feat: add fieldttl command that returns the ttl of the member (#2026)

Currently implemented only for saddex.

Signed-off-by: Roman Gershman <roman@dragonflydb.io>

src/core/dense_set.cc

@@ -57,6 +57,7 @@ void DenseSet::IteratorBase::Advance() {
       ++curr_list_;
       if (curr_list_ == owner_->entries_.end()) {
         curr_entry_ = nullptr;
+        owner_ = nullptr;
         return;
       }
       owner_->ExpireIfNeeded(nullptr, &(*curr_list_));

src/core/string_set.h

@@ -58,7 +58,7 @@ class StringSet : public DenseSet {
     iterator() : IteratorBase() {
     }
 
-    iterator(DenseSet* set, bool is_end) : IteratorBase(set, is_end) {
+    iterator(DenseSet* set) : IteratorBase(set, false) {
     }
 
     iterator& operator++() {
@@ -67,7 +67,10 @@ class StringSet : public DenseSet {
     }
 
     bool operator==(const iterator& b) const {
-      return curr_list_ == b.curr_list_;
+      if (owner_ == nullptr && b.owner_ == nullptr) {  // to allow comparison with end()
+        return true;
+      }
+      return owner_ == b.owner_ && curr_entry_ == b.curr_entry_;
     }
 
     bool operator!=(const iterator& b) const {
@@ -86,57 +89,14 @@ class StringSet : public DenseSet {
     using IteratorBase::HasExpiry;
   };
 
-  class const_iterator : private IteratorBase {
-   public:
-    using iterator_category = std::input_iterator_tag;
-    using value_type = const char*;
-    using pointer = value_type*;
-    using reference = value_type&;
-
-    const_iterator() : IteratorBase() {
-    }
-
-    const_iterator(const DenseSet* set, bool is_end) : IteratorBase(set, is_end) {
-    }
-
-    const_iterator& operator++() {
-      Advance();
-      return *this;
-    }
-
-    bool operator==(const const_iterator& b) const {
-      return curr_list_ == b.curr_list_;
-    }
-
-    bool operator!=(const const_iterator& b) const {
-      return !(*this == b);
-    }
-
-    value_type operator*() const {
-      return (value_type)curr_entry_->GetObject();
-    }
-
-    value_type operator->() const {
-      return (value_type)curr_entry_->GetObject();
-    }
-  };
-
   iterator begin() {
-    return iterator{this, false};
+    return iterator{this};
   }
 
   iterator end() {
-    return iterator{this, true};
+    return iterator{};
   }
-  /*
-    const_iterator cbegin() const {
-      return const_iterator{this, false};
-    }
 
-    const_iterator cend() const {
-      return const_iterator{this, true};
-    }
-  */
   uint32_t Scan(uint32_t, const std::function<void(sds)>&) const;
   iterator Find(std::string_view member) {
     return iterator{FindIt(&member, 1)};

src/server/generic_family.cc

@@ -24,6 +24,7 @@ extern "C" {
 #include "server/rdb_extensions.h"
 #include "server/rdb_load.h"
 #include "server/rdb_save.h"
+#include "server/set_family.h"
 #include "server/transaction.h"
 #include "util/varz.h"
 
@@ -618,6 +619,27 @@ OpStatus OpExpire(const OpArgs& op_args, string_view key, const DbSlice::ExpireP
   return res.status();
 }
 
+// returns -2 if the key was not found, -3 if the field was not found,
+// -1 if ttl on the field was not found.
+OpResult<long> OpFieldTtl(Transaction* t, EngineShard* shard, string_view key, string_view field) {
+  auto& db_slice = shard->db_slice();
+  const DbContext& db_cntx = t->GetDbContext();
+  auto [it, expire_it] = db_slice.FindExt(db_cntx, key);
+  if (!IsValid(it))
+    return -2;
+
+  if (it->second.ObjType() != OBJ_SET)  // TODO: to finish for hashes.
+    return OpStatus::WRONG_TYPE;
+
+  if (it->second.ObjType() == OBJ_SET) {
+    int32_t res = SetFamily::FieldExpireTime(db_cntx, it->second, field);
+    return res <= 0 ? res : int32_t(res - MemberTimeSeconds(db_cntx.time_now_ms));
+  }
+
+  // TODO: to finish with hash family.
+  return OpStatus::INVALID_VALUE;
+}
+
 }  // namespace
 
 void GenericFamily::Init(util::ProactorPool* pp) {
@@ -1060,6 +1082,24 @@ void GenericFamily::Restore(CmdArgList args, ConnectionContext* cntx) {
   }
 }
 
+// Returns -2 if key not found, WRONG_TYPE if key is not a set or hash
+// -1 if the field does not have associated TTL on it, and -3 if field is not found.
+void GenericFamily::FieldTtl(CmdArgList args, ConnectionContext* cntx) {
+  string_view key = ArgS(args, 0);
+  string_view field = ArgS(args, 1);
+
+  auto cb = [&](Transaction* t, EngineShard* shard) { return OpFieldTtl(t, shard, key, field); };
+
+  OpResult<long> result = cntx->transaction->ScheduleSingleHopT(std::move(cb));
+
+  if (result) {
+    (*cntx)->SendLong(*result);
+    return;
+  }
+
+  (*cntx)->SendError(result.status());
+}
+
 void GenericFamily::Move(CmdArgList args, ConnectionContext* cntx) {
   string_view key = ArgS(args, 0);
   string_view target_db_sv = ArgS(args, 1);
@@ -1455,6 +1495,7 @@ constexpr uint32_t kSelect = FAST | CONNECTION;
 constexpr uint32_t kScan = KEYSPACE | READ | SLOW;
 constexpr uint32_t kTTL = KEYSPACE | READ | FAST;
 constexpr uint32_t kPTTL = KEYSPACE | READ | FAST;
+constexpr uint32_t kFieldTtl = KEYSPACE | READ | FAST;
 constexpr uint32_t kTime = FAST;
 constexpr uint32_t kType = KEYSPACE | READ | FAST;
 constexpr uint32_t kDump = KEYSPACE | READ | SLOW;
@@ -1495,6 +1536,7 @@ void GenericFamily::Register(CommandRegistry* registry) {
       << CI{"SCAN", CO::READONLY | CO::FAST | CO::LOADING, -2, 0, 0, 0, acl::kScan}.HFUNC(Scan)
       << CI{"TTL", CO::READONLY | CO::FAST, 2, 1, 1, 1, acl::kTTL}.HFUNC(Ttl)
       << CI{"PTTL", CO::READONLY | CO::FAST, 2, 1, 1, 1, acl::kPTTL}.HFUNC(Pttl)
+      << CI{"FIELDTTL", CO::READONLY | CO::FAST, 3, 1, 1, 1, acl::kFieldTtl}.HFUNC(FieldTtl)
       << CI{"TIME", CO::LOADING | CO::FAST, 1, 0, 0, 0, acl::kTime}.HFUNC(Time)
       << CI{"TYPE", CO::READONLY | CO::FAST | CO::LOADING, 2, 1, 1, 1, acl::kType}.HFUNC(Type)
       << CI{"DUMP", CO::READONLY, 2, 1, 1, 1, acl::kDump}.HFUNC(Dump)

src/server/generic_family.h

@@ -60,6 +60,7 @@ class GenericFamily {
   static void Type(CmdArgList args, ConnectionContext* cntx);
   static void Dump(CmdArgList args, ConnectionContext* cntx);
   static void Restore(CmdArgList args, ConnectionContext* cntx);
+  static void FieldTtl(CmdArgList args, ConnectionContext* cntx);
 
   static OpResult<void> RenameGeneric(CmdArgList args, bool skip_exist_dest,
                                       ConnectionContext* cntx);

src/server/generic_family_test.cc

@@ -602,4 +602,21 @@ TEST_F(GenericFamilyTest, Info) {
   EXPECT_EQ(1, get_rdb_changes_since_last_save(resp.GetString()));
 }
 
+TEST_F(GenericFamilyTest, FieldTtl) {
+  TEST_current_time_ms = kMemberExpiryBase * 1000;  // to reset to test time.
+  EXPECT_THAT(Run({"saddex", "key", "1", "val1"}), IntArg(1));
+  EXPECT_THAT(Run({"saddex", "key", "2", "val2"}), IntArg(1));
+  EXPECT_EQ(-2, CheckedInt({"fieldttl", "nokey", "val1"}));  // key not found
+  EXPECT_EQ(-3, CheckedInt({"fieldttl", "key", "bar"}));     // field not found
+  EXPECT_EQ(1, CheckedInt({"fieldttl", "key", "val1"}));
+  EXPECT_EQ(2, CheckedInt({"fieldttl", "key", "val2"}));
+
+  AdvanceTime(1100);
+  EXPECT_EQ(-3, CheckedInt({"fieldttl", "key", "val1"}));
+  EXPECT_EQ(1, CheckedInt({"fieldttl", "key", "val2"}));
+
+  Run({"set", "str", "val"});
+  EXPECT_THAT(Run({"fieldttl", "str", "bar"}), ErrArg("wrong"));
+}
+
 }  // namespace dfly

src/server/set_family.cc

@@ -305,6 +305,31 @@ bool IsInSet(const DbContext& db_context, const SetType& st, string_view member)
   }
 }
 
+// returns -3 if member is not found, -1 if no ttl is associated with this member.
+int32_t GetExpiry(const DbContext& db_context, const SetType& st, string_view member) {
+  if (st.second == kEncodingIntSet) {
+    long long llval;
+    if (!string2ll(member.data(), member.size(), &llval))
+      return -3;
+
+    return -1;
+  }
+
+  if (IsDenseEncoding(st)) {
+    StringSet* ss = (StringSet*)st.first;
+    ss->set_time(MemberTimeSeconds(db_context.time_now_ms));
+
+    auto it = ss->Find(member);
+    if (it == ss->end())
+      return -3;
+
+    return it.ExpiryTime();
+  } else {
+    // Old encoding, does not support expiry.
+    return -1;
+  }
+}
+
 void FindInSet(StringVec& memberships, const DbContext& db_context, const SetType& st,
                const vector<string_view>& members) {
   for (const auto& member : members) {
@@ -1494,9 +1519,9 @@ void SAddEx(CmdArgList args, ConnectionContext* cntx) {
     return (*cntx)->SendError(kInvalidIntErr);
   }
 
-  vector<string_view> vals(args.size() - 3);
-  for (size_t i = 3; i < args.size(); ++i) {
-    vals[i - 3] = ArgS(args, i);
+  vector<string_view> vals(args.size() - 2);
+  for (size_t i = 2; i < args.size(); ++i) {
+    vals[i - 2] = ArgS(args, i);
   }
 
   ArgSlice arg_slice{vals.data(), vals.size()};
@@ -1628,4 +1653,12 @@ void SetFamily::ConvertTo(const intset* src, dict* dest) {
   }
 }
 
+int32_t SetFamily::FieldExpireTime(const DbContext& db_context, const PrimeValue& pv,
+                                   std::string_view field) {
+  DCHECK_EQ(OBJ_SET, pv.ObjType());
+
+  SetType st{pv.RObjPtr(), pv.Encoding()};
+  return GetExpiry(db_context, st, field);
+}
+
 }  // namespace dfly

src/server/set_family.h

@@ -6,6 +6,7 @@
 
 #include "facade/op_status.h"
 #include "server/common.h"
+#include "server/table.h"
 
 typedef struct intset intset;
 typedef struct redisObject robj;
@@ -30,6 +31,11 @@ class SetFamily {
   // Returns true if succeeded, false on OOM.
   static bool ConvertToStrSet(const intset* is, size_t expected_len, robj* dest);
 
+  // returns expiry time in seconds since kMemberExpiryBase date.
+  // returns -3 if field was not found, -1 if no ttl is associated with the item.
+  static int32_t FieldExpireTime(const DbContext& db_context, const PrimeValue& pv,
+                                 std::string_view field);
+
  private:
 };