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>
39 #include <senf/config.hh>
43 //#include "FIFORunner.mpp"
45 ///////////////////////////////cc.p////////////////////////////////////////
47 prefix_ senf::scheduler::detail::FIFORunner::FIFORunner()
48 : tasks_ (), next_ (tasks_.end()), watchdogRunning_ (false), watchdogMs_ (1000),
49 watchdogAbort_ (false), watchdogCount_(0), hangCount_ (0), yield_ (false)
52 ::memset(&ev, 0, sizeof(ev));
53 ev.sigev_notify = SIGEV_SIGNAL;
54 ev.sigev_signo = SIGURG;
55 ev.sigev_value.sival_ptr = this;
56 if (timer_create(CLOCK_MONOTONIC, &ev, &watchdogId_) < 0)
57 SENF_THROW_SYSTEM_EXCEPTION("timer_create()");
60 ::memset(&sa, 0, sizeof(sa));
61 sa.sa_sigaction = &watchdog;
62 sa.sa_flags = SA_SIGINFO;
63 if (sigaction(SIGURG, &sa, 0) < 0)
64 SENF_THROW_SYSTEM_EXCEPTION("sigaction()");
68 sigaddset(&mask, SIGURG);
69 if (sigprocmask(SIG_UNBLOCK, &mask, 0) < 0)
70 SENF_THROW_SYSTEM_EXCEPTION("sigprocmask()");
72 tasks_.push_back(highPriorityEnd_);
73 tasks_.push_back(normalPriorityEnd_);
76 prefix_ senf::scheduler::detail::FIFORunner::~FIFORunner()
78 timer_delete(watchdogId_);
79 signal(SIGURG, SIG_DFL);
82 prefix_ void senf::scheduler::detail::FIFORunner::startWatchdog()
84 if (watchdogMs_ > 0) {
85 struct itimerspec timer;
86 ::memset(&timer, 0, sizeof(timer));
88 timer.it_interval.tv_sec = watchdogMs_ / 1000;
89 timer.it_interval.tv_nsec = (watchdogMs_ % 1000) * 1000000ul;
90 timer.it_value.tv_sec = timer.it_interval.tv_sec;
91 timer.it_value.tv_nsec = timer.it_interval.tv_nsec;
93 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
94 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
96 watchdogRunning_ = true;
102 prefix_ void senf::scheduler::detail::FIFORunner::stopWatchdog()
104 struct itimerspec timer;
105 ::memset(&timer, 0, sizeof(timer));
107 if (timer_settime(watchdogId_, 0, &timer, 0) < 0)
108 SENF_THROW_SYSTEM_EXCEPTION("timer_settime()");
110 watchdogRunning_ = false;
113 // At the moment, the FIFORunner is not very efficient with many non-runnable tasks since the
114 // complete list of tasks is traversed on each run().
116 // To optimize this, we woould need a way to find the relative ordering of two tasks in O(1) (at the
117 // moment, this is an O(N) operation by traversing the list).
119 // One idea is, to give each task an 'order' value. Whenever a task is added at the end, it's order
120 // value is set to the order value of the last task + 1. Whenever the order value such added exceeds
121 // some threshold (e.g. 2^31 -1 or some such), the task list is traversed from beginning to end to
122 // assign new consecutive order values. This O(N) operation is so seldom, that it is amortized over
125 // With this value at hand, we can do several optimizations: One idea would be the following: The
126 // runnable set always has two types of tasks: There are tasks, which are heavily active and are
127 // signaled constantly and other tasks which lie dormant most of the time. Those dormant tasks will
128 // end up at the beginning of the task queue.
130 // With the above defined 'ordering' field available, we can manage an iterator pointing to the
131 // first and the last runnable task. This will often help a lot since the group of runnable tasks
132 // will mostly be localized to the end of the queue. only occasionally one of the dormant tasks will
133 // be runnable. This additional traversal time will be amortized over a larger time.
135 prefix_ void senf::scheduler::detail::FIFORunner::dequeue(TaskInfo * task)
137 TaskList::iterator i (TaskList::current(*task));
143 prefix_ void senf::scheduler::detail::FIFORunner::run()
146 TaskList::iterator f (tasks_.begin());
147 TaskList::iterator l (TaskList::current(highPriorityEnd_));
155 l = TaskList::current(normalPriorityEnd_);
173 prefix_ void senf::scheduler::detail::FIFORunner::run(TaskList::iterator f, TaskList::iterator l)
176 // We'll have problems inserting NullTask between f and l below, so just explicitly bail out
179 // This algorithm is carefully adjusted to make it work even when arbitrary tasks are removed
181 // - Before we begin, we add a NullTask to the queue. The only purpose of this node is, to mark
182 // the current end of the queue. The iterator to this node becomes the end iterator of the
184 // - We update the TaskInfo and move it to the next queue Element before calling the callback so
185 // we don't access the TaskInfo if it is removed while the callback is running
186 // - We keep the next to-be-processed node in a class variable which is checked and updated
187 // whenever a node is removed.
190 tasks_.insert(l, null);
191 TaskList::iterator end (TaskList::current(null));
194 using namespace boost::lambda;
196 var(watchdogCount_) = 0,
200 while (next_ != end) {
201 TaskInfo & task (*next_);
202 if (task.runnable_) {
203 task.runnable_ = false;
204 runningName_ = task.name();
206 runningBacktrace_ = task.backtrace_;
208 TaskList::iterator i (next_);
210 tasks_.splice(l, tasks_, i);
222 prefix_ senf::scheduler::detail::FIFORunner::TaskList::iterator
223 senf::scheduler::detail::FIFORunner::priorityEnd(TaskInfo::Priority p)
226 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_LOW :
228 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_NORMAL :
229 return TaskList::current(normalPriorityEnd_);
230 case senf::scheduler::detail::FIFORunner::TaskInfo::PRIORITY_HIGH :
231 return TaskList::current(highPriorityEnd_);
233 return tasks_.begin();
236 prefix_ void senf::scheduler::detail::FIFORunner::watchdog(int, siginfo_t * si, void *)
238 FIFORunner & runner (*static_cast<FIFORunner *>(si->si_value.sival_ptr));
239 if (runner.watchdogCount_ > 0) {
240 ++ runner.watchdogCount_;
241 if (runner.watchdogCount_ > 2) {
242 ++ runner.hangCount_;
243 runner.watchdogError();
248 prefix_ void senf::scheduler::detail::FIFORunner::watchdogError()
250 static char const hex[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
251 'a', 'b', 'c', 'd', 'e', 'f' };
252 static void * entries[SENF_DEBUG_BACKTRACE_NUMCALLERS];
254 // We don't care if the write commands below fail, we just give our best to inform the user
255 (void) write(1, "\n\n*** Scheduler task hanging (pid ",34);
257 ::snprintf(pid, 7, "%6d", ::getpid());
259 (void) write(1, pid, 6);
260 (void) write(1, "): ", 3);
261 (void) write(1, runningName_.c_str(), runningName_.size());
262 (void) write(1, " at\n ", 3);
264 unsigned nEntries( ::backtrace(entries, SENF_DEBUG_BACKTRACE_NUMCALLERS) );
265 for (unsigned i (0); i < nEntries; ++i) {
267 for (unsigned j (sizeof(void*)); j > 0; --j) {
268 uintptr_t v ( reinterpret_cast<uintptr_t>(entries[i]) >> (8*(j-1)) );
269 (void) write(1, &(hex[ (v >> 4) & 0x0f ]), 1);
270 (void) write(1, &(hex[ (v ) & 0x0f ]), 1);
274 (void) write(1, "\n", 1);
277 (void) write(1, "Task was initialized at\n", 24);
278 (void) write(1, runningBacktrace_.c_str(), runningBacktrace_.size());
280 (void) write(1, "\n", 1);
285 ///////////////////////////////cc.e////////////////////////////////////////
287 //#include "FIFORunner.mpp"
293 // comment-column: 40
294 // c-file-style: "senf"
295 // indent-tabs-mode: nil
296 // ispell-local-dictionary: "american"
297 // compile-command: "scons -u test"