From 8a4b370e2ac86e050f97982b1d14c36337325915 Mon Sep 17 00:00:00 2001
From: Andrew Noyes <andrew@weaselab.dev>
Date: Wed, 4 Sep 2024 12:04:58 -0700
Subject: [PATCH] Make CheckRange{Left,Right}Side into normal functions, WIP

---
 ConflictSet.cpp | 152 +++++++++++++++++++++---------------------------
 1 file changed, 67 insertions(+), 85 deletions(-)

diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index 7e35b57..5a5ff20 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -2532,58 +2532,29 @@ struct CheckRangeLeftSide {
   bool ok;
 
   bool step() {
-    if (remaining.size() == 0) {
-      assert(searchPathLen >= prefixLen);
-      ok = maxVersion(n) <= readVersion;
-      return true;
-    }
-
-    if (searchPathLen >= prefixLen) {
-      if (!checkMaxBetweenExclusive(n, remaining[0], 256, readVersion, tls)) {
-        ok = false;
-        return true;
-      }
-    }
-
-    auto [child, maxV] = getChildAndMaxVersion(n, remaining[0]);
-    if (child == nullptr) {
-      auto c = getChildGeq(n, remaining[0]);
-      if (c != nullptr) {
-        if (searchPathLen < prefixLen) {
-          n = c;
-          return downLeftSpine();
-        }
-        n = c;
+    for (;; ++tls->range_read_iterations_accum) {
+      if (remaining.size() == 0) {
+        assert(searchPathLen >= prefixLen);
         ok = maxVersion(n) <= readVersion;
         return true;
-      } else {
-        n = nextSibling(n);
-        if (n == nullptr) {
-          ok = true;
+      }
+
+      if (searchPathLen >= prefixLen) {
+        if (!checkMaxBetweenExclusive(n, remaining[0], 256, readVersion, tls)) {
+          ok = false;
           return true;
         }
-        return downLeftSpine();
       }
-    }
 
-    n = child;
-    remaining = remaining.subspan(1, remaining.size() - 1);
-    ++searchPathLen;
-
-    if (n->partialKeyLen > 0) {
-      int commonLen = std::min<int>(n->partialKeyLen, remaining.size());
-      int i = longestCommonPrefix(n->partialKey(), remaining.data(), commonLen);
-      searchPathLen += i;
-      if (i < commonLen) {
-        auto c = n->partialKey()[i] <=> remaining[i];
-        if (c > 0) {
+      auto [child, maxV] = getChildAndMaxVersion(n, remaining[0]);
+      if (child == nullptr) {
+        auto c = getChildGeq(n, remaining[0]);
+        if (c != nullptr) {
           if (searchPathLen < prefixLen) {
-            return downLeftSpine();
-          }
-          if (n->entryPresent && n->entry.rangeVersion > readVersion) {
-            ok = false;
-            return true;
+            n = c;
+            goto downLeftSpine;
           }
+          n = c;
           ok = maxVersion(n) <= readVersion;
           return true;
         } else {
@@ -2592,30 +2563,60 @@ struct CheckRangeLeftSide {
             ok = true;
             return true;
           }
-          return downLeftSpine();
+          goto downLeftSpine;
         }
       }
-      if (commonLen == n->partialKeyLen) {
-        // partial key matches
-        remaining = remaining.subspan(commonLen, remaining.size() - commonLen);
-      } else if (n->partialKeyLen > int(remaining.size())) {
-        assert(searchPathLen >= prefixLen);
-        if (n->entryPresent && n->entry.rangeVersion > readVersion) {
-          ok = false;
+
+      n = child;
+      remaining = remaining.subspan(1, remaining.size() - 1);
+      ++searchPathLen;
+
+      if (n->partialKeyLen > 0) {
+        int commonLen = std::min<int>(n->partialKeyLen, remaining.size());
+        int i =
+            longestCommonPrefix(n->partialKey(), remaining.data(), commonLen);
+        searchPathLen += i;
+        if (i < commonLen) {
+          auto c = n->partialKey()[i] <=> remaining[i];
+          if (c > 0) {
+            if (searchPathLen < prefixLen) {
+              goto downLeftSpine;
+            }
+            if (n->entryPresent && n->entry.rangeVersion > readVersion) {
+              ok = false;
+              return true;
+            }
+            ok = maxVersion(n) <= readVersion;
+            return true;
+          } else {
+            n = nextSibling(n);
+            if (n == nullptr) {
+              ok = true;
+              return true;
+            }
+            goto downLeftSpine;
+          }
+        }
+        if (commonLen == n->partialKeyLen) {
+          // partial key matches
+          remaining =
+              remaining.subspan(commonLen, remaining.size() - commonLen);
+        } else if (n->partialKeyLen > int(remaining.size())) {
+          assert(searchPathLen >= prefixLen);
+          if (n->entryPresent && n->entry.rangeVersion > readVersion) {
+            ok = false;
+            return true;
+          }
+          ok = maxVersion(n) <= readVersion;
           return true;
         }
-        ok = maxVersion(n) <= readVersion;
+      }
+      if (maxV <= readVersion) {
+        ok = true;
         return true;
       }
     }
-    if (maxV <= readVersion) {
-      ok = true;
-      return true;
-    }
-    return false;
-  }
-
-  bool downLeftSpine() {
+  downLeftSpine:
     for (; !n->entryPresent; n = getFirstChildExists(n)) {
     }
     ok = n->entry.rangeVersion <= readVersion;
@@ -2817,7 +2818,7 @@ bool checkRangeRead(Node *n, std::span<const uint8_t> begin,
 
   if (lcp == int(begin.size())) {
     CheckRangeRightSide checkRangeRightSide{n, end, lcp, readVersion, tls};
-    while (!checkRangeRightSide.step())
+    for (; !checkRangeRightSide.step(); ++tls->range_read_iterations_accum)
       ;
     return checkRangeRightSide.ok;
   }
@@ -2831,30 +2832,11 @@ bool checkRangeRead(Node *n, std::span<const uint8_t> begin,
   // were false, then we would have returned above since lcp == begin.size().
   assert(!(n->parent == nullptr && begin.size() == 0));
   CheckRangeLeftSide checkRangeLeftSide{n, begin, lcp + 1, readVersion, tls};
+  for (; !checkRangeLeftSide.step(); ++tls->range_read_iterations_accum)
+    ;
   CheckRangeRightSide checkRangeRightSide{n, end, lcp + 1, readVersion, tls};
-
-  for (;;) {
-    bool leftDone = checkRangeLeftSide.step();
-    bool rightDone = checkRangeRightSide.step();
-    if (!leftDone && !rightDone) {
-      tls->range_read_iterations_accum += 2;
-      continue;
-    }
-    if (leftDone && rightDone) {
-      break;
-    } else if (leftDone) {
-      while (!checkRangeRightSide.step()) {
-        ++tls->range_read_iterations_accum;
-      }
-      break;
-    } else {
-      assert(rightDone);
-      while (!checkRangeLeftSide.step()) {
-        ++tls->range_read_iterations_accum;
-      }
-    }
-    break;
-  }
+  for (; !checkRangeRightSide.step(); ++tls->range_read_iterations_accum)
+    ;
 
   return checkRangeLeftSide.ok && checkRangeRightSide.ok;
 }