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 <senf/Utils/Exception.hh>
34 #include <senf/Utils/senfassert.hh>
35 #include <senf/Utils/ScopeExit.hh>
37 #include <senf/config.hh>
41 //#include "FIFORunner.mpp"
43 ///////////////////////////////cc.p////////////////////////////////////////
45 prefix_ senf::scheduler::detail::FIFORunner::FIFORunner()
46 : tasks_ (), next_ (tasks_.end()), watchdogRunning_ (false), watchdogMs_ (1000),
47 watchdogAbort_ (false), watchdogCount_(0), hangCount_ (0), yield_ (false)
50 ::memset(&ev, 0, sizeof(ev));
51 ev.sigev_notify = SIGEV_SIGNAL;
52 ev.sigev_signo = SIGURG;
53 ev.sigev_value.sival_ptr = this;
54 if (timer_create(CLOCK_MONOTONIC, &ev, &watchdogId_) < 0)
55 SENF_THROW_SYSTEM_EXCEPTION("timer_create()");
58 ::memset(&sa, 0, sizeof(sa));
59 sa.sa_sigaction = &watchdog;
60 sa.sa_flags = SA_SIGINFO;
61 if (sigaction(SIGURG, &sa, 0) < 0)
62 SENF_THROW_SYSTEM_EXCEPTION("sigaction()");
66 sigaddset(&mask, SIGURG);
67 if (sigprocmask(SIG_UNBLOCK, &mask, 0) < 0)
68 SENF_THROW_SYSTEM_EXCEPTION("sigprocmask()");
70 tasks_.push_back(highPriorityEnd_);
71 tasks_.push_back(normalPriorityEnd_);
74 prefix_ senf::scheduler::detail::FIFORunner::~FIFORunner()
76 timer_delete(watchdogId_);
77 signal(SIGURG, SIG_DFL);
80 prefix_ void senf::scheduler::detail::FIFORunner::startWatchdog()
82 if (watchdogMs_ > 0) {
83 struct itimerspec timer;
84 ::memset(&timer, 0, sizeof(timer));
86 timer.it_interval.tv_sec = watchdogMs_ / 1000;
87 timer.it_interval.tv_nsec = (watchdogMs_ % 1000) * 1000000ul;
88 timer.it_value.tv_sec = timer.it_interval.tv_sec;
89 timer.it_value.tv_nsec = timer.it_interval.tv_nsec;
91 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
92 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
94 watchdogRunning_ = true;
100 prefix_ void senf::scheduler::detail::FIFORunner::stopWatchdog()
102 struct itimerspec timer;
103 ::memset(&timer, 0, sizeof(timer));
105 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
106 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
108 watchdogRunning_ = false;
111 // At the moment, the FIFORunner is not very efficient with many non-runnable tasks since the
112 // complete list of tasks is traversed on each run().
114 // To optimize this, we woould need a way to find the relative ordering of two tasks in O(1) (at the
115 // moment, this is an O(N) operation by traversing the list).
117 // One idea is, to give each task an 'order' value. Whenever a task is added at the end, it's order
118 // value is set to the order value of the last task + 1. Whenever the order value such added exceeds
119 // some threshold (e.g. 2^31 -1 or some such), the task list is traversed from beginning to end to
120 // assign new consecutive order values. This O(N) operation is so seldom, that it is amortized over
123 // With this value at hand, we can do several optimizations: One idea would be the following: The
124 // runnable set always has two types of tasks: There are tasks, which are heavily active and are
125 // signaled constantly and other tasks which lie dormant most of the time. Those dormant tasks will
126 // end up at the beginning of the task queue.
128 // With the above defined 'ordering' field available, we can manage an iterator pointing to the
129 // first and the last runnable task. This will often help a lot since the group of runnable tasks
130 // will mostly be localized to the end of the queue. only occasionally one of the dormant tasks will
131 // be runnable. This additional traversal time will be amortized over a larger time.
133 prefix_ void senf::scheduler::detail::FIFORunner::dequeue(TaskInfo * task)
135 TaskList::iterator i (TaskList::current(*task));
141 prefix_ void senf::scheduler::detail::FIFORunner::run()
144 TaskList::iterator f (tasks_.begin());
145 TaskList::iterator l (TaskList::current(highPriorityEnd_));
153 l = TaskList::current(normalPriorityEnd_);
171 prefix_ void senf::scheduler::detail::FIFORunner::run(TaskList::iterator f, TaskList::iterator l)
174 // We'll have problems inserting NullTask between f and l below, so just explicitly bail out
177 // This algorithm is carefully adjusted to make it work even when arbitrary tasks are removed
179 // - Before we begin, we add a NullTask to the queue. The only purpose of this node is, to mark
180 // the current end of the queue. The iterator to this node becomes the end iterator of the
182 // - We update the TaskInfo and move it to the next queue Element before calling the callback so
183 // we don't access the TaskInfo if it is removed while the callback is running
184 // - We keep the next to-be-processed node in a class variable which is checked and updated
185 // whenever a node is removed.
188 tasks_.insert(l, null);
189 TaskList::iterator end (TaskList::current(null));
192 using namespace boost::lambda;
194 var(watchdogCount_) = 0,
198 while (next_ != end) {
199 TaskInfo & task (*next_);
200 if (task.runnable_) {
201 task.runnable_ = false;
202 runningName_ = task.name();
204 runningBacktrace_ = task.backtrace_;
206 TaskList::iterator i (next_);
208 tasks_.splice(l, tasks_, i);
220 prefix_ senf::scheduler::detail::FIFORunner::TaskList::iterator
221 senf::scheduler::detail::FIFORunner::priorityEnd(TaskInfo::Priority p)
224 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_LOW :
226 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_NORMAL :
227 return TaskList::current(normalPriorityEnd_);
228 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_HIGH :
229 return TaskList::current(highPriorityEnd_);
231 return tasks_.begin();
234 prefix_ void senf::scheduler::detail::FIFORunner::watchdog(int, siginfo_t * si, void *)
236 FIFORunner & runner (*static_cast<FIFORunner *>(si->si_value.sival_ptr));
237 if (runner.watchdogCount_ > 0) {
238 ++ runner.watchdogCount_;
239 if (runner.watchdogCount_ > 2) {
240 ++ runner.hangCount_;
241 runner.watchdogError();
246 prefix_ void senf::scheduler::detail::FIFORunner::watchdogError()
248 static char const hex[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
249 'a', 'b', 'c', 'd', 'e', 'f' };
250 static void * entries[SENF_DEBUG_BACKTRACE_NUMCALLERS];
252 write(1, "\n\n*** Scheduler task hanging (pid ",34);
254 ::snprintf(pid, 7, "%6d", ::getpid());
258 write(1, runningName_.c_str(), runningName_.size());
259 write(1, " at\n ", 3);
261 unsigned nEntries( ::backtrace(entries, SENF_DEBUG_BACKTRACE_NUMCALLERS) );
262 for (unsigned i (0); i < nEntries; ++i) {
264 for (unsigned j (sizeof(void*)); j > 0; --j) {
265 uintptr_t v ( reinterpret_cast<uintptr_t>(entries[i]) >> (8*(j-1)) );
266 write(1, &(hex[ (v >> 4) & 0x0f ]), 1);
267 write(1, &(hex[ (v ) & 0x0f ]), 1);
273 write(1, "Task was initialized at\n", 24);
274 write(1, runningBacktrace_.c_str(), runningBacktrace_.size());
281 ///////////////////////////////cc.e////////////////////////////////////////
283 //#include "FIFORunner.mpp"
289 // comment-column: 40
290 // c-file-style: "senf"
291 // indent-tabs-mode: nil
292 // ispell-local-dictionary: "american"
293 // compile-command: "scons -u test"