Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 113 insertions, 0 deletions

diff --git a/src/rocksdb/examples/options_file_example.cc b/src/rocksdb/examples/options_file_example.cc
new file mode 100644
index 00000000..5dd0a479
--- /dev/null
+++ b/src/rocksdb/examples/options_file_example.cc
@@ -0,0 +1,113 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// This file demonstrates how to use the utility functions defined in
+// rocksdb/utilities/options_util.h to open a rocksdb database without
+// remembering all the rocksdb options.
+#include <cstdio>
+#include <string>
+#include <vector>
+
+#include "rocksdb/cache.h"
+#include "rocksdb/compaction_filter.h"
+#include "rocksdb/db.h"
+#include "rocksdb/options.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/table.h"
+#include "rocksdb/utilities/options_util.h"
+
+using namespace rocksdb;
+
+std::string kDBPath = "/tmp/rocksdb_options_file_example";
+
+namespace {
+// A dummy compaction filter
+class DummyCompactionFilter : public CompactionFilter {
+ public:
+  virtual ~DummyCompactionFilter() {}
+  virtual bool Filter(int level, const Slice& key, const Slice& existing_value,
+                      std::string* new_value, bool* value_changed) const {
+    return false;
+  }
+  virtual const char* Name() const { return "DummyCompactionFilter"; }
+};
+
+}  // namespace
+
+int main() {
+  DBOptions db_opt;
+  db_opt.create_if_missing = true;
+
+  std::vector<ColumnFamilyDescriptor> cf_descs;
+  cf_descs.push_back({kDefaultColumnFamilyName, ColumnFamilyOptions()});
+  cf_descs.push_back({"new_cf", ColumnFamilyOptions()});
+
+  // initialize BlockBasedTableOptions
+  auto cache = NewLRUCache(1 * 1024 * 1024 * 1024);
+  BlockBasedTableOptions bbt_opts;
+  bbt_opts.block_size = 32 * 1024;
+  bbt_opts.block_cache = cache;
+
+  // initialize column families options
+  std::unique_ptr<CompactionFilter> compaction_filter;
+  compaction_filter.reset(new DummyCompactionFilter());
+  cf_descs[0].options.table_factory.reset(NewBlockBasedTableFactory(bbt_opts));
+  cf_descs[0].options.compaction_filter = compaction_filter.get();
+  cf_descs[1].options.table_factory.reset(NewBlockBasedTableFactory(bbt_opts));
+
+  // destroy and open DB
+  DB* db;
+  Status s = DestroyDB(kDBPath, Options(db_opt, cf_descs[0].options));
+  assert(s.ok());
+  s = DB::Open(Options(db_opt, cf_descs[0].options), kDBPath, &db);
+  assert(s.ok());
+
+  // Create column family, and rocksdb will persist the options.
+  ColumnFamilyHandle* cf;
+  s = db->CreateColumnFamily(ColumnFamilyOptions(), "new_cf", &cf);
+  assert(s.ok());
+
+  // close DB
+  delete cf;
+  delete db;
+
+  // In the following code, we will reopen the rocksdb instance using
+  // the options file stored in the db directory.
+
+  // Load the options file.
+  DBOptions loaded_db_opt;
+  std::vector<ColumnFamilyDescriptor> loaded_cf_descs;
+  s = LoadLatestOptions(kDBPath, Env::Default(), &loaded_db_opt,
+                        &loaded_cf_descs);
+  assert(s.ok());
+  assert(loaded_db_opt.create_if_missing == db_opt.create_if_missing);
+
+  // Initialize pointer options for each column family
+  for (size_t i = 0; i < loaded_cf_descs.size(); ++i) {
+    auto* loaded_bbt_opt = reinterpret_cast<BlockBasedTableOptions*>(
+        loaded_cf_descs[0].options.table_factory->GetOptions());
+    // Expect the same as BlockBasedTableOptions will be loaded form file.
+    assert(loaded_bbt_opt->block_size == bbt_opts.block_size);
+    // However, block_cache needs to be manually initialized as documented
+    // in rocksdb/utilities/options_util.h.
+    loaded_bbt_opt->block_cache = cache;
+  }
+  // In addition, as pointer options are initialized with default value,
+  // we need to properly initialized all the pointer options if non-defalut
+  // values are used before calling DB::Open().
+  assert(loaded_cf_descs[0].options.compaction_filter == nullptr);
+  loaded_cf_descs[0].options.compaction_filter = compaction_filter.get();
+
+  // reopen the db using the loaded options.
+  std::vector<ColumnFamilyHandle*> handles;
+  s = DB::Open(loaded_db_opt, kDBPath, loaded_cf_descs, &handles, &db);
+  assert(s.ok());
+
+  // close DB
+  for (auto* handle : handles) {
+    delete handle;
+  }
+  delete db;
+}