use std::{collections::HashMap, sync::Arc, time::Duration};
use derivative::Derivative;
use serde::{de::Error, Deserialize, Deserializer};
use typed_builder::TypedBuilder;
use crate::{
bson::{doc, Bson, Document},
bson_util::deserialize_duration_from_u64_seconds,
error::{ErrorKind, Result},
options::StreamAddress,
sdam::public::ServerInfo,
};
#[derive(Clone, Derivative)]
#[derivative(Debug)]
#[non_exhaustive]
pub enum SelectionCriteria {
ReadPreference(ReadPreference),
Predicate(#[derivative(Debug = "ignore")] Predicate),
}
impl PartialEq for SelectionCriteria {
fn eq(&self, other: &Self) -> bool {
match (self, other) {
(Self::ReadPreference(r1), Self::ReadPreference(r2)) => r1 == r2,
_ => false,
}
}
}
impl From<ReadPreference> for SelectionCriteria {
fn from(read_pref: ReadPreference) -> Self {
Self::ReadPreference(read_pref)
}
}
impl SelectionCriteria {
pub(crate) fn as_read_pref(&self) -> Option<&ReadPreference> {
match self {
Self::ReadPreference(ref read_pref) => Some(read_pref),
Self::Predicate(..) => None,
}
}
#[cfg(test)]
pub(crate) fn as_predicate(&self) -> Option<&Predicate> {
match self {
Self::Predicate(ref p) => Some(p),
_ => None,
}
}
#[cfg(test)]
pub(crate) fn is_read_pref_primary(&self) -> bool {
matches!(self, Self::ReadPreference(ReadPreference::Primary))
}
pub(crate) fn max_staleness(&self) -> Option<Duration> {
self.as_read_pref().and_then(|pref| pref.max_staleness())
}
pub(crate) fn from_address(address: StreamAddress) -> Self {
SelectionCriteria::Predicate(Arc::new(move |server| server.address() == &address))
}
}
impl<'de> Deserialize<'de> for SelectionCriteria {
fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
where
D: Deserializer<'de>,
{
Ok(SelectionCriteria::ReadPreference(
ReadPreference::deserialize(deserializer)?,
))
}
}
pub type Predicate = Arc<dyn Send + Sync + Fn(&ServerInfo) -> bool>;
#[allow(missing_docs)]
#[derive(Clone, Debug, PartialEq)]
pub enum ReadPreference {
Primary,
Secondary { options: ReadPreferenceOptions },
PrimaryPreferred { options: ReadPreferenceOptions },
SecondaryPreferred { options: ReadPreferenceOptions },
Nearest { options: ReadPreferenceOptions },
}
impl<'de> Deserialize<'de> for ReadPreference {
fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
where
D: Deserializer<'de>,
{
#[derive(Deserialize)]
#[serde(rename_all = "camelCase", deny_unknown_fields)]
struct ReadPreferenceHelper {
mode: String,
#[serde(flatten)]
options: ReadPreferenceOptions,
}
let preference = ReadPreferenceHelper::deserialize(deserializer)?;
match preference.mode.as_str() {
"Primary" => Ok(ReadPreference::Primary),
"Secondary" => Ok(ReadPreference::Secondary {
options: preference.options,
}),
"PrimaryPreferred" => Ok(ReadPreference::PrimaryPreferred {
options: preference.options,
}),
"SecondaryPreferred" => Ok(ReadPreference::SecondaryPreferred {
options: preference.options,
}),
"Nearest" => Ok(ReadPreference::Nearest {
options: preference.options,
}),
other => Err(D::Error::custom(format!(
"Unknown read preference mode: {}",
other
))),
}
}
}
#[derive(Clone, Debug, Default, Deserialize, PartialEq, TypedBuilder)]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct ReadPreferenceOptions {
#[builder(default)]
pub tag_sets: Option<Vec<TagSet>>,
#[builder(default)]
#[serde(
rename = "maxStalenessSeconds",
deserialize_with = "deserialize_duration_from_u64_seconds"
)]
pub max_staleness: Option<Duration>,
#[builder(default)]
pub hedge: Option<HedgedReadOptions>,
}
#[derive(Clone, Debug, Deserialize, PartialEq, TypedBuilder)]
#[non_exhaustive]
pub struct HedgedReadOptions {
pub enabled: bool,
}
impl HedgedReadOptions {
pub fn with_enabled(enabled: bool) -> Self {
Self { enabled }
}
}
impl ReadPreference {
pub(crate) fn max_staleness(&self) -> Option<Duration> {
match self {
ReadPreference::Primary => None,
ReadPreference::Secondary { ref options }
| ReadPreference::PrimaryPreferred { ref options }
| ReadPreference::SecondaryPreferred { ref options }
| ReadPreference::Nearest { ref options } => options.max_staleness,
}
}
pub(crate) fn with_tags(mut self, tag_sets: Vec<TagSet>) -> Result<Self> {
let options = match self {
ReadPreference::Primary => {
return Err(ErrorKind::ArgumentError {
message: "read preference tags can only be specified when a non-primary mode \
is specified"
.to_string(),
}
.into());
}
ReadPreference::Secondary { ref mut options } => options,
ReadPreference::PrimaryPreferred { ref mut options } => options,
ReadPreference::SecondaryPreferred { ref mut options } => options,
ReadPreference::Nearest { ref mut options } => options,
};
options.tag_sets = Some(tag_sets);
Ok(self)
}
pub(crate) fn with_max_staleness(mut self, max_staleness: Duration) -> Result<Self> {
let options = match self {
ReadPreference::Primary => {
return Err(ErrorKind::ArgumentError {
message: "max staleness can only be specified when a non-primary mode is \
specified"
.to_string(),
}
.into());
}
ReadPreference::Secondary { ref mut options } => options,
ReadPreference::PrimaryPreferred { ref mut options } => options,
ReadPreference::SecondaryPreferred { ref mut options } => options,
ReadPreference::Nearest { ref mut options } => options,
};
options.max_staleness = Some(max_staleness);
Ok(self)
}
pub(crate) fn into_document(self) -> Document {
let (mode, tag_sets, max_staleness, hedge) = match self {
ReadPreference::Primary => ("primary", None, None, None),
ReadPreference::PrimaryPreferred { options } => (
"primaryPreferred",
options.tag_sets,
options.max_staleness,
options.hedge,
),
ReadPreference::Secondary { options } => (
"secondary",
options.tag_sets,
options.max_staleness,
options.hedge,
),
ReadPreference::SecondaryPreferred { options } => (
"secondaryPreferred",
options.tag_sets,
options.max_staleness,
options.hedge,
),
ReadPreference::Nearest { options } => (
"nearest",
options.tag_sets,
options.max_staleness,
options.hedge,
),
};
let mut doc = doc! { "mode": mode };
if let Some(max_stale) = max_staleness {
doc.insert("maxStalenessSeconds", max_stale.as_secs());
}
if let Some(tag_sets) = tag_sets {
let tags: Vec<Bson> = tag_sets
.into_iter()
.map(|tag_set| {
Bson::Document(tag_set.into_iter().map(|(k, v)| (k, v.into())).collect())
})
.collect();
doc.insert("tags", tags);
}
if let Some(hedge) = hedge {
doc.insert("hedge", doc! { "enabled": hedge.enabled });
}
doc
}
}
pub type TagSet = HashMap<String, String>;
#[cfg(test)]
mod test {
use super::{HedgedReadOptions, ReadPreference, ReadPreferenceOptions};
use crate::bson::doc;
#[test]
fn hedged_read_included_in_document() {
let options = ReadPreferenceOptions::builder()
.hedge(HedgedReadOptions { enabled: true })
.build();
let read_pref = ReadPreference::Secondary { options };
let doc = read_pref.into_document();
assert_eq!(
doc,
doc! { "mode": "secondary", "hedge": { "enabled": true } }
);
}
}