Add ConflictSet.h

ConflictSet.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <stdint.h>
+
+struct ConflictSet {
+  enum Result {
+    /// The result of a check which does not intersect any conflicting writes
+    Commit,
+    /// The result of a check which intersects a write at a version >
+    /// readVersion
+    Conflict,
+    /// The result of a check with a readVersion older than the highest call to
+    /// `setOldestVersion`
+    TooOld,
+  };
+  /// Bytes ordered lexicographically
+  struct Key {
+    const uint8_t *p;
+    int len;
+  };
+  /// Denotes a set of keys to be checked for conflicts
+  struct ReadRange {
+    Key begin;
+    /// `end` having length 0 denotes that this range is the single key {begin}.
+    /// Otherwise this denotes the range [begin, end)
+    Key end;
+    int64_t readVersion;
+  };
+  /// Denotes a set of keys to be considered written at `writeVersion`
+  struct WriteRange {
+    Key begin;
+    /// `end` having length 0 denotes that this range is the single key {begin}.
+    /// Otherwise this denotes the range [begin, end)
+    Key end;
+    int64_t writeVersion;
+  };
+  /// `reads` must be sorted ascending, and must not have adjacent or
+  /// overlapping ranges. The result of checking reads[i] is written in
+  /// results[i].
+  void check(const ReadRange *reads, Result *results, int count) const;
+  /// `writes` must be sorted ascending, and must not have adjacent or
+  /// overlapping ranges. Reads intersecting writes where readVersion <
+  /// writeVersion will result in `Conflict` (or `TooOld`, eventually)
+  void addWrites(const WriteRange *writes, int count);
+  /// Reads where readVersion < oldestVersion will result in `TooOld`
+  void setOldestVersion(int64_t oldestVersion);
+
+  /// Reads where readVersion < oldestVersion will result in `TooOld`. There are
+  /// no writes initially.
+  explicit ConflictSet(int64_t oldestVersion);
+  ~ConflictSet();
+
+  ConflictSet(ConflictSet &&) noexcept;
+  ConflictSet &operator=(ConflictSet &&) noexcept;
+  ConflictSet(const ConflictSet &) = delete;
+  ConflictSet &operator=(const ConflictSet &) = delete;
+
+private:
+  struct Impl *impl;
+};