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 "../config.hh"
40 //#include "FIFORunner.mpp"
42 ///////////////////////////////cc.p////////////////////////////////////////
44 prefix_ senf::scheduler::detail::FIFORunner::FIFORunner()
45 : tasks_ (), next_ (tasks_.end()), watchdogRunning_ (false), watchdogMs_ (1000),
46 watchdogAbort_ (false), watchdogCount_(0), hangCount_ (0), yield_ (false)
49 ::memset(&ev, 0, sizeof(ev));
50 ev.sigev_notify = SIGEV_SIGNAL;
51 ev.sigev_signo = SIGURG;
52 ev.sigev_value.sival_ptr = this;
53 if (timer_create(CLOCK_MONOTONIC, &ev, &watchdogId_) < 0)
54 SENF_THROW_SYSTEM_EXCEPTION("timer_create()");
57 ::memset(&sa, 0, sizeof(sa));
58 sa.sa_sigaction = &watchdog;
59 sa.sa_flags = SA_SIGINFO;
60 if (sigaction(SIGURG, &sa, 0) < 0)
61 SENF_THROW_SYSTEM_EXCEPTION("sigaction()");
65 sigaddset(&mask, SIGURG);
66 if (sigprocmask(SIG_UNBLOCK, &mask, 0) < 0)
67 SENF_THROW_SYSTEM_EXCEPTION("sigprocmask()");
69 tasks_.push_back(highPriorityEnd_);
70 tasks_.push_back(normalPriorityEnd_);
73 prefix_ senf::scheduler::detail::FIFORunner::~FIFORunner()
75 timer_delete(watchdogId_);
76 signal(SIGURG, SIG_DFL);
79 prefix_ void senf::scheduler::detail::FIFORunner::startWatchdog()
81 if (watchdogMs_ > 0) {
82 struct itimerspec timer;
83 ::memset(&timer, 0, sizeof(timer));
85 timer.it_interval.tv_sec = watchdogMs_ / 1000;
86 timer.it_interval.tv_nsec = (watchdogMs_ % 1000) * 1000000ul;
87 timer.it_value.tv_sec = timer.it_interval.tv_sec;
88 timer.it_value.tv_nsec = timer.it_interval.tv_nsec;
90 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
91 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
93 watchdogRunning_ = true;
99 prefix_ void senf::scheduler::detail::FIFORunner::stopWatchdog()
101 struct itimerspec timer;
102 ::memset(&timer, 0, sizeof(timer));
104 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
105 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
107 watchdogRunning_ = false;
110 // At the moment, the FIFORunner is not very efficient with many non-runnable tasks since the
111 // complete list of tasks is traversed on each run().
113 // To optimize this, we woould need a way to find the relative ordering of two tasks in O(1) (at the
114 // moment, this is an O(N) operation by traversing the list).
116 // One idea is, to give each task an 'order' value. Whenever a task is added at the end, it's order
117 // value is set to the order value of the last task + 1. Whenever the order value such added exceeds
118 // some threshold (e.g. 2^31 -1 or some such), the task list is traversed from beginning to end to
119 // assign new consecutive order values. This O(N) operation is so seldom, that it is amortized over
122 // With this value at hand, we can do several optimizations: One idea would be the following: The
123 // runnable set always has two types of tasks: There are tasks, which are heavily active and are
124 // signaled constantly and other tasks which lie dormant most of the time. Those dormant tasks will
125 // end up at the beginning of the task queue.
127 // With the above defined 'ordering' field available, we can manage an iterator pointing to the
128 // first and the last runnable task. This will often help a lot since the group of runnable tasks
129 // will mostly be localized to the end of the queue. only occasionally one of the dormant tasks will
130 // be runnable. This additional traversal time will be amortized over a larger time.
132 prefix_ void senf::scheduler::detail::FIFORunner::dequeue(TaskInfo * task)
134 TaskList::iterator i (TaskList::current(*task));
140 prefix_ void senf::scheduler::detail::FIFORunner::run()
143 TaskList::iterator f (tasks_.begin());
144 TaskList::iterator l (TaskList::current(highPriorityEnd_));
152 l = TaskList::current(normalPriorityEnd_);
170 prefix_ void senf::scheduler::detail::FIFORunner::run(TaskList::iterator f, TaskList::iterator l)
173 // We'll have problems inserting NullTask between f and l below, so just explicitly bail out
176 // This algorithm is carefully adjusted to make it work even when arbitrary tasks are removed
178 // - Before we begin, we add a NullTask to the queue. The only purpose of this node is, to mark
179 // the current end of the queue. The iterator to this node becomes the end iterator of the
181 // - We update the TaskInfo and move it to the next queue Element before calling the callback so
182 // we don't access the TaskInfo if it is removed while the callback is running
183 // - We keep the next to-be-processed node in a class variable which is checked and updated
184 // whenever a node is removed.
187 tasks_.insert(l, null);
188 TaskList::iterator end (TaskList::current(null));
191 using namespace boost::lambda;
193 var(watchdogCount_) = 0,
197 while (next_ != end) {
198 TaskInfo & task (*next_);
199 if (task.runnable_) {
200 task.runnable_ = false;
201 runningName_ = task.name();
203 runningBacktrace_ = task.backtrace_;
205 TaskList::iterator i (next_);
207 tasks_.splice(l, tasks_, i);
219 prefix_ senf::scheduler::detail::FIFORunner::TaskList::iterator
220 senf::scheduler::detail::FIFORunner::priorityEnd(TaskInfo::Priority p)
223 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_LOW :
225 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_NORMAL :
226 return TaskList::current(normalPriorityEnd_);
227 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_HIGH :
228 return TaskList::current(highPriorityEnd_);
230 return tasks_.begin();
233 prefix_ void senf::scheduler::detail::FIFORunner::watchdog(int, siginfo_t * si, void *)
235 FIFORunner & runner (*static_cast<FIFORunner *>(si->si_value.sival_ptr));
236 if (runner.watchdogCount_ > 0) {
237 ++ runner.watchdogCount_;
238 if (runner.watchdogCount_ > 2) {
239 ++ runner.hangCount_;
240 runner.watchdogError();
245 prefix_ void senf::scheduler::detail::FIFORunner::watchdogError()
247 static char const hex[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
248 'a', 'b', 'c', 'd', 'e', 'f' };
249 static void * entries[SENF_DEBUG_BACKTRACE_NUMCALLERS];
251 write(1, "\n\n*** Scheduler task hanging: ", 30);
252 write(1, runningName_.c_str(), runningName_.size());
253 write(1, " at\n ", 3);
255 unsigned nEntries( ::backtrace(entries, SENF_DEBUG_BACKTRACE_NUMCALLERS) );
256 for (unsigned i (0); i < nEntries; ++i) {
258 for (unsigned j (sizeof(void*)); j > 0; --j) {
259 ::uintptr_t v( ::uintptr_t (entries[i])>>(8*(j-1)));
260 write(1, &(hex[ (v >> 4) & 0x0f ]), 1);
261 write(1, &(hex[ (v ) & 0x0f ]), 1);
267 write(1, "Task was initialized at\n", 24);
268 write(1, runningBacktrace_.c_str(), runningBacktrace_.size());
275 ///////////////////////////////cc.e////////////////////////////////////////
277 //#include "FIFORunner.mpp"
283 // comment-column: 40
284 // c-file-style: "senf"
285 // indent-tabs-mode: nil
286 // ispell-local-dictionary: "american"
287 // compile-command: "scons -u test"