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/*
*
* Conky, a system monitor, based on torsmo
*
* Please see COPYING for details
*
* Copyright (C) 2010 Pavel Labath et al.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "config.h"
#include "logging.h"
#include "update-cb.hh"
#include <unistd.h>
#include <typeinfo>
namespace conky {
namespace {
semaphore sem_wait;
enum { UNUSED_MAX = 5 };
} // namespace
namespace priv {
callback_base::~callback_base() { stop(); }
void callback_base::stop() {
if (thread != nullptr) {
done = true;
sem_start.post();
if (pipefd.second >= 0) {
if (write(pipefd.second, "X", 1) != 1) {
NORM_ERR("can't write 'X' to pipefd %d: %s", pipefd.second,
strerror(errno));
}
}
thread->join();
delete thread;
thread = nullptr;
}
if (pipefd.first >= 0) {
close(pipefd.first);
pipefd.first = -1;
}
if (pipefd.second >= 0) {
close(pipefd.second);
pipefd.second = -1;
}
}
inline size_t callback_base::get_hash(const handle &h) { return h->hash; }
inline bool callback_base::is_equal(const handle &a, const handle &b) {
if (a->hash != b->hash) { return false; }
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wpotentially-evaluated-expression"
if (typeid(*a) != typeid(*b)) { return false; }
#pragma clang diagnostic pop
return *a == *b;
}
/*
* If a callback is not successfully inserted into the set, it must have
* the same hash as an existing callback. If this is so, merge the incoming
* callback with the one that prevented insertion. Keep the smaller of the
* two periods.
*/
void callback_base::merge(callback_base &&other) {
if (other.period < period) {
period = other.period;
remaining = 0;
}
assert(wait == other.wait);
unused = 0;
}
/*
* Register a callback (i.e. insert it into the callbacks set)
*/
callback_base::handle callback_base::do_register_cb(const handle &h) {
const auto &p = callbacks.insert(h);
/* insertion failed; callback already exists */
if (!p.second) { (*p.first)->merge(std::move(*h)); }
return *p.first;
}
void callback_base::run() {
if (thread == nullptr) {
thread = new std::thread(&callback_base::start_routine, this);
}
sem_start.post();
}
void callback_base::start_routine() {
for (;;) {
sem_start.wait();
if (done) { return; }
// clear any remaining posts in case the previous iteration was very slow
// (this should only happen if wait == false)
while (sem_start.trywait()) {
// do nothing
}
work();
if (wait) { sem_wait.post(); }
}
}
callback_base::Callbacks callback_base::callbacks(1, get_hash, is_equal);
} // namespace priv
void run_all_callbacks() {
using priv::callback_base;
size_t wait = 0;
for (auto i = callback_base::callbacks.begin();
i != callback_base::callbacks.end();) {
callback_base &cb = **i;
/* check whether enough update intervals have elapsed (up to period) */
if (cb.remaining-- == 0) {
/* run the callback as long as someone holds a pointer to it;
* if no one owns the callback, run it at most UNUSED_MAX times */
if (!i->unique() || ++cb.unused < UNUSED_MAX) {
cb.remaining = cb.period - 1;
cb.run();
if (cb.wait) { ++wait; }
}
}
if (cb.unused == UNUSED_MAX) {
auto t = i;
++i;
callback_base::callbacks.erase(t);
} else {
++i;
}
}
while (wait-- > 0) { sem_wait.wait(); }
}
} // namespace conky
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