Changes after review

Author: mkaruza

src/server/cluster/cluster_defs.h

@@ -174,6 +174,10 @@ class ClusterShardInfos {
 // MigrationState constants are ordered in state changing order
 enum class MigrationState : uint8_t { C_CONNECTING, C_SYNC, C_ERROR, C_FINISHED, C_FATAL };
 
+// Errors during slot migration
+static constexpr std::string_view kUnknownMigration = "UNKNOWN_MIGRATION";
+static constexpr std::string_view kIncomingMigrationOOM = "INCOMING_MIGRATION_OOM";
+
 // return error message if slot doesn't belong to this node
 facade::ErrorReply SlotOwnershipError(SlotId slot_id);
 

src/server/cluster/cluster_family.cc

@@ -9,17 +9,13 @@
 #include <string>
 
 #include "absl/cleanup/cleanup.h"
-#include "absl/strings/str_cat.h"
 #include "base/flags.h"
 #include "base/logging.h"
 #include "facade/cmd_arg_parser.h"
 #include "facade/dragonfly_connection.h"
 #include "facade/error.h"
 #include "server/acl/acl_commands_def.h"
 #include "server/channel_store.h"
-#include "server/cluster/cluster_defs.h"
-#include "server/cluster/incoming_slot_migration.h"
-#include "server/cluster/outgoing_slot_migration.h"
 #include "server/command_registry.h"
 #include "server/conn_context.h"
 #include "server/dflycmd.h"
@@ -839,7 +835,7 @@ ClusterFamily::TakeOutOutgoingMigrations(shared_ptr<ClusterConfig> new_config,
     removed_slots.Merge(slots);
     LOG(INFO) << "Outgoing migration cancelled: slots " << slots.ToString() << " to "
               << migration.GetHostIp() << ":" << migration.GetPort();
-    migration.Finish(MigrationState::C_FINISHED);
+    migration.Finish();
     res.migrations.push_back(std::move(*it));
     outgoing_migration_jobs_.erase(it);
   }
@@ -930,7 +926,7 @@ void ClusterFamily::InitMigration(CmdArgList args, SinkReplyBuilder* builder) {
 
   if (!migration) {
     VLOG(1) << "Unrecognized incoming migration from " << source_id;
-    return builder->SendSimpleString(OutgoingMigration::kUnknownMigration);
+    return builder->SendSimpleString(kUnknownMigration);
   }
 
   if (migration->GetState() != MigrationState::C_CONNECTING) {
@@ -942,7 +938,7 @@ void ClusterFamily::InitMigration(CmdArgList args, SinkReplyBuilder* builder) {
   }
 
   if (migration->GetState() == MigrationState::C_FATAL) {
-    return builder->SendError(absl::StrCat("-", IncomingSlotMigration::kMigrationOOM));
+    return builder->SendError(absl::StrCat("-", kIncomingMigrationOOM));
   }
 
   migration->Init(flows_num);
@@ -969,10 +965,6 @@ void ClusterFamily::DflyMigrateFlow(CmdArgList args, SinkReplyBuilder* builder,
     return builder->SendError(kIdNotFound);
   }
 
-  if (migration->GetState() == MigrationState::C_FATAL) {
-    return builder->SendError(absl::StrCat("-", IncomingSlotMigration::kMigrationOOM));
-  }
-
   DCHECK(cntx->sync_dispatch);
   // we do this to be ignored by the dispatch tracker
   // TODO provide a more clear approach
@@ -981,10 +973,6 @@ void ClusterFamily::DflyMigrateFlow(CmdArgList args, SinkReplyBuilder* builder,
   builder->SendOk();
 
   migration->StartFlow(shard_id, cntx->conn()->socket());
-
-  if (migration->GetState() == MigrationState::C_FATAL) {
-    migration->Stop();
-  }
 }
 
 void ClusterFamily::ApplyMigrationSlotRangeToConfig(std::string_view node_id,
@@ -1051,7 +1039,7 @@ void ClusterFamily::DflyMigrateAck(CmdArgList args, SinkReplyBuilder* builder) {
                    [source_id = source_id](const auto& m) { return m.node_info.id == source_id; });
   if (m_it == in_migrations.end()) {
     LOG(WARNING) << "migration isn't in config";
-    return builder->SendError(OutgoingMigration::kUnknownMigration);
+    return builder->SendError(kUnknownMigration);
   }
 
   auto migration = GetIncomingMigration(source_id);
@@ -1060,7 +1048,7 @@ void ClusterFamily::DflyMigrateAck(CmdArgList args, SinkReplyBuilder* builder) {
 
   if (!migration->Join(attempt)) {
     if (migration->GetState() == MigrationState::C_FATAL) {
-      return builder->SendError(absl::StrCat("-", IncomingSlotMigration::kMigrationOOM));
+      return builder->SendError(absl::StrCat("-", kIncomingMigrationOOM));
     } else {
       return builder->SendError("Join timeout happened");
     }

src/server/cluster/incoming_slot_migration.cc

@@ -7,15 +7,10 @@
 #include <absl/cleanup/cleanup.h>
 #include <absl/strings/str_cat.h>
 
-#include <utility>
-
 #include "base/flags.h"
 #include "base/logging.h"
 #include "cluster_utility.h"
-#include "facade/error.h"
 #include "server/cluster/cluster_defs.h"
-#include "server/cluster/outgoing_slot_migration.h"
-#include "server/common.h"
 #include "server/error.h"
 #include "server/journal/executor.h"
 #include "server/journal/tx_executor.h"
@@ -76,17 +71,11 @@ class ClusterShardMigration {
         break;
       }
 
-      auto oom_check = [&]() -> bool {
-        auto used_mem = used_mem_current.load(memory_order_relaxed);
-        if ((used_mem + tx_data->command.cmd_len) > max_memory_limit) {
-          cntx->ReportError(IncomingSlotMigration::kMigrationOOM);
-          in_migration_->ReportFatalError(GenericError(IncomingSlotMigration::kMigrationOOM));
-          return true;
-        }
-        return false;
-      };
-
-      if (oom_check()) {
+      auto used_mem = used_mem_current.load(memory_order_relaxed);
+      // If aplying transaction data will reach 90% of max_memory_limit we end migration.
+      if ((used_mem + tx_data->command.cmd_len) > (0.9 * max_memory_limit)) {
+        cntx->ReportError(std::string{kIncomingMigrationOOM});
+        in_migration_->ReportFatalError(std::string{kIncomingMigrationOOM});
         break;
       }
 
@@ -99,8 +88,8 @@ class ClusterShardMigration {
           VLOG(1) << "Finalized flow " << source_shard_id_;
           return;
         }
-        if (oom_check()) {
-          VLOG(2) << "Flow finalization " << source_shard_id_
+        if (in_migration_->GetState() == MigrationState::C_FATAL) {
+          VLOG(1) << "Flow finalization " << source_shard_id_
                   << " canceled due memory limit reached";
           return;
         }
@@ -248,6 +237,11 @@ void IncomingSlotMigration::Stop() {
     }
   }
 
+  // Don't wait if we reached FATAL state
+  if (state_ == MigrationState::C_FATAL) {
+    return;
+  }
+
   // we need to Join the migration process to prevent data corruption
   const absl::Time start = absl::Now();
   const absl::Duration timeout =
@@ -284,6 +278,9 @@ void IncomingSlotMigration::StartFlow(uint32_t shard, util::FiberSocketBase* sou
   VLOG(1) << "Incoming flow " << shard
           << (GetState() == MigrationState::C_FINISHED ? " finished " : " cancelled ") << "for "
           << source_id_;
+  if (GetState() == MigrationState::C_FATAL) {
+    Stop();
+  }
 }
 
 size_t IncomingSlotMigration::GetKeyCount() const {

src/server/cluster/incoming_slot_migration.h

@@ -3,9 +3,6 @@
 //
 #pragma once
 
-#include <string>
-
-#include "absl/base/thread_annotations.h"
 #include "helio/util/fiber_socket_base.h"
 #include "server/cluster/cluster_defs.h"
 #include "server/common.h"
@@ -82,8 +79,6 @@ class IncomingSlotMigration {
 
   void Pause(bool pause);
 
-  static constexpr char kMigrationOOM[] = "INCOMING_MIGRATION_OOM";
-
  private:
   std::string source_id_;
   Service& service_;

src/server/cluster/outgoing_slot_migration.cc

@@ -12,10 +12,7 @@
 #include "base/logging.h"
 #include "cluster_family.h"
 #include "cluster_utility.h"
-#include "facade/resp_expr.h"
 #include "server/cluster/cluster_defs.h"
-#include "server/cluster/incoming_slot_migration.h"
-#include "server/common.h"
 #include "server/db_slice.h"
 #include "server/engine_shard_set.h"
 #include "server/error.h"
@@ -40,8 +37,7 @@ class OutgoingMigration::SliceSlotMigration : private ProtocolClient {
   SliceSlotMigration(DbSlice* slice, ServerContext server_context, SlotSet slots,
                      journal::Journal* journal, OutgoingMigration* om)
       : ProtocolClient(server_context), streamer_(slice, std::move(slots), journal, &exec_st_) {
-    exec_st_.SwitchErrorHandler(
-        [om](auto ge) { om->Finish(MigrationState::C_ERROR, std::move(ge)); });
+    exec_st_.SwitchErrorHandler([om](auto ge) { om->Finish(std::move(ge)); });
   }
 
   ~SliceSlotMigration() {
@@ -143,8 +139,14 @@ void OutgoingMigration::OnAllShards(
   });
 }
 
-void OutgoingMigration::Finish(MigrationState next_state, GenericError error) {
+void OutgoingMigration::Finish(GenericError error) {
+  auto next_state = MigrationState::C_FINISHED;
   if (error) {
+    if (error.Format() == kIncomingMigrationOOM) {
+      next_state = MigrationState::C_FATAL;
+    } else {
+      next_state = MigrationState::C_ERROR;
+    }
     LOG(WARNING) << "Finish outgoing migration for " << cf_->MyID() << ": "
                  << migration_info_.node_info.id << " with error: " << error.Format();
     exec_st_.ReportError(std::move(error));
@@ -225,6 +227,15 @@ void OutgoingMigration::SyncFb() {
       continue;
     }
 
+    // Break outgoing migration if INIT from incoming node responded with OOM. Usually this will
+    // happen on second iteration after first failed with OOM. Sending second INIT is required to
+    // cleanup slots on incoming slot migration node.
+    if (CheckRespFirstTypes({RespExpr::ERROR}) &&
+        facade::ToSV(LastResponseArgs().front().GetBuf()) == kIncomingMigrationOOM) {
+      ChangeState(MigrationState::C_FATAL);
+      break;
+    }
+
     if (!CheckRespIsSimpleReply("OK")) {
       if (CheckRespIsSimpleReply(kUnknownMigration)) {
         const absl::Duration passed = absl::Now() - start_time;
@@ -275,20 +286,16 @@ void OutgoingMigration::SyncFb() {
     }
 
     long attempt = 0;
-    bool fatal_state = false;
     while (GetState() != MigrationState::C_FINISHED && !FinalizeMigration(++attempt)) {
-      // Don't sleep if we ended up in FATAL state
+      // Break loop and don't sleep in case of C_FATAL
       if (GetState() == MigrationState::C_FATAL) {
-        fatal_state = true;
         break;
-      } else {
-        // Process commands that were on pause and try again
-        VLOG(1) << "Waiting for migration to finalize...";
-        ThisFiber::SleepFor(500ms);
       }
+      // Process commands that were on pause and try again
+      VLOG(1) << "Waiting for migration to finalize...";
+      ThisFiber::SleepFor(500ms);
     }
-    // End outgoing slot migration if we are FINISHED or are in FATAL state
-    if (!exec_st_.IsRunning() && !fatal_state) {
+    if (!exec_st_.IsRunning()) {
       continue;
     }
     break;
@@ -371,13 +378,7 @@ bool OutgoingMigration::FinalizeMigration(long attempt) {
       auto error = facade::ToSV(LastResponseArgs().front().GetBuf());
       LOG(WARNING) << "Error response for " << cf_->MyID() << " : " << migration_info_.node_info.id
                    << " attempt " << attempt << " msg: " << error;
-      auto next_state = MigrationState::C_ERROR;
-      // Check if there is OOM response from incoming slot migration
-      if (error == IncomingSlotMigration::kMigrationOOM) {
-        SetLastError(GenericError(IncomingSlotMigration::kMigrationOOM));
-        next_state = MigrationState::C_FATAL;
-      }
-      Finish(next_state, std::string(error));
+      Finish(std::string(error));
       return false;
     }
 
@@ -397,7 +398,7 @@ bool OutgoingMigration::FinalizeMigration(long attempt) {
   }
 
   if (!exec_st_.GetError()) {
-    Finish(MigrationState::C_FINISHED);
+    Finish();
     keys_number_ = cluster::GetKeyCount(migration_info_.slot_ranges);
     cf_->ApplyMigrationSlotRangeToConfig(migration_info_.node_info.id, migration_info_.slot_ranges,
                                          false);

src/server/cluster/outgoing_slot_migration.h

@@ -30,7 +30,7 @@ class OutgoingMigration : private ProtocolClient {
   // if is_error = false mark migration as FINISHED and cancel migration if it's not finished yet
   // can be called from any thread, but only after Start()
   // if is_error = true and migration is in progress it will be restarted otherwise nothing happens
-  void Finish(MigrationState next_state, GenericError error = {}) ABSL_LOCKS_EXCLUDED(state_mu_);
+  void Finish(GenericError error = {}) ABSL_LOCKS_EXCLUDED(state_mu_);
 
   MigrationState GetState() const ABSL_LOCKS_EXCLUDED(state_mu_);
 
@@ -76,8 +76,6 @@ class OutgoingMigration : private ProtocolClient {
 
   size_t GetKeyCount() const ABSL_LOCKS_EXCLUDED(state_mu_);
 
-  static constexpr std::string_view kUnknownMigration = "UNKNOWN_MIGRATION";
-
  private:
   // should be run for all shards
   void StartFlow(journal::Journal* journal, io::Sink* dest);