passes 6a, totally available single node

Cargo.lock

@@ -53,6 +53,14 @@ dependencies = [
  "serde_json",
 ]
 
+[[package]]
+name = "gg-txn"
+version = "0.0.1"
+dependencies = [
+ "nebkor-maelstrom",
+ "serde_json",
+]
+
 [[package]]
 name = "gg-uid"
 version = "0.0.1"

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["gg-echo", "gg-uid", "gg-broadcast", "gg-g_counter", "gg-kafka"]
+members = ["gg-echo", "gg-uid", "gg-broadcast", "gg-g_counter", "gg-kafka", "gg-txn"]
 resolver = "2"
 
 [workspace.package]

gg-txn/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "gg-txn"
+edition = "2021"
+version.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[dependencies]
+nebkor-maelstrom.workspace = true
+serde_json.workspace = true

gg-txn/src/main.rs

@@ -0,0 +1,110 @@
+use std::collections::HashMap;
+
+use nebkor_maelstrom::{mk_payload, Body, Message, Node, Runner};
+use serde_json::Value;
+
+type Txn = Vec<TxnOp>;
+
+trait TxnSer {
+    fn serialize(&self) -> Value;
+}
+
+impl TxnSer for Txn {
+    fn serialize(&self) -> Value {
+        let out: Vec<Value> = self
+            .iter()
+            .map(|t| {
+                let v: Vec<Value> = vec![t.op.clone().into(), t.key.into(), t.value.into()];
+                v.into()
+            })
+            .collect();
+        out.into()
+    }
+}
+
+fn main() {
+    let node = TANode::default();
+    let runner = Runner::new(node);
+    runner.run(None);
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
+struct TxnOp {
+    op: String,
+    key: u64,
+    value: Option<u64>,
+}
+
+#[derive(Debug, Clone, Default)]
+struct TANode {
+    store: HashMap<u64, u64>,
+}
+
+impl TANode {
+    fn transact(&mut self, txn: &Txn) -> Txn {
+        let mut out = Txn::with_capacity(txn.len());
+        for txn_op in txn.iter() {
+            let op = txn_op.op.as_str();
+            match op {
+                "r" => {
+                    let key = txn_op.key;
+                    let op = TxnOp {
+                        op: "r".into(),
+                        key,
+                        value: self.store.get(&key).cloned(),
+                    };
+                    out.push(op);
+                }
+                "w" => {
+                    self.store.insert(txn_op.key, txn_op.value.unwrap());
+                    out.push(txn_op.clone());
+                }
+                _ => {
+                    eprintln!("unknown TxnOp op {op}");
+                }
+            }
+        }
+
+        out
+    }
+}
+
+impl Node for TANode {
+    fn handle(&mut self, runner: &Runner, msg: Message) {
+        let typ = msg.typ();
+
+        match typ {
+            "txn" => {
+                let txn = get_txn(&msg);
+
+                let txn = self.transact(&txn);
+
+                let payload = mk_payload(&[("txn", txn.serialize())]);
+                let body = Body::from_type("txn_ok").with_payload(payload);
+                runner.reply(&msg, body);
+            }
+            _ => {
+                eprintln!("unknown message type {typ}")
+            }
+        }
+    }
+}
+
+fn get_txn(msg: &Message) -> Txn {
+    msg.body
+        .payload
+        .get("txn")
+        .unwrap()
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|e| {
+            let o = e.as_array().unwrap();
+            TxnOp {
+                op: o[0].as_str().unwrap().to_string(),
+                key: o[1].as_u64().unwrap(),
+                value: o[2].as_u64(),
+            }
+        })
+        .collect()
+}