perf: Eliminate env map cloning and increase cache write buffer

- Change CommandProvider trait to take &EnvironmentVariableMap instead of
  by value, eliminating all HashMap clones of the environment variable map
  in the per-task command creation path. Previously each task execution
  cloned the entire env map (which can contain 100+ variables) once at
  the call site and again per command provider.

- Increase async cache mpsc channel buffer from 1 to max_workers so
  cache write requests don't block waiting for the semaphore permit
  inside the worker loop. The semaphore already limits concurrency.

- Remove unused get_global_hash_inputs re-export.

https://claude.ai/code/session_01CfUraGs872goKHRKSRyFXi

Author: claude

crates/turborepo-cache/src/async_cache.rs

@@ -49,7 +49,10 @@ impl AsyncCache {
             api_auth,
             analytics_recorder,
         )?);
-        let (writer_sender, mut write_consumer) = mpsc::channel(1);
+        // Buffer up to max_workers requests so that callers don't block
+        // waiting for a semaphore permit inside the worker loop. The
+        // semaphore already limits actual concurrency.
+        let (writer_sender, mut write_consumer) = mpsc::channel(max_workers);
 
         // start a task to manage workers
         let worker_real_cache = real_cache.clone();

crates/turborepo-lib/src/task_graph/visitor/command.rs

@@ -39,7 +39,7 @@ mod test {
         fn command(
             &self,
             _task_id: &TaskId,
-            _environment: EnvironmentVariableMap,
+            _environment: &EnvironmentVariableMap,
         ) -> Result<Option<Command>, Error> {
             Ok(Some(Command::new("echo")))
         }
@@ -51,7 +51,7 @@ mod test {
         fn command(
             &self,
             _task_id: &TaskId,
-            _environment: EnvironmentVariableMap,
+            _environment: &EnvironmentVariableMap,
         ) -> Result<Option<Command>, Error> {
             Err(Error::InternalErrors("oops!".into()))
         }
@@ -63,7 +63,7 @@ mod test {
         fn command(
             &self,
             _task_id: &TaskId,
-            _environment: EnvironmentVariableMap,
+            _environment: &EnvironmentVariableMap,
         ) -> Result<Option<Command>, Error> {
             Ok(None)
         }
@@ -77,7 +77,7 @@ mod test {
             .add_provider(ErrProvider);
         let task_id = TaskId::new("foo", "build");
         let cmd = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap()
             .unwrap();
         assert_eq!(cmd.program(), OsStr::new("echo"));
@@ -91,7 +91,7 @@ mod test {
             .add_provider(EchoCmdFactory);
         let task_id = TaskId::new("foo", "build");
         let cmd = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap_err();
         assert_snapshot!(cmd.to_string(), @"Internal errors encountered: oops!");
     }
@@ -104,7 +104,7 @@ mod test {
             .add_provider(NoneProvider);
         let task_id = TaskId::new("foo", "build");
         let cmd = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap()
             .unwrap();
         assert_eq!(cmd.program(), OsStr::new("echo"));
@@ -115,7 +115,7 @@ mod test {
         let factory = CommandFactory::new();
         let task_id = TaskId::new("foo", "build");
         let cmd = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap();
         assert!(cmd.is_none(), "expected no cmd, got {cmd:?}");
     }
@@ -193,7 +193,7 @@ mod test {
         let cmd = factory
             .command(
                 &TaskId::new("web", "proxy"),
-                EnvironmentVariableMap::default(),
+                &EnvironmentVariableMap::default(),
             )
             .unwrap()
             .unwrap();

crates/turborepo-lib/src/task_graph/visitor/exec.rs

@@ -94,7 +94,7 @@ impl<'a> ExecContextFactory<'a> {
 
         let Some(cmd) = self
             .command_factory
-            .command(&task_id, execution_env.clone())?
+            .command(&task_id, &execution_env)?
         else {
             return Ok(None);
         };

crates/turborepo-lib/src/task_hash.rs

@@ -5,8 +5,8 @@
 
 // Re-export all public types from turborepo-task-hash
 pub use turborepo_task_hash::{
-    collect_global_file_hash_inputs, get_external_deps_hash, get_global_hash_inputs,
-    get_internal_deps_hash, global_hash, Error, GlobalHashableInputs, PackageInputsHashes,
+    collect_global_file_hash_inputs, get_external_deps_hash, get_internal_deps_hash, global_hash,
+    Error, GlobalHashableInputs, PackageInputsHashes,
     TaskHashTracker, TaskHashTrackerState,
 };
 

crates/turborepo-task-executor/src/command.rs

@@ -42,7 +42,7 @@ pub trait CommandProvider<E> {
     fn command(
         &self,
         task_id: &TaskId,
-        environment: EnvironmentVariableMap,
+        environment: &EnvironmentVariableMap,
     ) -> Result<Option<Command>, E>;
 }
 
@@ -82,10 +82,10 @@ impl<'a, E> CommandFactory<'a, E> {
     pub fn command(
         &self,
         task_id: &TaskId,
-        environment: EnvironmentVariableMap,
+        environment: &EnvironmentVariableMap,
     ) -> Result<Option<Command>, E> {
         for provider in self.providers.iter() {
-            let cmd = provider.command(task_id, environment.clone())?;
+            let cmd = provider.command(task_id, environment)?;
             if cmd.is_some() {
                 return Ok(cmd);
             }
@@ -175,7 +175,7 @@ impl<'a, M: MfeConfigProvider, E: From<CommandProviderError>> CommandProvider<E>
     fn command(
         &self,
         task_id: &TaskId,
-        environment: EnvironmentVariableMap,
+        environment: &EnvironmentVariableMap,
     ) -> Result<Option<Command>, E> {
         let workspace_info = self.package_info(task_id)?;
 
@@ -305,7 +305,7 @@ impl<'a, T: PackageInfoProvider + Send + Sync, M: MfeConfigProvider, E: From<Com
     fn command(
         &self,
         task_id: &TaskId,
-        _environment: EnvironmentVariableMap,
+        _environment: &EnvironmentVariableMap,
     ) -> Result<Option<Command>, E> {
         debug!(
             "MicroFrontendProxyProvider::command - called for task: {}",
@@ -421,7 +421,7 @@ mod tests {
         fn command(
             &self,
             _task_id: &TaskId,
-            _environment: EnvironmentVariableMap,
+            _environment: &EnvironmentVariableMap,
         ) -> Result<Option<Command>, String> {
             Ok(Some(Command::new("echo")))
         }
@@ -433,7 +433,7 @@ mod tests {
         fn command(
             &self,
             _task_id: &TaskId,
-            _environment: EnvironmentVariableMap,
+            _environment: &EnvironmentVariableMap,
         ) -> Result<Option<Command>, String> {
             Ok(None)
         }
@@ -445,7 +445,7 @@ mod tests {
         fn command(
             &self,
             _task_id: &TaskId,
-            _environment: EnvironmentVariableMap,
+            _environment: &EnvironmentVariableMap,
         ) -> Result<Option<Command>, String> {
             Err("error".to_string())
         }
@@ -457,7 +457,7 @@ mod tests {
         factory.add_provider(EchoProvider).add_provider(ErrProvider);
         let task_id = TaskId::new("foo", "build");
         let cmd = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap()
             .unwrap();
         assert_eq!(cmd.program(), OsStr::new("echo"));
@@ -469,7 +469,7 @@ mod tests {
         factory.add_provider(ErrProvider).add_provider(EchoProvider);
         let task_id = TaskId::new("foo", "build");
         let err = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap_err();
         assert_eq!(err, "error");
     }
@@ -482,7 +482,7 @@ mod tests {
             .add_provider(EchoProvider);
         let task_id = TaskId::new("foo", "build");
         let cmd = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap()
             .unwrap();
         assert_eq!(cmd.program(), OsStr::new("echo"));
@@ -493,7 +493,7 @@ mod tests {
         let factory: CommandFactory<String> = CommandFactory::new();
         let task_id = TaskId::new("foo", "build");
         let cmd = factory
-            .command(&task_id, EnvironmentVariableMap::default())
+            .command(&task_id, &EnvironmentVariableMap::default())
             .unwrap();
         assert!(cmd.is_none(), "expected no cmd, got {cmd:?}");
     }