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122 lines
4.5 KiB
C++
122 lines
4.5 KiB
C++
/**
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* Copyright (c) 2015, Suresh Sundriyal
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of the copyright holder nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "timer.hh"
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#include "base/lnav_log.hh"
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#include "config.h"
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static const struct itimerval DISABLE_TV = {{0, 0}, {0, 0}};
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timer::error::error(int err) : e_err(err) {}
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timer::interrupt_timer::interrupt_timer(struct timeval t,
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sighandler_t_ sighandler = SIG_IGN)
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: new_handler(sighandler), new_val((struct itimerval){{0, 0}, t}),
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old_val(DISABLE_TV), armed(false)
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{
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memset(&this->old_handler, 0, sizeof(this->old_handler));
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}
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int
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timer::interrupt_timer::arm_timer()
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{
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struct sigaction sa;
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// Disable the interval timer before setting the handler and arming the
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// interval timer or else we will have a race-condition where the timer
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// might fire and the appropriate handler might not be set.
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if (setitimer(ITIMER_REAL, &DISABLE_TV, &this->old_val) != 0) {
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log_error("Unable to disable the timer: %s", strerror(errno));
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return -1;
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}
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memset(&sa, 0, sizeof(sa));
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sa.sa_handler = this->new_handler;
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if (sigaction(SIGALRM, &sa, &this->old_handler) == -1) {
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log_error("Unable to set the signal handler: %s", strerror(errno));
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if (setitimer(ITIMER_REAL, &this->old_val, NULL) != 0) {
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log_error("Unable to reset the interrupt timer: %s",
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strerror(errno));
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throw timer::error(errno);
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}
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return -1;
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}
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if (setitimer(ITIMER_REAL, &this->new_val, NULL) != 0) {
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if (sigaction(SIGALRM, &this->old_handler, NULL) == -1) {
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log_error("Unable to reset the signal handler: %s",
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strerror(errno));
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throw timer::error(errno);
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}
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log_error("Unable to set the timer: %s", strerror(errno));
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return -1;
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}
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this->armed = true;
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return 0;
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}
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bool
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timer::interrupt_timer::is_armed()
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{
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return this->armed;
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}
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void
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timer::interrupt_timer::disarm_timer()
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{
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if (this->armed) {
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// Disable the interval timer before resetting the handler and rearming
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// the previous interval timer or else we will have a race-condition
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// where the timer might fire and the appropriate handler might not be
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// set.
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if (setitimer(ITIMER_REAL, &DISABLE_TV, NULL) != 0) {
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log_error("Failed to disable the timer: %s", strerror(errno));
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throw timer::error(errno);
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}
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if (sigaction(SIGALRM, &this->old_handler, NULL) == -1) {
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log_error("Failed to reinstall previous SIGALRM handler: %s",
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strerror(errno));
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throw timer::error(errno);
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}
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if (setitimer(ITIMER_REAL, &this->old_val, NULL) != 0) {
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log_error("Failed to reset the timer to previous value: %s",
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strerror(errno));
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throw timer::error(errno);
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}
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this->armed = false;
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this->old_val = DISABLE_TV;
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memset(&this->old_handler, 0, sizeof(this->old_handler));
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}
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}
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timer::interrupt_timer::~interrupt_timer()
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{
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this->disarm_timer();
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}
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