add a standalone eden_gc utility

Summary:
Add a standalone program that can be used to garbage collect the local store
data when edenfs is not currently running.

Reviewed By: wez

Differential Revision: D14910392

fbshipit-source-id: 1cf8f959e5967cfbb797752653cc72223c87134f

eden/fs/service/CMakeLists.txt

@@ -16,6 +16,7 @@ add_thrift_cpp2_library(
 )
 
 file(GLOB SERVICE_SRCS "*.cpp")
+list(REMOVE_ITEM SERVICE_SRCS "${CMAKE_CURRENT_SOURCE_DIR}/eden_gc.cpp")
 add_library(
   eden_service STATIC
     ${SERVICE_SRCS}

eden/fs/service/eden_gc.cpp

@@ -0,0 +1,78 @@
+/*
+ *  Copyright (c) 2019-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+#include <sysexits.h>
+
+#include <folly/init/Init.h>
+#include <folly/logging/Init.h>
+#include <folly/logging/xlog.h>
+#include <folly/stop_watch.h>
+
+#include "eden/fs/config/EdenConfig.h"
+#include "eden/fs/config/ReloadableConfig.h"
+#include "eden/fs/fuse/privhelper/UserInfo.h"
+#include "eden/fs/service/EdenInit.h"
+#include "eden/fs/service/EdenStateDir.h"
+#include "eden/fs/store/RocksDbLocalStore.h"
+#include "eden/fs/utils/FaultInjector.h"
+
+using namespace facebook::eden;
+
+FOLLY_INIT_LOGGING_CONFIG("eden=DBG2; default:async=true");
+
+namespace {
+class StoreConfig : public ReloadableConfig {
+ public:
+  explicit StoreConfig(std::shared_ptr<EdenConfig> config)
+      : config_(std::move(config)) {}
+
+  std::shared_ptr<const EdenConfig> getEdenConfig(
+      bool /* skipUpdate */ = false) override {
+    // We don't ever bother checking for an update for now.
+    // We don't expect to be a long-lived process.
+    return config_;
+  }
+
+ private:
+  std::shared_ptr<EdenConfig> config_;
+};
+} // namespace
+
+int main(int argc, char** argv) {
+  folly::init(&argc, &argv);
+
+  auto userInfo = UserInfo::lookup();
+  std::shared_ptr<EdenConfig> config;
+  try {
+    config = getEdenConfig(userInfo);
+  } catch (const ArgumentError& ex) {
+    fprintf(stderr, "%s\n", ex.what());
+    return EX_SOFTWARE;
+  }
+
+  XLOG(INFO) << "Using Eden directory: " << config->getEdenDir();
+  EdenStateDir edenDir(config->getEdenDir());
+  if (!edenDir.acquireLock()) {
+    fprintf(stderr, "error: failed to acquire the Eden lock\n");
+    fprintf(stderr, "This utility cannot be used while edenfs is running.\n");
+    return EX_SOFTWARE;
+  }
+
+  FaultInjector faultInjector(/*enabled=*/false);
+  folly::stop_watch<std::chrono::milliseconds> watch;
+  const auto rocksPath = edenDir.getPath() + "storage/rocks-db"_relpath;
+  ensureDirectoryExists(rocksPath);
+  auto localStore = std::make_unique<RocksDbLocalStore>(
+      rocksPath, &faultInjector, std::make_shared<StoreConfig>(config));
+  XLOG(INFO) << "Opened RocksDB store in " << (watch.elapsed().count() / 1000.0)
+             << " seconds.";
+
+  localStore->clearCachesAndCompactAll();
+  return 0;
+}