add initiateShutdown() thrift method with a shutdown reason

Summary:
We've seen what appears to be phantom calls to shutdown() so we'd like
to add some degree of auditing.  This diff adds a new method with some
context; this will allow us to distinguish between `eden stop`, `eden restart`
and eden server internal calls to the `shutdown` method.   It may still
be possible that something else is calling our shutdown method, but it
seems unlikely as we're only accessible to our own code via a unix domain
socket.

Reviewed By: chadaustin

Differential Revision: D8341595

fbshipit-source-id: 50d58ea0b56e5f42cd37c404048d710bde0d13a3

eden/cli/main.py

@@ -739,7 +739,10 @@ class RestartCmd(Subcmd):
                     stop_aux_processes(client)
                     # Ask the old edenfs daemon to shutdown
                     self.msg("Stopping the existing edenfs daemon (pid {})...", pid)
-                    client.shutdown()
+                    client.initiateShutdown(
+                        f"`eden restart` requested by pid={os.getpid()} "
+                        f"uid={os.getuid()}"
+                    )
                     stopping = True
         except EdenNotRunningError:
             pass
@@ -832,7 +835,9 @@ class StopCmd(Subcmd):
                 stop_aux_processes(client)
                 # Ask the client to shutdown
                 print(f"Stopping edenfs daemon (pid {pid})...")
-                client.shutdown()
+                client.initiateShutdown(
+                    f"`eden stop` requested by pid={os.getpid()} uid={os.getuid()}"
+                )
         except EdenNotRunningError:
             print_stderr("error: edenfs is not running")
             return SHUTDOWN_EXIT_CODE_NOT_RUNNING_ERROR

eden/fs/service/EdenServiceHandler.cpp

@@ -981,5 +981,11 @@ void EdenServiceHandler::shutdown() {
   auto helper = INSTRUMENT_THRIFT_CALL(INFO);
   server_->stop();
 }
+
+void EdenServiceHandler::initiateShutdown(std::unique_ptr<std::string> reason) {
+  auto helper = INSTRUMENT_THRIFT_CALL(INFO);
+  XLOG(INFO) << "initiateShutdown requested, reason: " << *reason;
+  server_->stop();
+}
 } // namespace eden
 } // namespace facebook

eden/fs/service/EdenServiceHandler.h

@@ -166,10 +166,18 @@ class EdenServiceHandler : virtual public StreamingEdenServiceSvIf,
 
   /**
    * When this Thrift handler is notified to shutdown, it notifies the
-   * EdenServer to shut down, as well.
+   * EdenServer to shut down, as well.  We prefer that external
+   * clients use initiateShutdown() instead so that we can log some
+   * context.
    */
   void shutdown() override;
 
+  /**
+   * A thrift client has requested that we shutdown and provided
+   * the reason why.
+   */
+  void initiateShutdown(std::unique_ptr<std::string> reason) override;
+
  private:
   folly::Future<Hash> getSHA1ForPath(
       folly::StringPiece mountPoint,

eden/fs/service/client.py

@@ -12,6 +12,7 @@ from typing import Any, cast
 
 from facebook.eden import EdenService
 from thrift.protocol.THeaderProtocol import THeaderProtocol
+from thrift.Thrift import TApplicationException
 from thrift.transport.THeaderTransport import THeaderTransport
 from thrift.transport.TSocket import TSocket
 from thrift.transport.TTransport import TTransportException
@@ -85,6 +86,29 @@ class EdenClient(EdenService.Client):
             self._transport.close()
             self._transport = None
 
+    def shutdown(self):
+        self.initiateShutdown(
+            "EdenClient.shutdown() invoked with no reason by pid=%s uid=%s"
+            % (os.getpid(), os.getuid())
+        )
+
+    def initiateShutdown(self, reason):
+        """Helper for stopping the server.
+        To swing through the transition from calling the base shutdown() method
+        with context to the initiateShutdown() method with a reason, we want to
+        try the latter method first, falling back to the old way to handle the
+        case where we deploy a newer client while an older server is still
+        running on the local system."""
+        try:
+            super().initiateShutdown(reason)
+        except TApplicationException as ex:
+            if ex.type == TApplicationException.UNKNOWN_METHOD:
+                # Running an older server build, fall back to the old shutdown
+                # method with no context
+                super().shutdown()
+            else:
+                raise
+
 
 def create_thrift_client(eden_dir=None, socket_path=None):
     """Construct a thrift client to speak to the running eden server

eden/fs/service/eden.thrift

@@ -676,4 +676,9 @@ service EdenService extends fb303.FacebookService {
    * Gets the number of inodes unloaded by periodic job on an EdenMount.
    */
   InternalStats getStatInfo() throws (1: EdenError ex)
+
+  /**
+   * Ask the server to shutdown and provide it some context for its logs
+   */
+  void initiateShutdown(1: string reason);
 }

eden/integration/helpers/fake_edenfs.cpp

@@ -57,6 +57,11 @@ class FakeEdenServiceHandler : virtual public StreamingEdenServiceSvIf {
   void shutdown() override {
     printf("received shutdown() thrift request\n");
   }
+
+  void initiateShutdown(std::unique_ptr<std::string> reason) override {
+    printf(
+        "received initiateShutdown() thrift requested: %s\n", reason->c_str());
+  }
 };
 
 class SignalHandler : public folly::AsyncSignalHandler {