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Reduces locking in SimulatedNetwork class.

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Bug: webrtc:9883
Change-Id: I07c78fd2dbba5e7481194b0d1aabfb56809ff6fc
Reviewed-on: https://webrtc-review.googlesource.com/c/120612
Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26491}
This commit is contained in:
Sebastian Jansson 2019-01-31 11:50:04 +01:00 committed by Commit Bot
parent 8102a1a8ea
commit eceea31cc2
3 changed files with 134 additions and 138 deletions
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1
call/BUILD.gn
View File

@ -287,6 +287,7 @@ rtc_source_set("simulated_network") {
"../api/units:time_delta",
"../rtc_base:checks",
"../rtc_base:rtc_base_approved",
"../rtc_base:sequenced_task_checker",
"//third_party/abseil-cpp/absl/memory",
"//third_party/abseil-cpp/absl/types:optional",
]

227
call/simulated_network.cc
View File

@ -31,12 +31,12 @@ SimulatedNetwork::~SimulatedNetwork() = default;
void SimulatedNetwork::SetConfig(const SimulatedNetwork::Config& config) {
rtc::CritScope crit(&config_lock_);
config_ = config; // Shallow copy of the struct.
config_state_.config = config; // Shallow copy of the struct.
double prob_loss = config.loss_percent / 100.0;
if (config_.avg_burst_loss_length == -1) {
if (config_state_.config.avg_burst_loss_length == -1) {
// Uniform loss
prob_loss_bursting_ = prob_loss;
prob_start_bursting_ = prob_loss;
config_state_.prob_loss_bursting = prob_loss;
config_state_.prob_start_bursting = prob_loss;
} else {
// Lose packets according to a gilbert-elliot model.
int avg_burst_loss_length = config.avg_burst_loss_length;
@ -47,29 +47,27 @@ void SimulatedNetwork::SetConfig(const SimulatedNetwork::Config& config) {
<< " avg_burst_loss_length must be " << min_avg_burst_loss_length + 1
<< " or higher.";
prob_loss_bursting_ = (1.0 - 1.0 / avg_burst_loss_length);
prob_start_bursting_ = prob_loss / (1 - prob_loss) / avg_burst_loss_length;
config_state_.prob_loss_bursting = (1.0 - 1.0 / avg_burst_loss_length);
config_state_.prob_start_bursting =
prob_loss / (1 - prob_loss) / avg_burst_loss_length;
}
}
void SimulatedNetwork::PauseTransmissionUntil(int64_t until_us) {
rtc::CritScope crit(&config_lock_);
pause_transmission_until_us_ = until_us;
config_state_.pause_transmission_until_us = until_us;
}
bool SimulatedNetwork::EnqueuePacket(PacketInFlightInfo packet) {
Config config;
{
rtc::CritScope crit(&config_lock_);
config = config_;
}
RTC_DCHECK_RUNS_SERIALIZED(&process_checker_);
ConfigState state = GetConfigState();
UpdateCapacityQueue(packet.send_time_us);
UpdateCapacityQueue(state, packet.send_time_us);
packet.size += config.packet_overhead;
rtc::CritScope crit(&process_lock_);
if (config.queue_length_packets > 0 &&
capacity_link_.size() >= config.queue_length_packets) {
packet.size += state.config.packet_overhead;
if (state.config.queue_length_packets > 0 &&
capacity_link_.size() >= state.config.queue_length_packets) {
// Too many packet on the link, drop this one.
return false;
}
@ -83,123 +81,114 @@ bool SimulatedNetwork::EnqueuePacket(PacketInFlightInfo packet) {
}
absl::optional<int64_t> SimulatedNetwork::NextDeliveryTimeUs() const {
rtc::CritScope crit(&process_lock_);
RTC_DCHECK_RUNS_SERIALIZED(&process_checker_);
if (!delay_link_.empty())
return delay_link_.begin()->arrival_time_us;
return absl::nullopt;
}
void SimulatedNetwork::UpdateCapacityQueue(int64_t time_now_us) {
Config config;
double prob_loss_bursting;
double prob_start_bursting;
int64_t pause_transmission_until_us;
{
rtc::CritScope crit(&config_lock_);
config = config_;
prob_loss_bursting = prob_loss_bursting_;
prob_start_bursting = prob_start_bursting_;
pause_transmission_until_us = pause_transmission_until_us_.value_or(0);
}
{
rtc::CritScope crit(&process_lock_);
bool needs_sort = false;
void SimulatedNetwork::UpdateCapacityQueue(ConfigState state,
int64_t time_now_us) {
bool needs_sort = false;
// Catch for thread races.
if (time_now_us < last_capacity_link_visit_us_.value_or(time_now_us))
return;
// Catch for thread races.
if (time_now_us < last_capacity_link_visit_us_.value_or(time_now_us))
return;
int64_t time_us = last_capacity_link_visit_us_.value_or(time_now_us);
// Check the capacity link first.
while (!capacity_link_.empty()) {
int64_t time_until_front_exits_us = 0;
if (config.link_capacity_kbps > 0) {
int64_t remaining_bits =
capacity_link_.front().packet.size * 8 - pending_drain_bits_;
RTC_DCHECK(remaining_bits > 0);
// Division rounded up - packet not delivered until its last bit is.
time_until_front_exits_us =
(1000 * remaining_bits + config.link_capacity_kbps - 1) /
config.link_capacity_kbps;
}
if (time_us + time_until_front_exits_us > time_now_us) {
// Packet at front will not exit yet. Will not enter here on infinite
// capacity(=0) so no special handling needed.
pending_drain_bits_ +=
((time_now_us - time_us) * config.link_capacity_kbps) / 1000;
break;
}
if (config.link_capacity_kbps > 0) {
pending_drain_bits_ +=
(time_until_front_exits_us * config.link_capacity_kbps) / 1000;
} else {
// Enough to drain the whole queue.
pending_drain_bits_ = queue_size_bytes_ * 8;
}
// Time to get this packet.
PacketInfo packet = std::move(capacity_link_.front());
capacity_link_.pop();
time_us += time_until_front_exits_us;
RTC_DCHECK(time_us >= packet.packet.send_time_us);
packet.arrival_time_us = std::max(pause_transmission_until_us, time_us);
queue_size_bytes_ -= packet.packet.size;
pending_drain_bits_ -= packet.packet.size * 8;
RTC_DCHECK(pending_drain_bits_ >= 0);
// Drop packets at an average rate of |config_.loss_percent| with
// and average loss burst length of |config_.avg_burst_loss_length|.
if ((bursting_ && random_.Rand<double>() < prob_loss_bursting) ||
(!bursting_ && random_.Rand<double>() < prob_start_bursting)) {
bursting_ = true;
packet.arrival_time_us = PacketDeliveryInfo::kNotReceived;
} else {
bursting_ = false;
int64_t arrival_time_jitter_us = std::max(
random_.Gaussian(config.queue_delay_ms * 1000,
config.delay_standard_deviation_ms * 1000),
0.0);
// If reordering is not allowed then adjust arrival_time_jitter
// to make sure all packets are sent in order.
int64_t last_arrival_time_us =
delay_link_.empty() ? -1 : delay_link_.back().arrival_time_us;
if (!config.allow_reordering && !delay_link_.empty() &&
packet.arrival_time_us + arrival_time_jitter_us <
last_arrival_time_us) {
arrival_time_jitter_us =
last_arrival_time_us - packet.arrival_time_us;
}
packet.arrival_time_us += arrival_time_jitter_us;
if (packet.arrival_time_us >= last_arrival_time_us) {
last_arrival_time_us = packet.arrival_time_us;
} else {
needs_sort = true;
}
}
delay_link_.emplace_back(std::move(packet));
int64_t time_us = last_capacity_link_visit_us_.value_or(time_now_us);
// Check the capacity link first.
while (!capacity_link_.empty()) {
int64_t time_until_front_exits_us = 0;
if (state.config.link_capacity_kbps > 0) {
int64_t remaining_bits =
capacity_link_.front().packet.size * 8 - pending_drain_bits_;
RTC_DCHECK(remaining_bits > 0);
// Division rounded up - packet not delivered until its last bit is.
time_until_front_exits_us =
(1000 * remaining_bits + state.config.link_capacity_kbps - 1) /
state.config.link_capacity_kbps;
}
last_capacity_link_visit_us_ = time_now_us;
// Cannot save unused capacity for later.
pending_drain_bits_ = std::min(pending_drain_bits_, queue_size_bytes_ * 8);
if (needs_sort) {
// Packet(s) arrived out of order, make sure list is sorted.
std::sort(delay_link_.begin(), delay_link_.end(),
[](const PacketInfo& p1, const PacketInfo& p2) {
return p1.arrival_time_us < p2.arrival_time_us;
});
if (time_us + time_until_front_exits_us > time_now_us) {
// Packet at front will not exit yet. Will not enter here on infinite
// capacity(=0) so no special handling needed.
pending_drain_bits_ +=
((time_now_us - time_us) * state.config.link_capacity_kbps) / 1000;
break;
}
if (state.config.link_capacity_kbps > 0) {
pending_drain_bits_ +=
(time_until_front_exits_us * state.config.link_capacity_kbps) / 1000;
} else {
// Enough to drain the whole queue.
pending_drain_bits_ = queue_size_bytes_ * 8;
}
// Time to get this packet.
PacketInfo packet = std::move(capacity_link_.front());
capacity_link_.pop();
time_us += time_until_front_exits_us;
RTC_DCHECK(time_us >= packet.packet.send_time_us);
packet.arrival_time_us =
std::max(state.pause_transmission_until_us, time_us);
queue_size_bytes_ -= packet.packet.size;
pending_drain_bits_ -= packet.packet.size * 8;
RTC_DCHECK(pending_drain_bits_ >= 0);
// Drop packets at an average rate of |state.config.loss_percent| with
// and average loss burst length of |state.config.avg_burst_loss_length|.
if ((bursting_ && random_.Rand<double>() < state.prob_loss_bursting) ||
(!bursting_ && random_.Rand<double>() < state.prob_start_bursting)) {
bursting_ = true;
packet.arrival_time_us = PacketDeliveryInfo::kNotReceived;
} else {
bursting_ = false;
int64_t arrival_time_jitter_us = std::max(
random_.Gaussian(state.config.queue_delay_ms * 1000,
state.config.delay_standard_deviation_ms * 1000),
0.0);
// If reordering is not allowed then adjust arrival_time_jitter
// to make sure all packets are sent in order.
int64_t last_arrival_time_us =
delay_link_.empty() ? -1 : delay_link_.back().arrival_time_us;
if (!state.config.allow_reordering && !delay_link_.empty() &&
packet.arrival_time_us + arrival_time_jitter_us <
last_arrival_time_us) {
arrival_time_jitter_us = last_arrival_time_us - packet.arrival_time_us;
}
packet.arrival_time_us += arrival_time_jitter_us;
if (packet.arrival_time_us >= last_arrival_time_us) {
last_arrival_time_us = packet.arrival_time_us;
} else {
needs_sort = true;
}
}
delay_link_.emplace_back(std::move(packet));
}
last_capacity_link_visit_us_ = time_now_us;
// Cannot save unused capacity for later.
pending_drain_bits_ = std::min(pending_drain_bits_, queue_size_bytes_ * 8);
if (needs_sort) {
// Packet(s) arrived out of order, make sure list is sorted.
std::sort(delay_link_.begin(), delay_link_.end(),
[](const PacketInfo& p1, const PacketInfo& p2) {
return p1.arrival_time_us < p2.arrival_time_us;
});
}
}
SimulatedNetwork::ConfigState SimulatedNetwork::GetConfigState() const {
rtc::CritScope crit(&config_lock_);
return config_state_;
}
std::vector<PacketDeliveryInfo> SimulatedNetwork::DequeueDeliverablePackets(
int64_t receive_time_us) {
UpdateCapacityQueue(receive_time_us);
rtc::CritScope crit(&process_lock_);
RTC_DCHECK_RUNS_SERIALIZED(&process_checker_);
UpdateCapacityQueue(GetConfigState(), receive_time_us);
std::vector<PacketDeliveryInfo> packets_to_deliver;
// Check the extra delay queue.
while (!delay_link_.empty() &&

44
call/simulated_network.h
View File

@ -18,8 +18,10 @@
#include "absl/types/optional.h"
#include "api/test/simulated_network.h"
#include "rtc_base/critical_section.h"
#include "rtc_base/race_checker.h"
#include "rtc_base/random.h"
#include "rtc_base/thread_annotations.h"
#include "rtc_base/thread_checker.h"
namespace webrtc {
@ -48,39 +50,43 @@ class SimulatedNetwork : public NetworkBehaviorInterface {
PacketInFlightInfo packet;
int64_t arrival_time_us;
};
// Contains current configuration state.
struct ConfigState {
// Static link configuration.
Config config;
// The probability to drop the packet if we are currently dropping a
// burst of packet
double prob_loss_bursting;
// The probability to drop a burst of packets.
double prob_start_bursting;
// Used for temporary delay spikes.
int64_t pause_transmission_until_us = 0;
};
// Moves packets from capacity- to delay link.
void UpdateCapacityQueue(int64_t time_now_us);
void UpdateCapacityQueue(ConfigState state, int64_t time_now_us)
RTC_RUN_ON(&process_checker_);
ConfigState GetConfigState() const;
rtc::CriticalSection config_lock_;
// |process_lock| guards the data structures involved in delay and loss
// |process_checker_| guards the data structures involved in delay and loss
// processes, such as the packet queues.
rtc::CriticalSection process_lock_;
std::queue<PacketInfo> capacity_link_ RTC_GUARDED_BY(process_lock_);
rtc::RaceChecker process_checker_;
std::queue<PacketInfo> capacity_link_ RTC_GUARDED_BY(process_checker_);
Random random_;
std::deque<PacketInfo> delay_link_ RTC_GUARDED_BY(process_lock_);
std::deque<PacketInfo> delay_link_ RTC_GUARDED_BY(process_checker_);
// Link configuration.
Config config_ RTC_GUARDED_BY(config_lock_);
absl::optional<int64_t> pause_transmission_until_us_
RTC_GUARDED_BY(config_lock_);
ConfigState config_state_ RTC_GUARDED_BY(config_lock_);
// Are we currently dropping a burst of packets?
bool bursting_;
// The probability to drop the packet if we are currently dropping a
// burst of packet
double prob_loss_bursting_ RTC_GUARDED_BY(config_lock_);
// The probability to drop a burst of packets.
double prob_start_bursting_ RTC_GUARDED_BY(config_lock_);
int64_t queue_size_bytes_ RTC_GUARDED_BY(process_lock_) = 0;
int64_t pending_drain_bits_ RTC_GUARDED_BY(process_lock_) = 0;
int64_t queue_size_bytes_ RTC_GUARDED_BY(process_checker_) = 0;
int64_t pending_drain_bits_ RTC_GUARDED_BY(process_checker_) = 0;
absl::optional<int64_t> last_capacity_link_visit_us_
RTC_GUARDED_BY(process_lock_);
RTC_GUARDED_BY(process_checker_);
};
} // namespace webrtc