gui: Check return value of para_exec_cmdline_pid().
[paraslash.git] / sched.c
diff --git a/sched.c b/sched.c
index 62d45d5..74f6a1b 100644 (file)
--- a/sched.c
+++ b/sched.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2010 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2012 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -7,7 +7,6 @@
 /** \file sched.c Paraslash's scheduling functions. */
 
 #include <regex.h>
-#include <dirent.h> /* readdir() */
 #include <assert.h>
 #include <sys/time.h>
 
 #include "list.h"
 #include "sched.h"
 #include "string.h"
+#include "time.h"
 #include "error.h"
 
-static struct list_head pre_select_list, post_select_list;
-static int initialized;
-
 static struct timeval now_struct;
 struct timeval *now = &now_struct;
 
@@ -35,51 +32,74 @@ struct timeval *now = &now_struct;
  */
 static void unregister_task(struct task *t)
 {
-       if (!initialized)
-               return;
+       assert(t->error < 0);
        PARA_INFO_LOG("unregistering %s (%s)\n", t->status,
-               t->error <0? para_strerror(-t->error) : "shutdown");
+               para_strerror(-t->error));
        if (t->pre_select)
                list_del(&t->pre_select_node);
        if (t->post_select)
                list_del(&t->post_select_node);
-       t->error = -E_TASK_UNREGISTERED;
 }
 
+static inline bool timeout_is_zero(struct sched *s)
+{
+       struct timeval *tv = &s->select_timeout;
+       return tv->tv_sec == 0 && tv->tv_usec == 0;
+}
 
 static void sched_preselect(struct sched *s)
 {
        struct task *t, *tmp;
-       list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
-               if (t->error >= 0 && t->pre_select)
-                       t->pre_select(s, t);
-//             PARA_INFO_LOG("%s \n", t->status);
-               if (t->error >= 0)
+       list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) {
+               if (t->error < 0) {
+                       unregister_task(t);
                        continue;
-               /*
-                * We have to check whether the list is empty because the call
-                * to ->pre_select() might have called sched_shutdown(). In
-                * this case t has been unregistered already, so we must not
-                * unregister it again.
-                */
-               if (list_empty(&pre_select_list))
-                       return;
-               unregister_task(t);
+               }
+               if (!t->pre_select)
+                       continue;
+               t->pre_select(s, t);
+               if (timeout_is_zero(s))
+                       break;
        }
 }
 
+//#define SCHED_DEBUG 1
+static inline void call_post_select(struct sched *s, struct task *t)
+{
+#ifndef SCHED_DEBUG
+       t->post_select(s, t);
+#else
+       struct timeval t1, t2, diff;
+       unsigned long pst;
+
+       gettimeofday(&t1, NULL);
+       t->post_select(s, t);
+       gettimeofday(&t2, NULL);
+       tv_diff(&t1, &t2, &diff);
+       pst = tv2ms(&diff);
+       if (pst > 50)
+               PARA_WARNING_LOG("%s: post_select time: %lums\n",
+                       t->status, pst);
+#endif
+}
+
 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) {
+       list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) {
                if (t->error >= 0)
-                       t->post_select(s, t);
+                       call_post_select(s, t);
 //             PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
                if (t->error >= 0)
                        continue;
-               /* nec., see sched_preselect() */
-               if (list_empty(&post_select_list))
+               /*
+                * We have to check whether the list is empty because the call
+                * to ->post_select() might have called sched_shutdown(). In
+                * this case t has been unregistered already, so we must not
+                * unregister it again.
+                */
+               if (list_empty(&s->post_select_list))
                        return;
                unregister_task(t);
        }
@@ -104,72 +124,68 @@ int schedule(struct sched *s)
 {
        int ret;
 
-       if (!initialized)
-               return -E_NOT_INITIALIZED;
        if (!s->select_function)
                s->select_function = para_select;
 again:
        FD_ZERO(&s->rfds);
        FD_ZERO(&s->wfds);
-       s->timeout = s->default_timeout;
+       s->select_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))
+       if (list_empty(&s->pre_select_list) && list_empty(&s->post_select_list))
                return 0;
-       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.
-                */
+       if (!timeout_is_zero(s)) {
+               ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds,
+                       &s->select_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);
+       } else {
                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))
+       if (list_empty(&s->pre_select_list) && list_empty(&s->post_select_list))
                return 0;
        goto again;
 }
 
-/*
- * Initialize the paraslash scheduler.
- */
-static void init_sched(void)
-{
-       PARA_INFO_LOG("initializing scheduler\n");
-       INIT_LIST_HEAD(&pre_select_list);
-       INIT_LIST_HEAD(&post_select_list);
-       initialized = 1;
-}
-
 /**
  * Add a task to the scheduler.
  *
- * \param t the task to add
+ * \param t The task to add.
+ * \param s The scheduler instance to add the task to.
  *
  * If the pre_select pointer of \a t is not \p NULL, it is added to
  * the pre_select list of the scheduler. Same goes for post_select.
  *
  * \sa task::pre_select, task::post_select
  */
-void register_task(struct task *t)
+void register_task(struct sched *s, struct task *t)
 {
-       if (!initialized)
-               init_sched();
        PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
+       if (!s->pre_select_list.next)
+               INIT_LIST_HEAD(&s->pre_select_list);
+       if (!s->post_select_list.next)
+               INIT_LIST_HEAD(&s->post_select_list);
        if (t->pre_select) {
                PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select);
-               list_add_tail(&t->pre_select_node, &pre_select_list);
+               list_add_tail(&t->pre_select_node, &s->pre_select_list);
        }
        if (t->post_select) {
                PARA_DEBUG_LOG("post_select: %p\n", &t->post_select);
-               list_add_tail(&t->post_select_node, &post_select_list);
+               list_add_tail(&t->post_select_node, &s->post_select_list);
        }
 }
 
@@ -177,19 +193,21 @@ void register_task(struct task *t)
  * Unregister all tasks.
  *
  * This will cause \a schedule() to return immediately because both the
- * \a pre_select_list and the \a post_select_list are empty.
+ * \a pre_select_list and the \a post_select_list are empty. This function
+ * must be called from the post_select (rather than the pre_select) method.
  */
-void sched_shutdown(void)
+void sched_shutdown(struct sched *s)
 {
        struct task *t, *tmp;
 
-       if (!initialized)
-               return;
-       list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node)
+       list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) {
+               t->error = -E_SCHED_SHUTDOWN;
                unregister_task(t);
-       list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node)
+       }
+       list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) {
+               t->error = -E_SCHED_SHUTDOWN;
                unregister_task(t);
-       initialized = 0;
+       }
 }
 
 /**
@@ -197,24 +215,21 @@ void sched_shutdown(void)
  *
  * \return The task list.
  *
- * 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.
+ * Each entry of the list contains an identifier which is simply a hex number.
  * The result is dynamically allocated and must be freed by the caller.
  */
-char *get_task_list(void)
+char *get_task_list(struct sched *s)
 {
        struct task *t, *tmp;
        char *msg = NULL;
 
-       if (!initialized)
-               return NULL;
-       list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
+       list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) {
                char *tmp_msg;
                tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status);
                free(msg);
                msg = tmp_msg;
        }
-       list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
+       list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) {
                char *tmp_msg;
 //             if (t->pre_select)
 //                     continue;
@@ -226,41 +241,6 @@ char *get_task_list(void)
        return msg;
 }
 
-/**
- * Simulate an error for the given task.
- *
- * \param id The task identifier.
- *
- * Find the task identified by \a id, set the tasks' error value to
- * \p -E_TASK_KILLED and unregister the task.
- *
- * \return Positive on success, negative on errors (e.g. if \a id does not
- * correspond to a registered task).
- */
-int kill_task(char *id)
-{
-       struct task *t, *tmp;
-       char buf[20];
-
-       if (!initialized)
-               return -E_NOT_INITIALIZED;
-       list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
-               sprintf(buf, "%p", t);
-               if (strcmp(id, buf))
-                       continue;
-               t->error = -E_TASK_KILLED;
-               return 1;
-       }
-       list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
-               sprintf(buf, "%p", t);
-               if (strcmp(id, buf))
-                       continue;
-               t->error = -E_TASK_KILLED;
-               return 1;
-       }
-       return -E_NO_SUCH_TASK;
-}
-
 /**
  * Set the select timeout to the minimal possible value.
  *
@@ -270,26 +250,25 @@ int kill_task(char *id)
  */
 void sched_min_delay(struct sched *s)
 {
-       s->timeout.tv_sec = 0;
-       s->timeout.tv_usec = 1;
+       s->select_timeout.tv_sec = s->select_timeout.tv_usec = 0;
 }
 
 /**
  * Impose an upper bound for the timeout of the next select() call.
  *
- * \param timeout Maximal allowed timeout.
+ * \param to Maximal allowed timeout.
  * \param s Pointer to the scheduler struct.
  *
- * If the current scheduler timeout is already smaller than \a timeout, this
+ * If the current scheduler timeout is already smaller than \a to, 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)
+void sched_request_timeout(struct timeval *to, struct sched *s)
 {
-       if (tv_diff(&s->timeout, timeout, NULL) > 0)
-               s->timeout = *timeout;
+       if (tv_diff(&s->select_timeout, to, NULL) > 0)
+               s->select_timeout = *to;
 }
 
 /**
@@ -314,17 +293,19 @@ void sched_request_timeout_ms(long unsigned ms, struct sched *s)
  * \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.
+ * \return If \a barrier is in the past, this function does nothing and returns
+ * zero. Otherwise it returns one.
  *
  * \sa sched_request_barrier_or_min_delay().
  */
-void sched_request_barrier(struct timeval *barrier, struct sched *s)
+int sched_request_barrier(struct timeval *barrier, struct sched *s)
 {
        struct timeval diff;
 
        if (tv_diff(now, barrier, &diff) > 0)
-               return;
+               return 0;
        sched_request_timeout(&diff, s);
+       return 1;
 }
 
 /**
@@ -333,15 +314,19 @@ void sched_request_barrier(struct timeval *barrier, struct sched *s)
  * \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.
+ * \return If \a barrier is in the past, this function requests a minimal
+ * timeout and returns zero. Otherwise it returns one.
  *
  * \sa sched_min_delay(), sched_request_barrier().
  */
-void sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s)
+int 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);
+       if (tv_diff(now, barrier, &diff) > 0) {
+               sched_min_delay(s);
+               return 0;
+       }
        sched_request_timeout(&diff, s);
+       return 1;
 }