just-mr: lock garbage collection

just-mr accesses the CAS at several occations, most importantly,
the generated multi-repository configuration is written there. In
particular, when used as a launcher, it needs to keep that file in
its location as the path is passed to the exec of just.

2 files changed, 11 insertions, 0 deletions

diff --git a/src/other_tools/just_mr/TARGETS b/src/other_tools/just_mr/TARGETS
index 02876feb..9bd70659 100644
--- a/src/other_tools/just_mr/TARGETS
+++ b/src/other_tools/just_mr/TARGETS
@@ -19,6 +19,7 @@
     , ["src/other_tools/just_mr/progress_reporting", "progress"]
     , ["src/other_tools/just_mr/progress_reporting", "statistics"]
     , ["src/other_tools/just_mr/progress_reporting", "progress_reporter"]
+    , ["src/buildtool/storage", "storage"]
     ]
   , "stage": ["src", "other_tools", "just_mr"]
   , "private-ldflags":
diff --git a/src/other_tools/just_mr/main.cpp b/src/other_tools/just_mr/main.cpp
index 56ba4a18..e331a063 100644
--- a/src/other_tools/just_mr/main.cpp
+++ b/src/other_tools/just_mr/main.cpp
@@ -24,6 +24,7 @@
 #include "src/buildtool/logging/log_sink_cmdline.hpp"
 #include "src/buildtool/logging/log_sink_file.hpp"
 #include "src/buildtool/main/version.hpp"
+#include "src/buildtool/storage/garbage_collector.hpp"
 #include "src/other_tools/just_mr/cli.hpp"
 #include "src/other_tools/just_mr/exit_codes.hpp"
 #include "src/other_tools/just_mr/progress_reporting/progress.hpp"
@@ -1276,9 +1277,14 @@ void DefaultReachableRepositories(
     bool supports_defines{false};
     std::optional<std::filesystem::path> mr_config_path{std::nullopt};
 
+    std::optional<LockFile> lock{};
     if (subcommand and kKnownJustSubcommands.contains(*subcommand)) {
         // Read the config file if needed
         if (kKnownJustSubcommands.at(*subcommand).config) {
+            lock = GarbageCollector::SharedLock();
+            if (not lock) {
+                return kExitGenericFailure;
+            }
             auto config = ReadConfiguration(config_file);
 
             use_config = true;
@@ -1502,6 +1508,10 @@ auto main(int argc, char* argv[]) -> int {
             arguments.cmd == SubCommand::kJustSubCmd) {
             return CallJust(config_file, arguments, forward_build_root);
         }
+        auto lock = GarbageCollector::SharedLock();
+        if (not lock) {
+            return kExitGenericFailure;
+        }
 
         // The remaining options all need the config file
         auto config = ReadConfiguration(config_file);