From f3e7279c2c18b16e4059737470f60317fe74dde2 Mon Sep 17 00:00:00 2001
From: Andrew Noyes <andrew@weaselab.dev>
Date: Fri, 9 Feb 2024 13:08:14 -0800
Subject: [PATCH] Do less work

---
 ConflictSet.cpp | 33 ++++++++++-----------------------
 1 file changed, 10 insertions(+), 23 deletions(-)

diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index 61c7a24..049b95f 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -744,31 +744,11 @@ bool checkRangeRead(Node *n, const std::span<const uint8_t> begin,
   for (auto *iter = right.n; iter != nullptr; iter = iter->parent) {
     rightPath.push_back(iter);
   }
-  std::reverse(leftPath.begin(), leftPath.end());
-  std::reverse(rightPath.begin(), rightPath.end());
-  Node *lca = n;
-  int longestCommonPrefixSize = 0;
-  for (int i = 0, end = std::min<int>(leftPath.size(), rightPath.size());
-       i < end; ++i, ++longestCommonPrefixSize) {
-    if (leftPath[i] != rightPath[i]) {
-      break;
-    }
-    lca = leftPath[i];
-  }
-  auto border = vector<Node *>(arena);
-  for (int i = longestCommonPrefixSize; i < int(leftPath.size()); ++i) {
-    border.push_back(leftPath[i]);
-  }
-  for (int i = longestCommonPrefixSize; i < int(rightPath.size()); ++i) {
-    border.push_back(rightPath[i]);
-  }
-
 #if DEBUG_VERBOSE && !defined(NDEBUG)
   fprintf(stderr, "firstGeq for `%s' got `%s'\n", printable(begin).c_str(),
           getSearchPath(left.n).c_str());
   fprintf(stderr, "firstGeq for `%s' got `%s'\n", printable(end).c_str(),
           getSearchPath(right.n).c_str());
-  fprintf(stderr, "lca `%s'\n", getSearchPath(lca).c_str());
 #endif
 
   if (left.n != nullptr && left.cmp != 0 &&
@@ -783,15 +763,22 @@ bool checkRangeRead(Node *n, const std::span<const uint8_t> begin,
     return false;
   }
 
-  // TODO make it sublinear
+  // TODO better data structure for pointer set. Also collect during first
+  // traversal.
   for (auto *iter = nextPhysical(left.n); iter != right.n;) {
-    assert(iter != lca);
-    if (std::find(border.begin(), border.end(), iter) == border.end()) {
+    const bool onLeftPath =
+        std::find(leftPath.begin(), leftPath.end(), iter) != leftPath.end();
+    const bool onRightPath =
+        std::find(rightPath.begin(), rightPath.end(), iter) != rightPath.end();
+    if (!onLeftPath && !onRightPath) {
       if (iter->maxVersion > readVersion) {
         return false;
       }
       iter = nextPhysicalSkipSubtree(iter);
     } else {
+      if (onRightPath && iter->maxVersion <= readVersion) {
+        return true;
+      }
       if (iter->entryPresent &&
           std::max(iter->entry.pointVersion, iter->entry.rangeVersion) >
               readVersion) {