Optionally clean up server connections (#444)

* Optionally clean up server connections

* move setting to pool

* fix test

* Print setting to screen

* fmt

* Fix pool_settings override in tests

Author: levkk

src/config.rs

@@ -487,10 +487,15 @@ pub struct Pool {
     #[serde(default)] // False
     pub primary_reads_enabled: bool,
 
+    /// Maximum time to allow for establishing a new server connection.
     pub connect_timeout: Option<u64>,
 
+    /// Close idle connections that have been opened for longer than this.
     pub idle_timeout: Option<u64>,
 
+    /// Close server connections that have been opened for longer than this.
+    /// Only applied to idle connections. If the connection is actively used for
+    /// longer than this period, the pool will not interrupt it.
     pub server_lifetime: Option<u64>,
 
     #[serde(default = "Pool::default_sharding_function")]
@@ -507,6 +512,9 @@ pub struct Pool {
     pub auth_query_user: Option<String>,
     pub auth_query_password: Option<String>,
 
+    #[serde(default = "Pool::default_cleanup_server_connections")]
+    pub cleanup_server_connections: bool,
+
     pub plugins: Option<Plugins>,
     pub shards: BTreeMap<String, Shard>,
     pub users: BTreeMap<String, User>,
@@ -548,6 +556,10 @@ impl Pool {
         ShardingFunction::PgBigintHash
     }
 
+    pub fn default_cleanup_server_connections() -> bool {
+        true
+    }
+
     pub fn validate(&mut self) -> Result<(), Error> {
         match self.default_role.as_ref() {
             "any" => (),
@@ -637,6 +649,7 @@ impl Default for Pool {
             auth_query_password: None,
             server_lifetime: None,
             plugins: None,
+            cleanup_server_connections: true,
         }
     }
 }
@@ -1066,6 +1079,10 @@ impl Config {
                     None => "default".to_string(),
                 }
             );
+            info!(
+                "[pool: {}] Cleanup server connections: {}",
+                pool_name, pool_config.cleanup_server_connections
+            );
             info!(
                 "[pool: {}] Plugins: {}",
                 pool_name,

src/mirrors.rs

@@ -44,6 +44,7 @@ impl MirroredClient {
             Arc::new(PoolStats::new(identifier, cfg.clone())),
             Arc::new(RwLock::new(None)),
             None,
+            true,
         );
 
         Pool::builder()

src/pool.rs

@@ -364,6 +364,7 @@ impl ConnectionPool {
                                 Some(ref plugins) => Some(plugins.clone()),
                                 None => config.plugins.clone(),
                             },
+                            pool_config.cleanup_server_connections,
                         );
 
                         let connect_timeout = match pool_config.connect_timeout {
@@ -914,13 +915,29 @@ impl ConnectionPool {
 
 /// Wrapper for the bb8 connection pool.
 pub struct ServerPool {
+    /// Server address.
     address: Address,
+
+    /// Server Postgres user.
     user: User,
+
+    /// Server database.
     database: String,
+
+    /// Client/server mapping.
     client_server_map: ClientServerMap,
+
+    /// Server statistics.
     stats: Arc<PoolStats>,
+
+    /// Server auth hash (for auth passthrough).
     auth_hash: Arc<RwLock<Option<String>>>,
+
+    /// Server plugins.
     plugins: Option<Plugins>,
+
+    /// Should we clean up dirty connections before putting them into the pool?
+    cleanup_connections: bool,
 }
 
 impl ServerPool {
@@ -932,6 +949,7 @@ impl ServerPool {
         stats: Arc<PoolStats>,
         auth_hash: Arc<RwLock<Option<String>>>,
         plugins: Option<Plugins>,
+        cleanup_connections: bool,
     ) -> ServerPool {
         ServerPool {
             address,
@@ -941,6 +959,7 @@ impl ServerPool {
             stats,
             auth_hash,
             plugins,
+            cleanup_connections,
         }
     }
 }
@@ -970,6 +989,7 @@ impl ManageConnection for ServerPool {
             self.client_server_map.clone(),
             stats.clone(),
             self.auth_hash.clone(),
+            self.cleanup_connections,
         )
         .await
         {

src/server.rs

@@ -188,13 +188,16 @@ pub struct Server {
     /// Application name using the server at the moment.
     application_name: String,
 
-    // Last time that a successful server send or response happened
+    /// Last time that a successful server send or response happened
     last_activity: SystemTime,
 
     mirror_manager: Option<MirroringManager>,
 
-    // Associated addresses used
+    /// Associated addresses used
     addr_set: Option<AddrSet>,
+
+    /// Should clean up dirty connections?
+    cleanup_connections: bool,
 }
 
 impl Server {
@@ -207,6 +210,7 @@ impl Server {
         client_server_map: ClientServerMap,
         stats: Arc<ServerStats>,
         auth_hash: Arc<RwLock<Option<String>>>,
+        cleanup_connections: bool,
     ) -> Result<Server, Error> {
         let cached_resolver = CACHED_RESOLVER.load();
         let mut addr_set: Option<AddrSet> = None;
@@ -687,6 +691,7 @@ impl Server {
                                 address.mirrors.clone(),
                             )),
                         },
+                        cleanup_connections,
                     };
 
                     server.set_name("pgcat").await?;
@@ -1004,7 +1009,7 @@ impl Server {
         // to avoid leaking state between clients. For performance reasons we only
         // send `DISCARD ALL` if we think the session is altered instead of just sending
         // it before each checkin.
-        if self.cleanup_state.needs_cleanup() {
+        if self.cleanup_state.needs_cleanup() && self.cleanup_connections {
             warn!("Server returned with session state altered, discarding state ({}) for application {}", self.cleanup_state, self.application_name);
             self.query("DISCARD ALL").await?;
             self.query("RESET ROLE").await?;
@@ -1084,6 +1089,7 @@ impl Server {
             client_server_map,
             Arc::new(ServerStats::default()),
             Arc::new(RwLock::new(None)),
+            true,
         )
         .await?;
         debug!("Connected!, sending query.");

tests/ruby/helpers/pgcat_helper.rb

@@ -118,7 +118,7 @@ def self.single_instance_setup(pool_name, pool_size, pool_mode="transaction", lb
       end
     end
 
-    def self.single_shard_setup(pool_name, pool_size, pool_mode="transaction", lb_mode="random", log_level="info")
+    def self.single_shard_setup(pool_name, pool_size, pool_mode="transaction", lb_mode="random", log_level="info", pool_settings={})
       user = {
         "password" => "sharding_user",
         "pool_size" => pool_size,
@@ -134,28 +134,32 @@ def self.single_shard_setup(pool_name, pool_size, pool_mode="transaction", lb_mo
       replica1 = PgInstance.new(8432, user["username"], user["password"], "shard0")
       replica2 = PgInstance.new(9432, user["username"], user["password"], "shard0")
 
+      pool_config = {
+        "default_role" => "any",
+        "pool_mode" => pool_mode,
+        "load_balancing_mode" => lb_mode,
+        "primary_reads_enabled" => false,
+        "query_parser_enabled" => false,
+        "sharding_function" => "pg_bigint_hash",
+        "shards" => {
+          "0" => {
+            "database" => "shard0",
+            "servers" => [
+              ["localhost", primary.port.to_s, "primary"],
+              ["localhost", replica0.port.to_s, "replica"],
+              ["localhost", replica1.port.to_s, "replica"],
+              ["localhost", replica2.port.to_s, "replica"]
+            ]
+          },
+        },
+        "users" => { "0" => user }
+      }
+
+      pool_config = pool_config.merge(pool_settings)
+
       # Main proxy configs
       pgcat_cfg["pools"] = {
-        "#{pool_name}" => {
-          "default_role" => "any",
-          "pool_mode" => pool_mode,
-          "load_balancing_mode" => lb_mode,
-          "primary_reads_enabled" => false,
-          "query_parser_enabled" => false,
-          "sharding_function" => "pg_bigint_hash",
-          "shards" => {
-            "0" => {
-              "database" => "shard0",
-              "servers" => [
-                ["localhost", primary.port.to_s, "primary"],
-                ["localhost", replica0.port.to_s, "replica"],
-                ["localhost", replica1.port.to_s, "replica"],
-                ["localhost", replica2.port.to_s, "replica"]
-              ]
-            },
-          },
-          "users" => { "0" => user }
-        }
+        "#{pool_name}" => pool_config,
       }
       pgcat_cfg["general"]["port"] = pgcat.port
       pgcat.update_config(pgcat_cfg)

tests/ruby/misc_spec.rb

@@ -320,6 +320,31 @@
         expect(processes.primary.count_query("DISCARD ALL")).to eq(0)
       end
     end
+
+    context "server cleanup disabled" do
+      let(:processes) { Helpers::Pgcat.single_shard_setup("sharded_db", 1, "transaction", "random", "info", { "cleanup_server_connections" => false }) }
+
+      it "will not clean up connection state" do
+        conn = PG::connect(processes.pgcat.connection_string("sharded_db", "sharding_user"))
+        processes.primary.reset_stats
+        conn.async_exec("SET statement_timeout TO 1000")
+        conn.close
+
+        puts processes.pgcat.logs
+        expect(processes.primary.count_query("DISCARD ALL")).to eq(0)
+      end
+
+      it "will not clean up prepared statements" do
+        conn = PG::connect(processes.pgcat.connection_string("sharded_db", "sharding_user"))
+        processes.primary.reset_stats
+        conn.async_exec("PREPARE prepared_q (int) AS SELECT $1")
+
+        conn.close
+
+        puts processes.pgcat.logs
+        expect(processes.primary.count_query("DISCARD ALL")).to eq(0)
+      end
+    end
   end
 
   describe "Idle client timeout" do