Return string instead of output pointer in metadata

src/cluster/redis_slot.cc

@@ -53,7 +53,7 @@ uint16_t Crc16(const char *buf, size_t len) {
   return crc;
 }
 
-uint16_t GetSlotIdFromKey(const std::string &key) {
+uint16_t GetSlotIdFromKey(std::string_view key) {
   auto tag = GetTagFromKey(key);
   if (tag.empty()) {
     tag = key;
@@ -63,7 +63,7 @@ uint16_t GetSlotIdFromKey(const std::string &key) {
   return crc & HASH_SLOTS_MASK;
 }
 
-std::string GetTagFromKey(const std::string &key) {
+std::string_view GetTagFromKey(std::string_view key) {
   auto left_pos = key.find('{');
   if (left_pos == std::string::npos) return {};
 

src/cluster/redis_slot.h

@@ -28,5 +28,5 @@ constexpr const uint16_t HASH_SLOTS_SIZE = HASH_SLOTS_MASK + 1;  // 16384
 constexpr const uint16_t HASH_SLOTS_MAX_ITERATIONS = 50;
 
 uint16_t Crc16(const char *buf, size_t len);
-uint16_t GetSlotIdFromKey(const std::string &key);
-std::string GetTagFromKey(const std::string &key);
+uint16_t GetSlotIdFromKey(std::string_view key);
+std::string_view GetTagFromKey(std::string_view key);

src/cluster/slot_migrate.cc

@@ -313,8 +313,7 @@ Status SlotMigrator::sendSnapshot() {
   auto iter = util::UniqueIterator(storage_->GetDB()->NewIterator(read_options, cf_handle));
 
   // Construct key prefix to iterate the keys belong to the target slot
-  std::string prefix;
-  ComposeSlotKeyPrefix(namespace_, slot, &prefix);
+  std::string prefix = ComposeSlotKeyPrefix(namespace_, slot);
   LOG(INFO) << "[migrate] Iterate keys of slot, key's prefix: " << prefix;
 
   // Seek to the beginning of keys start with 'prefix' and iterate all these keys
@@ -331,8 +330,7 @@ Status SlotMigrator::sendSnapshot() {
     }
 
     // Get user key
-    std::string ns, user_key;
-    ExtractNamespaceKey(iter->key(), &ns, &user_key, true);
+    auto [_, user_key] = ExtractNamespaceKey(iter->key(), true);
 
     // Add key's constructed commands to restore_cmds, send pipeline or not according to task's max_pipeline_size
     auto result = migrateOneKey(user_key, iter->value(), &restore_cmds);
@@ -665,9 +663,8 @@ Status SlotMigrator::migrateComplexKey(const rocksdb::Slice &key, const Metadata
   auto iter = util::UniqueIterator(storage_->GetDB()->NewIterator(read_options));
 
   // Construct key prefix to iterate values of the complex type user key
-  std::string slot_key, prefix_subkey;
-  AppendNamespacePrefix(key, &slot_key);
-  InternalKey(slot_key, "", metadata.version, true).Encode(&prefix_subkey);
+  std::string slot_key = AppendNamespacePrefix(key);
+  std::string prefix_subkey = InternalKey(slot_key, "", metadata.version, true).Encode();
   int item_count = 0;
 
   for (iter->Seek(prefix_subkey); iter->Valid(); iter->Next()) {
@@ -766,11 +763,9 @@ Status SlotMigrator::migrateStream(const Slice &key, const StreamMetadata &metad
   auto iter = util::UniqueIterator(
       storage_->GetDB()->NewIterator(read_options, storage_->GetCFHandle(engine::kStreamColumnFamilyName)));
 
-  std::string ns_key;
-  AppendNamespacePrefix(key, &ns_key);
+  std::string ns_key = AppendNamespacePrefix(key);
   // Construct key prefix to iterate values of the stream
-  std::string prefix_key;
-  InternalKey(ns_key, "", metadata.version, true).Encode(&prefix_key);
+  std::string prefix_key = InternalKey(ns_key, "", metadata.version, true).Encode();
 
   std::vector<std::string> user_cmd = {type_to_cmd[metadata.Type()], key.ToString()};
 

src/commands/cmd_server.cc

@@ -814,8 +814,7 @@ class CommandCompact : public Commander {
     auto ns = conn->GetNamespace();
 
     if (ns != kDefaultNamespace) {
-      std::string prefix;
-      ComposeNamespaceKey(ns, "", &prefix, false);
+      std::string prefix = ComposeNamespaceKey(ns, "", false);
 
       redis::Database redis_db(svr->storage, conn->GetNamespace());
       auto s = redis_db.FindKeyRangeWithPrefix(prefix, std::string(), &begin_key, &end_key);

src/common/db_util.h

@@ -22,6 +22,8 @@
 
 #include <memory>
 
+#include "fmt/ostream.h"
+#include "fmt/std.h"
 #include "rocksdb/db.h"
 #include "rocksdb/iterator.h"
 #include "rocksdb/utilities/backup_engine.h"
@@ -103,3 +105,14 @@ inline StatusOr<std::unique_ptr<rocksdb::BackupEngine>> BackupEngineOpen(rocksdb
 }
 
 }  // namespace util
+
+namespace rocksdb {
+
+inline std::ostream& operator<<(std::ostream& os, const Slice& slice) {
+  return os << std::string_view{slice.data(), slice.size()};
+}
+
+}  // namespace rocksdb
+
+template <>
+struct fmt::formatter<rocksdb::Slice> : fmt::ostream_formatter {};

src/stats/disk_stats.cc

@@ -33,9 +33,9 @@ namespace redis {
 rocksdb::Status Disk::GetApproximateSizes(const Metadata &metadata, const Slice &ns_key,
                                           rocksdb::ColumnFamilyHandle *column_family, uint64_t *key_size,
                                           Slice subkeyleft, Slice subkeyright) {
-  std::string prefix_key, next_version_prefix_key;
-  InternalKey(ns_key, subkeyleft, metadata.version, storage_->IsSlotIdEncoded()).Encode(&prefix_key);
-  InternalKey(ns_key, subkeyright, metadata.version + 1, storage_->IsSlotIdEncoded()).Encode(&next_version_prefix_key);
+  std::string prefix_key = InternalKey(ns_key, subkeyleft, metadata.version, storage_->IsSlotIdEncoded()).Encode();
+  std::string next_version_prefix_key =
+      InternalKey(ns_key, subkeyright, metadata.version + 1, storage_->IsSlotIdEncoded()).Encode();
   auto key_range = rocksdb::Range(prefix_key, next_version_prefix_key);
   uint64_t tmp_size = 0;
   rocksdb::Status s = storage_->GetDB()->GetApproximateSizes(option_, column_family, &key_range, 1, &tmp_size);
@@ -46,8 +46,7 @@ rocksdb::Status Disk::GetApproximateSizes(const Metadata &metadata, const Slice
 
 rocksdb::Status Disk::GetKeySize(const Slice &user_key, RedisType type, uint64_t *key_size) {
   *key_size = 0;
-  std::string ns_key;
-  AppendNamespacePrefix(user_key, &ns_key);
+  std::string ns_key = AppendNamespacePrefix(user_key);
   switch (type) {
     case RedisType::kRedisString:
       return GetStringSize(ns_key, key_size);

src/storage/batch_extractor.cc

@@ -48,23 +48,26 @@ rocksdb::Status WriteBatchExtractor::PutCF(uint32_t column_family_id, const Slic
     return rocksdb::Status::OK();
   }
 
-  std::string ns, user_key;
+  std::string ns;
   std::vector<std::string> command_args;
 
   if (column_family_id == kColumnFamilyIDMetadata) {
-    ExtractNamespaceKey(key, &ns, &user_key, is_slot_id_encoded_);
-    if (slot_id_ >= 0 && static_cast<uint16_t>(slot_id_) != GetSlotIdFromKey(user_key)) {
+    auto [ns_s, user_key] = ExtractNamespaceKey(key, is_slot_id_encoded_);
+    if (slot_id_ >= 0 && static_cast<uint16_t>(slot_id_) != GetSlotIdFromKey(user_key.ToStringView())) {
       return rocksdb::Status::OK();
     }
 
+    ns = ns_s.ToString();
+    auto user_key_str = user_key.ToString();
+
     Metadata metadata(kRedisNone);
     metadata.Decode(value.ToString());
 
     if (metadata.Type() == kRedisString) {
-      command_args = {"SET", user_key, value.ToString().substr(Metadata::GetOffsetAfterExpire(value[0]))};
+      command_args = {"SET", user_key_str, value.ToString().substr(Metadata::GetOffsetAfterExpire(value[0]))};
       resp_commands_[ns].emplace_back(redis::Command2RESP(command_args));
       if (metadata.expire > 0) {
-        command_args = {"PEXPIREAT", user_key, std::to_string(metadata.expire)};
+        command_args = {"PEXPIREAT", user_key_str, std::to_string(metadata.expire)};
         resp_commands_[ns].emplace_back(redis::Command2RESP(command_args));
       }
     } else if (metadata.expire > 0) {
@@ -78,7 +81,7 @@ rocksdb::Status WriteBatchExtractor::PutCF(uint32_t column_family_id, const Slic
 
         auto cmd = static_cast<RedisCommand>(*parse_result);
         if (cmd == kRedisCmdExpire) {
-          command_args = {"PEXPIREAT", user_key, std::to_string(metadata.expire)};
+          command_args = {"PEXPIREAT", user_key_str, std::to_string(metadata.expire)};
           resp_commands_[ns].emplace_back(redis::Command2RESP(command_args));
         }
       }
@@ -96,7 +99,7 @@ rocksdb::Status WriteBatchExtractor::PutCF(uint32_t column_family_id, const Slic
       if (!s.ok()) return s;
 
       command_args = {"XSETID",
-                      user_key,
+                      user_key_str,
                       stream_metadata.last_entry_id.ToString(),
                       "ENTRIESADDED",
                       std::to_string(stream_metadata.entries_added),
@@ -110,7 +113,7 @@ rocksdb::Status WriteBatchExtractor::PutCF(uint32_t column_family_id, const Slic
 
   if (column_family_id == kColumnFamilyIDDefault) {
     InternalKey ikey(key, is_slot_id_encoded_);
-    user_key = ikey.GetKey().ToString();
+    auto user_key = ikey.GetKey().ToString();
     if (slot_id_ >= 0 && static_cast<uint16_t>(slot_id_) != GetSlotIdFromKey(user_key)) {
       return rocksdb::Status::OK();
     }
@@ -271,14 +274,14 @@ rocksdb::Status WriteBatchExtractor::DeleteCF(uint32_t column_family_id, const S
   std::string ns;
 
   if (column_family_id == kColumnFamilyIDMetadata) {
-    std::string user_key;
-    ExtractNamespaceKey(key, &ns, &user_key, is_slot_id_encoded_);
+    auto [ns_s, user_key] = ExtractNamespaceKey(key, is_slot_id_encoded_);
+    ns = ns_s.ToString();
 
-    if (slot_id_ >= 0 && static_cast<uint16_t>(slot_id_) != GetSlotIdFromKey(user_key)) {
+    if (slot_id_ >= 0 && static_cast<uint16_t>(slot_id_) != GetSlotIdFromKey(user_key.ToStringView())) {
       return rocksdb::Status::OK();
     }
 
-    command_args = {"DEL", user_key};
+    command_args = {"DEL", user_key.ToString()};
   } else if (column_family_id == kColumnFamilyIDDefault) {
     InternalKey ikey(key, is_slot_id_encoded_);
     std::string user_key = ikey.GetKey().ToString();

src/storage/compact_filter.cc

@@ -25,6 +25,7 @@
 #include <string>
 #include <utility>
 
+#include "db_util.h"
 #include "time_util.h"
 #include "types/redis_bitmap.h"
 
@@ -34,10 +35,10 @@ using rocksdb::Slice;
 
 bool MetadataFilter::Filter(int level, const Slice &key, const Slice &value, std::string *new_value,
                             bool *modified) const {
-  std::string ns, user_key, bytes = value.ToString();
+  std::string bytes = value.ToString();
   Metadata metadata(kRedisNone, false);
   rocksdb::Status s = metadata.Decode(bytes);
-  ExtractNamespaceKey(key, &ns, &user_key, stor_->IsSlotIdEncoded());
+  auto [ns, user_key] = ExtractNamespaceKey(key, stor_->IsSlotIdEncoded());
   if (!s.ok()) {
     LOG(WARNING) << "[compact_filter/metadata] Failed to decode,"
                  << ", namespace: " << ns << ", key: " << user_key << ", err: " << s.ToString();
@@ -50,13 +51,11 @@ bool MetadataFilter::Filter(int level, const Slice &key, const Slice &value, std
 }
 
 Status SubKeyFilter::GetMetadata(const InternalKey &ikey, Metadata *metadata) const {
-  std::string metadata_key;
-
   auto db = stor_->GetDB();
   const auto cf_handles = stor_->GetCFHandles();
   // storage close the would delete the column family handler and DB
   if (!db || cf_handles->size() < 2) return {Status::NotOK, "storage is closed"};
-  ComposeNamespaceKey(ikey.GetNamespace(), ikey.GetKey(), &metadata_key, stor_->IsSlotIdEncoded());
+  std::string metadata_key = ComposeNamespaceKey(ikey.GetNamespace(), ikey.GetKey(), stor_->IsSlotIdEncoded());
 
   if (cached_key_.empty() || metadata_key != cached_key_) {
     std::string bytes;