Start to build a test query for caching layer

disk/src/cache.rs

@@ -0,0 +1,64 @@
+#[allow(unused_imports)]
+use tracing::{error, warn, info, debug, trace};
+use err::Error;
+use netpod::{Node, Cluster, AggKind, NanoRange, ToNanos};
+use futures_core::Stream;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use bytes::Bytes;
+use chrono::{DateTime, Utc};
+
+
+#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
+pub struct Query {
+    range: NanoRange,
+    agg_kind: AggKind,
+}
+
+impl Query {
+
+    pub fn from_request(req: &http::request::Parts) -> Result<Self, Error> {
+        let params = netpod::query_params(req.uri.query());
+        let beg_date = params.get("beg_date").ok_or(Error::with_msg("missing beg_date"))?;
+        let end_date = params.get("end_date").ok_or(Error::with_msg("missing end_date"))?;
+        let ret = Query {
+            range: NanoRange {
+                beg: beg_date.parse::<DateTime<Utc>>()?.to_nanos(),
+                end: end_date.parse::<DateTime<Utc>>()?.to_nanos(),
+            },
+            agg_kind: AggKind::DimXBins1,
+        };
+        info!("Query::from_request  {:?}", ret);
+        Ok(ret)
+    }
+
+}
+
+
+pub struct BinParams {
+    pub node: Node,
+    pub cluster: Cluster,
+}
+
+pub fn binned_bytes_for_http(params: BinParams) -> Result<BinnedBytesForHttpStream, Error> {
+
+    // TODO
+    // Translate the Query TimeRange + AggKind into an iterator over the pre-binned patches.
+
+    let ret = BinnedBytesForHttpStream {};
+    Ok(ret)
+}
+
+pub struct BinnedBytesForHttpStream {
+}
+
+impl Stream for BinnedBytesForHttpStream {
+    type Item = Result<Bytes, Error>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
+        // TODO
+        use Poll::*;
+        Ready(None)
+    }
+
+}