Revert "chore: get rid of kv_args and replace it with slices to full_… (

#3024)

Revert "chore: get rid of kv_args and replace it with slices to full_args (#2942)"

This reverts commit de0e5cb.

src/server/command_registry.cc

@@ -40,6 +40,9 @@ CommandId::CommandId(const char* name, uint32_t mask, int8_t arity, int8_t first
     : facade::CommandId(name, mask, arity, first_key, last_key, acl_categories) {
   if (mask & CO::ADMIN)
     opt_mask_ |= CO::NOSCRIPT;
+
+  if (mask & CO::BLOCKING)
+    opt_mask_ |= CO::REVERSE_MAPPING;
 }
 
 bool CommandId::IsTransactional() const {
@@ -170,6 +173,8 @@ const char* OptName(CO::CommandOpt fl) {
       return "readonly";
     case DENYOOM:
       return "denyoom";
+    case REVERSE_MAPPING:
+      return "reverse-mapping";
     case FAST:
       return "fast";
     case LOADING:

src/server/command_registry.h

@@ -27,13 +27,16 @@ enum CommandOpt : uint32_t {
   LOADING = 1U << 3,  // Command allowed during LOADING state.
   DENYOOM = 1U << 4,  // use-memory in redis.
 
-  // UNUSED = 1U << 5,
+  // marked commands that demand preserve the order of keys to work correctly.
+  // For example, MGET needs to know the order of keys to return the values in the same order.
+  // BLPOP needs to know the order of keys to return the first non-empty list from the left.
+  REVERSE_MAPPING = 1U << 5,
 
   VARIADIC_KEYS = 1U << 6,  // arg 2 determines number of keys. Relevant for ZUNIONSTORE, EVAL etc.
 
   ADMIN = 1U << 7,  // implies NOSCRIPT,
   NOSCRIPT = 1U << 8,
-  BLOCKING = 1U << 9,
+  BLOCKING = 1U << 9,           // implies REVERSE_MAPPING
   HIDDEN = 1U << 10,            // does not show in COMMAND command output
   INTERLEAVED_KEYS = 1U << 11,  // keys are interleaved with arguments
   GLOBAL_TRANS = 1U << 12,

src/server/container_utils.cc

@@ -40,12 +40,14 @@ OpResult<std::pair<DbSlice::ConstIterator, unsigned>> FindFirstReadOnly(const Db
                                                                         int req_obj_type) {
   DCHECK(!args.Empty());
 
-  for (auto it = args.begin(); it != args.end(); ++it) {
-    OpResult<DbSlice::ConstIterator> res = db_slice.FindReadOnly(cntx, *it, req_obj_type);
+  unsigned i = 0;
+  for (string_view key : args) {
+    OpResult<DbSlice::ConstIterator> res = db_slice.FindReadOnly(cntx, key, req_obj_type);
     if (res)
-      return make_pair(res.value(), unsigned(it.index()));
+      return make_pair(res.value(), i);
     if (res.status() != OpStatus::KEY_NOTFOUND)
       return res.status();
+    ++i;
   }
 
   VLOG(2) << "FindFirst not found";
@@ -117,8 +119,8 @@ OpResult<ShardFFResult> FindFirstNonEmpty(Transaction* trans, int req_obj_type)
   auto comp = [trans](const OpResult<FFResult>& lhs, const OpResult<FFResult>& rhs) {
     if (!lhs || !rhs)
       return lhs.ok();
-    size_t i1 = std::get<1>(*lhs);
-    size_t i2 = std::get<1>(*rhs);
+    size_t i1 = trans->ReverseArgIndex(std::get<ShardId>(*lhs), std::get<unsigned>(*lhs));
+    size_t i2 = trans->ReverseArgIndex(std::get<ShardId>(*rhs), std::get<unsigned>(*rhs));
     return i1 < i2;
   };
 

src/server/journal/types.h

@@ -42,17 +42,15 @@ struct Entry : public EntryBase {
   struct Payload {
     std::string_view cmd;
     std::variant<CmdArgList,  // Parts of a full command.
-                 ShardArgs,   // Shard parts.
-                 ArgSlice>
+                 ShardArgs    // Command and its shard parts.
+                 >
         args;
 
     Payload() = default;
     Payload(std::string_view c, CmdArgList a) : cmd(c), args(a) {
     }
     Payload(std::string_view c, const ShardArgs& a) : cmd(c), args(a) {
     }
-    Payload(std::string_view c, ArgSlice a) : cmd(c), args(a) {
-    }
   };
 
   Entry(TxId txid, Op opcode, DbIndex dbid, uint32_t shard_cnt,

src/server/json_family.cc

@@ -1543,14 +1543,12 @@ void JsonFamily::MGet(CmdArgList args, ConnectionContext* cntx) {
       continue;
 
     vector<OptString>& res = mget_resp[sid];
-    ShardArgs shard_args = transaction->GetShardArgs(sid);
-    unsigned src_index = 0;
-    for (auto it = shard_args.begin(); it != shard_args.end(); ++it, ++src_index) {
-      if (!res[src_index])
+    for (size_t j = 0; j < res.size(); ++j) {
+      if (!res[j])
         continue;
 
-      uint32_t dst_indx = it.index();
-      results[dst_indx] = std::move(res[src_index]);
+      uint32_t indx = transaction->ReverseArgIndex(sid, j);
+      results[indx] = std::move(res[j]);
     }
   }
 
@@ -2093,7 +2091,8 @@ void JsonFamily::Register(CommandRegistry* registry) {
   constexpr size_t kMsetFlags = CO::WRITE | CO::DENYOOM | CO::FAST | CO::INTERLEAVED_KEYS;
   registry->StartFamily();
   *registry << CI{"JSON.GET", CO::READONLY | CO::FAST, -2, 1, 1, acl::JSON}.HFUNC(Get);
-  *registry << CI{"JSON.MGET", CO::READONLY | CO::FAST, -3, 1, -2, acl::JSON}.HFUNC(MGet);
+  *registry << CI{"JSON.MGET", CO::READONLY | CO::FAST | CO::REVERSE_MAPPING, -3, 1, -2, acl::JSON}
+                   .HFUNC(MGet);
   *registry << CI{"JSON.TYPE", CO::READONLY | CO::FAST, 3, 1, 1, acl::JSON}.HFUNC(Type);
   *registry << CI{"JSON.STRLEN", CO::READONLY | CO::FAST, 3, 1, 1, acl::JSON}.HFUNC(StrLen);
   *registry << CI{"JSON.OBJLEN", CO::READONLY | CO::FAST, 3, 1, 1, acl::JSON}.HFUNC(ObjLen);

src/server/list_family.cc

@@ -158,22 +158,6 @@ struct CircularMessages {
 // Used to recover logs for BLPOP failures. See OpBPop.
 thread_local CircularMessages debugMessages{50};
 
-// A bit awkward translation from a single key to ShardArgs.
-// We create a mutable slice (which will never be mutated) from the key, then we create
-// a CmdArgList of size 1 that references mslice and finally
-// we reference the first element in the CmdArgList via islice.
-struct SingleArg {
-  MutableSlice mslice;
-  IndexSlice islice{0, 1};
-
-  SingleArg(string_view arg) : mslice(const_cast<char*>(arg.data()), arg.size()) {
-  }
-
-  ShardArgs Get() {
-    return ShardArgs{CmdArgList{&mslice, 1}, absl::MakeSpan(&islice, 1)};
-  }
-};
-
 class BPopPusher {
  public:
   BPopPusher(string_view pop_key, string_view push_key, ListDir popdir, ListDir pushdir);
@@ -464,9 +448,7 @@ OpResult<string> MoveTwoShards(Transaction* trans, string_view src, string_view
           // hack, again. since we hacked which queue we are waiting on (see RunPair)
           // we must clean-up src key here manually. See RunPair why we do this.
           // in short- we suspended on "src" on both shards.
-
-          SingleArg single_arg{src};
-          shard->blocking_controller()->FinalizeWatched(single_arg.Get(), t);
+          shard->blocking_controller()->FinalizeWatched(ArgSlice{&src, 1}, t);
         }
       } else {
         DVLOG(1) << "Popping value from list: " << key;
@@ -891,8 +873,7 @@ OpResult<string> BPopPusher::RunSingle(ConnectionContext* cntx, time_point tp) {
     return op_res;
   }
 
-  SingleArg single_arg{pop_key_};
-  auto wcb = [&](Transaction* t, EngineShard* shard) { return single_arg.Get(); };
+  auto wcb = [&](Transaction* t, EngineShard* shard) { return ShardArgs{&this->pop_key_, 1}; };
 
   const auto key_checker = [](EngineShard* owner, const DbContext& context, Transaction*,
                               std::string_view key) -> bool {
@@ -919,13 +900,11 @@ OpResult<string> BPopPusher::RunPair(ConnectionContext* cntx, time_point tp) {
     return op_res;
   }
 
-  SingleArg single_arg(this->pop_key_);
-
   // a hack: we watch in both shards for pop_key but only in the source shard it's relevant.
   // Therefore we follow the regular flow of watching the key but for the destination shard it
   // will never be triggerred.
   // This allows us to run Transaction::Execute on watched transactions in both shards.
-  auto wcb = [&](Transaction* t, EngineShard* shard) { return single_arg.Get(); };
+  auto wcb = [&](Transaction* t, EngineShard* shard) { return ArgSlice{&this->pop_key_, 1}; };
 
   const auto key_checker = [](EngineShard* owner, const DbContext& context, Transaction*,
                               std::string_view key) -> bool {

src/server/stream_family.cc

@@ -2989,19 +2989,17 @@ void XReadImpl(CmdArgList args, std::optional<ReadOpts> opts, ConnectionContext*
       continue;
 
     vector<RecordVec>& results = xread_resp[sid];
-    unsigned src_index = 0;
-    ShardArgs shard_args = cntx->transaction->GetShardArgs(sid);
 
-    for (auto it = shard_args.begin(); it != shard_args.end(); ++it, ++src_index) {
-      if (results[src_index].size() == 0) {
+    for (size_t i = 0; i < results.size(); ++i) {
+      if (results[i].size() == 0) {
         continue;
       }
 
       resolved_streams++;
 
       // Add the stream records ordered by the original stream arguments.
-      size_t dst_indx = it.index();
-      res[dst_indx - opts->streams_arg] = std::move(results[src_index]);
+      size_t indx = cntx->transaction->ReverseArgIndex(sid, i);
+      res[indx - opts->streams_arg] = std::move(results[i]);
     }
   }
 
@@ -3325,7 +3323,7 @@ constexpr uint32_t kXAutoClaim = WRITE | STREAM | FAST;
 void StreamFamily::Register(CommandRegistry* registry) {
   using CI = CommandId;
   registry->StartFamily();
-  constexpr auto kReadFlags = CO::READONLY | CO::BLOCKING | CO::VARIADIC_KEYS;
+  constexpr auto kReadFlags = CO::READONLY | CO::BLOCKING | CO::REVERSE_MAPPING | CO::VARIADIC_KEYS;
   *registry << CI{"XADD", CO::WRITE | CO::DENYOOM | CO::FAST, -5, 1, 1, acl::kXAdd}.HFUNC(XAdd)
             << CI{"XCLAIM", CO::WRITE | CO::FAST, -6, 1, 1, acl::kXClaim}.HFUNC(XClaim)
             << CI{"XDEL", CO::WRITE | CO::FAST, -3, 1, 1, acl::kXDel}.HFUNC(XDel)

src/server/string_family.cc

@@ -270,15 +270,13 @@ void OpMSet(const OpArgs& op_args, const ShardArgs& args, atomic_bool* success)
   SetCmd sg(op_args, false);
 
   size_t index = 0;
-  bool partial = false;
   for (auto it = args.begin(); it != args.end(); ++it) {
     string_view key = *it;
     ++it;
     string_view value = *it;
     DVLOG(1) << "MSet " << key << ":" << value;
     if (sg.Set(params, key, value) != OpStatus::OK) {  // OOM for example.
       success->store(false);
-      partial = true;
       break;
     }
     index += 2;
@@ -287,29 +285,18 @@ void OpMSet(const OpArgs& op_args, const ShardArgs& args, atomic_bool* success)
   if (auto journal = op_args.shard->journal(); journal) {
     // We write a custom journal because an OOM in the above loop could lead to partial success, so
     // we replicate only what was changed.
-    if (partial) {
-      string_view cmd;
-      ArgSlice cmd_args;
-      vector<string_view> store_args(index);
-      if (index == 0) {
-        // All shards must record the tx was executed for the replica to execute it, so we send a
-        // PING in case nothing was changed
-        cmd = "PING";
-      } else {
-        // journal [0, i)
-        cmd = "MSET";
-        unsigned i = 0;
-        for (string_view arg : args) {
-          store_args[i++] = arg;
-          if (i >= store_args.size())
-            break;
-        }
-        cmd_args = absl::MakeSpan(store_args);
-      }
-      RecordJournal(op_args, cmd, cmd_args, op_args.tx->GetUniqueShardCnt());
+    string_view cmd;
+    ArgSlice cmd_args;
+    if (index == 0) {
+      // All shards must record the tx was executed for the replica to execute it, so we send a PING
+      // in case nothing was changed
+      cmd = "PING";
     } else {
-      RecordJournal(op_args, "MSET", args, op_args.tx->GetUniqueShardCnt());
+      // journal [0, i)
+      cmd = "MSET";
+      cmd_args = ArgSlice(args.begin(), index);
     }
+    RecordJournal(op_args, cmd, cmd_args, op_args.tx->GetUniqueShardCnt());
   }
 }
 
@@ -1179,17 +1166,16 @@ void StringFamily::MGet(CmdArgList args, ConnectionContext* cntx) {
     src.storage_list->next = res.storage_list;
     res.storage_list = src.storage_list;
     src.storage_list = nullptr;
-    ShardArgs shard_args = transaction->GetShardArgs(sid);
-    unsigned src_indx = 0;
-    for (auto it = shard_args.begin(); it != shard_args.end(); ++it, ++src_indx) {
-      if (!src.resp_arr[src_indx])
+
+    for (size_t j = 0; j < src.resp_arr.size(); ++j) {
+      if (!src.resp_arr[j])
         continue;
 
-      uint32_t indx = it.index();
+      uint32_t indx = transaction->ReverseArgIndex(sid, j);
 
-      res.resp_arr[indx] = std::move(src.resp_arr[src_indx]);
+      res.resp_arr[indx] = std::move(src.resp_arr[j]);
       if (cntx->protocol() == Protocol::MEMCACHE) {
-        res.resp_arr[indx]->key = *it;
+        res.resp_arr[indx]->key = ArgS(args, indx);
       }
     }
   }
@@ -1505,7 +1491,9 @@ void StringFamily::Register(CommandRegistry* registry) {
       << CI{"GETEX", CO::WRITE | CO::DENYOOM | CO::FAST | CO::NO_AUTOJOURNAL, -1, 1, 1, acl::kGetEx}
              .HFUNC(GetEx)
       << CI{"GETSET", CO::WRITE | CO::DENYOOM | CO::FAST, 3, 1, 1, acl::kGetSet}.HFUNC(GetSet)
-      << CI{"MGET", CO::READONLY | CO::FAST | CO::IDEMPOTENT, -2, 1, -1, acl::kMGet}.HFUNC(MGet)
+      << CI{"MGET",    CO::READONLY | CO::FAST | CO::REVERSE_MAPPING | CO::IDEMPOTENT, -2, 1, -1,
+            acl::kMGet}
+             .HFUNC(MGet)
       << CI{"MSET", kMSetMask, -3, 1, -1, acl::kMSet}.HFUNC(MSet)
       << CI{"MSETNX", kMSetMask, -3, 1, -1, acl::kMSetNx}.HFUNC(MSetNx)
       << CI{"STRLEN", CO::READONLY | CO::FAST, 2, 1, 1, acl::kStrLen}.HFUNC(StrLen)