4 // Fraunhofer Institute for Open Communication Systems (FOKUS)
5 // Competence Center NETwork research (NET), St. Augustin, GERMANY
6 // Stefan Bund <g0dil@berlios.de>
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 2 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the
20 // Free Software Foundation, Inc.,
21 // 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
24 \brief FIFORunner non-inline non-template implementation */
26 #include "FIFORunner.hh"
27 //#include "FIFORunner.ih"
32 #include <boost/lambda/lambda.hpp>
33 #include "../Utils/Exception.hh"
34 #include "../Utils/senfassert.hh"
35 #include "../Utils/ScopeExit.hh"
37 //#include "FIFORunner.mpp"
39 ///////////////////////////////cc.p////////////////////////////////////////
41 prefix_ senf::scheduler::detail::FIFORunner::FIFORunner()
42 : tasks_ (), next_ (tasks_.end()), watchdogRunning_ (false), watchdogMs_ (1000),
43 watchdogCount_(0), hangCount_ (0)
46 ::memset(&ev, 0, sizeof(ev));
47 ev.sigev_notify = SIGEV_SIGNAL;
48 ev.sigev_signo = SIGURG;
49 ev.sigev_value.sival_ptr = this;
50 if (timer_create(CLOCK_MONOTONIC, &ev, &watchdogId_) < 0)
51 SENF_THROW_SYSTEM_EXCEPTION("timer_create()");
54 ::memset(&sa, 0, sizeof(sa));
55 sa.sa_sigaction = &watchdog;
56 sa.sa_flags = SA_SIGINFO;
57 if (sigaction(SIGURG, &sa, 0) < 0)
58 SENF_THROW_SYSTEM_EXCEPTION("sigaction()");
62 sigaddset(&mask, SIGURG);
63 if (sigprocmask(SIG_UNBLOCK, &mask, 0) < 0)
64 SENF_THROW_SYSTEM_EXCEPTION("sigprocmask()");
66 tasks_.push_back(highPriorityEnd_);
67 tasks_.push_back(normalPriorityEnd_);
70 prefix_ senf::scheduler::detail::FIFORunner::~FIFORunner()
72 timer_delete(watchdogId_);
73 signal(SIGURG, SIG_DFL);
76 prefix_ void senf::scheduler::detail::FIFORunner::startWatchdog()
78 struct itimerspec timer;
79 ::memset(&timer, 0, sizeof(timer));
81 timer.it_interval.tv_sec = watchdogMs_ / 1000;
82 timer.it_interval.tv_nsec = (watchdogMs_ % 1000) * 1000000ul;
83 timer.it_value.tv_sec = timer.it_interval.tv_sec;
84 timer.it_value.tv_nsec = timer.it_interval.tv_nsec;
86 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
87 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
89 watchdogRunning_ = true;
92 prefix_ void senf::scheduler::detail::FIFORunner::stopWatchdog()
94 struct itimerspec timer;
95 ::memset(&timer, 0, sizeof(timer));
97 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
98 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
100 watchdogRunning_ = false;
103 // At the moment, the FIFORunner is not very efficient with many non-runnable tasks since the
104 // complete list of tasks is traversed on each run().
106 // To optimize this, we woould need a way to find the relative ordering of two tasks in O(1) (at the
107 // moment, this is an O(N) operation by traversing the list).
109 // One idea is, to give each task an 'order' value. Whenever a task is added at the end, it's order
110 // value is set to the order value of the last task + 1. Whenever the order value such added exceeds
111 // some threshold (e.g. 2^31 -1 or some such), the task list is traversed from beginning to end to
112 // assign new consecutive order values. This O(N) operation is so seldom, that it is amortized over
115 // With this value at hand, we can do several optimizations: One idea would be the following: The
116 // runnable set always has two types of tasks: There are tasks, which are heavily active and are
117 // signaled constantly and other tasks which lie dormant most of the time. Those dormant tasks will
118 // end up at the beginning of the task queue.
120 // With the above defined 'ordering' field available, we can manage an iterator pointing to the
121 // first and the last runnable task. This will often help a lot since the group of runnable tasks
122 // will mostly be localized to the end of the queue. only occasionally one of the dormant tasks will
123 // be runnable. This additional traversal time will be amortized over a larger time.
125 prefix_ void senf::scheduler::detail::FIFORunner::dequeue(TaskInfo * task)
127 TaskList::iterator i (TaskList::current(*task));
133 prefix_ void senf::scheduler::detail::FIFORunner::run()
135 TaskList::iterator f (tasks_.begin());
136 TaskList::iterator l (TaskList::current(highPriorityEnd_));
140 l = TaskList::current(normalPriorityEnd_);
148 prefix_ void senf::scheduler::detail::FIFORunner::run(TaskList::iterator f, TaskList::iterator l)
151 // We'll have problems inserting NullTask between f and l below, so just explicitly bail out
154 // This algorithm is carefully adjusted to make it work even when arbitrary tasks are removed
156 // - Before we begin, we add a NullTask to the queue. The only purpose of this node is, to mark
157 // the current end of the queue. The iterator to this node becomes the end iterator of the
159 // - We update the TaskInfo and move it to the next queue Element before calling the callback so
160 // we don't access the TaskInfo if it is removed while the callback is running
161 // - We keep the next to-be-processed node in a class variable which is checked and updated
162 // whenever a node is removed.
165 tasks_.insert(l, null);
166 TaskList::iterator end (TaskList::current(null));
169 using namespace boost::lambda;
171 var(watchdogCount_) = 0,
175 while (next_ != end) {
176 TaskInfo & task (*next_);
177 if (task.runnable_) {
178 task.runnable_ = false;
179 runningName_ = task.name();
181 runningBacktrace_ = task.backtrace_;
183 TaskList::iterator i (next_);
185 tasks_.splice(l, tasks_, i);
194 prefix_ senf::scheduler::detail::FIFORunner::TaskList::iterator
195 senf::scheduler::detail::FIFORunner::priorityEnd(TaskInfo::Priority p)
198 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_LOW :
200 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_NORMAL :
201 return TaskList::current(normalPriorityEnd_);
202 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_HIGH :
203 return TaskList::current(highPriorityEnd_);
205 return tasks_.begin();
208 prefix_ void senf::scheduler::detail::FIFORunner::watchdog(int, siginfo_t * si, void *)
210 FIFORunner & runner (*static_cast<FIFORunner *>(si->si_value.sival_ptr));
211 if (runner.watchdogCount_ > 0) {
212 ++ runner.watchdogCount_;
213 if (runner.watchdogCount_ > 2) {
214 ++ runner.hangCount_;
215 write(1, "\n\n*** Scheduler task hanging: ", 30);
216 write(1, runner.runningName_.c_str(), runner.runningName_.size());
219 write(1, "Task was initialized at\n", 24);
220 write(1, runner.runningBacktrace_.c_str(), runner.runningBacktrace_.size());
227 ///////////////////////////////cc.e////////////////////////////////////////
229 //#include "FIFORunner.mpp"
235 // comment-column: 40
236 // c-file-style: "senf"
237 // indent-tabs-mode: nil
238 // ispell-local-dictionary: "american"
239 // compile-command: "scons -u test"