_reschedule_slotlist(wt);
 }
 
+wheel_timer_t*
+init_wheel_timer(int wheel_size, int clock_tic_interval){
+	
+	wheel_timer_t *wt = calloc(1, sizeof(wheel_timer_t) + 
+				(wheel_size * sizeof(slotlist_t)));
+
+	wt->clock_tic_interval = clock_tic_interval;
+	wt->wheel_size = wheel_size;
+
+	wt->wheel_thread = setup_timer(wheel_fn,
+							wt->clock_tic_interval * 1000,
+							wt->clock_tic_interval * 1000,
+							0,
+							(void *)wt,
+							false);
+
+	int i = 0;
+
+	for(; i < wheel_size; i++){
+        init_glthread(WT_SLOTLIST_HEAD(wt, i));
+        pthread_mutex_init(WT_SLOTLIST_MUTEX(wt, i), NULL);
+    }
+
+    wt->no_of_wt_elem = 0;
+	return wt;
+}
+
+
 static void
 _wt_elem_reschedule(wheel_timer_t *wt, 
                     wheel_timer_elem_t *wt_elem, 
@@ -179,12 +178,14 @@ _wt_elem_reschedule(wheel_timer_t *wt,
         case WTELEM_DELETE:
             
                wt_elem->new_time_interval = new_time_interval;
+			   pause_timer(wt->wheel_thread);
                WT_LOCK_SLOT_LIST(WT_GET_RESCHD_SLOTLIST(wt));
                wt_elem->opcode = opcode;
                remove_glthread(&wt_elem->reschedule_glue);
                glthread_add_next(WT_GET_RESCHD_SLOTLIST_HEAD(wt), 
-                &wt_elem->reschedule_glue);
-               WT_UNLOCK_SLOT_LIST(WT_GET_RESCHD_SLOTLIST(wt));         
+               		&wt_elem->reschedule_glue);
+               WT_UNLOCK_SLOT_LIST(WT_GET_RESCHD_SLOTLIST(wt));
+ 			   resume_timer(wt->wheel_thread);
             break;
         default:
             assert(0);
@@ -300,11 +301,7 @@ print_wheel_timer(wheel_timer_t *wt){
 void
 start_wheel_timer(wheel_timer_t *wt){
 
-	if (pthread_create(&wt->wheel_thread, NULL, wheel_fn, (void*)wt))
-	{
-		printf("Wheel Timer Thread initialization failed, exiting ... \n");
-		exit(0);
-	}
+	start_timer(wt->wheel_thread);
 }
 
 void
@@ -336,3 +333,11 @@ hrs_min_sec_format(unsigned int seconds){
     return time_f;
 }
 
+void
+cancel_wheel_timer(wheel_timer_t *wt){
+
+	if(wt->wheel_thread){
+		cancel_timer(wt->wheel_thread);
+	}
+}
+

WheelTimer/libtimer/WheelTimer.h

@@ -2,6 +2,7 @@
 #define __WHEEL_TIMER__
 
 #include <pthread.h>
+#include "timerlib.h"
 #include "gluethread/glthread.h"
 
 typedef struct _wheel_timer_elem_t wheel_timer_elem_t;
@@ -45,7 +46,7 @@ typedef struct _wheel_timer_t {
 	int clock_tic_interval;
 	int wheel_size;
 	int current_cycle_no;
-	pthread_t wheel_thread;
+	Timer_t *wheel_thread;
     slotlist_t reschd_list;
     unsigned int no_of_wt_elem;
     slotlist_t slotlist[0];

WheelTimer/libtimer/WheelTimerDemo.c

@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include "WheelTimer.h"
+#include <string.h>
+
+#define WHEEL_SIZE 10
+#define WHEEL_TIMER_CLOCK_TIC_INTERVAL 1
+
+/* Application routine to be (indirectly) invoked by Wheel timer.
+ * It could be of any prototype*/
+void
+print_hello(char *S){ 
+    printf("%s\n", S);
+}
+
+/* But Only routines (Events) which have prototype : void *(fn)(void *arg, int arg_size) 
+ * could be registered with wheel timer. Therefore, we need to encapsulate
+ * the actual routine print_hello() to be invoked inside the routine of 
+ * void *(fn)(void *arg, int arg_size) prototype. It is the wrapper which will be registered 
+ * with wheel timer and invoked by wheel timer. We will unwrap the argument and invoke the actual 
+ * appln routine with correct arguments. This technique is called 'Masking of routines'*/
+
+void wrapper_print_hello(void *arg, int arg_size){
+    char *S = (char *)arg;
+    print_hello(S);
+}
+
+int
+main(int argc, char **argv){
+
+    /*create a wheel timer object*/
+    wheel_timer_t *wt = init_wheel_timer(WHEEL_SIZE, WHEEL_TIMER_CLOCK_TIC_INTERVAL);
+    /*start the wheel timer thread*/
+    start_wheel_timer(wt);
+
+    /*Now Wheel timer has started running in a separte thread. 
+     * Register the events to be triggered with Wheel timer now.*/
+
+    wheel_timer_elem_t * wt_elem = 
+        register_app_event(wt, wrapper_print_hello, "MyString", 
+                           strlen("MyString"), 
+                           5,  /*wrapper_print_hello fn will be called after every 5 seconds*/
+                           1); /*1 indefinitely, 0 only once : call for wrapper_print_hello*/
+
+    wt_elem = 
+        register_app_event(wt, wrapper_print_hello, "Udemy", 
+                           strlen("Udemy"), 
+                           3,  /*wrapper_print_hello fn will be called after every 5 seconds*/
+                           1); /*1 indefinitely, 0 only once : call for wrapper_print_hello*/
+    /*stop the main program from gettin terminated, otherwise wheel timer
+     * thread we created will also get terminated*/
+    scanf("\n");
+    return 0;
+}

WheelTimer/libtimer/compile.sh

@@ -3,3 +3,7 @@ rm *exe
 gcc -g -c timerlib.c -o timerlib.o
 gcc -g -c timerlib_test.c -o timerlib_test.o
 gcc -g timerlib.o timerlib_test.o -o exe -lrt
+gcc -g -c WheelTimer.c -o WheelTimer.o
+gcc -g -c WheelTimerDemo.c -o WheelTimerDemo.o
+gcc -g -c gluethread/glthread.c -o gluethread/glthread.o
+gcc -g WheelTimerDemo.o WheelTimer.o timerlib.o gluethread/glthread.o -o WheelTimerDemo.exe -lrt

WheelTimer/libtimer/timerlib.c

@@ -183,8 +183,9 @@ cancel_timer(Timer_t *timer){
 void
 pause_timer(Timer_t *timer){
 
-	assert(timer->timer_state == TIMER_RUNNING);
-	
+	if ( timer_get_current_state(timer) == TIMER_PAUSED)
+		return;
+
 	timer->time_remaining = 
 		timer_get_time_remaining_in_mill_sec(timer);