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"
39 //#include "FIFORunner.mpp"
41 ///////////////////////////////cc.p////////////////////////////////////////
43 prefix_ senf::scheduler::detail::FIFORunner::FIFORunner()
44 : tasks_ (), next_ (tasks_.end()), watchdogRunning_ (false), watchdogMs_ (1000),
45 watchdogAbort_ (false), watchdogCount_(0), hangCount_ (0), yield_ (false)
48 ::memset(&ev, 0, sizeof(ev));
49 ev.sigev_notify = SIGEV_SIGNAL;
50 ev.sigev_signo = SIGURG;
51 ev.sigev_value.sival_ptr = this;
52 if (timer_create(CLOCK_MONOTONIC, &ev, &watchdogId_) < 0)
53 SENF_THROW_SYSTEM_EXCEPTION("timer_create()");
56 ::memset(&sa, 0, sizeof(sa));
57 sa.sa_sigaction = &watchdog;
58 sa.sa_flags = SA_SIGINFO;
59 if (sigaction(SIGURG, &sa, 0) < 0)
60 SENF_THROW_SYSTEM_EXCEPTION("sigaction()");
64 sigaddset(&mask, SIGURG);
65 if (sigprocmask(SIG_UNBLOCK, &mask, 0) < 0)
66 SENF_THROW_SYSTEM_EXCEPTION("sigprocmask()");
68 tasks_.push_back(highPriorityEnd_);
69 tasks_.push_back(normalPriorityEnd_);
72 prefix_ senf::scheduler::detail::FIFORunner::~FIFORunner()
74 timer_delete(watchdogId_);
75 signal(SIGURG, SIG_DFL);
78 prefix_ void senf::scheduler::detail::FIFORunner::startWatchdog()
80 if (watchdogMs_ > 0) {
81 struct itimerspec timer;
82 ::memset(&timer, 0, sizeof(timer));
84 timer.it_interval.tv_sec = watchdogMs_ / 1000;
85 timer.it_interval.tv_nsec = (watchdogMs_ % 1000) * 1000000ul;
86 timer.it_value.tv_sec = timer.it_interval.tv_sec;
87 timer.it_value.tv_nsec = timer.it_interval.tv_nsec;
89 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
90 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
92 watchdogRunning_ = true;
98 prefix_ void senf::scheduler::detail::FIFORunner::stopWatchdog()
100 struct itimerspec timer;
101 ::memset(&timer, 0, sizeof(timer));
103 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
104 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
106 watchdogRunning_ = false;
109 // At the moment, the FIFORunner is not very efficient with many non-runnable tasks since the
110 // complete list of tasks is traversed on each run().
112 // To optimize this, we woould need a way to find the relative ordering of two tasks in O(1) (at the
113 // moment, this is an O(N) operation by traversing the list).
115 // One idea is, to give each task an 'order' value. Whenever a task is added at the end, it's order
116 // value is set to the order value of the last task + 1. Whenever the order value such added exceeds
117 // some threshold (e.g. 2^31 -1 or some such), the task list is traversed from beginning to end to
118 // assign new consecutive order values. This O(N) operation is so seldom, that it is amortized over
121 // With this value at hand, we can do several optimizations: One idea would be the following: The
122 // runnable set always has two types of tasks: There are tasks, which are heavily active and are
123 // signaled constantly and other tasks which lie dormant most of the time. Those dormant tasks will
124 // end up at the beginning of the task queue.
126 // With the above defined 'ordering' field available, we can manage an iterator pointing to the
127 // first and the last runnable task. This will often help a lot since the group of runnable tasks
128 // will mostly be localized to the end of the queue. only occasionally one of the dormant tasks will
129 // be runnable. This additional traversal time will be amortized over a larger time.
131 prefix_ void senf::scheduler::detail::FIFORunner::dequeue(TaskInfo * task)
133 TaskList::iterator i (TaskList::current(*task));
139 prefix_ void senf::scheduler::detail::FIFORunner::run()
142 TaskList::iterator f (tasks_.begin());
143 TaskList::iterator l (TaskList::current(highPriorityEnd_));
151 l = TaskList::current(normalPriorityEnd_);
169 prefix_ void senf::scheduler::detail::FIFORunner::run(TaskList::iterator f, TaskList::iterator l)
172 // We'll have problems inserting NullTask between f and l below, so just explicitly bail out
175 // This algorithm is carefully adjusted to make it work even when arbitrary tasks are removed
177 // - Before we begin, we add a NullTask to the queue. The only purpose of this node is, to mark
178 // the current end of the queue. The iterator to this node becomes the end iterator of the
180 // - We update the TaskInfo and move it to the next queue Element before calling the callback so
181 // we don't access the TaskInfo if it is removed while the callback is running
182 // - We keep the next to-be-processed node in a class variable which is checked and updated
183 // whenever a node is removed.
186 tasks_.insert(l, null);
187 TaskList::iterator end (TaskList::current(null));
190 using namespace boost::lambda;
192 var(watchdogCount_) = 0,
196 while (next_ != end) {
197 TaskInfo & task (*next_);
198 if (task.runnable_) {
199 task.runnable_ = false;
200 runningName_ = task.name();
202 runningBacktrace_ = task.backtrace_;
204 TaskList::iterator i (next_);
206 tasks_.splice(l, tasks_, i);
218 prefix_ senf::scheduler::detail::FIFORunner::TaskList::iterator
219 senf::scheduler::detail::FIFORunner::priorityEnd(TaskInfo::Priority p)
222 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_LOW :
224 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_NORMAL :
225 return TaskList::current(normalPriorityEnd_);
226 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_HIGH :
227 return TaskList::current(highPriorityEnd_);
229 return tasks_.begin();
232 prefix_ void senf::scheduler::detail::FIFORunner::watchdog(int, siginfo_t * si, void *)
234 FIFORunner & runner (*static_cast<FIFORunner *>(si->si_value.sival_ptr));
235 if (runner.watchdogCount_ > 0) {
236 ++ runner.watchdogCount_;
237 if (runner.watchdogCount_ > 2) {
238 ++ runner.hangCount_;
239 runner.watchdogError();
244 prefix_ void senf::scheduler::detail::FIFORunner::watchdogError()
246 static char const hex[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
247 'a', 'b', 'c', 'd', 'e', 'f' };
248 static void * entries[SENF_DEBUG_BACKTRACE_NUMCALLERS];
250 write(1, "\n\n*** Scheduler task hanging: ", 30);
251 write(1, runningName_.c_str(), runningName_.size());
252 write(1, " at\n ", 3);
254 unsigned nEntries( ::backtrace(entries, SENF_DEBUG_BACKTRACE_NUMCALLERS) );
255 for (unsigned i (0); i < nEntries; ++i) {
257 for (unsigned j (sizeof(void*)); j > 0; --j) {
258 unsigned v (unsigned(entries[i])>>(8*(j-1)));
259 write(1, &(hex[ (v >> 4) & 0x0f ]), 1);
260 write(1, &(hex[ (v ) & 0x0f ]), 1);
266 write(1, "Task was initialized at\n", 24);
267 write(1, runningBacktrace_.c_str(), runningBacktrace_.size());
274 ///////////////////////////////cc.e////////////////////////////////////////
276 //#include "FIFORunner.mpp"
282 // comment-column: 40
283 // c-file-style: "senf"
284 // indent-tabs-mode: nil
285 // ispell-local-dictionary: "american"
286 // compile-command: "scons -u test"