weaselab/conflict-set
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Add version window constants

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Andrew Noyes
2024-07-02 12:45:35 -07:00
parent 0be97a34b6
commit a04e81b3ff
1 changed files with 9 additions and 3 deletions
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12
ConflictSet.cpp
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@@ -78,13 +78,18 @@ constexpr void removeKey(struct Node *) {}
// ==================== BEGIN IMPLEMENTATION ==================== // ==================== BEGIN IMPLEMENTATION ====================
constexpr int64_t kNominalVersionWindow = 2e9;
constexpr int64_t kMaxCorrectVersionWindow =
std::numeric_limits<int32_t>::max();
static_assert(kNominalVersionWindow <= kMaxCorrectVersionWindow);
struct InternalVersionT { struct InternalVersionT {
constexpr InternalVersionT() = default; constexpr InternalVersionT() = default;
constexpr explicit InternalVersionT(int64_t value) : value(value) {} constexpr explicit InternalVersionT(int64_t value) : value(value) {}
constexpr int64_t toInt64() const { return value; } // GCOVR_EXCL_LINE constexpr int64_t toInt64() const { return value; } // GCOVR_EXCL_LINE
constexpr auto operator<=>(const InternalVersionT &rhs) const { constexpr auto operator<=>(const InternalVersionT &rhs) const {
// Maintains ordering after overflow, as long as the full-precision versions // Maintains ordering after overflow, as long as the full-precision versions
// are within ~2e9 of eachother. // are within `kMaxCorrectVersionWindow` of eachother.
return int32_t(value - rhs.value) <=> 0; return int32_t(value - rhs.value) <=> 0;
} }
constexpr bool operator==(const InternalVersionT &) const = default; constexpr bool operator==(const InternalVersionT &) const = default;
@@ -2834,7 +2839,8 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
auto end = std::span<const uint8_t>(r.end.p, r.end.len); auto end = std::span<const uint8_t>(r.end.p, r.end.len);
result[i] = result[i] =
InternalVersionT(reads[i].readVersion) < oldestVersion || InternalVersionT(reads[i].readVersion) < oldestVersion ||
reads[i].readVersion < newestVersionFullPrecision - 2e9 reads[i].readVersion <
newestVersionFullPrecision - kNominalVersionWindow
? TooOld ? TooOld
: (end.size() > 0 : (end.size() > 0
? checkRangeRead(root, begin, end, ? checkRangeRead(root, begin, end,
@@ -2950,7 +2956,7 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
InternalVersionT oldestVersion; InternalVersionT oldestVersion;
// TODO this doesn't fully mitigate the 32-bit precision issue, since we still // 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 // need to make sure we clean up versions in the tree before they fall out of
// the 2e9 window. // the `kMaxCorrectVersionWindow` window.
int64_t oldestVersionFullPrecision; int64_t oldestVersionFullPrecision;
int64_t newestVersionFullPrecision; int64_t newestVersionFullPrecision;
int64_t totalBytes = 0; int64_t totalBytes = 0;