From 88334aa583f25a0f5a7d58ba0cb872e271738f47 Mon Sep 17 00:00:00 2001
From: thawk105 <thawk105@gmail.com>
Date: Thu, 14 May 2026 07:31:06 +0000
Subject: [PATCH] masstree: add remove_value_if_present() and use it in
 DELETE-commit paths (#59)

---
 cc/d2pl/transaction.cc      | 2 +-
 cc/mocc/transaction.cc      | 4 ++--
 cc/silo/transaction.cc      | 4 ++--
 cc/ss2pl/transaction.cc     | 2 +-
 cc/tictoc/transaction.cc    | 4 ++--
 include/masstree_wrapper.hh | 6 ++++++
 6 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/cc/d2pl/transaction.cc b/cc/d2pl/transaction.cc
index 16fee0fd..3b3fa371 100644
--- a/cc/d2pl/transaction.cc
+++ b/cc/d2pl/transaction.cc
@@ -85,7 +85,7 @@ bool TxExecutor::commit() {
       case OpType::DELETE: {
         // Return value intentionally ignored: a missing key still needs the
         // record put on the GC queue below.
-        (void)Masstrees[get_storage((*itr).storage_)].remove_value((*itr).key_);
+        Masstrees[get_storage((*itr).storage_)].remove_value_if_present((*itr).key_);
         // create information for garbage collection
         gc_records_.push_back((*itr).rcdptr_);
         break;
diff --git a/cc/mocc/transaction.cc b/cc/mocc/transaction.cc
index 17c82dc2..c5abdc38 100644
--- a/cc/mocc/transaction.cc
+++ b/cc/mocc/transaction.cc
@@ -958,7 +958,7 @@ void TxExecutor::abort() {
   // remove inserted records
   for (auto& we : write_set_) {
     if (we.op_ == OpType::INSERT) {
-      Masstrees[get_storage(we.storage_)].remove_value(we.key_);
+      Masstrees[get_storage(we.storage_)].remove_value_if_present(we.key_);
       delete we.rcdptr_;
     }
   }
@@ -1047,7 +1047,7 @@ void TxExecutor::writePhase() {
         maxtid.absent = true;
         // Return value intentionally ignored: a missing key still needs the
         // record put on the GC queue below.
-        (void)Masstrees[get_storage((*itr).storage_)].remove_value((*itr).key_);
+        Masstrees[get_storage((*itr).storage_)].remove_value_if_present((*itr).key_);
         gc_records_.push_back((*itr).rcdptr_);
         break;
       }
diff --git a/cc/silo/transaction.cc b/cc/silo/transaction.cc
index 65bacf1e..2f83e216 100644
--- a/cc/silo/transaction.cc
+++ b/cc/silo/transaction.cc
@@ -27,7 +27,7 @@ void TxExecutor::abort() {
   // remove inserted records
   for (auto& we : write_set_) {
     if (we.op_ == OpType::INSERT) {
-      Masstrees[get_storage(we.storage_)].remove_value(we.key_);
+      Masstrees[get_storage(we.storage_)].remove_value_if_present(we.key_);
       delete we.rcdptr_;
     }
   }
@@ -554,7 +554,7 @@ void TxExecutor::writePhase() {
         maxtid.absent = true;
         // Return value intentionally ignored: a missing key still needs the
         // tid bump and gc_records_ push below.
-        (void)Masstrees[get_storage((*itr).storage_)].remove_value((*itr).key_);
+        Masstrees[get_storage((*itr).storage_)].remove_value_if_present((*itr).key_);
         storeRelease((*itr).rcdptr_->tidword_.obj_, maxtid.obj_);
         // create information for garbage collection
         gc_records_.push_back((*itr).rcdptr_);
diff --git a/cc/ss2pl/transaction.cc b/cc/ss2pl/transaction.cc
index 0b33388f..5c05fe3d 100644
--- a/cc/ss2pl/transaction.cc
+++ b/cc/ss2pl/transaction.cc
@@ -85,7 +85,7 @@ bool TxExecutor::commit() {
       case OpType::DELETE: {
         // Return value intentionally ignored: a missing key still needs the
         // record put on the GC queue below.
-        (void)Masstrees[get_storage((*itr).storage_)].remove_value((*itr).key_);
+        Masstrees[get_storage((*itr).storage_)].remove_value_if_present((*itr).key_);
         // create information for garbage collection
         gc_records_.push_back((*itr).rcdptr_);
         break;
diff --git a/cc/tictoc/transaction.cc b/cc/tictoc/transaction.cc
index f2a76419..c0460e7f 100644
--- a/cc/tictoc/transaction.cc
+++ b/cc/tictoc/transaction.cc
@@ -477,7 +477,7 @@ void TxExecutor::abort() {
   // remove inserted records
   for (auto& we : write_set_) {
     if (we.op_ == OpType::INSERT) {
-      Masstrees[get_storage(we.storage_)].remove_value(we.key_);
+      Masstrees[get_storage(we.storage_)].remove_value_if_present(we.key_);
       delete we.rcdptr_;
     }
   }
@@ -526,7 +526,7 @@ void TxExecutor::writePhase() {
         result.absent = true;
         // Return value intentionally ignored: a missing key still needs the
         // record put on the GC queue below.
-        (void)Masstrees[get_storage((*itr).storage_)].remove_value((*itr).key_);
+        Masstrees[get_storage((*itr).storage_)].remove_value_if_present((*itr).key_);
         gc_records_.emplace_back((*itr).storage_, (*itr).key_, (*itr).rcdptr_, ThLocalEpoch[thid_].obj_);
         break;
       }
diff --git a/include/masstree_wrapper.hh b/include/masstree_wrapper.hh
index 2ff5680d..3384d00c 100644
--- a/include/masstree_wrapper.hh
+++ b/include/masstree_wrapper.hh
@@ -165,6 +165,12 @@ public:
     return Status::WARN_NOT_FOUND;
   }
 
+  // "delete if present" — discards "not found" since callers in the
+  // DELETE-commit path may race with concurrent deletions of the same key.
+  void remove_value_if_present(std::string_view key) {
+    (void) remove_value(key);
+  }
+
   T *get_value(std::string_view key) {
     unlocked_cursor_type lp(table_, key.data(), key.size());
     bool found = lp.find_unlocked(*ti);