[WIP] Cached local process execution

src/python/pants/engine/native.py

@@ -740,6 +740,7 @@ def tc(constraint):
         self.context.utf8_buf(build_root),
         self.context.utf8_buf(work_dir),
         self.context.utf8_buf(local_store_dir),
+        self.context.utf8_buf(execution_options.local_execution_process_cache_namespace or ""),
         self.context.utf8_buf_buf(ignore_patterns),
         self.to_ids_buf(root_subject_types),
         # Remote execution config.

src/python/pants/engine/scheduler.py

@@ -88,6 +88,8 @@ def __init__(
     self._tasks = native.new_tasks()
     self._register_rules(rule_index)
 
+    # TODO: we REALLY need to have a datatype for all of these so that we don't mix up arguments by
+    # order.
     self._scheduler = native.new_scheduler(
       tasks=self._tasks,
       root_subject_types=self._root_subject_types,

src/python/pants/option/global_options.py

@@ -30,6 +30,7 @@ class GlobMatchErrorBehavior(enum('failure_behavior', ['ignore', 'warn', 'error'
 
 
 class ExecutionOptions(datatype([
+  'local_execution_process_cache_namespace',
   'remote_store_server',
   'remote_store_thread_count',
   'remote_execution_server',
@@ -52,6 +53,7 @@ class ExecutionOptions(datatype([
   @classmethod
   def from_bootstrap_options(cls, bootstrap_options):
     return cls(
+      local_execution_process_cache_namespace=bootstrap_options.local_execution_process_cache_namespace,
       remote_store_server=bootstrap_options.remote_store_server,
       remote_execution_server=bootstrap_options.remote_execution_server,
       remote_store_thread_count=bootstrap_options.remote_store_thread_count,
@@ -68,6 +70,7 @@ def from_bootstrap_options(cls, bootstrap_options):
 
 
 DEFAULT_EXECUTION_OPTIONS = ExecutionOptions(
+    local_execution_process_cache_namespace=None,
     remote_store_server=[],
     remote_store_thread_count=1,
     remote_execution_server=None,
@@ -291,6 +294,11 @@ def register_bootstrap_options(cls, register):
              # This default is also hard-coded into the engine's rust code in
              # fs::Store::default_path
              default=os.path.expanduser('~/.cache/pants/lmdb_store'))
+    register('--local-execution-process-cache-namespace', advanced=True,
+             help="The cache namespace for local process execution. "
+                  "Bump this to invalidate every artifact's local execution. "
+                  "This is the hermetic execution equivalent of the legacy cache-key-gen-version "
+                  "flag.")
     register('--remote-store-server', advanced=True, type=list, default=[],
              help='host:port of grpc server to use as remote execution file store.')
     register('--remote-store-thread-count', type=int, advanced=True,

src/rust/engine/fs/Cargo.toml

@@ -25,6 +25,7 @@ lazy_static = "1"
 lmdb = { git = "https://github.com/pantsbuild/lmdb-rs.git", rev = "06bdfbfc6348f6804127176e561843f214fc17f8" }
 log = "0.4"
 parking_lot = "0.6"
+prost = "0.4"
 protobuf = { version = "2.0.4", features = ["with-bytes"] }
 serverset = { path = "../serverset" }
 sha2 = "0.8"