name from id binary search

src/bin/import.rs

@@ -119,7 +119,7 @@ async fn save_nodes(mut rx: Receiver<String>) -> anyhow::Result<()> {
         .into_iter()
         .map(|(id, offset)| {
             // An allocation in here is gross
-            let mut x = id.to_le_bytes().to_vec();
+            let mut x = id.to_le_bytes().to_vec(); // TODO no reason to put id here?
             x.extend(offset.to_le_bytes());
 
             x

src/bin/serve.rs

@@ -4,7 +4,9 @@ use commoncrawl_graph::graph::NodeReader;
 async fn main() -> anyhow::Result<()> {
     let mut nr = NodeReader::new().await?;
 
-    nr.id_from_name("com.scd31").await?;
+    let id = nr.id_from_name("com.scd31").await?.unwrap();
+    let host = nr.name_from_id(id).await?;
+    println!("{:?}", host);
 
     Ok(())
 }

src/graph.rs

@@ -59,4 +59,33 @@ impl NodeReader {
             }
         }
     }
+
+    pub async fn name_from_id(&mut self, id: u32) -> anyhow::Result<Option<String>> {
+        let mut min = 0;
+        let mut max = self.num_nodes;
+
+        loop {
+            let cur = (max + min) / 2 + 1;
+
+            self.id_index.seek(SeekFrom::Start(cur * 12 + 4)).await?;
+            let offset = self.id_index.read_u64_le().await?;
+
+            self.nodes.seek(SeekFrom::Start(offset.into())).await?;
+            let host_id = self.nodes.read_u32_le().await?;
+            let host = BufReader::new(&mut self.nodes)
+                .lines()
+                .next_line()
+                .await?
+                .context("Missing line")?;
+
+            let c = id.cmp(&host_id);
+            match c {
+                Ordering::Less => max = cur,
+                Ordering::Equal => {
+                    return Ok(Some(host));
+                }
+                Ordering::Greater => min = cur,
+            }
+        }
+    }
 }