chore!: remove walredo_process_kind config option & kind type

refs #7753

Preceding PR #7754
laid out the plan, this one wraps it up.

pageserver/src/config.rs

@@ -99,8 +99,6 @@ pub mod defaults {
 
     pub const DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB: usize = 0;
 
-    pub const DEFAULT_WALREDO_PROCESS_KIND: &str = "sync";
-
     ///
     /// Default built-in configuration file.
     ///
@@ -146,8 +144,6 @@ pub mod defaults {
 
 #validate_vectored_get = '{DEFAULT_VALIDATE_VECTORED_GET}'
 
-#walredo_process_kind = '{DEFAULT_WALREDO_PROCESS_KIND}'
-
 [tenant_config]
 #checkpoint_distance = {DEFAULT_CHECKPOINT_DISTANCE} # in bytes
 #checkpoint_timeout = {DEFAULT_CHECKPOINT_TIMEOUT}
@@ -300,8 +296,6 @@ pub struct PageServerConf {
     ///
     /// Setting this to zero disables limits on total ephemeral layer size.
     pub ephemeral_bytes_per_memory_kb: usize,
-
-    pub walredo_process_kind: crate::walredo::ProcessKind,
 }
 
 /// We do not want to store this in a PageServerConf because the latter may be logged
@@ -407,8 +401,6 @@ struct PageServerConfigBuilder {
     validate_vectored_get: BuilderValue<bool>,
 
     ephemeral_bytes_per_memory_kb: BuilderValue<usize>,
-
-    walredo_process_kind: BuilderValue<crate::walredo::ProcessKind>,
 }
 
 impl PageServerConfigBuilder {
@@ -497,8 +489,6 @@ impl PageServerConfigBuilder {
             )),
             validate_vectored_get: Set(DEFAULT_VALIDATE_VECTORED_GET),
             ephemeral_bytes_per_memory_kb: Set(DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB),
-
-            walredo_process_kind: Set(DEFAULT_WALREDO_PROCESS_KIND.parse().unwrap()),
         }
     }
 }
@@ -686,10 +676,6 @@ impl PageServerConfigBuilder {
         self.ephemeral_bytes_per_memory_kb = BuilderValue::Set(value);
     }
 
-    pub fn get_walredo_process_kind(&mut self, value: crate::walredo::ProcessKind) {
-        self.walredo_process_kind = BuilderValue::Set(value);
-    }
-
     pub fn build(self) -> anyhow::Result<PageServerConf> {
         let default = Self::default_values();
 
@@ -747,7 +733,6 @@ impl PageServerConfigBuilder {
                 max_vectored_read_bytes,
                 validate_vectored_get,
                 ephemeral_bytes_per_memory_kb,
-                walredo_process_kind,
             }
             CUSTOM LOGIC
             {
@@ -1044,9 +1029,6 @@ impl PageServerConf {
                 "ephemeral_bytes_per_memory_kb" => {
                     builder.get_ephemeral_bytes_per_memory_kb(parse_toml_u64("ephemeral_bytes_per_memory_kb", item)? as usize)
                 }
-                "walredo_process_kind" => {
-                    builder.get_walredo_process_kind(parse_toml_from_str("walredo_process_kind", item)?)
-                }
                 _ => bail!("unrecognized pageserver option '{key}'"),
             }
         }
@@ -1130,7 +1112,6 @@ impl PageServerConf {
             ),
             validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
             ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB,
-            walredo_process_kind: defaults::DEFAULT_WALREDO_PROCESS_KIND.parse().unwrap(),
         }
     }
 }
@@ -1370,7 +1351,6 @@ background_task_maximum_delay = '334 s'
                 ),
                 validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
                 ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB,
-                walredo_process_kind: defaults::DEFAULT_WALREDO_PROCESS_KIND.parse().unwrap(),
             },
             "Correct defaults should be used when no config values are provided"
         );
@@ -1444,7 +1424,6 @@ background_task_maximum_delay = '334 s'
                 ),
                 validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
                 ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB,
-                walredo_process_kind: defaults::DEFAULT_WALREDO_PROCESS_KIND.parse().unwrap(),
             },
             "Should be able to parse all basic config values correctly"
         );

pageserver/src/walredo.rs

@@ -20,7 +20,6 @@
 
 /// Process lifecycle and abstracction for the IPC protocol.
 mod process;
-pub use process::Kind as ProcessKind;
 
 /// Code to apply [`NeonWalRecord`]s.
 pub(crate) mod apply_neon;
@@ -55,7 +54,7 @@ pub struct PostgresRedoManager {
     tenant_shard_id: TenantShardId,
     conf: &'static PageServerConf,
     last_redo_at: std::sync::Mutex<Option<Instant>>,
-    /// The current [`process::Process`] that is used by new redo requests.
+    /// The current [`process::WalRedoProcess`] that is used by new redo requests.
     /// We use [`heavier_once_cell`] for coalescing the spawning, but the redo
     /// requests don't use the [`heavier_once_cell::Guard`] to keep ahold of the
     /// their process object; we use [`Arc::clone`] for that.
@@ -67,7 +66,7 @@ pub struct PostgresRedoManager {
     /// still be using the old redo process. But, those other tasks will most likely
     /// encounter an error as well, and errors are an unexpected condition anyway.
     /// So, probably we could get rid of the `Arc` in the future.
-    redo_process: heavier_once_cell::OnceCell<Arc<process::Process>>,
+    redo_process: heavier_once_cell::OnceCell<Arc<process::WalRedoProcess>>,
 }
 
 ///
@@ -212,26 +211,31 @@ impl PostgresRedoManager {
         const MAX_RETRY_ATTEMPTS: u32 = 1;
         let mut n_attempts = 0u32;
         loop {
-            let proc: Arc<process::Process> = match self.redo_process.get_or_init_detached().await {
-                Ok(guard) => Arc::clone(&guard),
-                Err(permit) => {
-                    // don't hold poison_guard, the launch code can bail
-                    let start = Instant::now();
-                    let proc = Arc::new(
-                        process::Process::launch(self.conf, self.tenant_shard_id, pg_version)
+            let proc: Arc<process::WalRedoProcess> =
+                match self.redo_process.get_or_init_detached().await {
+                    Ok(guard) => Arc::clone(&guard),
+                    Err(permit) => {
+                        // don't hold poison_guard, the launch code can bail
+                        let start = Instant::now();
+                        let proc = Arc::new(
+                            process::WalRedoProcess::launch(
+                                self.conf,
+                                self.tenant_shard_id,
+                                pg_version,
+                            )
                             .context("launch walredo process")?,
-                    );
-                    let duration = start.elapsed();
-                    WAL_REDO_PROCESS_LAUNCH_DURATION_HISTOGRAM.observe(duration.as_secs_f64());
-                    info!(
-                        duration_ms = duration.as_millis(),
-                        pid = proc.id(),
-                        "launched walredo process"
-                    );
-                    self.redo_process.set(Arc::clone(&proc), permit);
-                    proc
-                }
-            };
+                        );
+                        let duration = start.elapsed();
+                        WAL_REDO_PROCESS_LAUNCH_DURATION_HISTOGRAM.observe(duration.as_secs_f64());
+                        info!(
+                            duration_ms = duration.as_millis(),
+                            pid = proc.id(),
+                            "launched walredo process"
+                        );
+                        self.redo_process.set(Arc::clone(&proc), permit);
+                        proc
+                    }
+                };
 
             let started_at = std::time::Instant::now();