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rmw_wait.cpp
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rmw_wait.cpp
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// Copyright 2016-2018 Proyectos y Sistemas de Mantenimiento SL (eProsima).
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "fastrtps/subscriber/Subscriber.h"
#include "rcutils/macros.h"
#include "rmw/error_handling.h"
#include "rmw/rmw.h"
#include "rmw_fastrtps_shared_cpp/custom_client_info.hpp"
#include "rmw_fastrtps_shared_cpp/custom_service_info.hpp"
#include "rmw_fastrtps_shared_cpp/custom_subscriber_info.hpp"
#include "rmw_fastrtps_shared_cpp/rmw_common.hpp"
#include "types/custom_wait_set_info.hpp"
#include "types/guard_condition.hpp"
// helper function for wait
bool
check_wait_set_for_data(
const rmw_subscriptions_t * subscriptions,
const rmw_guard_conditions_t * guard_conditions,
const rmw_services_t * services,
const rmw_clients_t * clients,
const rmw_events_t * events)
{
if (subscriptions) {
for (size_t i = 0; i < subscriptions->subscriber_count; ++i) {
void * data = subscriptions->subscribers[i];
auto custom_subscriber_info = static_cast<CustomSubscriberInfo *>(data);
// Short circuiting out of this function is possible
if (custom_subscriber_info && custom_subscriber_info->listener_->hasData()) {
return true;
}
}
}
if (clients) {
for (size_t i = 0; i < clients->client_count; ++i) {
void * data = clients->clients[i];
CustomClientInfo * custom_client_info = static_cast<CustomClientInfo *>(data);
if (custom_client_info && custom_client_info->listener_->hasData()) {
return true;
}
}
}
if (services) {
for (size_t i = 0; i < services->service_count; ++i) {
void * data = services->services[i];
CustomServiceInfo * custom_service_info = static_cast<CustomServiceInfo *>(data);
if (custom_service_info && custom_service_info->listener_->hasData()) {
return true;
}
}
}
if (events) {
for (size_t i = 0; i < events->event_count; ++i) {
auto event = static_cast<rmw_event_t *>(events->events[i]);
auto custom_event_info = static_cast<CustomEventInfo *>(event->data);
if (custom_event_info->getListener()->hasEvent(event->event_type)) {
return true;
}
}
}
if (guard_conditions) {
for (size_t i = 0; i < guard_conditions->guard_condition_count; ++i) {
void * data = guard_conditions->guard_conditions[i];
auto guard_condition = static_cast<GuardCondition *>(data);
if (guard_condition && guard_condition->hasTriggered()) {
return true;
}
}
}
return false;
}
namespace rmw_fastrtps_shared_cpp
{
rmw_ret_t
__rmw_wait(
const char * identifier,
rmw_subscriptions_t * subscriptions,
rmw_guard_conditions_t * guard_conditions,
rmw_services_t * services,
rmw_clients_t * clients,
rmw_events_t * events,
rmw_wait_set_t * wait_set,
const rmw_time_t * wait_timeout)
{
RCUTILS_CAN_RETURN_WITH_ERROR_OF(RMW_RET_INVALID_ARGUMENT);
RCUTILS_CAN_RETURN_WITH_ERROR_OF(RMW_RET_INCORRECT_RMW_IMPLEMENTATION);
RMW_CHECK_ARGUMENT_FOR_NULL(wait_set, RMW_RET_INVALID_ARGUMENT);
RMW_CHECK_TYPE_IDENTIFIERS_MATCH(
wait set handle,
wait_set->implementation_identifier, identifier,
return RMW_RET_INCORRECT_RMW_IMPLEMENTATION)
// If wait_set_info is ever nullptr, it can only mean one of three things:
// - Wait set is invalid. Caller did not respect preconditions.
// - Implementation is logically broken. Definitely not something we want to treat as a normal
// error.
// - Heap is corrupt.
// In all three cases, it's better if this crashes soon enough.
CustomWaitsetInfo * wait_set_info = static_cast<CustomWaitsetInfo *>(wait_set->data);
std::mutex * conditionMutex = &wait_set_info->condition_mutex;
std::condition_variable * conditionVariable = &wait_set_info->condition;
if (subscriptions) {
for (size_t i = 0; i < subscriptions->subscriber_count; ++i) {
void * data = subscriptions->subscribers[i];
auto custom_subscriber_info = static_cast<CustomSubscriberInfo *>(data);
custom_subscriber_info->listener_->attachCondition(conditionMutex, conditionVariable);
}
}
if (clients) {
for (size_t i = 0; i < clients->client_count; ++i) {
void * data = clients->clients[i];
CustomClientInfo * custom_client_info = static_cast<CustomClientInfo *>(data);
custom_client_info->listener_->attachCondition(conditionMutex, conditionVariable);
}
}
if (services) {
for (size_t i = 0; i < services->service_count; ++i) {
void * data = services->services[i];
auto custom_service_info = static_cast<CustomServiceInfo *>(data);
custom_service_info->listener_->attachCondition(conditionMutex, conditionVariable);
}
}
if (events) {
for (size_t i = 0; i < events->event_count; ++i) {
auto event = static_cast<rmw_event_t *>(events->events[i]);
auto custom_event_info = static_cast<CustomEventInfo *>(event->data);
custom_event_info->getListener()->attachCondition(conditionMutex, conditionVariable);
}
}
if (guard_conditions) {
for (size_t i = 0; i < guard_conditions->guard_condition_count; ++i) {
void * data = guard_conditions->guard_conditions[i];
auto guard_condition = static_cast<GuardCondition *>(data);
guard_condition->attachCondition(conditionMutex, conditionVariable);
}
}
// This mutex prevents any of the listeners
// to change the internal state and notify the condition
// between the call to hasData() / hasTriggered() and wait()
// otherwise the decision to wait might be incorrect
std::unique_lock<std::mutex> lock(*conditionMutex);
bool hasData = check_wait_set_for_data(
subscriptions, guard_conditions, services, clients, events);
auto predicate = [subscriptions, guard_conditions, services, clients, events]() {
return check_wait_set_for_data(subscriptions, guard_conditions, services, clients, events);
};
bool timeout = false;
if (!hasData) {
if (!wait_timeout) {
conditionVariable->wait(lock, predicate);
} else if (wait_timeout->sec > 0 || wait_timeout->nsec > 0) {
auto n = std::chrono::duration_cast<std::chrono::nanoseconds>(
std::chrono::seconds(wait_timeout->sec));
n += std::chrono::nanoseconds(wait_timeout->nsec);
timeout = !conditionVariable->wait_for(lock, n, predicate);
} else {
timeout = true;
}
}
// Unlock the condition variable mutex to prevent deadlocks that can occur if
// a listener triggers while the condition variable is being detached.
// Listeners will no longer be prevented from changing their internal state,
// but that should not cause issues (if a listener has data / has triggered
// after we check, it will be caught on the next call to this function).
lock.unlock();
if (subscriptions) {
for (size_t i = 0; i < subscriptions->subscriber_count; ++i) {
void * data = subscriptions->subscribers[i];
auto custom_subscriber_info = static_cast<CustomSubscriberInfo *>(data);
custom_subscriber_info->listener_->detachCondition();
if (!custom_subscriber_info->listener_->hasData()) {
subscriptions->subscribers[i] = 0;
}
}
}
if (clients) {
for (size_t i = 0; i < clients->client_count; ++i) {
void * data = clients->clients[i];
CustomClientInfo * custom_client_info = static_cast<CustomClientInfo *>(data);
custom_client_info->listener_->detachCondition();
if (!custom_client_info->listener_->hasData()) {
clients->clients[i] = 0;
}
}
}
if (services) {
for (size_t i = 0; i < services->service_count; ++i) {
void * data = services->services[i];
auto custom_service_info = static_cast<CustomServiceInfo *>(data);
custom_service_info->listener_->detachCondition();
if (!custom_service_info->listener_->hasData()) {
services->services[i] = 0;
}
}
}
if (events) {
for (size_t i = 0; i < events->event_count; ++i) {
auto event = static_cast<rmw_event_t *>(events->events[i]);
auto custom_event_info = static_cast<CustomEventInfo *>(event->data);
custom_event_info->getListener()->detachCondition();
if (!custom_event_info->getListener()->hasEvent(event->event_type)) {
events->events[i] = nullptr;
}
}
}
if (guard_conditions) {
for (size_t i = 0; i < guard_conditions->guard_condition_count; ++i) {
void * data = guard_conditions->guard_conditions[i];
auto guard_condition = static_cast<GuardCondition *>(data);
guard_condition->detachCondition();
if (!guard_condition->getHasTriggered()) {
guard_conditions->guard_conditions[i] = 0;
}
}
}
return timeout ? RMW_RET_TIMEOUT : RMW_RET_OK;
}
} // namespace rmw_fastrtps_shared_cpp