implement "eden_store_util show_sizes"

Summary:
Implement the `show_sizes` function which reports the approximate size on disk
used by each column family.

The initial skeleton for this command was accidentally included in D15162813.

Reviewed By: wez

Differential Revision: D15307391

fbshipit-source-id: 03efee939d65500e17b48047552dec1dbb7aff7e

eden/fs/store/RocksDbLocalStore.cpp

@@ -91,6 +91,24 @@ const std::vector<rocksdb::ColumnFamilyDescriptor>& columnFamilies() {
   return families;
 }
 
+/**
+ * Return a rocksdb::Range that contains all possible keys that we store.
+ *
+ * The input string will be used to store data for the Range slices.
+ * The caller must ensure that the rangeStorage parameter remains valid and
+ * unmodified until they are done using the returned Range.
+ */
+rocksdb::Range getFullRange(std::string& rangeStorage) {
+  // An empty slice is the lowest possible value.
+  Slice begin;
+  // All of our keys are currently 20 bytes.
+  // Use a longer key to ensure that this is greater than any valid key.
+  rangeStorage = std::string(
+      21, static_cast<char>(std::numeric_limits<unsigned char>::max()));
+  Slice end(rangeStorage);
+  return rocksdb::Range(begin, end);
+}
+
 rocksdb::Slice _createSlice(folly::ByteRange bytes) {
   return Slice(reinterpret_cast<const char*>(bytes.data()), bytes.size());
 }
@@ -274,18 +292,14 @@ void RocksDbLocalStore::clearKeySpace(KeySpace keySpace) {
   std::unique_ptr<rocksdb::Iterator> it{
       dbHandles_.db->NewIterator(ReadOptions(), columnFamily)};
   XLOG(DBG2) << "clearing column family \"" << columnFamily->GetName() << "\"";
-  Slice begin;
-  // All of our keys are currently 20 bytes.  Use a longer key to ensure that
-  // this is greater than any valid key.
-  std::string endStr(
-      21, static_cast<char>(std::numeric_limits<unsigned char>::max()));
-  Slice end(endStr);
+  std::string rangeStorage;
+  const auto fullRange = getFullRange(rangeStorage);
 
   // Delete all SST files that only contain keys in the specified range.
   // Since we are deleting everything in this column family this should
   // effectively delete everything.
-  auto status =
-      DeleteFilesInRange(dbHandles_.db.get(), columnFamily, &begin, &end);
+  auto status = DeleteFilesInRange(
+      dbHandles_.db.get(), columnFamily, &fullRange.start, &fullRange.limit);
   if (!status.ok()) {
     throw RocksException::build(
         status,
@@ -298,7 +312,8 @@ void RocksDbLocalStore::clearKeySpace(KeySpace keySpace) {
   // everything in the range (but it probably will in our case since we are
   // intending to delete everything).
   const WriteOptions writeOptions;
-  status = dbHandles_.db->DeleteRange(writeOptions, columnFamily, begin, end);
+  status = dbHandles_.db->DeleteRange(
+      writeOptions, columnFamily, fullRange.start, fullRange.limit);
   if (!status.ok()) {
     throw RocksException::build(
         status,
@@ -489,5 +504,16 @@ void RocksDbLocalStore::put(
       _createSlice(value));
 }
 
+uint64_t RocksDbLocalStore::getApproximateSize(
+    LocalStore::KeySpace keySpace) const {
+  std::string rangeStorage;
+  const auto range = getFullRange(rangeStorage);
+
+  uint64_t size = 0;
+  dbHandles_.db->GetApproximateSizes(
+      dbHandles_.columns[keySpace].get(), &range, 1, &size);
+  return size;
+}
+
 } // namespace eden
 } // namespace facebook

eden/fs/store/RocksDbLocalStore.h

@@ -54,6 +54,10 @@ class RocksDbLocalStore : public LocalStore {
   // Call RocksDB's RepairDB() function on the DB at the specified location
   static void repairDB(AbsolutePathPiece path);
 
+  // Get the approximate number of bytes stored on disk for the
+  // specified key space.
+  uint64_t getApproximateSize(KeySpace keySpace) const;
+
  private:
   FaultInjector& faultInjector_;
   RocksHandles dbHandles_;

eden/fs/store/eden_store_util.cpp

@@ -13,6 +13,7 @@
 
 #include <folly/Range.h>
 #include <folly/container/Array.h>
+#include <folly/container/Enumerate.h>
 #include <folly/init/Init.h>
 #include <folly/logging/Init.h>
 #include <folly/logging/xlog.h>
@@ -23,6 +24,7 @@
 #include "eden/fs/fuse/privhelper/UserInfo.h"
 #include "eden/fs/service/EdenInit.h"
 #include "eden/fs/service/EdenStateDir.h"
+#include "eden/fs/store/KeySpaces.h"
 #include "eden/fs/store/RocksDbLocalStore.h"
 #include "eden/fs/utils/FaultInjector.h"
 
@@ -194,8 +196,12 @@ class ShowSizesCommand : public Command {
 
   void run() override {
     auto localStore = openLocalStore();
-    (void)localStore;
-    printf("show sizes\n");
+
+    for (const auto& iter : folly::enumerate(kKeySpaceRecords)) {
+      LOG(INFO) << "Column family \"" << iter->name << "\": "
+                << localStore->getApproximateSize(
+                       static_cast<LocalStore::KeySpace>(iter.index));
+    }
   }
 };