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|
use super::mailbox::MailMeta;
use super::snapshot::FrozenMailbox;
use super::unique_ident::UniqueIdent;
use anyhow::Result;
use futures::stream::{FuturesOrdered, StreamExt};
/// Query is in charge of fetching efficiently
/// requested data for a list of emails
pub struct Query<'a, 'b> {
pub frozen: &'a FrozenMailbox,
pub emails: &'b [UniqueIdent],
pub scope: QueryScope,
}
#[derive(Debug)]
pub enum QueryScope {
Index,
Partial,
Full,
}
impl QueryScope {
pub fn union(&self, other: &QueryScope) -> QueryScope {
match (self, other) {
(QueryScope::Full, _) | (_, QueryScope::Full) => QueryScope::Full,
(QueryScope::Partial, _) | (_, QueryScope::Partial) => QueryScope::Partial,
(QueryScope::Index, QueryScope::Index) => QueryScope::Index,
}
}
}
impl<'a, 'b> Query<'a, 'b> {
pub async fn fetch(&self) -> Result<Vec<QueryResult>> {
match self.scope {
QueryScope::Index => Ok(self.emails.iter().map(|&uuid| QueryResult::IndexResult { uuid }).collect()),
QueryScope::Partial =>self.partial().await,
QueryScope::Full => self.full().await,
}
}
// --- functions below are private *for reasons*
async fn partial(&self) -> Result<Vec<QueryResult>> {
let meta = self.frozen.mailbox.fetch_meta(self.emails).await?;
let result = meta
.into_iter()
.zip(self.emails.iter())
.map(|(metadata, &uuid)| {
QueryResult::PartialResult { uuid, metadata }
})
.collect::<Vec<_>>();
Ok(result)
}
/// @FIXME WARNING: THIS CAN ALLOCATE A LOT OF MEMORY
/// AND GENERATE SO MUCH NETWORK TRAFFIC.
/// THIS FUNCTION SHOULD BE REWRITTEN, FOR EXAMPLE WITH
/// SOMETHING LIKE AN ITERATOR
async fn full(&self) -> Result<Vec<QueryResult>> {
let meta_list = self.partial().await?;
meta_list
.into_iter()
.map(|meta| async move {
let content = self
.frozen
.mailbox
.fetch_full(
*meta.uuid(),
&meta
.metadata()
.expect("meta to be PartialResult")
.message_key,
)
.await?;
Ok(meta.into_full(content).expect("meta to be PartialResult"))
})
.collect::<FuturesOrdered<_>>()
.collect::<Vec<_>>()
.await
.into_iter()
.collect::<Result<Vec<_>, _>>()
}
}
#[derive(Debug)]
pub enum QueryResult {
IndexResult {
uuid: UniqueIdent,
},
PartialResult {
uuid: UniqueIdent,
metadata: MailMeta,
},
FullResult {
uuid: UniqueIdent,
metadata: MailMeta,
content: Vec<u8>,
},
}
impl QueryResult {
pub fn uuid(&self) -> &UniqueIdent {
match self {
Self::IndexResult { uuid, .. } => uuid,
Self::PartialResult { uuid, .. } => uuid,
Self::FullResult { uuid, .. } => uuid,
}
}
pub fn metadata(&self) -> Option<&MailMeta> {
match self {
Self::IndexResult { .. } => None,
Self::PartialResult { metadata, .. } => Some(metadata),
Self::FullResult { metadata, .. } => Some(metadata),
}
}
#[allow(dead_code)]
pub fn content(&self) -> Option<&[u8]> {
match self {
Self::FullResult { content, .. } => Some(content),
_ => None,
}
}
fn into_partial(self, metadata: MailMeta) -> Option<Self> {
match self {
Self::IndexResult { uuid } => Some(Self::PartialResult {
uuid,
metadata,
}),
_ => None,
}
}
fn into_full(self, content: Vec<u8>) -> Option<Self> {
match self {
Self::PartialResult {
uuid,
metadata,
} => Some(Self::FullResult {
uuid,
metadata,
content,
}),
_ => None,
}
}
}
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