rustdds/dds/

qos.rs

use std::collections::BTreeMap;

use serde::{Deserialize, Serialize};
use speedy::{Readable, Writable};
#[allow(unused_imports)]
use log::{debug, error, info, trace, warn};

use crate::{
  dds::result::QosError,
  messages::submessages::elements::parameter::Parameter,
  serialization::{
    pl_cdr_adapters::{PlCdrDeserializeError, PlCdrSerializeError},
    speedy_pl_cdr_helpers::*,
  },
  structure::{duration::Duration, endpoint::ReliabilityKind, parameter_id::ParameterId},
};

// This is to be implemented by all DomainParticipant, Publisher, Subscriber,
// DataWriter, DataReader, Topic
/// Trait that is implemented by all necessary DDS Entities that are required to
/// provide QosPolicies.
pub trait HasQoSPolicy {
  fn qos(&self) -> QosPolicies;
}

/// Trait that is implemented by all necessary DDS Entities that are required to
/// have a mutable QosPolicies.
pub trait MutQosPolicy {
  fn set_qos(&mut self, new_qos: &QosPolicies) -> Result<(), QosError>;
}

/// DDS spec 2.3.3 defines this as "long" with named constants from 0 to 22.
/// numbering is from IDL PSM, but it should be unnecessary at the Rust
/// application interface
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
pub enum QosPolicyId {
  // Invalid  // We should represent this using Option<QosPolicyId> where needed
  // UserData,  // 1
  Durability,   // 2
  Presentation, // 3
  Deadline,
  LatencyBudget, // 5
  Ownership,
  // OwnershipStrength, // 7
  Liveliness,
  TimeBasedFilter, // 9
  // Partition,

  // Note: If "Partition" is ever implemented, observe also DDS Security spec v1.1
  // Section "7.3.5 Immutability of Publisher Partition Qos in combination with non-volatile
  // Durability kind" when implementing.
  Reliability, // 11
  DestinationOrder,
  History, // 13
  ResourceLimits,
  // EntityFactory, // 15
  // WriterDataLifeCycle,
  // ReaderDataLifeCycle, // 17
  // TopicData, // 18
  // GroupData,
  // TransportPriority, // 20
  Lifespan,
  // DurabilityService, // 22
  Property, // No Id in the security spec (But this is from older DDS/RTPs spec.)
}

/// Utility for building [QosPolicies]
#[derive(Default, Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct QosPolicyBuilder {
  durability: Option<policy::Durability>,
  presentation: Option<policy::Presentation>,
  deadline: Option<policy::Deadline>,
  latency_budget: Option<policy::LatencyBudget>,
  ownership: Option<policy::Ownership>,
  liveliness: Option<policy::Liveliness>,
  time_based_filter: Option<policy::TimeBasedFilter>,
  reliability: Option<policy::Reliability>,
  destination_order: Option<policy::DestinationOrder>,
  history: Option<policy::History>,
  resource_limits: Option<policy::ResourceLimits>,
  lifespan: Option<policy::Lifespan>,
  #[cfg(feature = "security")]
  property: Option<policy::Property>,
}

impl QosPolicyBuilder {
  pub fn new() -> Self {
    Self::default()
  }

  #[must_use]
  pub const fn durability(mut self, durability: policy::Durability) -> Self {
    self.durability = Some(durability);
    self
  }

  #[must_use]
  pub const fn presentation(mut self, presentation: policy::Presentation) -> Self {
    self.presentation = Some(presentation);
    self
  }

  #[must_use]
  pub const fn deadline(mut self, deadline: policy::Deadline) -> Self {
    self.deadline = Some(deadline);
    self
  }

  #[must_use]
  pub const fn latency_budget(mut self, latency_budget: policy::LatencyBudget) -> Self {
    self.latency_budget = Some(latency_budget);
    self
  }

  #[must_use]
  pub const fn ownership(mut self, ownership: policy::Ownership) -> Self {
    self.ownership = Some(ownership);
    self
  }

  #[must_use]
  pub const fn liveliness(mut self, liveliness: policy::Liveliness) -> Self {
    self.liveliness = Some(liveliness);
    self
  }

  #[must_use]
  pub const fn time_based_filter(mut self, time_based_filter: policy::TimeBasedFilter) -> Self {
    self.time_based_filter = Some(time_based_filter);
    self
  }

  #[must_use]
  pub const fn reliability(mut self, reliability: policy::Reliability) -> Self {
    self.reliability = Some(reliability);
    self
  }

  #[must_use]
  pub const fn best_effort(mut self) -> Self {
    self.reliability = Some(policy::Reliability::BestEffort);
    self
  }

  #[must_use]
  pub const fn reliable(mut self, max_blocking_time: Duration) -> Self {
    self.reliability = Some(policy::Reliability::Reliable { max_blocking_time });
    self
  }

  #[must_use]
  pub const fn destination_order(mut self, destination_order: policy::DestinationOrder) -> Self {
    self.destination_order = Some(destination_order);
    self
  }

  #[must_use]
  pub const fn history(mut self, history: policy::History) -> Self {
    self.history = Some(history);
    self
  }

  #[must_use]
  pub const fn resource_limits(mut self, resource_limits: policy::ResourceLimits) -> Self {
    self.resource_limits = Some(resource_limits);
    self
  }

  #[must_use]
  pub const fn lifespan(mut self, lifespan: policy::Lifespan) -> Self {
    self.lifespan = Some(lifespan);
    self
  }

  #[cfg(feature = "security")]
  #[must_use]
  pub fn property(mut self, property: policy::Property) -> Self {
    self.property = Some(property);
    self
  }

  pub fn build(self) -> QosPolicies {
    QosPolicies {
      durability: self.durability,
      presentation: self.presentation,
      deadline: self.deadline,
      latency_budget: self.latency_budget,
      ownership: self.ownership,
      liveliness: self.liveliness,
      time_based_filter: self.time_based_filter,
      reliability: self.reliability,
      destination_order: self.destination_order,
      history: self.history,
      resource_limits: self.resource_limits,
      lifespan: self.lifespan,
      #[cfg(feature = "security")]
      property: self.property,
    }
  }
}

/// Describes a set of RTPS/DDS QoS policies
///
/// QosPolicies are constructed using a [`QosPolicyBuilder`]
#[derive(Clone, Debug, PartialEq, Eq, Default, Serialize, Deserialize)]
pub struct QosPolicies {
  // pub(crate) because as we want to have some builtin QoS Policies as constant.
  pub(crate) durability: Option<policy::Durability>,
  pub(crate) presentation: Option<policy::Presentation>,
  pub(crate) deadline: Option<policy::Deadline>,
  pub(crate) latency_budget: Option<policy::LatencyBudget>,
  pub(crate) ownership: Option<policy::Ownership>,
  pub(crate) liveliness: Option<policy::Liveliness>,
  pub(crate) time_based_filter: Option<policy::TimeBasedFilter>,
  pub(crate) reliability: Option<policy::Reliability>,
  pub(crate) destination_order: Option<policy::DestinationOrder>,
  pub(crate) history: Option<policy::History>,
  pub(crate) resource_limits: Option<policy::ResourceLimits>,
  pub(crate) lifespan: Option<policy::Lifespan>,
  #[cfg(feature = "security")]
  pub(crate) property: Option<policy::Property>,
}

impl QosPolicies {
  // TODO: rename this to "none", as this is already member of QosPolicies, so
  // context in implied
  pub fn qos_none() -> Self {
    Self::default()
  }

  pub fn builder() -> QosPolicyBuilder {
    QosPolicyBuilder::new()
  }

  pub const fn durability(&self) -> Option<policy::Durability> {
    self.durability
  }

  pub fn is_volatile(&self) -> bool {
    matches!(self.durability, Some(policy::Durability::Volatile))
  }

  pub const fn presentation(&self) -> Option<policy::Presentation> {
    self.presentation
  }

  pub const fn deadline(&self) -> Option<policy::Deadline> {
    self.deadline
  }

  pub const fn latency_budget(&self) -> Option<policy::LatencyBudget> {
    self.latency_budget
  }

  pub const fn ownership(&self) -> Option<policy::Ownership> {
    self.ownership
  }

  pub const fn liveliness(&self) -> Option<policy::Liveliness> {
    self.liveliness
  }

  pub const fn time_based_filter(&self) -> Option<policy::TimeBasedFilter> {
    self.time_based_filter
  }

  pub const fn reliability(&self) -> Option<policy::Reliability> {
    self.reliability
  }

  pub fn is_reliable(&self) -> bool {
    matches!(self.reliability, Some(policy::Reliability::Reliable { .. }))
  }

  pub const fn reliable_max_blocking_time(&self) -> Option<Duration> {
    if let Some(policy::Reliability::Reliable { max_blocking_time }) = self.reliability {
      Some(max_blocking_time)
    } else {
      None
    }
  }

  pub const fn destination_order(&self) -> Option<policy::DestinationOrder> {
    self.destination_order
  }

  pub const fn history(&self) -> Option<policy::History> {
    self.history
  }

  pub const fn resource_limits(&self) -> Option<policy::ResourceLimits> {
    self.resource_limits
  }

  pub const fn lifespan(&self) -> Option<policy::Lifespan> {
    self.lifespan
  }

  #[cfg(feature = "security")]
  pub fn property(&self) -> Option<policy::Property> {
    self.property.clone()
  }

  /// Merge two QosPolicies
  ///
  /// Constructs a QosPolicy, where each policy is taken from `self`,
  /// and overwritten with those policies from `other` that are defined.
  #[must_use]
  pub fn modify_by(&self, other: &Self) -> Self {
    Self {
      durability: other.durability.or(self.durability),
      presentation: other.presentation.or(self.presentation),
      deadline: other.deadline.or(self.deadline),
      latency_budget: other.latency_budget.or(self.latency_budget),
      ownership: other.ownership.or(self.ownership),
      liveliness: other.liveliness.or(self.liveliness),
      time_based_filter: other.time_based_filter.or(self.time_based_filter),
      reliability: other.reliability.or(self.reliability),
      destination_order: other.destination_order.or(self.destination_order),
      history: other.history.or(self.history),
      resource_limits: other.resource_limits.or(self.resource_limits),
      lifespan: other.lifespan.or(self.lifespan),
      #[cfg(feature = "security")]
      property: other.property.clone().or(self.property.clone()),
    }
  }

  /// Check if policy complies to another policy.
  ///
  /// `self` is the "offered" (publisher) QoS
  /// `other` is the "requested" (subscriber) QoS
  ///
  /// * None => Policies are compatible
  /// * Some(policyId) => Failure, where policyId is (any) one of the policies
  ///   causing incompliance
  ///
  /// Compliance (compatibility) is defined in the table in DDS spec v1.4
  /// Section "2.2.3 Supported QoS"
  ///
  /// This is not symmetric.
  pub fn compliance_failure_wrt(&self, other: &Self) -> Option<QosPolicyId> {
    trace!("QoS compatibility check - offered: {self:?} - requested {other:?}");
    let result = self.compliance_failure_wrt_impl(other);
    trace!("Result: {result:?}");
    result
  }

  fn compliance_failure_wrt_impl(&self, other: &Self) -> Option<QosPolicyId> {
    // TODO: Check for cases where policy is requested, but not offered (None)

    // check Durability: Offered must be better than or equal to Requested.
    if let (Some(off), Some(req)) = (self.durability, other.durability) {
      if off < req {
        return Some(QosPolicyId::Durability);
      }
    }

    // check Presentation:
    // * If coherent_access is requested, it must be offered also. AND
    // * Same for ordered_access. AND
    // * Offered access scope is broader than requested.
    if let (Some(off), Some(req)) = (self.presentation, other.presentation) {
      if (req.coherent_access && !off.coherent_access)
        || (req.ordered_access && !off.ordered_access)
        || (req.access_scope > off.access_scope)
      {
        return Some(QosPolicyId::Presentation);
      }
    }

    // check Deadline: offered period <= requested period
    if let (Some(off), Some(req)) = (self.deadline, other.deadline) {
      if off.0 > req.0 {
        return Some(QosPolicyId::Deadline);
      }
    }

    // check Latency Budget:
    // offered duration <= requested duration
    if let (Some(off), Some(req)) = (self.latency_budget, other.latency_budget) {
      if off.duration > req.duration {
        return Some(QosPolicyId::LatencyBudget);
      }
    }

    // check Ownership:
    // offered kind == requested kind
    if let (Some(off), Some(req)) = (self.ownership, other.ownership) {
      if off != req {
        return Some(QosPolicyId::Ownership);
      }
    }

    // check Liveliness
    // offered kind >= requested kind
    // Definition: AUTOMATIC < MANUAL_BY_PARTICIPANT < MANUAL_BY_TOPIC
    // AND offered lease_duration <= requested lease_duration
    //
    // See Ord implementation on Liveliness.
    if let (Some(off), Some(req)) = (self.liveliness, other.liveliness) {
      if off < req {
        return Some(QosPolicyId::Liveliness);
      }
    }

    // check Reliability
    // offered kind >= requested kind
    // kind ranking: BEST_EFFORT < RELIABLE
    if let (Some(off), Some(req)) = (self.reliability, other.reliability) {
      if off < req {
        return Some(QosPolicyId::Reliability);
      }
    }

    // check Destination Order
    // offered kind >= requested kind
    // kind ranking: BY_RECEPTION_TIMESTAMP < BY_SOURCE_TIMESTAMP
    if let (Some(off), Some(req)) = (self.destination_order, other.destination_order) {
      if off < req {
        return Some(QosPolicyId::DestinationOrder);
      }
    }

    // default value. no incompatibility detected.
    None
  }

  // serialization
  pub fn to_parameter_list(
    &self,
    ctx: speedy::Endianness,
  ) -> Result<Vec<Parameter>, PlCdrSerializeError> {
    let mut pl = Vec::with_capacity(8);

    let QosPolicies {
      // bind self to (a) destructure, and (b) ensure all fields are handled
      durability,
      presentation,
      deadline,
      latency_budget,
      ownership,
      liveliness,
      time_based_filter,
      reliability,
      destination_order,
      history,
      resource_limits,
      lifespan,
      #[cfg(feature = "security")]
        property: _, // TODO: properties to parameter list?
    } = self;

    macro_rules! emit {
      ($pid:ident, $member:expr, $type:ty) => {
        pl.push(Parameter::new(ParameterId::$pid, {
          let m: &$type = $member;
          m.write_to_vec_with_ctx(ctx)?
        }))
      };
    }
    macro_rules! emit_option {
      ($pid:ident, $member:expr, $type:ty) => {
        if let Some(m) = $member {
          emit!($pid, m, $type)
        }
      };
    }

    use policy::*;

    emit_option!(PID_DURABILITY, durability, Durability);
    emit_option!(PID_PRESENTATION, presentation, Presentation);
    emit_option!(PID_DEADLINE, deadline, Deadline);
    emit_option!(PID_LATENCY_BUDGET, latency_budget, LatencyBudget);

    // Ownership serializes to (maybe) two separate Parameters
    match ownership {
      Some(Ownership::Exclusive { strength }) => {
        emit!(PID_OWNERSHIP, &OwnershipKind::Exclusive, OwnershipKind);
        emit!(PID_OWNERSHIP_STRENGTH, strength, i32);
      }
      Some(Ownership::Shared) => {
        emit!(PID_OWNERSHIP, &OwnershipKind::Shared, OwnershipKind);
      }
      None => (),
    }
    // This should serialize as is
    emit_option!(PID_LIVELINESS, liveliness, policy::Liveliness);
    emit_option!(
      PID_TIME_BASED_FILTER,
      time_based_filter,
      policy::TimeBasedFilter
    );

    if let Some(rel) = reliability.as_ref() {
      let reliability_ser = match rel {
        Reliability::BestEffort => ReliabilitySerialization {
          reliability_kind: ReliabilityKind::BestEffort,
          max_blocking_time: Duration::ZERO, // dummy value for serialization
        },
        Reliability::Reliable { max_blocking_time } => ReliabilitySerialization {
          reliability_kind: ReliabilityKind::Reliable,
          max_blocking_time: *max_blocking_time,
        },
      };
      emit!(PID_RELIABILITY, &reliability_ser, ReliabilitySerialization);
    }

    emit_option!(
      PID_DESTINATION_ORDER,
      destination_order,
      policy::DestinationOrder
    );

    if let Some(history) = history.as_ref() {
      let history_ser = match history {
        History::KeepLast { depth } => HistorySerialization {
          kind: HistoryKind::KeepLast,
          depth: *depth,
        },
        History::KeepAll => HistorySerialization {
          kind: HistoryKind::KeepAll,
          depth: 0,
        },
      };
      emit!(PID_HISTORY, &history_ser, HistorySerialization);
    }
    emit_option!(PID_RESOURCE_LIMITS, resource_limits, policy::ResourceLimits);
    emit_option!(PID_LIFESPAN, lifespan, policy::Lifespan);

    Ok(pl)
  }

  pub fn from_parameter_list(
    ctx: speedy::Endianness,
    pl_map: &BTreeMap<ParameterId, Vec<&Parameter>>,
  ) -> Result<QosPolicies, PlCdrDeserializeError> {
    macro_rules! get_option {
      ($pid:ident) => {
        get_option_from_pl_map(pl_map, ctx, ParameterId::$pid, "<not_used>")?
      };
    }

    let durability: Option<policy::Durability> = get_option!(PID_DURABILITY);
    let presentation: Option<policy::Presentation> = get_option!(PID_PRESENTATION);
    let deadline: Option<policy::Deadline> = get_option!(PID_DEADLINE);
    let latency_budget: Option<policy::LatencyBudget> = get_option!(PID_LATENCY_BUDGET);

    // Ownership is in 2 parts
    let ownership_kind: Option<OwnershipKind> = get_option!(PID_OWNERSHIP);
    let ownership_strength: Option<i32> = get_option!(PID_OWNERSHIP_STRENGTH);
    let ownership = match (ownership_kind, ownership_strength) {
      (Some(OwnershipKind::Shared), None) => Some(policy::Ownership::Shared),
      (Some(OwnershipKind::Shared), Some(_strength)) => {
        warn!("QosPolicies deserializer: Received OwnershipKind::Shared and a strength value.");
        None
      }
      (Some(OwnershipKind::Exclusive), Some(strength)) => {
        Some(policy::Ownership::Exclusive { strength })
      }
      (Some(OwnershipKind::Exclusive), None) => {
        warn!("QosPolicies deserializer: Received OwnershipKind::Exclusive but no strength value.");
        None
      }
      (None, Some(_strength)) => {
        warn!(
          "QosPolicies deserializer: Received ownership strength value, but no kind parameter."
        );
        None
      }
      (None, None) => None,
    };

    let reliability_ser: Option<ReliabilitySerialization> = get_option!(PID_RELIABILITY);
    let reliability = reliability_ser.map(|rs| match rs.reliability_kind {
      ReliabilityKind::BestEffort => policy::Reliability::BestEffort,
      ReliabilityKind::Reliable => policy::Reliability::Reliable {
        max_blocking_time: rs.max_blocking_time,
      },
    });
    let destination_order: Option<policy::DestinationOrder> = get_option!(PID_DESTINATION_ORDER);

    let history_ser: Option<HistorySerialization> = get_option!(PID_HISTORY);
    let history = history_ser.map(|h| match h.kind {
      HistoryKind::KeepAll => policy::History::KeepAll,
      HistoryKind::KeepLast => policy::History::KeepLast { depth: h.depth },
    });

    let liveliness: Option<policy::Liveliness> = get_option!(PID_LIVELINESS);
    let time_based_filter: Option<policy::TimeBasedFilter> = get_option!(PID_TIME_BASED_FILTER);

    let resource_limits: Option<policy::ResourceLimits> = get_option!(PID_RESOURCE_LIMITS);
    let lifespan: Option<policy::Lifespan> = get_option!(PID_LIFESPAN);

    #[cfg(feature = "security")]
    let property: Option<policy::Property> = None; // TODO: Should also properties be read?

    // We construct using the struct syntax directly rather than the builder,
    // so we cannot forget any field.
    Ok(QosPolicies {
      durability,
      presentation,
      deadline,
      latency_budget,
      ownership,
      liveliness,
      time_based_filter,
      reliability,
      destination_order,
      history,
      resource_limits,
      lifespan,
      #[cfg(feature = "security")]
      property,
    })
  }
}

#[derive(Writable, Readable, Clone)]
//#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
enum HistoryKind {
  KeepLast,
  KeepAll,
}

#[derive(Writable, Readable, Clone)]
struct HistorySerialization {
  pub kind: HistoryKind,
  pub depth: i32,
}

#[derive(Writable, Readable)]
//#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
enum OwnershipKind {
  Shared,
  Exclusive,
}

#[derive(Writable, Readable, Clone)]
struct ReliabilitySerialization {
  pub reliability_kind: ReliabilityKind,
  pub max_blocking_time: Duration,
}

// DDS spec v1.4 p.139
// TODO: Replace this with Option construct so that
// None means no limit and Some(limit) gives the limit when defined.
// Use is in resource_limits.
pub const LENGTH_UNLIMITED: i32 = -1;

// put these into a submodule to avoid repeating the word "policy" or
// "qospolicy"
/// Contains all available QoSPolicies
pub mod policy {
  use std::cmp::Ordering;

  use speedy::{Readable, Writable};
  use serde::{Deserialize, Serialize};
  #[allow(unused_imports)]
  use log::{debug, error, info, trace, warn};
  #[cfg(feature = "security")]
  use speedy::{Context, IsEof, Reader, Writer};

  use crate::structure::duration::Duration;
  #[cfg(feature = "security")]
  use crate::serialization::speedy_pl_cdr_helpers::*;

  /*
  pub struct UserData {
    pub value: Vec<u8>,
  }

  pub struct TopicData {
    pub value: Vec<u8>,
  }

  pub struct GroupData {
    pub value: Vec<u8>,
  }

  pub struct TransportPriority {
    pub value: i32,
  }
  */

  /// DDS 2.2.3.16 LIFESPAN
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Readable, Writable, Serialize, Deserialize)]
  pub struct Lifespan {
    pub duration: Duration,
  }

  /// DDS 2.2.3.4 DURABILITY
  ///
  /// DDS Spec 1.4:
  ///
  /// "This QoS policy controls whether the Service will actually make data
  /// available to late-joining readers. Note that although related, this does
  /// not strictly control what data the Service will maintain internally. That
  /// is, the Service may choose to maintain some data for its own purposes
  /// (e.g., flow control) and yet not make it available to late-joining readers
  /// if the DURABILITY QoS policy is set to VOLATILE."
  #[derive(
    Copy,
    Clone,
    Debug,
    PartialEq,
    Eq,
    PartialOrd,
    Ord,
    Hash,
    Readable,
    Writable,
    Serialize,
    Deserialize,
  )]
  pub enum Durability {
    Volatile,
    TransientLocal,
    Transient,
    Persistent,
  }

  /// DDS 2.2.3.6 PRESENTATION
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Readable, Writable, Serialize, Deserialize)]
  pub struct Presentation {
    pub access_scope: PresentationAccessScope,
    pub coherent_access: bool,
    pub ordered_access: bool,
  }

  /// Access scope that is part of DDS 2.2.3.6 PRESENTATION
  #[derive(
    Copy,
    Clone,
    Debug,
    PartialEq,
    Eq,
    PartialOrd,
    Ord,
    Hash,
    Readable,
    Writable,
    Serialize,
    Deserialize,
  )]
  pub enum PresentationAccessScope {
    Instance,
    Topic,
    Group,
  }

  /// DDS 2.2.3.7 DEADLINE
  #[derive(
    Copy,
    Clone,
    Debug,
    PartialEq,
    Eq,
    Ord,
    PartialOrd,
    Hash,
    Readable,
    Writable,
    Serialize,
    Deserialize,
  )]
  pub struct Deadline(pub Duration);

  /// DDS 2.2.3.8 LATENCY_BUDGET
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Readable, Writable, Serialize, Deserialize)]
  pub struct LatencyBudget {
    pub duration: Duration,
  }

  /// DDS 2.2.3.9 OWNERSHIP
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
  pub enum Ownership {
    Shared,
    Exclusive { strength: i32 }, // This also implements OwnershipStrength
  }

  /// DDS 2.2.3.11 LIVELINESS
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Readable, Writable, Serialize, Deserialize)]
  pub enum Liveliness {
    Automatic { lease_duration: Duration },
    ManualByParticipant { lease_duration: Duration },
    ManualByTopic { lease_duration: Duration },
  }

  impl Liveliness {
    fn kind_num(&self) -> i32 {
      match self {
        Self::Automatic { .. } => 0,
        Self::ManualByParticipant { .. } => 1,
        Self::ManualByTopic { .. } => 2,
      }
    }

    pub fn duration(&self) -> Duration {
      match self {
        Self::Automatic { lease_duration }
        | Self::ManualByParticipant { lease_duration }
        | Self::ManualByTopic { lease_duration } => *lease_duration,
      }
    }
  }

  impl Ord for Liveliness {
    fn cmp(&self, other: &Self) -> Ordering {
      // Manual liveliness is greater than automatic, but
      // duration compares in reverse
      other
        .kind_num()
        .cmp(&other.kind_num())
        .then_with(|| self.duration().cmp(&other.duration()).reverse())
    }
  }

  impl PartialOrd for Liveliness {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
      Some(self.cmp(other))
    }
  }

  /// DDS 2.2.3.12 TIME_BASED_FILTER
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Readable, Writable, Serialize, Deserialize)]
  pub struct TimeBasedFilter {
    pub minimum_separation: Duration,
  }

  /*
  pub struct Partition {
    pub name: Vec<Vec<u8>>,
  }
  */

  /// DDS 2.2.3.14 RELIABILITY
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
  pub enum Reliability {
    BestEffort,
    Reliable { max_blocking_time: Duration },
  }

  impl Ord for Reliability {
    // max_blocking_time is not compared.
    // TODO: This is kind of bad, because now Eq and Ord are inconsistent:
    // If we have A and B both Reliability::Reliable, but with different
    // max_blocking_time, then Ord will say they are Ordering::Equal,
    // but Eq will say they are not equal.
    fn cmp(&self, other: &Self) -> Ordering {
      match (self, other) {
        (Self::BestEffort, Self::BestEffort) | (Self::Reliable { .. }, Self::Reliable { .. }) => {
          Ordering::Equal
        }
        (Self::BestEffort, Self::Reliable { .. }) => Ordering::Less,
        (Self::Reliable { .. }, Self::BestEffort) => Ordering::Greater,
      }
    }
  }

  impl PartialOrd for Reliability {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
      Some(self.cmp(other))
    }
  }

  /// DDS 2.2.3.17 DESTINATION_ORDER
  #[derive(
    Copy,
    Clone,
    Debug,
    PartialEq,
    Eq,
    Ord,
    PartialOrd,
    Hash,
    Readable,
    Writable,
    Serialize,
    Deserialize,
  )]
  pub enum DestinationOrder {
    ByReceptionTimestamp,
    BySourceTimeStamp,
  }

  /// DDS 2.2.3.18 HISTORY
  #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
  pub enum History {
    // Variants must be in this order ot derive Ord correctly.
    KeepLast { depth: i32 },
    KeepAll,
  }

  /// DDS Spec v1.4 Section 2.2.3.19 RESOURCE_LIMITS
  ///
  /// DDS Spec v1.4 p.147 "struct ResourceLimitsQosPolicy" defines the
  /// fields as "long". The "long" type of OMG IDL is defined to have
  /// 32-bit (signed, 2's complement) range in the OMG IDL spec v4.2, Table
  /// 7-13: Integer Types.
  ///
  /// But it does not make sense to have negative limits, so these should be
  /// unsigned.
  ///
  /// Negative values are needed, because DDS spec defines the special value
  /// const long LENGTH_UNLIMITED = -1;
  #[derive(Copy, Clone, Debug, PartialEq, Eq, Writable, Readable, Serialize, Deserialize)]
  pub struct ResourceLimits {
    pub max_samples: i32,
    pub max_instances: i32,
    pub max_samples_per_instance: i32,
  }

  #[cfg(feature = "security")]
  use crate::security;
  // DDS Security spec v1.1
  // Section 7.2.5 PropertyQosPolicy, DomainParticipantQos, DataWriterQos, and
  // DataReaderQos
  #[cfg(feature = "security")]
  #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
  pub struct Property {
    pub value: Vec<security::types::Property>,
    pub binary_value: Vec<security::types::BinaryProperty>,
  }

  #[cfg(feature = "security")]
  impl<'a, C: Context> Readable<'a, C> for Property {
    fn read_from<R: Reader<'a, C>>(reader: &mut R) -> Result<Self, C::Error> {
      let count = reader.read_u32()?;
      let mut value = Vec::new();

      let mut prev_len = 0;
      for _ in 0..count {
        read_pad(reader, prev_len, 4)?;
        let s: security::types::Property = reader.read_value()?;
        prev_len = s.serialized_len();
        value.push(s);
      }

      // Depending on the RTPS version used by writer, PropertyQoSPolicy may end here,
      // i.e. there is no "binary_value". Pad should still always exist.
      read_pad(reader, prev_len, 4)?;
      let mut binary_value = Vec::new();

      match reader.read_u32() {
        Ok(count) => {
          prev_len = 0;
          for _ in 0..count {
            read_pad(reader, prev_len, 4)?;
            let s: security::types::BinaryProperty = reader.read_value()?;
            prev_len = s.serialized_len();
            binary_value.push(s);
          }
        }
        Err(e) => {
          if e.is_eof() {
            // This is ok. Only String properties, no binary.
            debug!("Non-security PropertyQosPolicy");
          } else {
            return Err(e);
          }
        }
      }

      Ok(Property {
        value,
        binary_value,
      })
    }
  }

  // Writing several strings is a bit complicated, because
  // we have to keep track of alignment.
  // Again, alignment comes BEFORE string length, or vector item count, not after
  // string.
  #[cfg(feature = "security")]
  impl<C: Context> Writable<C> for Property {
    fn write_to<T: ?Sized + Writer<C>>(&self, writer: &mut T) -> Result<(), C::Error> {
      // First self.value
      // Only those properties with propagate=true are written
      let propagate_value: Vec<&security::Property> =
        self.value.iter().filter(|p| p.propagate).collect();

      // propagate_value vector length
      writer.write_u32(propagate_value.len() as u32)?;

      let mut prev_len = 0;
      for prop in propagate_value {
        write_pad(writer, prev_len, 4)?;
        writer.write_value(prop)?;
        prev_len = prop.serialized_len();
      }

      // Then self.bin_value
      // Only those binary properties with propagate=true are written
      let propagate_bin_value: Vec<&security::BinaryProperty> =
        self.binary_value.iter().filter(|p| p.propagate).collect();

      // propagate_bin_value vector length
      write_pad(writer, prev_len, 4)?;
      writer.write_u32(propagate_bin_value.len() as u32)?;
      // and the elements
      let mut prev_len = 0;
      for prop in propagate_bin_value {
        write_pad(writer, prev_len, 4)?;
        writer.write_value(prop)?;
        prev_len = prop.serialized_len();
      }

      Ok(())
    }
  }

  // DDS Security spec v1.1
  // Section 7.2.5 PropertyQosPolicy, DomainParticipantQos, DataWriterQos, and
  // DataReaderQos
  //
  // so this is DataTagQosPolicy, which is an alias for "DataTags"
  // We call it qos::policy::DataTag
  #[derive(Clone, Debug, PartialEq, Eq, Default)]
  #[cfg(feature = "security")]
  pub struct DataTag {
    pub tags: Vec<security::types::Tag>,
  }

  #[cfg(feature = "security")]
  impl<'a, C: Context> Readable<'a, C> for DataTag {
    fn read_from<R: Reader<'a, C>>(reader: &mut R) -> Result<Self, C::Error> {
      let count = reader.read_u32()?;
      let mut tags = Vec::new();

      let mut prev_len = 0;
      for _ in 0..count {
        read_pad(reader, prev_len, 4)?;
        let s: security::types::Tag = reader.read_value()?;
        prev_len = s.serialized_len();
        tags.push(s);
      }
      Ok(DataTag { tags })
    }
  }

  // Writing several strings is a bit complicated, because
  // we have to keep track of alignment.
  // Again, alignment comes BEFORE string length, or vector item count, not after
  // string.
  #[cfg(feature = "security")]
  impl<C: Context> Writable<C> for DataTag {
    fn write_to<T: ?Sized + Writer<C>>(&self, writer: &mut T) -> Result<(), C::Error> {
      writer.write_u32(self.tags.len() as u32)?;

      let mut prev_len = 0;
      for tag in &self.tags {
        write_pad(writer, prev_len, 4)?;
        writer.write_value(tag)?;
        prev_len = tag.serialized_len();
      }
      Ok(())
    }
  }
} // mod policy