Merge branch 'maint'
[paraslash.git] / sched.c
diff --git a/sched.c b/sched.c
index 5d4901d..62d45d5 100644 (file)
--- a/sched.c
+++ b/sched.c
@@ -1,11 +1,12 @@
 /*
- * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2010 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
 
 /** \file sched.c Paraslash's scheduling functions. */
 
+#include <regex.h>
 #include <dirent.h> /* readdir() */
 #include <assert.h>
 #include <sys/time.h>
@@ -24,7 +25,7 @@ static int initialized;
 static struct timeval now_struct;
 struct timeval *now = &now_struct;
 
-/**
+/*
  * Remove a task from the scheduler.
  *
  * \param t The task to remove.
@@ -32,25 +33,26 @@ struct timeval *now = &now_struct;
  * If the pre_select pointer of \a t is not \p NULL, it is removed from
  * the pre_select list of the scheduler. Same goes for \a post_select.
  */
-void unregister_task(struct task *t)
+static void unregister_task(struct task *t)
 {
        if (!initialized)
                return;
-       PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t);
+       PARA_INFO_LOG("unregistering %s (%s)\n", t->status,
+               t->error <0? para_strerror(-t->error) : "shutdown");
        if (t->pre_select)
                list_del(&t->pre_select_node);
        if (t->post_select)
                list_del(&t->post_select_node);
-       if (t->error >= 0)
-               t->error = -E_TASK_KILLED;
-};
+       t->error = -E_TASK_UNREGISTERED;
+}
 
 
 static void sched_preselect(struct sched *s)
 {
        struct task *t, *tmp;
        list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
-               t->pre_select(s, t);
+               if (t->error >= 0 && t->pre_select)
+                       t->pre_select(s, t);
 //             PARA_INFO_LOG("%s \n", t->status);
                if (t->error >= 0)
                        continue;
@@ -71,7 +73,8 @@ static void sched_post_select(struct sched *s)
        struct task *t, *tmp;
 
        list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
-               t->post_select(s, t);
+               if (t->error >= 0)
+                       t->post_select(s, t);
 //             PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
                if (t->error >= 0)
                        continue;
@@ -103,18 +106,30 @@ int schedule(struct sched *s)
 
        if (!initialized)
                return -E_NOT_INITIALIZED;
-       gettimeofday(now, NULL);
+       if (!s->select_function)
+               s->select_function = para_select;
 again:
        FD_ZERO(&s->rfds);
        FD_ZERO(&s->wfds);
        s->timeout = s->default_timeout;
        s->max_fileno = -1;
+       gettimeofday(now, NULL);
        sched_preselect(s);
        if (list_empty(&pre_select_list) && list_empty(&post_select_list))
                return 0;
-       ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
+       ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
        if (ret < 0)
                return ret;
+       if (ret == 0) {
+               /*
+                * APUE: Be careful not to check the descriptor sets on return
+                * unless the return value is greater than zero. The return
+                * state of the descriptor sets is implementation dependent if
+                * either a signal is caught or the timer expires.
+                */
+               FD_ZERO(&s->rfds);
+               FD_ZERO(&s->wfds);
+       }
        gettimeofday(now, NULL);
        sched_post_select(s);
        if (list_empty(&pre_select_list) && list_empty(&post_select_list))
@@ -122,7 +137,7 @@ again:
        goto again;
 }
 
-/**
+/*
  * Initialize the paraslash scheduler.
  */
 static void init_sched(void)
@@ -131,7 +146,7 @@ static void init_sched(void)
        INIT_LIST_HEAD(&pre_select_list);
        INIT_LIST_HEAD(&post_select_list);
        initialized = 1;
-};
+}
 
 /**
  * Add a task to the scheduler.
@@ -153,7 +168,7 @@ void register_task(struct task *t)
                list_add_tail(&t->pre_select_node, &pre_select_list);
        }
        if (t->post_select) {
-               PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select);
+               PARA_DEBUG_LOG("post_select: %p\n", &t->post_select);
                list_add_tail(&t->post_select_node, &post_select_list);
        }
 }
@@ -172,11 +187,10 @@ void sched_shutdown(void)
                return;
        list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node)
                unregister_task(t);
-       /* remove tasks which do not have a pre_select hook */
        list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node)
                unregister_task(t);
        initialized = 0;
-};
+}
 
 /**
  * Get the list of all registered tasks.
@@ -185,7 +199,7 @@ void sched_shutdown(void)
  *
  * Each entry of the list contains an identifier which is simply a hex number
  * that may be used in \a kill_task() to terminate the task.
- * The result ist dynamically allocated and must be freed by the caller.
+ * The result is dynamically allocated and must be freed by the caller.
  */
 char *get_task_list(void)
 {
@@ -235,7 +249,6 @@ int kill_task(char *id)
                if (strcmp(id, buf))
                        continue;
                t->error = -E_TASK_KILLED;
-               unregister_task(t);
                return 1;
        }
        list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
@@ -243,8 +256,92 @@ int kill_task(char *id)
                if (strcmp(id, buf))
                        continue;
                t->error = -E_TASK_KILLED;
-               unregister_task(t);
                return 1;
        }
        return -E_NO_SUCH_TASK;
 }
+
+/**
+ * Set the select timeout to the minimal possible value.
+ *
+ * \param s Pointer to the scheduler struct.
+ *
+ * This causes the next select() call to return immediately.
+ */
+void sched_min_delay(struct sched *s)
+{
+       s->timeout.tv_sec = 0;
+       s->timeout.tv_usec = 1;
+}
+
+/**
+ * Impose an upper bound for the timeout of the next select() call.
+ *
+ * \param timeout Maximal allowed timeout.
+ * \param s Pointer to the scheduler struct.
+ *
+ * If the current scheduler timeout is already smaller than \a timeout, this
+ * function does nothing. Otherwise the timeout for the next select() call is
+ * set to the given value.
+ *
+ * \sa sched_request_timeout_ms().
+ */
+void sched_request_timeout(struct timeval *timeout, struct sched *s)
+{
+       if (tv_diff(&s->timeout, timeout, NULL) > 0)
+               s->timeout = *timeout;
+}
+
+/**
+ * Force the next select() call to return before the given amount of milliseconds.
+ *
+ * \param ms The maximal allowed timeout in milliseconds.
+ * \param s Pointer to the scheduler struct.
+ *
+ * Like sched_request_timeout() this imposes an upper bound on the timeout
+ * value for the next select() call.
+ */
+void sched_request_timeout_ms(long unsigned ms, struct sched *s)
+{
+       struct timeval tv;
+       ms2tv(ms, &tv);
+       sched_request_timeout(&tv, s);
+}
+
+/**
+ * Force the next select() call to return before the given future time.
+ *
+ * \param barrier Absolute time before select() should return.
+ * \param s Pointer to the scheduler struct.
+ *
+ * If \a barrier is in the past, this function does nothing.
+ *
+ * \sa sched_request_barrier_or_min_delay().
+ */
+void sched_request_barrier(struct timeval *barrier, struct sched *s)
+{
+       struct timeval diff;
+
+       if (tv_diff(now, barrier, &diff) > 0)
+               return;
+       sched_request_timeout(&diff, s);
+}
+
+/**
+ * Force the next select() call to return before the given time.
+ *
+ * \param barrier Absolute time before select() should return.
+ * \param s Pointer to the scheduler struct.
+ *
+ * If \a barrier is in the past, this function requests a minimal timeout.
+ *
+ * \sa sched_min_delay(), sched_request_barrier().
+ */
+void sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s)
+{
+       struct timeval diff;
+
+       if (tv_diff(now, barrier, &diff) > 0)
+               return sched_min_delay(s);
+       sched_request_timeout(&diff, s);
+}