Returns now GNUNET_SYSERR
[oweals/gnunet.git] / src / util / scheduler.c
index 6b12c7d1a2cabc518d4a3787e3a1f445c49576ac..49d491bd7843546e48974b39f0a53159256dd52a 100644 (file)
  */
 #include "platform.h"
 #include "gnunet_common.h"
+#include "gnunet_os_lib.h"
 #include "gnunet_scheduler_lib.h"
 #include "gnunet_signal_lib.h"
 #include "gnunet_time_lib.h"
+#include "disk.h"
+#ifdef LINUX
+#include "execinfo.h"
+
+
+/**
+ * Use lsof to generate file descriptor reports on select error?
+ * (turn off for stable releases).
+ */
+#define USE_LSOF GNUNET_YES
+
+/**
+ * Obtain trace information for all scheduler calls that schedule tasks.
+ */
+#define EXECINFO GNUNET_NO
+
+/**
+ * Depth of the traces collected via EXECINFO.
+ */
+#define MAX_TRACE_DEPTH 50
+#endif
 
 #define DEBUG_TASKS GNUNET_NO
 
+/**
+ * Should we figure out which tasks are delayed for a while
+ * before they are run? (Consider using in combination with EXECINFO).
+ */
+#define PROFILE_DELAYS GNUNET_NO
+
+/**
+ * Task that were in the queue for longer than this are reported if
+ * PROFILE_DELAYS is active.
+ */
+#define DELAY_THRESHOLD GNUNET_TIME_UNIT_SECONDS
+
 /**
  * Linked list of pending tasks.
  */
@@ -60,10 +94,9 @@ struct Task
   struct GNUNET_NETWORK_FDSet *read_set;
 
   /**
-   * Set of file descriptors this task is waiting
-   * for for writing.  Once ready, this is updated
-   * to reflect the set of file descriptors ready
-   * for operation.
+   * Set of file descriptors this task is waiting for for writing.
+   * Once ready, this is updated to reflect the set of file
+   * descriptors ready for operation.
    */
   struct GNUNET_NETWORK_FDSet *write_set;
 
@@ -83,6 +116,13 @@ struct Task
    */
   struct GNUNET_TIME_Absolute timeout;
 
+#if PROFILE_DELAYS
+  /**
+   * When was the task scheduled?
+   */
+  struct GNUNET_TIME_Absolute start_time;
+#endif
+
   /**
    * Why is the task ready?  Set after task is added to ready queue.
    * Initially set to zero.  All reasons that have already been
@@ -95,62 +135,99 @@ struct Task
    */
   enum GNUNET_SCHEDULER_Priority priority;
 
-};
-
-
-/**
- * Handle for the scheduling service.
- */
-struct GNUNET_SCHEDULER_Handle
-{
-
   /**
-   * List of tasks waiting for an event.
+   * Set if we only wait for reading from a single FD, otherwise -1.
    */
-  struct Task *pending;
+  int read_fd;
 
   /**
-   * ID of the task that is running right now.
+   * Set if we only wait for writing to a single FD, otherwise -1.
    */
-  struct Task *active_task;
+  int write_fd;
 
+#if EXECINFO
   /**
-   * List of tasks ready to run right now,
-   * grouped by importance.
+   * Array of strings which make up a backtrace from the point when this
+   * task was scheduled (essentially, who scheduled the task?)
    */
-  struct Task *ready[GNUNET_SCHEDULER_PRIORITY_COUNT];
+  char **backtrace_strings;
 
   /**
-   * Identity of the last task queued.  Incremented for each task to
-   * generate a unique task ID (it is virtually impossible to start
-   * more than 2^64 tasks during the lifetime of a process).
+   * Size of the backtrace_strings array
    */
-  GNUNET_SCHEDULER_TaskIdentifier last_id;
+  int num_backtrace_strings;
+#endif
 
-  /**
-   * Highest number so that all tasks with smaller identifiers
-   * have already completed.  Also the lowest number of a task
-   * still waiting to be executed.
-   */
-  GNUNET_SCHEDULER_TaskIdentifier lowest_pending_id;
 
-  /**
-   * Number of tasks on the ready list.
-   */
-  unsigned int ready_count;
+};
 
-  /**
-   * How many tasks have we run so far?
-   */
-  unsigned long long tasks_run;
 
-  /**
-   * Priority of the task running right now.  Only
-   * valid while a task is running.
-   */
-  enum GNUNET_SCHEDULER_Priority current_priority;
+/**
+ * List of tasks waiting for an event.
+ */
+static struct Task *pending;
 
-};
+/**
+ * List of tasks waiting ONLY for a timeout event.
+ * Sorted by timeout (earliest first).  Used so that
+ * we do not traverse the list of these tasks when
+ * building select sets (we just look at the head
+ * to determine the respective timeout ONCE).
+ */
+static struct Task *pending_timeout;
+
+/**
+ * Last inserted task waiting ONLY for a timeout event.
+ * Used to (heuristically) speed up insertion.
+ */
+static struct Task *pending_timeout_last;
+
+/**
+ * ID of the task that is running right now.
+ */
+static struct Task *active_task;
+
+/**
+ * List of tasks ready to run right now,
+ * grouped by importance.
+ */
+static struct Task *ready[GNUNET_SCHEDULER_PRIORITY_COUNT];
+
+/**
+ * Identity of the last task queued.  Incremented for each task to
+ * generate a unique task ID (it is virtually impossible to start
+ * more than 2^64 tasks during the lifetime of a process).
+ */
+static GNUNET_SCHEDULER_TaskIdentifier last_id;
+
+/**
+ * Highest number so that all tasks with smaller identifiers
+ * have already completed.  Also the lowest number of a task
+ * still waiting to be executed.
+ */
+static GNUNET_SCHEDULER_TaskIdentifier lowest_pending_id;
+
+/**
+ * Number of tasks on the ready list.
+ */
+static unsigned int ready_count;
+
+/**
+ * How many tasks have we run so far?
+ */
+static unsigned long long tasks_run;
+
+/**
+ * Priority of the task running right now.  Only
+ * valid while a task is running.
+ */
+static enum GNUNET_SCHEDULER_Priority current_priority;
+
+/**
+ * Priority of the highest task added in the current select
+ * iteration.
+ */
+static enum GNUNET_SCHEDULER_Priority max_priority_added;
 
 
 /**
@@ -175,22 +252,29 @@ check_priority (enum GNUNET_SCHEDULER_Priority p)
  * future), but only if the return value is "GNUNET_NO" (and
  * the "lowest_pending_id" check failed).
  *
- * @param sched the scheduler
  * @param id which task are we checking for
  * @return GNUNET_YES if so, GNUNET_NO if not
  */
 static int
-is_pending (struct GNUNET_SCHEDULER_Handle *sched,
-            GNUNET_SCHEDULER_TaskIdentifier id)
+is_pending (GNUNET_SCHEDULER_TaskIdentifier id)
 {
   struct Task *pos;
   enum GNUNET_SCHEDULER_Priority p;
   GNUNET_SCHEDULER_TaskIdentifier min;
 
-  if (id < sched->lowest_pending_id)
+  if (id < lowest_pending_id)
     return GNUNET_NO;
   min = -1;                     /* maximum value */
-  pos = sched->pending;
+  pos = pending;
+  while (pos != NULL)
+    {
+      if (pos->id == id)
+        return GNUNET_YES;
+      if (pos->id < min)
+        min = pos->id;
+      pos = pos->next;
+    }
+  pos = pending_timeout;
   while (pos != NULL)
     {
       if (pos->id == id)
@@ -201,7 +285,7 @@ is_pending (struct GNUNET_SCHEDULER_Handle *sched,
     }
   for (p = 0; p < GNUNET_SCHEDULER_PRIORITY_COUNT; p++)
     {
-      pos = sched->ready[p];
+      pos = ready[p];
       while (pos != NULL)
         {
           if (pos->id == id)
@@ -211,7 +295,7 @@ is_pending (struct GNUNET_SCHEDULER_Handle *sched,
           pos = pos->next;
         }
     }
-  sched->lowest_pending_id = min;
+  lowest_pending_id = min;
   return GNUNET_NO;
 }
 
@@ -219,37 +303,48 @@ is_pending (struct GNUNET_SCHEDULER_Handle *sched,
 /**
  * Update all sets and timeout for select.
  *
- * @param sched the scheduler
  * @param rs read-set, set to all FDs we would like to read (updated)
  * @param ws write-set, set to all FDs we would like to write (updated)
  * @param timeout next timeout (updated)
  */
 static void
-update_sets (struct GNUNET_SCHEDULER_Handle *sched,
-             struct GNUNET_NETWORK_FDSet *rs,
+update_sets (struct GNUNET_NETWORK_FDSet *rs,
              struct GNUNET_NETWORK_FDSet *ws,
              struct GNUNET_TIME_Relative *timeout)
 {
   struct Task *pos;
+  struct GNUNET_TIME_Absolute now;
+  struct GNUNET_TIME_Relative to;
 
-  pos = sched->pending;
+  now = GNUNET_TIME_absolute_get ();
+  pos = pending_timeout;
+  if (pos != NULL) 
+    {
+      to = GNUNET_TIME_absolute_get_difference (now, pos->timeout);
+      if (timeout->rel_value > to.rel_value)
+       *timeout = to;
+      if (pos->reason != 0)
+        *timeout = GNUNET_TIME_UNIT_ZERO;
+    }
+  pos = pending;
   while (pos != NULL)
     {
       if ((pos->prereq_id != GNUNET_SCHEDULER_NO_TASK) &&
-          (GNUNET_YES == is_pending (sched, pos->prereq_id)))
+          (GNUNET_YES == is_pending (pos->prereq_id)))
         {
           pos = pos->next;
           continue;
         }
-
-      if (pos->timeout.value != GNUNET_TIME_UNIT_FOREVER_ABS.value)
+      if (pos->timeout.abs_value != GNUNET_TIME_UNIT_FOREVER_ABS.abs_value)
         {
-          struct GNUNET_TIME_Relative to;
-
-          to = GNUNET_TIME_absolute_get_remaining (pos->timeout);
-          if (timeout->value > to.value)
+          to = GNUNET_TIME_absolute_get_difference (now, pos->timeout);
+          if (timeout->rel_value > to.rel_value)
             *timeout = to;
         }
+      if (pos->read_fd != -1)
+       GNUNET_NETWORK_fdset_set_native (rs, pos->read_fd);
+      if (pos->write_fd != -1)
+       GNUNET_NETWORK_fdset_set_native (ws, pos->write_fd);
       if (pos->read_set != NULL)
         GNUNET_NETWORK_fdset_add (rs, pos->read_set);
       if (pos->write_set != NULL)
@@ -274,7 +369,7 @@ static int
 set_overlaps (const struct GNUNET_NETWORK_FDSet *ready,
               struct GNUNET_NETWORK_FDSet *want)
 {
-  if (NULL == want)
+  if ( (NULL == want) || (NULL == ready) )
     return GNUNET_NO;
   if (GNUNET_NETWORK_fdset_overlap (ready, want))
     {
@@ -291,7 +386,6 @@ set_overlaps (const struct GNUNET_NETWORK_FDSet *ready,
  * Check if the given task is eligible to run now.
  * Also set the reason why it is eligible.
  *
- * @param sched the scheduler
  * @param task task to check if it is ready
  * @param now the current time
  * @param rs set of FDs ready for reading
@@ -299,28 +393,38 @@ set_overlaps (const struct GNUNET_NETWORK_FDSet *ready,
  * @return GNUNET_YES if we can run it, GNUNET_NO if not.
  */
 static int
-is_ready (struct GNUNET_SCHEDULER_Handle *sched,
-          struct Task *task,
+is_ready (struct Task *task,
           struct GNUNET_TIME_Absolute now,
           const struct GNUNET_NETWORK_FDSet *rs,
           const struct GNUNET_NETWORK_FDSet *ws)
 {
-  if (now.value >= task->timeout.value)
-    task->reason |= GNUNET_SCHEDULER_REASON_TIMEOUT;
-  if ((0 == (task->reason & GNUNET_SCHEDULER_REASON_READ_READY)) &&
-      (rs != NULL) && (set_overlaps (rs, task->read_set)))
-    task->reason |= GNUNET_SCHEDULER_REASON_READ_READY;
-  if ((0 == (task->reason & GNUNET_SCHEDULER_REASON_WRITE_READY)) &&
-      (ws != NULL) && (set_overlaps (ws, task->write_set)))
-    task->reason |= GNUNET_SCHEDULER_REASON_WRITE_READY;
-  if (task->reason == 0)
-    return GNUNET_NO;           /* not ready */
+  enum GNUNET_SCHEDULER_Reason reason;
+
+  reason = task->reason;
+  if (now.abs_value >= task->timeout.abs_value)
+    reason |= GNUNET_SCHEDULER_REASON_TIMEOUT;
+  if ( (0 == (reason & GNUNET_SCHEDULER_REASON_READ_READY)) &&
+       ( ( (task->read_fd != -1) &&
+          (GNUNET_YES == GNUNET_NETWORK_fdset_test_native (rs, task->read_fd)) ) ||
+        (set_overlaps (rs, task->read_set) ) ) )
+    reason |= GNUNET_SCHEDULER_REASON_READ_READY;
+  if ((0 == (reason & GNUNET_SCHEDULER_REASON_WRITE_READY)) &&
+      ( ( (task->write_fd != -1) &&
+         (GNUNET_YES == GNUNET_NETWORK_fdset_test_native (ws, task->write_fd)) ) ||
+       (set_overlaps (ws, task->write_set) ) ) )
+    reason |= GNUNET_SCHEDULER_REASON_WRITE_READY;
+  if (reason == 0)
+    return GNUNET_NO;           /* not ready */    
   if (task->prereq_id != GNUNET_SCHEDULER_NO_TASK)
     {
-      if (GNUNET_YES == is_pending (sched, task->prereq_id))
-        return GNUNET_NO;       /* prereq waiting */
-      task->reason |= GNUNET_SCHEDULER_REASON_PREREQ_DONE;
+      if (GNUNET_YES == is_pending (task->prereq_id))
+       {
+         task->reason = reason;
+         return GNUNET_NO;       /* prereq waiting */
+       }
+      reason |= GNUNET_SCHEDULER_REASON_PREREQ_DONE;
     }
+  task->reason = reason;
   return GNUNET_YES;
 }
 
@@ -332,11 +436,14 @@ is_ready (struct GNUNET_SCHEDULER_Handle *sched,
  * @param task task ready for execution
  */
 static void
-queue_ready_task (struct GNUNET_SCHEDULER_Handle *handle, struct Task *task)
+queue_ready_task (struct Task *task)
 {
-  task->next = handle->ready[check_priority (task->priority)];
-  handle->ready[check_priority (task->priority)] = task;
-  handle->ready_count++;
+  enum GNUNET_SCHEDULER_Priority p = task->priority;
+  if (0 != (task->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
+    p = GNUNET_SCHEDULER_PRIORITY_SHUTDOWN;
+  task->next = ready[check_priority (p)];
+  ready[check_priority (p)] = task;
+  ready_count++;
 }
 
 
@@ -349,8 +456,7 @@ queue_ready_task (struct GNUNET_SCHEDULER_Handle *handle, struct Task *task)
  * @param ws FDs ready for writing
  */
 static void
-check_ready (struct GNUNET_SCHEDULER_Handle *handle,
-             const struct GNUNET_NETWORK_FDSet *rs,
+check_ready (const struct GNUNET_NETWORK_FDSet *rs,
              const struct GNUNET_NETWORK_FDSet *ws)
 {
   struct Task *pos;
@@ -360,7 +466,21 @@ check_ready (struct GNUNET_SCHEDULER_Handle *handle,
 
   now = GNUNET_TIME_absolute_get ();
   prev = NULL;
-  pos = handle->pending;
+  pos = pending_timeout;
+  while (pos != NULL)
+    {
+      next = pos->next;
+      if (now.abs_value >= pos->timeout.abs_value)
+       pos->reason |= GNUNET_SCHEDULER_REASON_TIMEOUT;
+      if (0 == pos->reason)
+       break;
+      pending_timeout = next;
+      if (pending_timeout_last == pos)
+       pending_timeout_last = NULL;
+      queue_ready_task (pos);
+      pos = next;
+    }
+  pos = pending;
   while (pos != NULL)
     {
 #if DEBUG_TASKS
@@ -369,13 +489,13 @@ check_ready (struct GNUNET_SCHEDULER_Handle *handle,
                   pos->id, pos->callback_cls);
 #endif
       next = pos->next;
-      if (GNUNET_YES == is_ready (handle, pos, now, rs, ws))
+      if (GNUNET_YES == is_ready (pos, now, rs, ws))
         {
           if (prev == NULL)
-            handle->pending = next;
+            pending = next;
           else
             prev->next = next;
-          queue_ready_task (handle, pos);
+          queue_ready_task (pos);
           pos = next;
           continue;
         }
@@ -391,16 +511,23 @@ check_ready (struct GNUNET_SCHEDULER_Handle *handle,
  * cause all tasks to run (as soon as possible, respecting
  * priorities and prerequisite tasks).  Note that tasks
  * scheduled AFTER this call may still be delayed arbitrarily.
- *
- * @param sched the scheduler
  */
 void
-GNUNET_SCHEDULER_shutdown (struct GNUNET_SCHEDULER_Handle *sched)
+GNUNET_SCHEDULER_shutdown ()
 {
   struct Task *pos;
   int i;
 
-  pos = sched->pending;
+  pos = pending_timeout;
+  while (pos != NULL)
+    {
+      pos->reason |= GNUNET_SCHEDULER_REASON_SHUTDOWN;
+      /* we don't move the task into the ready queue yet; check_ready
+         will do that later, possibly adding additional
+         readiness-factors */
+      pos = pos->next;
+    }
+  pos = pending;
   while (pos != NULL)
     {
       pos->reason |= GNUNET_SCHEDULER_REASON_SHUTDOWN;
@@ -411,7 +538,7 @@ GNUNET_SCHEDULER_shutdown (struct GNUNET_SCHEDULER_Handle *sched)
     }
   for (i=0;i<GNUNET_SCHEDULER_PRIORITY_COUNT;i++)
     {
-      pos = sched->ready[i];
+      pos = ready[i];
       while (pos != NULL)
        {
          pos->reason |= GNUNET_SCHEDULER_REASON_SHUTDOWN;
@@ -436,6 +563,9 @@ destroy_task (struct Task *t)
     GNUNET_NETWORK_fdset_destroy (t->read_set);
   if (NULL != t->write_set)
     GNUNET_NETWORK_fdset_destroy (t->write_set);
+#if EXECINFO
+  GNUNET_free (t->backtrace_strings);
+#endif
   GNUNET_free (t);
 }
 
@@ -447,56 +577,102 @@ destroy_task (struct Task *t)
  * may become ready, hence we should select on it).  Naturally, if
  * there are no more ready tasks, we also return.  
  *
- * @param sched the scheduler
+ * @param rs FDs ready for reading
+ * @param ws FDs ready for writing
  */
 static void
-run_ready (struct GNUNET_SCHEDULER_Handle *sched)
+run_ready (struct GNUNET_NETWORK_FDSet *rs,
+          struct GNUNET_NETWORK_FDSet *ws)
 {
   enum GNUNET_SCHEDULER_Priority p;
   struct Task *pos;
   struct GNUNET_SCHEDULER_TaskContext tc;
 
+  max_priority_added = GNUNET_SCHEDULER_PRIORITY_KEEP;
   do
     {
-      if (sched->ready_count == 0)
+      if (ready_count == 0)
         return;
-      GNUNET_assert (sched->ready[GNUNET_SCHEDULER_PRIORITY_KEEP] == NULL);
+      GNUNET_assert (ready[GNUNET_SCHEDULER_PRIORITY_KEEP] == NULL);
       /* yes, p>0 is correct, 0 is "KEEP" which should
          always be an empty queue (see assertion)! */
       for (p = GNUNET_SCHEDULER_PRIORITY_COUNT - 1; p > 0; p--)
         {
-          pos = sched->ready[p];
+          pos = ready[p];
           if (pos != NULL)
             break;
         }
       GNUNET_assert (pos != NULL);      /* ready_count wrong? */
-      sched->ready[p] = pos->next;
-      sched->ready_count--;
-      sched->current_priority = p;
-      GNUNET_assert (pos->priority == p);
-      sched->active_task = pos;
-      tc.sched = sched;
+      ready[p] = pos->next;
+      ready_count--;
+      if (current_priority != pos->priority)
+       {
+         current_priority = pos->priority;
+         (void) GNUNET_OS_set_process_priority (GNUNET_OS_process_current (), pos->priority);
+       }
+      active_task = pos;
+#if PROFILE_DELAYS
+      if (GNUNET_TIME_absolute_get_duration (pos->start_time).rel_value >
+         DELAY_THRESHOLD.rel_value)
+       {
+         GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                     "Task %llu took %llums to be scheduled\n",
+                     pos->id,
+                     (unsigned long long) GNUNET_TIME_absolute_get_duration (pos->start_time).rel_value);
+       }
+#endif
       tc.reason = pos->reason;
-      tc.read_ready = pos->read_set;
-      tc.write_ready = pos->write_set;
-      pos->callback (pos->callback_cls, &tc);
+      tc.read_ready = (pos->read_set == NULL) ? rs : pos->read_set; 
+      if ( (pos->read_fd != -1) &&
+          (0 != (pos->reason & GNUNET_SCHEDULER_REASON_READ_READY)) )
+       GNUNET_NETWORK_fdset_set_native (rs,
+                                        pos->read_fd);
+      tc.write_ready = (pos->write_set == NULL) ? ws : pos->write_set;
+      if ( (pos->write_fd != -1) &&
+          (0 != (pos->reason & GNUNET_SCHEDULER_REASON_WRITE_READY)) )
+       GNUNET_NETWORK_fdset_set_native (ws,
+                                        pos->write_fd);
+      if ( ( (tc.reason & GNUNET_SCHEDULER_REASON_WRITE_READY) != 0) &&
+          (pos->write_fd != -1) &&
+          (! GNUNET_NETWORK_fdset_test_native (ws,
+                                               pos->write_fd))) 
+       abort (); // added to ready in previous select loop!
 #if DEBUG_TASKS
       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                   "Running task: %llu / %p\n", pos->id, pos->callback_cls);
 #endif
-      sched->active_task = NULL;
+      pos->callback (pos->callback_cls, &tc);
+#if EXECINFO
+      int i;
+      for (i=0;i<pos->num_backtrace_strings;i++)
+        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                    "Task %llu trace %d: %s\n",
+                    pos->id,
+                    i,
+                    pos->backtrace_strings[i]);
+#endif
+      active_task = NULL;
       destroy_task (pos);
-      sched->tasks_run++;
+      tasks_run++;
     }
-  while ((sched->pending == NULL) || (p == GNUNET_SCHEDULER_PRIORITY_URGENT));
+  while ( (pending == NULL) || (p >= max_priority_added) );
 }
 
 /**
  * Pipe used to communicate shutdown via signal.
  */
-static struct GNUNET_DISK_PipeHandle *sigpipe;
-
+static struct GNUNET_DISK_PipeHandle *shutdown_pipe_handle;
 
+/**
+ * Signal handler called for SIGPIPE.
+ */
+#ifndef MINGW
+static void
+sighandler_pipe ()
+{
+  return;
+}
+#endif
 /**
  * Signal handler called for signals that should cause us to shutdown.
  */
@@ -504,10 +680,12 @@ static void
 sighandler_shutdown ()
 {
   static char c;
+  int old_errno = errno; /* backup errno */
 
   GNUNET_DISK_file_write (GNUNET_DISK_pipe_handle
-                          (sigpipe, GNUNET_DISK_PIPE_END_WRITE), &c,
+                          (shutdown_pipe_handle, GNUNET_DISK_PIPE_END_WRITE), &c,
                           sizeof (c));
+  errno = old_errno;
 }
 
 
@@ -528,49 +706,53 @@ sighandler_shutdown ()
 void
 GNUNET_SCHEDULER_run (GNUNET_SCHEDULER_Task task, void *task_cls)
 {
-  struct GNUNET_SCHEDULER_Handle sched;
   struct GNUNET_NETWORK_FDSet *rs;
   struct GNUNET_NETWORK_FDSet *ws;
   struct GNUNET_TIME_Relative timeout;
   int ret;
   struct GNUNET_SIGNAL_Context *shc_int;
   struct GNUNET_SIGNAL_Context *shc_term;
+#ifndef MINGW
   struct GNUNET_SIGNAL_Context *shc_quit;
   struct GNUNET_SIGNAL_Context *shc_hup;
+  struct GNUNET_SIGNAL_Context *shc_pipe;
+#endif
   unsigned long long last_tr;
   unsigned int busy_wait_warning;
   const struct GNUNET_DISK_FileHandle *pr;
   char c;
 
+  GNUNET_assert (active_task == NULL);
   rs = GNUNET_NETWORK_fdset_create ();
   ws = GNUNET_NETWORK_fdset_create ();
-  GNUNET_assert (sigpipe == NULL);
-  sigpipe = GNUNET_DISK_pipe (GNUNET_NO);
-  GNUNET_assert (sigpipe != NULL);
-  pr = GNUNET_DISK_pipe_handle (sigpipe, GNUNET_DISK_PIPE_END_READ);
+  GNUNET_assert (shutdown_pipe_handle == NULL);
+  shutdown_pipe_handle =  GNUNET_DISK_pipe (GNUNET_NO, GNUNET_NO, GNUNET_NO);
+  GNUNET_assert (shutdown_pipe_handle != NULL);
+  pr = GNUNET_DISK_pipe_handle (shutdown_pipe_handle, GNUNET_DISK_PIPE_END_READ);
   GNUNET_assert (pr != NULL);
   shc_int = GNUNET_SIGNAL_handler_install (SIGINT, &sighandler_shutdown);
   shc_term = GNUNET_SIGNAL_handler_install (SIGTERM, &sighandler_shutdown);
 #ifndef MINGW
+  shc_pipe = GNUNET_SIGNAL_handler_install (SIGPIPE, &sighandler_pipe);
   shc_quit = GNUNET_SIGNAL_handler_install (SIGQUIT, &sighandler_shutdown);
   shc_hup = GNUNET_SIGNAL_handler_install (SIGHUP, &sighandler_shutdown);
 #endif
-  memset (&sched, 0, sizeof (sched));
-  sched.current_priority = GNUNET_SCHEDULER_PRIORITY_DEFAULT;
-  GNUNET_SCHEDULER_add_continuation (&sched,
-                                     task,
+  current_priority = GNUNET_SCHEDULER_PRIORITY_DEFAULT;
+  GNUNET_SCHEDULER_add_continuation (task,
                                      task_cls,
                                      GNUNET_SCHEDULER_REASON_STARTUP);
   last_tr = 0;
   busy_wait_warning = 0;
-  while ((sched.pending != NULL) || (sched.ready_count > 0))
+  while ((pending != NULL) ||
+        (pending_timeout != NULL) ||
+        (ready_count > 0))
     {
       GNUNET_NETWORK_fdset_zero (rs);
       GNUNET_NETWORK_fdset_zero (ws);
       timeout = GNUNET_TIME_UNIT_FOREVER_REL;
-      update_sets (&sched, rs, ws, &timeout);
+      update_sets (rs, ws, &timeout);
       GNUNET_NETWORK_fdset_handle_set (rs, pr);
-      if (sched.ready_count > 0)
+      if (ready_count > 0)
         {
           /* no blocking, more work already ready! */
           timeout = GNUNET_TIME_UNIT_ZERO;
@@ -580,42 +762,54 @@ GNUNET_SCHEDULER_run (GNUNET_SCHEDULER_Task task, void *task_cls)
         {
           if (errno == EINTR)
             continue;
+
           GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "select");
-          break;
+#ifndef MINGW
+#if USE_LSOF
+         char lsof[512];
+         snprintf (lsof, sizeof (lsof), "lsof -p %d", getpid());
+         close (1);
+         dup2 (2, 1);
+         ret = system (lsof);            
+#endif
+#endif
+          abort ();
+         break;
         }
+      if ((ret == 0) && (timeout.rel_value == 0) && (busy_wait_warning > 16))
+        {
+          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                      _("Looks like we're busy waiting...\n"));
+          sleep (1);            /* mitigate */
+        }
+      check_ready (rs, ws);
+      run_ready (rs, ws);
       if (GNUNET_NETWORK_fdset_handle_isset (rs, pr))
         {
           /* consume the signal */
           GNUNET_DISK_file_read (pr, &c, sizeof (c));
           /* mark all active tasks as ready due to shutdown */
-          GNUNET_SCHEDULER_shutdown (&sched);
+          GNUNET_SCHEDULER_shutdown ();
         }
-      if (last_tr == sched.tasks_run)
+      if (last_tr == tasks_run)
         {
           busy_wait_warning++;
         }
       else
         {
-          last_tr = sched.tasks_run;
+          last_tr = tasks_run;
           busy_wait_warning = 0;
         }
-      if ((ret == 0) && (timeout.value == 0) && (busy_wait_warning > 16))
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                      _("Looks like we're busy waiting...\n"));
-          sleep (1);            /* mitigate */
-        }
-      check_ready (&sched, rs, ws);
-      run_ready (&sched);
     }
   GNUNET_SIGNAL_handler_uninstall (shc_int);
   GNUNET_SIGNAL_handler_uninstall (shc_term);
 #ifndef MINGW
+  GNUNET_SIGNAL_handler_uninstall (shc_pipe);
   GNUNET_SIGNAL_handler_uninstall (shc_quit);
   GNUNET_SIGNAL_handler_uninstall (shc_hup);
 #endif
-  GNUNET_DISK_pipe_close (sigpipe);
-  sigpipe = NULL;
+  GNUNET_DISK_pipe_close (shutdown_pipe_handle);
+  shutdown_pipe_handle = NULL;
   GNUNET_NETWORK_fdset_destroy (rs);
   GNUNET_NETWORK_fdset_destroy (ws);
 }
@@ -626,13 +820,13 @@ GNUNET_SCHEDULER_run (GNUNET_SCHEDULER_Task task, void *task_cls)
  * started.  Will return the same value as 
  * the GNUNET_SCHEDULER_TaskContext's reason field.
  *
- * @param sched scheduler to query
  * @return reason(s) why the current task is run
  */
 enum GNUNET_SCHEDULER_Reason
-GNUNET_SCHEDULER_get_reason (struct GNUNET_SCHEDULER_Handle *sched)
+GNUNET_SCHEDULER_get_reason ()
 {
-  return sched->active_task->reason;
+  GNUNET_assert (active_task != NULL);
+  return active_task->reason;
 }
 
 
@@ -642,23 +836,22 @@ GNUNET_SCHEDULER_get_reason (struct GNUNET_SCHEDULER_Handle *sched)
  * dropped (if the decision should be made based on the number of
  * tasks ready to run).
  *
- * @param sched scheduler to query
  * @param p priority level to look at
  * @return number of tasks pending right now
  */
 unsigned int
-GNUNET_SCHEDULER_get_load (struct GNUNET_SCHEDULER_Handle *sched,
-                           enum GNUNET_SCHEDULER_Priority p)
+GNUNET_SCHEDULER_get_load (enum GNUNET_SCHEDULER_Priority p)
 {
   struct Task *pos;
   unsigned int ret;
 
+  GNUNET_assert (active_task != NULL);
   if (p == GNUNET_SCHEDULER_PRIORITY_COUNT)
-    return sched->ready_count;
+    return ready_count;
   if (p == GNUNET_SCHEDULER_PRIORITY_KEEP)
-    p = sched->current_priority;
+    p = current_priority;
   ret = 0;
-  pos = sched->ready[p];
+  pos = ready[check_priority (p)];
   while (pos != NULL)
     {
       pos = pos->next;
@@ -672,21 +865,22 @@ GNUNET_SCHEDULER_get_load (struct GNUNET_SCHEDULER_Handle *sched,
  * Cancel the task with the specified identifier.
  * The task must not yet have run.
  *
- * @param sched scheduler to use
  * @param task id of the task to cancel
  * @return original closure of the task
  */
 void *
-GNUNET_SCHEDULER_cancel (struct GNUNET_SCHEDULER_Handle *sched,
-                         GNUNET_SCHEDULER_TaskIdentifier task)
+GNUNET_SCHEDULER_cancel (GNUNET_SCHEDULER_TaskIdentifier task)
 {
   struct Task *t;
   struct Task *prev;
   enum GNUNET_SCHEDULER_Priority p;
+  int to;
   void *ret;
 
+  GNUNET_assert (active_task != NULL);
+  to = 0;
   prev = NULL;
-  t = sched->pending;
+  t = pending;
   while (t != NULL)
     {
       if (t->id == task)
@@ -694,18 +888,33 @@ GNUNET_SCHEDULER_cancel (struct GNUNET_SCHEDULER_Handle *sched,
       prev = t;
       t = t->next;
     }
+  if (t == NULL)
+    {
+      prev = NULL;
+      to = 1;
+      t = pending_timeout;
+      while (t != NULL)
+       {
+         if (t->id == task)
+           break;
+         prev = t;
+         t = t->next;
+       }
+      if (pending_timeout_last == t)
+       pending_timeout_last = NULL;
+    }
   p = 0;
   while (t == NULL)
     {
       p++;
       GNUNET_assert (p < GNUNET_SCHEDULER_PRIORITY_COUNT);
       prev = NULL;
-      t = sched->ready[p];
+      t = ready[p];
       while (t != NULL)
         {
           if (t->id == task)
             {
-              sched->ready_count--;
+              ready_count--;
               break;
             }
           prev = t;
@@ -715,12 +924,25 @@ GNUNET_SCHEDULER_cancel (struct GNUNET_SCHEDULER_Handle *sched,
   if (prev == NULL)
     {
       if (p == 0)
-        sched->pending = t->next;
+       {
+         if (to == 0)
+           {
+             pending = t->next;
+           }
+         else
+           {
+             pending_timeout = t->next;
+           }
+       }
       else
-        sched->ready[p] = t->next;
+       {
+         ready[p] = t->next;
+       }
     }
   else
-    prev->next = t->next;
+    {
+      prev->next = t->next;
+    }
   ret = t->callback_cls;
 #if DEBUG_TASKS
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
@@ -736,31 +958,43 @@ GNUNET_SCHEDULER_cancel (struct GNUNET_SCHEDULER_Handle *sched,
  * similar to the other "add" functions except that there is no delay
  * and the reason code can be specified.
  *
- * @param sched scheduler to use
  * @param task main function of the task
  * @param task_cls closure for 'main'
  * @param reason reason for task invocation
  */
 void
-GNUNET_SCHEDULER_add_continuation (struct GNUNET_SCHEDULER_Handle *sched,
-                                   GNUNET_SCHEDULER_Task task,
+GNUNET_SCHEDULER_add_continuation (GNUNET_SCHEDULER_Task task,
                                    void *task_cls,
                                    enum GNUNET_SCHEDULER_Reason reason)
 {
   struct Task *t;
+#if EXECINFO
+  void *backtrace_array[50];
+#endif
 
+  GNUNET_assert ( (active_task != NULL) ||
+                 (reason == GNUNET_SCHEDULER_REASON_STARTUP) );
   t = GNUNET_malloc (sizeof (struct Task));
+#if EXECINFO
+  t->num_backtrace_strings = backtrace(backtrace_array, 50);
+  t->backtrace_strings = backtrace_symbols(backtrace_array, t->num_backtrace_strings);
+#endif
+  t->read_fd = -1;
+  t->write_fd = -1;
   t->callback = task;
   t->callback_cls = task_cls;
-  t->id = ++sched->last_id;
+  t->id = ++last_id;
+#if PROFILE_DELAYS
+  t->start_time = GNUNET_TIME_absolute_get ();
+#endif
   t->reason = reason;
-  t->priority = sched->current_priority;
+  t->priority = current_priority;
 #if DEBUG_TASKS
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Adding continuation task: %llu / %p\n",
               t->id, t->callback_cls);
 #endif
-  queue_ready_task (sched, t);
+  queue_ready_task (t);
 }
 
 
@@ -770,7 +1004,6 @@ GNUNET_SCHEDULER_add_continuation (struct GNUNET_SCHEDULER_Handle *sched,
  * has completed. It will be run with the priority of the calling
  * task.
  *
- * @param sched scheduler to use
  * @param prerequisite_task run this task after the task with the given
  *        task identifier completes (and any of our other
  *        conditions, such as delay, read or write-readiness
@@ -783,12 +1016,10 @@ GNUNET_SCHEDULER_add_continuation (struct GNUNET_SCHEDULER_Handle *sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_after (struct GNUNET_SCHEDULER_Handle *sched,
-                            GNUNET_SCHEDULER_TaskIdentifier prerequisite_task,
+GNUNET_SCHEDULER_add_after (GNUNET_SCHEDULER_TaskIdentifier prerequisite_task,
                             GNUNET_SCHEDULER_Task task, void *task_cls)
 {
-  return GNUNET_SCHEDULER_add_select (sched,
-                                      GNUNET_SCHEDULER_PRIORITY_KEEP,
+  return GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_KEEP,
                                       prerequisite_task,
                                       GNUNET_TIME_UNIT_ZERO,
                                       NULL, NULL, task, task_cls);
@@ -798,7 +1029,6 @@ GNUNET_SCHEDULER_add_after (struct GNUNET_SCHEDULER_Handle *sched,
 /**
  * Schedule a new task to be run with a specified priority.
  *
- * @param sched scheduler to use
  * @param prio how important is the new task?
  * @param task main function of the task
  * @param task_cls closure of task
@@ -806,13 +1036,11 @@ GNUNET_SCHEDULER_add_after (struct GNUNET_SCHEDULER_Handle *sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_with_priority (struct GNUNET_SCHEDULER_Handle * sched,
-                                    enum GNUNET_SCHEDULER_Priority prio,
+GNUNET_SCHEDULER_add_with_priority (enum GNUNET_SCHEDULER_Priority prio,
                                     GNUNET_SCHEDULER_Task task,
                                     void *task_cls)
 {
-  return GNUNET_SCHEDULER_add_select (sched,
-                                      prio,
+  return GNUNET_SCHEDULER_add_select (prio,
                                       GNUNET_SCHEDULER_NO_TASK,
                                       GNUNET_TIME_UNIT_ZERO,
                                       NULL, NULL, task, task_cls);
@@ -825,7 +1053,6 @@ GNUNET_SCHEDULER_add_with_priority (struct GNUNET_SCHEDULER_Handle * sched,
  * will be scheduled for execution once the delay has expired. It
  * will be run with the priority of the calling task.
  *
- * @param sched scheduler to use
  * @param delay when should this operation time out? Use 
  *        GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
  * @param task main function of the task
@@ -834,14 +1061,87 @@ GNUNET_SCHEDULER_add_with_priority (struct GNUNET_SCHEDULER_Handle * sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_delayed (struct GNUNET_SCHEDULER_Handle * sched,
-                              struct GNUNET_TIME_Relative delay,
+GNUNET_SCHEDULER_add_delayed (struct GNUNET_TIME_Relative delay,
                               GNUNET_SCHEDULER_Task task, void *task_cls)
 {
-  return GNUNET_SCHEDULER_add_select (sched,
-                                      GNUNET_SCHEDULER_PRIORITY_KEEP,
+#if 1
+  /* new, optimized version */
+  struct Task *t;
+  struct Task *pos;
+  struct Task *prev;
+#if EXECINFO
+  void *backtrace_array[MAX_TRACE_DEPTH];
+#endif
+
+  GNUNET_assert (active_task != NULL);
+  GNUNET_assert (NULL != task);
+  t = GNUNET_malloc (sizeof (struct Task));
+  t->callback = task;
+  t->callback_cls = task_cls;
+#if EXECINFO
+  t->num_backtrace_strings = backtrace(backtrace_array, MAX_TRACE_DEPTH);
+  t->backtrace_strings = backtrace_symbols(backtrace_array, t->num_backtrace_strings);
+#endif
+  t->read_fd = -1;
+  t->write_fd = -1;
+  t->id = ++last_id;
+#if PROFILE_DELAYS
+  t->start_time = GNUNET_TIME_absolute_get ();
+#endif
+  t->timeout = GNUNET_TIME_relative_to_absolute (delay);
+  t->priority = current_priority;
+  /* try tail first (optimization in case we are
+     appending to a long list of tasks with timeouts) */
+  prev = pending_timeout_last;
+  if (prev != NULL) 
+    {
+      if (prev->timeout.abs_value > t->timeout.abs_value)
+       prev = NULL;
+      else
+       pos = prev->next; /* heuristic success! */
+    }
+  if (prev == NULL)
+    {
+      /* heuristic failed, do traversal of timeout list */
+      pos = pending_timeout;
+    }
+  while ( (pos != NULL) &&
+         ( (pos->timeout.abs_value <= t->timeout.abs_value) ||
+           (pos->reason != 0) ) )
+    {
+      prev = pos;
+      pos = pos->next;
+    }
+  if (prev == NULL)
+    pending_timeout = t;
+  else
+    prev->next = t;
+  t->next = pos;
+  /* hyper-optimization... */
+  pending_timeout_last = t;
+
+#if DEBUG_TASKS
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Adding task: %llu / %p\n", t->id, t->callback_cls);
+#endif
+#if EXECINFO
+  int i;
+
+  for (i=0;i<t->num_backtrace_strings;i++)
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  "Task %llu trace %d: %s\n",
+                  t->id,
+                  i,
+                  t->backtrace_strings[i]);
+#endif
+  return t->id;
+
+#else
+  /* unoptimized version */
+  return GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_KEEP,
                                       GNUNET_SCHEDULER_NO_TASK, delay,
                                       NULL, NULL, task, task_cls);
+#endif
 }
 
 
@@ -850,19 +1150,16 @@ GNUNET_SCHEDULER_add_delayed (struct GNUNET_SCHEDULER_Handle * sched,
  * Schedule a new task to be run as soon as possible. The task
  * will be run with the priority of the calling task.
  *
- * @param sched scheduler to use
  * @param task main function of the task
  * @param task_cls closure of task
  * @return unique task identifier for the job
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_now (struct GNUNET_SCHEDULER_Handle *sched,
-                         GNUNET_SCHEDULER_Task task,
-                         void *task_cls)
+GNUNET_SCHEDULER_add_now (GNUNET_SCHEDULER_Task task,
+                                                 void *task_cls)
 {
-  return GNUNET_SCHEDULER_add_select (sched,
-                                      GNUNET_SCHEDULER_PRIORITY_KEEP,
+  return GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_KEEP,
                                       GNUNET_SCHEDULER_NO_TASK,
                                      GNUNET_TIME_UNIT_ZERO,
                                       NULL, NULL, task, task_cls);
@@ -870,6 +1167,85 @@ GNUNET_SCHEDULER_add_now (struct GNUNET_SCHEDULER_Handle *sched,
 
 
 
+
+/**
+ * Schedule a new task to be run with a specified delay or when any of
+ * the specified file descriptor sets is ready.  The delay can be used
+ * as a timeout on the socket(s) being ready.  The task will be
+ * scheduled for execution once either the delay has expired or any of
+ * the socket operations is ready.  This is the most general
+ * function of the "add" family.  Note that the "prerequisite_task"
+ * must be satisfied in addition to any of the other conditions.  In
+ * other words, the task will be started when
+ * <code>
+ * (prerequisite-run)
+ * && (delay-ready
+ *     || any-rs-ready
+ *     || any-ws-ready
+ *     || shutdown-active )
+ * </code>
+ *
+ * @param delay how long should we wait? Use GNUNET_TIME_UNIT_FOREVER_REL for "forever",
+ *        which means that the task will only be run after we receive SIGTERM
+ * @param rfd file descriptor we want to read (can be -1)
+ * @param wfd file descriptors we want to write (can be -1)
+ * @param task main function of the task
+ * @param task_cls closure of task
+ * @return unique task identifier for the job
+ *         only valid until "task" is started!
+ */
+GNUNET_SCHEDULER_TaskIdentifier
+add_without_sets (struct GNUNET_TIME_Relative delay,
+                 int rfd,
+                 int wfd,
+                 GNUNET_SCHEDULER_Task task, void *task_cls)
+{
+  struct Task *t;
+#if EXECINFO
+  void *backtrace_array[MAX_TRACE_DEPTH];
+#endif
+
+  GNUNET_assert (active_task != NULL);
+  GNUNET_assert (NULL != task);
+  t = GNUNET_malloc (sizeof (struct Task));
+  t->callback = task;
+  t->callback_cls = task_cls;
+#if EXECINFO
+  t->num_backtrace_strings = backtrace(backtrace_array, MAX_TRACE_DEPTH);
+  t->backtrace_strings = backtrace_symbols(backtrace_array, t->num_backtrace_strings);
+#endif
+  t->read_fd = rfd;
+  t->write_fd = wfd;
+  t->id = ++last_id;
+#if PROFILE_DELAYS
+  t->start_time = GNUNET_TIME_absolute_get ();
+#endif
+  t->prereq_id = GNUNET_SCHEDULER_NO_TASK;
+  t->timeout = GNUNET_TIME_relative_to_absolute (delay);
+  t->priority = check_priority (current_priority);
+  t->next = pending;
+  pending = t;
+  max_priority_added = GNUNET_MAX (max_priority_added,
+                                         t->priority);
+#if DEBUG_TASKS
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Adding task: %llu / %p\n", t->id, t->callback_cls);
+#endif
+#if EXECINFO
+  int i;
+
+  for (i=0;i<t->num_backtrace_strings;i++)
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  "Task %llu trace %d: %s\n",
+                  t->id,
+                  i,
+                  t->backtrace_strings[i]);
+#endif
+  return t->id;
+}
+
+
+
 /**
  * Schedule a new task to be run with a specified delay or when the
  * specified file descriptor is ready for reading.  The delay can be
@@ -878,7 +1254,6 @@ GNUNET_SCHEDULER_add_now (struct GNUNET_SCHEDULER_Handle *sched,
  * socket operation is ready.  It will be run with the priority of
  * the calling task.
  *
- * @param sched scheduler to use
  * @param delay when should this operation time out? Use 
  *        GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
  * @param rfd read file-descriptor
@@ -888,23 +1263,15 @@ GNUNET_SCHEDULER_add_now (struct GNUNET_SCHEDULER_Handle *sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_read_net (struct GNUNET_SCHEDULER_Handle * sched,
-                               struct GNUNET_TIME_Relative delay,
+GNUNET_SCHEDULER_add_read_net (struct GNUNET_TIME_Relative delay,
                                struct GNUNET_NETWORK_Handle * rfd,
                                GNUNET_SCHEDULER_Task task, void *task_cls)
 {
-  struct GNUNET_NETWORK_FDSet *rs;
-  GNUNET_SCHEDULER_TaskIdentifier ret;
-
-  GNUNET_assert (rfd != NULL);
-  rs = GNUNET_NETWORK_fdset_create ();
-  GNUNET_NETWORK_fdset_set (rs, rfd);
-  ret = GNUNET_SCHEDULER_add_select (sched,
-                                     GNUNET_SCHEDULER_PRIORITY_KEEP,
-                                     GNUNET_SCHEDULER_NO_TASK,
-                                     delay, rs, NULL, task, task_cls);
-  GNUNET_NETWORK_fdset_destroy (rs);
-  return ret;
+  return add_without_sets (delay,
+                          GNUNET_NETWORK_get_fd (rfd),
+                          -1,
+                          task,
+                          task_cls);
 }
 
 
@@ -916,7 +1283,6 @@ GNUNET_SCHEDULER_add_read_net (struct GNUNET_SCHEDULER_Handle * sched,
  * socket operation is ready.  It will be run with the priority of
  * the calling task.
  *
- * @param sched scheduler to use
  * @param delay when should this operation time out? Use 
  *        GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
  * @param wfd write file-descriptor
@@ -926,23 +1292,15 @@ GNUNET_SCHEDULER_add_read_net (struct GNUNET_SCHEDULER_Handle * sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_write_net (struct GNUNET_SCHEDULER_Handle * sched,
-                                struct GNUNET_TIME_Relative delay,
+GNUNET_SCHEDULER_add_write_net (struct GNUNET_TIME_Relative delay,
                                 struct GNUNET_NETWORK_Handle * wfd,
                                 GNUNET_SCHEDULER_Task task, void *task_cls)
 {
-  struct GNUNET_NETWORK_FDSet *ws;
-  GNUNET_SCHEDULER_TaskIdentifier ret;
-
-  GNUNET_assert (wfd != NULL);
-  ws = GNUNET_NETWORK_fdset_create ();
-  GNUNET_NETWORK_fdset_set (ws, wfd);
-  ret = GNUNET_SCHEDULER_add_select (sched,
-                                     GNUNET_SCHEDULER_PRIORITY_KEEP,
-                                     GNUNET_SCHEDULER_NO_TASK, delay,
-                                     NULL, ws, task, task_cls);
-  GNUNET_NETWORK_fdset_destroy (ws);
-  return ret;
+  return add_without_sets (delay,
+                          -1,
+                          GNUNET_NETWORK_get_fd (wfd),
+                          task,
+                          task_cls);
 }
 
 
@@ -954,7 +1312,6 @@ GNUNET_SCHEDULER_add_write_net (struct GNUNET_SCHEDULER_Handle * sched,
  * socket operation is ready. It will be run with the priority of
  * the calling task.
  *
- * @param sched scheduler to use
  * @param delay when should this operation time out? Use 
  *        GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
  * @param rfd read file-descriptor
@@ -964,23 +1321,33 @@ GNUNET_SCHEDULER_add_write_net (struct GNUNET_SCHEDULER_Handle * sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_read_file (struct GNUNET_SCHEDULER_Handle * sched,
-                                struct GNUNET_TIME_Relative delay,
+GNUNET_SCHEDULER_add_read_file (struct GNUNET_TIME_Relative delay,
                                 const struct GNUNET_DISK_FileHandle * rfd,
                                 GNUNET_SCHEDULER_Task task, void *task_cls)
 {
+#if MINGW
   struct GNUNET_NETWORK_FDSet *rs;
   GNUNET_SCHEDULER_TaskIdentifier ret;
 
   GNUNET_assert (rfd != NULL);
   rs = GNUNET_NETWORK_fdset_create ();
   GNUNET_NETWORK_fdset_handle_set (rs, rfd);
-  ret = GNUNET_SCHEDULER_add_select (sched,
-                                     GNUNET_SCHEDULER_PRIORITY_KEEP,
+  ret = GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_KEEP,
                                      GNUNET_SCHEDULER_NO_TASK, delay,
                                      rs, NULL, task, task_cls);
   GNUNET_NETWORK_fdset_destroy (rs);
   return ret;
+#else
+  int fd;
+
+  GNUNET_DISK_internal_file_handle_ (rfd, &fd, sizeof (int));
+  return add_without_sets (delay,
+                          fd,
+                          -1,
+                          task,
+                          task_cls);
+
+#endif
 }
 
 
@@ -992,7 +1359,6 @@ GNUNET_SCHEDULER_add_read_file (struct GNUNET_SCHEDULER_Handle * sched,
  * socket operation is ready. It will be run with the priority of
  * the calling task.
  *
- * @param sched scheduler to use
  * @param delay when should this operation time out? Use 
  *        GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
  * @param wfd write file-descriptor
@@ -1002,23 +1368,33 @@ GNUNET_SCHEDULER_add_read_file (struct GNUNET_SCHEDULER_Handle * sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_write_file (struct GNUNET_SCHEDULER_Handle * sched,
-                                 struct GNUNET_TIME_Relative delay,
+GNUNET_SCHEDULER_add_write_file (struct GNUNET_TIME_Relative delay,
                                  const struct GNUNET_DISK_FileHandle * wfd,
                                  GNUNET_SCHEDULER_Task task, void *task_cls)
 {
+#if MINGW
   struct GNUNET_NETWORK_FDSet *ws;
   GNUNET_SCHEDULER_TaskIdentifier ret;
 
   GNUNET_assert (wfd != NULL);
   ws = GNUNET_NETWORK_fdset_create ();
   GNUNET_NETWORK_fdset_handle_set (ws, wfd);
-  ret = GNUNET_SCHEDULER_add_select (sched,
-                                     GNUNET_SCHEDULER_PRIORITY_KEEP,
+  ret = GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_KEEP,
                                      GNUNET_SCHEDULER_NO_TASK,
                                      delay, NULL, ws, task, task_cls);
   GNUNET_NETWORK_fdset_destroy (ws);
   return ret;
+#else
+  int fd;
+
+  GNUNET_DISK_internal_file_handle_ (wfd, &fd, sizeof (int));
+  return add_without_sets (delay,
+                          -1,
+                          fd,
+                          task,
+                          task_cls);
+
+#endif
 }
 
 
@@ -1040,7 +1416,6 @@ GNUNET_SCHEDULER_add_write_file (struct GNUNET_SCHEDULER_Handle * sched,
  *     || (shutdown-active && run-on-shutdown) )
  * </code>
  *
- * @param sched scheduler to use
  * @param prio how important is this task?
  * @param prerequisite_task run this task after the task with the given
  *        task identifier completes (and any of our other
@@ -1057,8 +1432,7 @@ GNUNET_SCHEDULER_add_write_file (struct GNUNET_SCHEDULER_Handle * sched,
  *         only valid until "task" is started!
  */
 GNUNET_SCHEDULER_TaskIdentifier
-GNUNET_SCHEDULER_add_select (struct GNUNET_SCHEDULER_Handle * sched,
-                             enum GNUNET_SCHEDULER_Priority prio,
+GNUNET_SCHEDULER_add_select (enum GNUNET_SCHEDULER_Priority prio,
                              GNUNET_SCHEDULER_TaskIdentifier
                              prerequisite_task,
                              struct GNUNET_TIME_Relative delay,
@@ -1067,10 +1441,21 @@ GNUNET_SCHEDULER_add_select (struct GNUNET_SCHEDULER_Handle * sched,
                              GNUNET_SCHEDULER_Task task, void *task_cls)
 {
   struct Task *t;
+#if EXECINFO
+  void *backtrace_array[MAX_TRACE_DEPTH];
+#endif
 
+  GNUNET_assert (active_task != NULL);
+  GNUNET_assert (NULL != task);
   t = GNUNET_malloc (sizeof (struct Task));
   t->callback = task;
   t->callback_cls = task_cls;
+#if EXECINFO
+  t->num_backtrace_strings = backtrace(backtrace_array, MAX_TRACE_DEPTH);
+  t->backtrace_strings = backtrace_symbols(backtrace_array, t->num_backtrace_strings);
+#endif
+  t->read_fd = -1;
+  t->write_fd = -1;
   if (rs != NULL)
     {
       t->read_set = GNUNET_NETWORK_fdset_create ();
@@ -1081,18 +1466,33 @@ GNUNET_SCHEDULER_add_select (struct GNUNET_SCHEDULER_Handle * sched,
       t->write_set = GNUNET_NETWORK_fdset_create ();
       GNUNET_NETWORK_fdset_copy (t->write_set, ws);
     }
-  t->id = ++sched->last_id;
+  t->id = ++last_id;
+#if PROFILE_DELAYS
+  t->start_time = GNUNET_TIME_absolute_get ();
+#endif
   t->prereq_id = prerequisite_task;
   t->timeout = GNUNET_TIME_relative_to_absolute (delay);
   t->priority =
     check_priority ((prio ==
-                     GNUNET_SCHEDULER_PRIORITY_KEEP) ? sched->current_priority
+                     GNUNET_SCHEDULER_PRIORITY_KEEP) ? current_priority
                     : prio);
-  t->next = sched->pending;
-  sched->pending = t;
+  t->next = pending;
+  pending = t;
+  max_priority_added = GNUNET_MAX (max_priority_added,
+                                         t->priority);
 #if DEBUG_TASKS
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Adding task: %llu / %p\n", t->id, t->callback_cls);
+#endif
+#if EXECINFO
+  int i;
+
+  for (i=0;i<t->num_backtrace_strings;i++)
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  "Task %llu trace %d: %s\n",
+                  t->id,
+                  i,
+                  t->backtrace_strings[i]);
 #endif
   return t->id;
 }