137 lines
4 KiB
Rust
137 lines
4 KiB
Rust
use super::mailbox::MailMeta;
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use super::snapshot::FrozenMailbox;
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use crate::unique_ident::UniqueIdent;
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use anyhow::Result;
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use futures::future::FutureExt;
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use futures::stream::{BoxStream, Stream, StreamExt};
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/// Query is in charge of fetching efficiently
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/// requested data for a list of emails
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pub struct Query<'a, 'b> {
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pub frozen: &'a FrozenMailbox,
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pub emails: &'b [UniqueIdent],
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pub scope: QueryScope,
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}
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#[derive(Debug)]
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pub enum QueryScope {
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Index,
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Partial,
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Full,
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}
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impl QueryScope {
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pub fn union(&self, other: &QueryScope) -> QueryScope {
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match (self, other) {
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(QueryScope::Full, _) | (_, QueryScope::Full) => QueryScope::Full,
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(QueryScope::Partial, _) | (_, QueryScope::Partial) => QueryScope::Partial,
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(QueryScope::Index, QueryScope::Index) => QueryScope::Index,
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}
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}
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}
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//type QueryResultStream = Box<dyn Stream<Item = Result<QueryResult>>>;
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impl<'a, 'b> Query<'a, 'b> {
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pub fn fetch(&self) -> BoxStream<Result<QueryResult>> {
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match self.scope {
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QueryScope::Index => Box::pin(
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futures::stream::iter(self.emails)
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.map(|&uuid| Ok(QueryResult::IndexResult { uuid })),
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),
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QueryScope::Partial => Box::pin(self.partial()),
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QueryScope::Full => Box::pin(self.full()),
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}
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}
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// --- functions below are private *for reasons*
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fn partial<'d>(&'d self) -> impl Stream<Item = Result<QueryResult>> + 'd + Send {
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async move {
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let maybe_meta_list: Result<Vec<MailMeta>> =
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self.frozen.mailbox.fetch_meta(self.emails).await;
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let list_res = maybe_meta_list
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.map(|meta_list| {
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meta_list
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.into_iter()
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.zip(self.emails)
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.map(|(metadata, &uuid)| Ok(QueryResult::PartialResult { uuid, metadata }))
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.collect()
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})
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.unwrap_or_else(|e| vec![Err(e)]);
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futures::stream::iter(list_res)
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}
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.flatten_stream()
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}
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fn full<'d>(&'d self) -> impl Stream<Item = Result<QueryResult>> + 'd + Send {
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self.partial().then(move |maybe_meta| async move {
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let meta = maybe_meta?;
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let content = self
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.frozen
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.mailbox
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.fetch_full(
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*meta.uuid(),
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&meta
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.metadata()
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.expect("meta to be PartialResult")
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.message_key,
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)
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.await?;
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Ok(meta.into_full(content).expect("meta to be PartialResult"))
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})
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}
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}
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#[derive(Debug, Clone)]
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pub enum QueryResult {
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IndexResult {
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uuid: UniqueIdent,
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},
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PartialResult {
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uuid: UniqueIdent,
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metadata: MailMeta,
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},
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FullResult {
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uuid: UniqueIdent,
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metadata: MailMeta,
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content: Vec<u8>,
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},
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}
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impl QueryResult {
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pub fn uuid(&self) -> &UniqueIdent {
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match self {
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Self::IndexResult { uuid, .. } => uuid,
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Self::PartialResult { uuid, .. } => uuid,
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Self::FullResult { uuid, .. } => uuid,
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}
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}
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pub fn metadata(&self) -> Option<&MailMeta> {
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match self {
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Self::IndexResult { .. } => None,
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Self::PartialResult { metadata, .. } => Some(metadata),
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Self::FullResult { metadata, .. } => Some(metadata),
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}
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}
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#[allow(dead_code)]
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pub fn content(&self) -> Option<&[u8]> {
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match self {
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Self::FullResult { content, .. } => Some(content),
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_ => None,
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}
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}
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fn into_full(self, content: Vec<u8>) -> Option<Self> {
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match self {
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Self::PartialResult { uuid, metadata } => Some(Self::FullResult {
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uuid,
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metadata,
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content,
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}),
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_ => None,
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}
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}
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}
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