From 8331ce865c69a72bae83b5d772248bd1a2a0ac94 Mon Sep 17 00:00:00 2001
From: Stas Kelvich <stas.kelvich@gmail.com>
Date: Mon, 27 Sep 2021 10:44:27 +0300
Subject: [PATCH] Interceipt and log error in mgmt interface.

That PostgresBackend is better be replaced with the http server or redis
subscription. For now let's improve logging and move on.
---
 proxy/src/mgmt.rs | 58 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/proxy/src/mgmt.rs b/proxy/src/mgmt.rs
index 90fccd770d..2b3259f8ec 100644
--- a/proxy/src/mgmt.rs
+++ b/proxy/src/mgmt.rs
@@ -49,7 +49,7 @@ struct MgmtHandler {
 //             "host": "127.0.0.1",
 //             "port": 5432,
 //             "dbname": "stas",
-//             "user": "stas"
+//             "user": "stas",
 //             "password": "mypass"
 //         }
 //     }
@@ -60,6 +60,9 @@ struct MgmtHandler {
 //         "Failure": "oops"
 //     }
 // }
+//
+// // to test manually by sending a query to mgmt interface:
+// psql -h 127.0.0.1 -p 9999 -c '{"session_id":"4f10dde522e14739","result":{"Success":{"host":"127.0.0.1","port":5432,"dbname":"stas","user":"stas","password":"stas"}}}'
 #[derive(Deserialize)]
 pub struct PsqlSessionResponse {
     session_id: String,
@@ -78,34 +81,47 @@ impl postgres_backend::Handler for MgmtHandler {
         pgb: &mut PostgresBackend,
         query_string: Bytes,
     ) -> anyhow::Result<()> {
-        let query_string = query_from_cstring(query_string);
+        let res = try_process_query(self, pgb, query_string);
+        // intercept and log error message
+        if res.is_err() {
+            println!("Mgmt query failed: #{:?}", res);
+        }
+        res
+    }
+}
 
-        println!("Got mgmt query: '{}'", std::str::from_utf8(&query_string)?);
+fn try_process_query(
+    mgmt: &mut MgmtHandler,
+    pgb: &mut PostgresBackend,
+    query_string: Bytes,
+) -> anyhow::Result<()> {
+    let query_string = query_from_cstring(query_string);
 
-        let resp: PsqlSessionResponse = serde_json::from_slice(&query_string)?;
+    println!("Got mgmt query: '{}'", std::str::from_utf8(&query_string)?);
 
-        let waiters = self.state.waiters.lock().unwrap();
+    let resp: PsqlSessionResponse = serde_json::from_slice(&query_string)?;
 
-        let sender = waiters
-            .get(&resp.session_id)
-            .ok_or_else(|| anyhow::Error::msg("psql_session_id is not found"))?;
+    let waiters = mgmt.state.waiters.lock().unwrap();
 
-        match resp.result {
-            PsqlSessionResult::Success(db_info) => {
-                sender.send(Ok(db_info))?;
+    let sender = waiters
+        .get(&resp.session_id)
+        .ok_or_else(|| anyhow::Error::msg("psql_session_id is not found"))?;
 
-                pgb.write_message_noflush(&SINGLE_COL_ROWDESC)?
-                    .write_message_noflush(&BeMessage::DataRow(&[Some(b"ok")]))?
-                    .write_message_noflush(&BeMessage::CommandComplete(b"SELECT 1"))?;
-                pgb.flush()?;
-                Ok(())
-            }
+    match resp.result {
+        PsqlSessionResult::Success(db_info) => {
+            sender.send(Ok(db_info))?;
 
-            PsqlSessionResult::Failure(message) => {
-                sender.send(Err(anyhow::Error::msg(message.clone())))?;
+            pgb.write_message_noflush(&SINGLE_COL_ROWDESC)?
+                .write_message_noflush(&BeMessage::DataRow(&[Some(b"ok")]))?
+                .write_message_noflush(&BeMessage::CommandComplete(b"SELECT 1"))?;
+            pgb.flush()?;
+            Ok(())
+        }
 
-                bail!("psql session request failed: {}", message)
-            }
+        PsqlSessionResult::Failure(message) => {
+            sender.send(Err(anyhow::Error::msg(message.clone())))?;
+
+            bail!("psql session request failed: {}", message)
         }
     }
 }