Allow write version to jump by more than 2e9

ConflictSet.cpp

@@ -2892,8 +2892,10 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
   void addWrites(const WriteRange *writes, int count, int64_t writeVersion) {
     assert(writeVersion >= newestVersionFullPrecision);
 
-    // TODO allow this condition
-    assert(writeVersion < newestVersionFullPrecision + kNominalVersionWindow);
+    if (writeVersion > newestVersionFullPrecision + kNominalVersionWindow) {
+      destroyTree(root);
+      init(writeVersion - kNominalVersionWindow);
+    }
 
     newestVersionFullPrecision = writeVersion;
     setOldestVersion(
@@ -2985,14 +2987,18 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
     keyUpdates = gcScanStep(keyUpdates);
   }
 
-  explicit Impl(int64_t oldestVersion)
-      : oldestVersion(oldestVersion), oldestVersionFullPrecision(oldestVersion),
-        oldestExtantVersion(oldestVersion),
-        oldestVersionAtGcBegin(oldestVersion),
-        newestVersionFullPrecision(oldestVersion) {
-#if DEBUG_VERBOSE
-    fprintf(stderr, "radix_tree: create\n");
-#endif
+  int64_t getBytes() const { return totalBytes; }
+
+  void init(int64_t oldestVersion) {
+    this->oldestVersion = InternalVersionT(oldestVersion);
+    oldestVersionFullPrecision = oldestExtantVersion = oldestVersionAtGcBegin =
+        newestVersionFullPrecision = oldestVersion;
+
+    allocators = {};
+
+    removalKeyArena = Arena{};
+    removalKey = {};
+    keyUpdates = 10;
 
     // Insert ""
     root = allocators.node0.allocate(0);
@@ -3009,26 +3015,22 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
     root->entry.rangeVersion = this->oldestVersion;
 
     InternalVersionT::zero = this->oldestVersion;
+
+    // Intentionally not resetting totalBytes
   }
-  ~Impl() {
-#if DEBUG_VERBOSE
-    fprintf(stderr, "radix_tree: destroy\n");
-#endif
-    destroyTree(root);
-  }
+
+  explicit Impl(int64_t oldestVersion) { init(oldestVersion); }
+  ~Impl() { destroyTree(root); }
 
   NodeAllocators allocators;
 
   Arena removalKeyArena;
   std::span<const uint8_t> removalKey;
-  int64_t keyUpdates = 10;
+  int64_t keyUpdates;
 
   Node *root;
   InternalVersionT rootMaxVersion;
   InternalVersionT oldestVersion;
-  // TODO this doesn't fully mitigate the 32-bit precision issue, since we still
-  // need to make sure we clean up versions in the tree before they fall out of
-  // the `kMaxCorrectVersionWindow` window.
   int64_t oldestVersionFullPrecision;
   int64_t oldestExtantVersion;
   int64_t oldestVersionAtGcBegin;
@@ -3163,7 +3165,7 @@ void internal_destroy(ConflictSet::Impl *impl) {
   safe_free(impl, sizeof(ConflictSet::Impl));
 }
 
-int64_t internal_getBytes(ConflictSet::Impl *impl) { return impl->totalBytes; }
+int64_t internal_getBytes(ConflictSet::Impl *impl) { return impl->getBytes(); }
 
 // ==================== END IMPLEMENTATION ====================
 

Internal.h

@@ -598,6 +598,7 @@ template <class ConflictSetImpl> struct TestDriver {
   // Call until it returns true, for "done". Check internal invariants etc
   // between calls to next.
   bool next() {
+    assert(cs.getBytes() >= 0);
     if (!arbitrary.hasEntropy()) {
       return true;
     }
@@ -605,7 +606,9 @@ template <class ConflictSetImpl> struct TestDriver {
     {
       int numPointWrites = arbitrary.bounded(100);
       int numRangeWrites = arbitrary.bounded(100);
-      int64_t v = (writeVersion += arbitrary.bounded(2e9));
+      int64_t v =
+          (writeVersion += arbitrary.bounded(10) == 0 ? arbitrary.bounded(10)
+                                                      : arbitrary.next());
       auto *writes =
           new (arena) ConflictSet::WriteRange[numPointWrites + numRangeWrites];
       auto keys = set<std::string_view>(arena);

test_conflict_set.py

@@ -84,6 +84,14 @@ def test_two_billion_versions():
         cs.check(read(1, b"\x00", b"\xff"))
 
 
+def test_positive_bytes():
+    with DebugConflictSet() as cs:
+        cs.addWrites(1, write(b"hello"))
+        assert cs.getBytes() > 0
+        cs.addWrites(1 + 2**32)
+        assert cs.getBytes() > 0
+
+
 def test_decrease_capacity():
     # make a Node48, then a Node256
     for count in (17, 49):