Add checks to sample task systems to ensure that TasksInit has been

called; if not, print an informative error message.

examples/mandelbrot_tasks/tasks_concrt.cpp

@@ -39,6 +39,7 @@
 using namespace Concurrency;
 #include <assert.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 // ispc expects these functions to have C linkage / not be mangled
 extern "C" { 
@@ -61,12 +62,14 @@ static int taskOffset;
 static TaskInfo taskInfo[MAX_TASKS];
 static event *events[MAX_TASKS];
 static CRITICAL_SECTION criticalSection;
+static bool initialized = false;
 
 void
 TasksInit() {
     InitializeCriticalSection(&criticalSection);
     for (int i = 0; i < MAX_TASKS; ++i)
         events[i] = new event;
+    initialized = true;
 }
 
 
@@ -91,6 +94,11 @@ lRunTask(LPVOID param) {
 
 void
 ISPCLaunch(void *func, void *data) {
+    if (!initialized) {
+        fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
+        exit(1);
+    }
+
     // Get a TaskInfo struct for this task
     EnterCriticalSection(&criticalSection);
     TaskInfo *ti = &taskInfo[taskOffset++];
@@ -105,6 +113,11 @@ ISPCLaunch(void *func, void *data) {
 
 
 void ISPCSync() {
+    if (!initialized) {
+        fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
+        exit(1);
+    }
+
     event::wait_for_multiple(&events[0], taskOffset, true, 
                              COOPERATIVE_TIMEOUT_INFINITE);
 

examples/mandelbrot_tasks/tasks_gcd.cpp

@@ -35,7 +35,10 @@
    Dispatch. */
 
 #include <dispatch/dispatch.h>
+#include <stdio.h>
+#include <stdlib.h>
 
+static bool initialized = false;
 static dispatch_queue_t gcdQueue;
 static dispatch_group_t gcdGroup;
 
@@ -55,6 +58,7 @@ void
 TasksInit() {
     gcdQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
     gcdGroup = dispatch_group_create();
+    initialized = true;
 }
 
 
@@ -77,6 +81,10 @@ lRunTask(void *ti) {
 
 
 void ISPCLaunch(void *func, void *data) {
+    if (!initialized) {
+        fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
+        exit(1);
+    }
     TaskInfo *ti = new TaskInfo;
     ti->func = func;
     ti->data = data;
@@ -85,6 +93,11 @@ void ISPCLaunch(void *func, void *data) {
 
 
 void ISPCSync() {
+    if (!initialized) {
+        fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
+        exit(1);
+    }
+
     // Wait for all of the tasks in the group to complete before returning
     dispatch_group_wait(gcdGroup, DISPATCH_TIME_FOREVER);
 }

examples/mandelbrot_tasks/tasks_pthreads.cpp

@@ -135,6 +135,11 @@ TasksInit() {
 
 void
 ISPCLaunch(void *f, void *d) {
+    if (threads == NULL) {
+        fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
+        exit(1);
+    }
+
     //
     // Acquire mutex, add task
     //
@@ -256,6 +261,11 @@ lTaskEntry(void *arg) {
 
 
 void ISPCSync() {
+    if (threads == NULL) {
+        fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
+        exit(1);
+    }
+
     int err;
     if ((err = pthread_mutex_lock(&tasksRunningConditionMutex)) != 0) {
         fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));