feat(database): add an optional master replica max connections settin…

…gs (#1472)

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---------

Co-authored-by: Roman Brodetski <rb@matterlabs.dev>
Co-authored-by: perekopskiy <53865202+perekopskiy@users.noreply.github.com>

core/lib/config/src/configs/database.rs

@@ -133,6 +133,8 @@ pub struct PostgresConfig {
     pub prover_url: Option<String>,
     /// Maximum size of the connection pool.
     pub max_connections: Option<u32>,
+    /// Maximum size of the connection pool to master DB.
+    pub max_connections_master: Option<u32>,
 
     /// Acquire timeout in seconds for a single connection attempt. There are multiple attempts (currently 3)
     /// before acquire methods will return an error.
@@ -173,6 +175,10 @@ impl PostgresConfig {
         self.max_connections.context("Max connections is absent")
     }
 
+    pub fn max_connections_master(&self) -> Option<u32> {
+        self.max_connections_master
+    }
+
     /// Returns the Postgres statement timeout.
     pub fn statement_timeout(&self) -> Option<Duration> {
         self.statement_timeout_sec.map(Duration::from_secs)

core/lib/config/src/testonly.rs

@@ -422,6 +422,7 @@ impl RandomConfig for configs::database::PostgresConfig {
             replica_url: g.gen(),
             prover_url: g.gen(),
             max_connections: g.gen(),
+            max_connections_master: g.gen(),
             acquire_timeout_sec: g.gen(),
             statement_timeout_sec: g.gen(),
             long_connection_threshold_ms: g.gen(),

core/lib/env_config/src/database.rs

@@ -38,6 +38,7 @@ impl FromEnv for PostgresConfig {
             .ok()
             .or_else(|| master_url.clone());
         let max_connections = parse_optional_var("DATABASE_POOL_SIZE")?;
+        let max_connections_master = parse_optional_var("DATABASE_POOL_SIZE_MASTER")?;
         let acquire_timeout_sec = parse_optional_var("DATABASE_ACQUIRE_TIMEOUT_SEC")?;
         let statement_timeout_sec = parse_optional_var("DATABASE_STATEMENT_TIMEOUT_SEC")?;
         let long_connection_threshold_ms =
@@ -49,6 +50,7 @@ impl FromEnv for PostgresConfig {
             replica_url,
             prover_url,
             max_connections,
+            max_connections_master,
             acquire_timeout_sec,
             statement_timeout_sec,
             long_connection_threshold_ms,

core/lib/protobuf_config/src/database.rs

@@ -92,6 +92,7 @@ impl ProtoRepr for proto::Postgres {
             replica_url: self.replica_url.clone(),
             prover_url: self.prover_url.clone(),
             max_connections: self.max_connections,
+            max_connections_master: self.max_connections_master,
             acquire_timeout_sec: self.acquire_timeout_sec,
             statement_timeout_sec: self.statement_timeout_sec,
             long_connection_threshold_ms: self.long_connection_threshold_ms,
@@ -105,6 +106,7 @@ impl ProtoRepr for proto::Postgres {
             replica_url: this.replica_url.clone(),
             prover_url: this.prover_url.clone(),
             max_connections: this.max_connections,
+            max_connections_master: this.max_connections_master,
             acquire_timeout_sec: this.acquire_timeout_sec,
             statement_timeout_sec: this.statement_timeout_sec,
             long_connection_threshold_ms: this.long_connection_threshold_ms,

core/lib/protobuf_config/src/proto/database.proto

@@ -31,4 +31,5 @@ message Postgres {
   optional uint64 acquire_timeout_sec = 6; // optional; s
   optional uint64 long_connection_threshold_ms = 7; // optional; ms
   optional uint64 slow_query_threshold_ms = 8; // optional; ms
+  optional uint32 max_connections_master = 9; // optional
 }

core/lib/zksync_core/src/lib.rs

@@ -324,10 +324,15 @@ pub async fn initialize_components(
     }
 
     let pool_size = postgres_config.max_connections()?;
-    let connection_pool = ConnectionPool::<Core>::builder(postgres_config.master_url()?, pool_size)
-        .build()
-        .await
-        .context("failed to build connection_pool")?;
+    let pool_size_master = postgres_config
+        .max_connections_master()
+        .unwrap_or(pool_size);
+
+    let connection_pool =
+        ConnectionPool::<Core>::builder(postgres_config.master_url()?, pool_size_master)
+            .build()
+            .await
+            .context("failed to build connection_pool")?;
     // We're most interested in setting acquire / statement timeouts for the API server, which puts the most load
     // on Postgres.
     let replica_connection_pool =