Fix a bunch of issues related to server startup/shutdown:

- Only try to communicate with the server if it passes verification (i.e. the indicated PID exists and its start time is correct)
- Use only one thread to delete files on exit
- Don't set restart reason to NEW_VERSION unless there is an existing server

RELNOTES: None.
PiperOrigin-RevId: 158131470

1 files changed, 13 insertions, 25 deletions

diff --git a/src/main/cpp/blaze.cc b/src/main/cpp/blaze.cc
index 438253422a..0b22226aac 100644
--- a/src/main/cpp/blaze.cc
+++ b/src/main/cpp/blaze.cc
@@ -711,7 +711,7 @@ static void SetRestartReasonIfNotSet(RestartReason restart_reason) {
   }
 }
 
-// Starts up a new server and connects to it. Exits if it didn't work not.
+// Starts up a new server and connects to it. Exits if it didn't work out.
 static void StartServerAndConnect(const WorkspaceLayout *workspace_layout,
                                   BlazeServer *server) {
   string server_dir =
@@ -1077,9 +1077,9 @@ static void EnsureCorrectRunningVersion(BlazeServer *server) {
                                    globals->options->install_base)) {
     if (server->Connected()) {
       server->KillRunningServer();
+      globals->restart_reason = NEW_VERSION;
     }
 
-    globals->restart_reason = NEW_VERSION;
     blaze_util::UnlinkPath(installation_path);
     if (!SymlinkDirectories(globals->options->install_base,
                             installation_path)) {
@@ -1444,6 +1444,16 @@ bool GrpcBlazeServer::Connect() {
     return false;
   }
 
+  pid_t server_pid = GetServerPid(server_dir);
+  if (server_pid < 0) {
+    return false;
+  }
+
+  if (!VerifyServerProcess(server_pid, globals->options->output_base,
+      globals->options->install_base)) {
+    return false;
+  }
+
   std::shared_ptr<grpc::Channel> channel(
       grpc::CreateChannel(port, grpc::InsecureChannelCredentials()));
   std::unique_ptr<command_server::CommandServer::Stub> client(
@@ -1455,29 +1465,7 @@ bool GrpcBlazeServer::Connect() {
 
   this->client_ = std::move(client);
   connected_ = true;
-
-  globals->server_pid = GetServerPid(server_dir);
-  if (globals->server_pid <= 0) {
-    fprintf(stderr,
-            "Can't get PID of existing server (server dir=%s). "
-            "Shutting it down and starting a new one...\n",
-            server_dir.c_str());
-    // This means that we have a server we could connect to but without a PID
-    // file, which in turn means that something went wrong before. Kill the
-    // server so that we can start with as clean a slate as possible. This may
-    // happen if someone (e.g. a client or server that's very old and uses an
-    // AF_UNIX socket instead of gRPC) deletes the server.pid.txt file.
-    KillRunningServer();
-    // Then wait until it actually dies
-    do {
-      auto next_attempt_time(std::chrono::system_clock::now() +
-                             std::chrono::milliseconds(1000));
-      std::this_thread::sleep_until(next_attempt_time);
-    } while (TryConnect(client_.get()));
-
-    return false;
-  }
-
+  globals->server_pid = server_pid;
   return true;
 }