Try specifying filter multiple times

150% pessimized the "real data" benchmark

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.18)
 project(
   conflict-set
-  VERSION 0.0.10
+  VERSION 0.0.12
   DESCRIPTION
     "A data structure for optimistic concurrency control on ranges of bitwise-lexicographically-ordered keys."
   HOMEPAGE_URL "https://git.weaselab.dev/weaselab/conflict-set"
@@ -31,14 +31,12 @@ if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
                                                "MinSizeRel" "RelWithDebInfo")
 endif()
 
-add_compile_options(
-  -fdata-sections
-  -ffunction-sections
-  -Wswitch-enum
-  -Werror=switch-enum
-  -fPIC
-  -g
-  -fno-omit-frame-pointer)
+add_compile_options(-fdata-sections -ffunction-sections -Wswitch-enum
+                    -Werror=switch-enum -fPIC)
+if(NOT APPLE)
+  # This causes some versions of clang to crash on macos
+  add_compile_options(-g -fno-omit-frame-pointer)
+endif()
 
 set(full_relro_flags "-pie;LINKER:-z,relro,-z,now,-z,noexecstack")
 cmake_push_check_state()

ConflictSet.cpp

@@ -16,12 +16,12 @@ limitations under the License.
 
 #include "ConflictSet.h"
 #include "Internal.h"
+#include "LongestCommonPrefix.h"
 
 #include <algorithm>
 #include <atomic>
 #include <bit>
 #include <cassert>
-#include <compare>
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
@@ -1687,167 +1687,6 @@ Node *nextSibling(Node *node) {
   }
 }
 
-#if defined(HAS_AVX) || defined(HAS_ARM_NEON)
-constexpr int kStride = 64;
-#else
-constexpr int kStride = 16;
-#endif
-
-constexpr int kUnrollFactor = 4;
-
-bool compareStride(const uint8_t *ap, const uint8_t *bp) {
-#if defined(HAS_ARM_NEON)
-  static_assert(kStride == 64);
-  uint8x16_t x[4]; // GCOVR_EXCL_LINE
-  for (int i = 0; i < 4; ++i) {
-    x[i] = vceqq_u8(vld1q_u8(ap + i * 16), vld1q_u8(bp + i * 16));
-  }
-  auto results = vreinterpretq_u16_u8(
-      vandq_u8(vandq_u8(x[0], x[1]), vandq_u8(x[2], x[3])));
-  bool eq = vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(results, 4)), 0) ==
-            uint64_t(-1);
-#elif defined(HAS_AVX)
-  static_assert(kStride == 64);
-  __m128i x[4]; // GCOVR_EXCL_LINE
-  for (int i = 0; i < 4; ++i) {
-    x[i] = _mm_cmpeq_epi8(_mm_loadu_si128((__m128i *)(ap + i * 16)),
-                          _mm_loadu_si128((__m128i *)(bp + i * 16)));
-  }
-  auto eq =
-      _mm_movemask_epi8(_mm_and_si128(_mm_and_si128(x[0], x[1]),
-                                      _mm_and_si128(x[2], x[3]))) == 0xffff;
-#else
-  // Hope it gets vectorized
-  auto eq = memcmp(ap, bp, kStride) == 0;
-#endif
-  return eq;
-}
-
-// Precondition: ap[:kStride] != bp[:kStride]
-int firstNeqStride(const uint8_t *ap, const uint8_t *bp) {
-#if defined(HAS_AVX)
-  static_assert(kStride == 64);
-  uint64_t c[kStride / 16]; // GCOVR_EXCL_LINE
-  for (int i = 0; i < kStride; i += 16) {
-    const auto a = _mm_loadu_si128((__m128i *)(ap + i));
-    const auto b = _mm_loadu_si128((__m128i *)(bp + i));
-    const auto compared = _mm_cmpeq_epi8(a, b);
-    c[i / 16] = _mm_movemask_epi8(compared) & 0xffff;
-  }
-  return std::countr_zero(~(c[0] | c[1] << 16 | c[2] << 32 | c[3] << 48));
-#elif defined(HAS_ARM_NEON)
-  static_assert(kStride == 64);
-  for (int i = 0; i < kStride; i += 16) {
-    // 0xff for each match
-    uint16x8_t results =
-        vreinterpretq_u16_u8(vceqq_u8(vld1q_u8(ap + i), vld1q_u8(bp + i)));
-    // 0xf for each mismatch
-    uint64_t bitfield =
-        ~vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(results, 4)), 0);
-    if (bitfield) {
-      return i + (std::countr_zero(bitfield) >> 2);
-    }
-  }
-  __builtin_unreachable(); // GCOVR_EXCL_LINE
-#else
-  int i = 0;
-  for (; i < kStride - 1; ++i) {
-    if (*ap++ != *bp++) {
-      break;
-    }
-  }
-  return i;
-#endif
-}
-
-// This gets covered in local development
-// GCOVR_EXCL_START
-#if defined(HAS_AVX) && !defined(__SANITIZE_THREAD__)
-__attribute__((target("avx512f,avx512bw"))) int
-longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
-  int i = 0;
-  int end = cl & ~63;
-  while (i < end) {
-    const uint64_t eq =
-        _mm512_cmpeq_epi8_mask(_mm512_loadu_epi8(ap), _mm512_loadu_epi8(bp));
-    if (eq != uint64_t(-1)) {
-      return i + std::countr_one(eq);
-    }
-    i += 64;
-    ap += 64;
-    bp += 64;
-  }
-  if (i < cl) {
-    const uint64_t mask = (uint64_t(1) << (cl - i)) - 1;
-    const uint64_t eq = _mm512_cmpeq_epi8_mask(
-        _mm512_maskz_loadu_epi8(mask, ap), _mm512_maskz_loadu_epi8(mask, bp));
-    return i + std::countr_one(eq & mask);
-  }
-  assert(i == cl);
-  return i;
-}
-__attribute__((target("default")))
-#endif
-// GCOVR_EXCL_STOP
-
-int longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
-  assume(cl >= 0);
-  int i = 0;
-  int end;
-
-  // kStride * kUnrollCount at a time
-  end = cl & ~(kStride * kUnrollFactor - 1);
-  while (i < end) {
-    for (int j = 0; j < kUnrollFactor; ++j) {
-      if (!compareStride(ap, bp)) {
-        return i + firstNeqStride(ap, bp);
-      }
-      i += kStride;
-      ap += kStride;
-      bp += kStride;
-    }
-  }
-
-  // kStride at a time
-  end = cl & ~(kStride - 1);
-  while (i < end) {
-    if (!compareStride(ap, bp)) {
-      return i + firstNeqStride(ap, bp);
-    }
-    i += kStride;
-    ap += kStride;
-    bp += kStride;
-  }
-
-  // word at a time
-  end = cl & ~(sizeof(uint64_t) - 1);
-  while (i < end) {
-    uint64_t a; // GCOVR_EXCL_LINE
-    uint64_t b; // GCOVR_EXCL_LINE
-    memcpy(&a, ap, 8);
-    memcpy(&b, bp, 8);
-    const auto mismatched = a ^ b;
-    if (mismatched) {
-      return i + std::countr_zero(mismatched) / 8;
-    }
-    i += 8;
-    ap += 8;
-    bp += 8;
-  }
-
-  // byte at a time
-  while (i < cl) {
-    if (*ap != *bp) {
-      break;
-    }
-    ++ap;
-    ++bp;
-    ++i;
-  }
-
-  return i;
-}
-
 // Logically this is the same as performing firstGeq and then checking against
 // point or range version according to cmp, but this version short circuits as
 // soon as it can prove that there's no conflict.
@@ -2922,25 +2761,22 @@ void consumePartialKey(Node *&self, std::span<const uint8_t> &key,
   key = key.subspan(partialKeyIndex, key.size() - partialKeyIndex);
 }
 
-// Returns a pointer to the newly inserted node.  Caller must set
-// `entryPresent`, and `entry` fields.  All nodes along the search path of the
-// result will have `maxVersion` set to `writeVersion` as a postcondition. Nodes
-// along the search path may be invalidated.
+// Returns a pointer the pointer to the newly inserted node in the tree.  Caller
+// must set `entryPresent`, and `entry` fields.  All nodes along the search path
+// of the result will have `maxVersion` set to `writeVersion` as a
+// postcondition. Nodes along the search path may be invalidated.
 [[nodiscard]]
-Node *insert(Node **self, std::span<const uint8_t> key,
-             InternalVersionT writeVersion, WriteContext *tls,
-             ConflictSet::Impl *impl) {
+Node **insert(Node **self, std::span<const uint8_t> key,
+              InternalVersionT writeVersion, WriteContext *tls,
+              ConflictSet::Impl *impl) {
 
-  if ((*self)->partialKeyLen > 0) {
-    consumePartialKey(*self, key, writeVersion, tls);
-  }
   assert(maxVersion(*self, impl) <= writeVersion);
   setMaxVersion(*self, impl, writeVersion);
 
   for (;; ++tls->accum.insert_iterations) {
 
     if (key.size() == 0) {
-      return *self;
+      return self;
     }
 
     auto &child = getOrCreateChild(*self, key.front(), writeVersion, tls);
@@ -2953,7 +2789,7 @@ Node *insert(Node **self, std::span<const uint8_t> key,
       child->parentsIndex = key.front();
       setMaxVersion(child, impl, writeVersion);
       memcpy(child->partialKey(), key.data() + 1, child->partialKeyLen);
-      return child;
+      return &child;
     }
 
     self = &child;
@@ -2996,7 +2832,7 @@ void addPointWrite(Node *&root, std::span<const uint8_t> key,
                    InternalVersionT writeVersion, WriteContext *tls,
                    ConflictSet::Impl *impl) {
   ++tls->accum.point_writes;
-  auto *n = insert(&root, key, writeVersion, tls, impl);
+  auto *n = *insert(&root, key, writeVersion, tls, impl);
   if (!n->entryPresent) {
     ++tls->accum.entries_inserted;
     auto *p = nextLogical(n);
@@ -3063,41 +2899,16 @@ void addWriteRange(Node *&root, std::span<const uint8_t> begin,
   }
   ++tls->accum.range_writes;
   const bool beginIsPrefix = lcp == int(begin.size());
-  auto remaining = begin.subspan(0, lcp);
 
-  auto *n = root;
+  Node **useAsRoot =
+      insert(&root, begin.subspan(0, lcp), writeVersion, tls, impl);
 
-  for (;;) {
-    if (int(remaining.size()) <= n->partialKeyLen) {
-      break;
-    }
-    int i = longestCommonPrefix(n->partialKey(), remaining.data(),
-                                n->partialKeyLen);
-    if (i != n->partialKeyLen) {
-      break;
-    }
-
-    auto *child = getChild(n, remaining[n->partialKeyLen]);
-    if (child == nullptr) {
-      break;
-    }
-
-    assert(maxVersion(n, impl) <= writeVersion);
-    setMaxVersion(n, impl, writeVersion);
-
-    remaining = remaining.subspan(n->partialKeyLen + 1,
-                                  remaining.size() - (n->partialKeyLen + 1));
-    n = child;
-  }
-
-  Node **useAsRoot = &getInTree(n, impl);
-
-  int consumed = lcp - remaining.size();
+  int consumed = lcp;
 
   begin = begin.subspan(consumed, begin.size() - consumed);
   end = end.subspan(consumed, end.size() - consumed);
 
-  auto *beginNode = insert(useAsRoot, begin, writeVersion, tls, impl);
+  auto *beginNode = *insert(useAsRoot, begin, writeVersion, tls, impl);
 
   const bool insertedBegin = !beginNode->entryPresent;
 
@@ -3114,7 +2925,7 @@ void addWriteRange(Node *&root, std::span<const uint8_t> begin,
   assert(writeVersion >= beginNode->entry.pointVersion);
   beginNode->entry.pointVersion = writeVersion;
 
-  auto *endNode = insert(useAsRoot, end, writeVersion, tls, impl);
+  auto *endNode = *insert(useAsRoot, end, writeVersion, tls, impl);
 
   const bool insertedEnd = !endNode->entryPresent;
 
@@ -3132,7 +2943,7 @@ void addWriteRange(Node *&root, std::span<const uint8_t> begin,
   if (beginIsPrefix && insertedEnd) {
     // beginNode may have been invalidated when inserting end. TODO can we do
     // better?
-    beginNode = insert(useAsRoot, begin, writeVersion, tls, impl);
+    beginNode = *insert(useAsRoot, begin, writeVersion, tls, impl);
     assert(beginNode->entryPresent);
   }
 
@@ -3246,6 +3057,8 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
     InternalVersionT::zero = tls.zero = oldestVersion;
 
     assert(writeVersion >= newestVersionFullPrecision);
+    assert(tls.accum.entries_erased == 0);
+    assert(tls.accum.entries_inserted == 0);
 
     if (oldestExtantVersion < writeVersion - kMaxCorrectVersionWindow)
         [[unlikely]] {
@@ -3273,15 +3086,19 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
       auto begin = std::span<const uint8_t>(w.begin.p, w.begin.len);
       auto end = std::span<const uint8_t>(w.end.p, w.end.len);
       if (w.end.len > 0) {
-        keyUpdates += 3;
         addWriteRange(root, begin, end, InternalVersionT(writeVersion), &tls,
                       this);
       } else {
-        keyUpdates += 2;
         addPointWrite(root, begin, InternalVersionT(writeVersion), &tls, this);
       }
     }
 
+    // Run gc at least 200% the rate we're inserting entries
+    keyUpdates +=
+        std::max<int64_t>(tls.accum.entries_inserted - tls.accum.entries_erased,
+                          0) *
+        2;
+
     memory_bytes.set(totalBytes);
     point_writes_total.add(tls.accum.point_writes);
     range_writes_total.add(tls.accum.range_writes);

Jenkinsfile

@@ -117,15 +117,18 @@ pipeline {
                 }
             }
             steps {
+                script {
+                    filter_args = "-f ConflictSet.cpp -f LongestCommonPrefix.h"
+                }
                 CleanBuildAndTest("-DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ -DCMAKE_C_FLAGS=--coverage -DCMAKE_CXX_FLAGS=--coverage -DCMAKE_BUILD_TYPE=Debug -DDISABLE_TSAN=ON")
-                sh '''
-                gcovr -f ConflictSet.cpp --cobertura > build/coverage.xml
-                '''
+                sh """
+                gcovr ${filter_args} --cobertura > build/coverage.xml
+                """
                 recordCoverage qualityGates: [[criticality: 'NOTE', metric: 'MODULE']], tools: [[parser: 'COBERTURA', pattern: 'build/coverage.xml']]
-                sh '''
-                gcovr -f ConflictSet.cpp
-                gcovr -f ConflictSet.cpp --fail-under-line 100 > /dev/null
-                '''
+                sh """
+                gcovr ${filter_args}
+                gcovr ${filter_args} --fail-under-line 100 > /dev/null
+                """
             }
         }
     }

LongestCommonPrefix.h

@@ -0,0 +1,177 @@
+#pragma once
+
+#include <assert.h>
+#include <bit>
+#include <stdint.h>
+#include <string.h>
+
+#ifdef HAS_AVX
+#include <immintrin.h>
+#elif HAS_ARM_NEON
+#include <arm_neon.h>
+#endif
+
+#if defined(HAS_AVX) || defined(HAS_ARM_NEON)
+constexpr int kStride = 64;
+#else
+constexpr int kStride = 16;
+#endif
+
+constexpr int kUnrollFactor = 4;
+
+inline bool compareStride(const uint8_t *ap, const uint8_t *bp) {
+#if defined(HAS_ARM_NEON)
+  static_assert(kStride == 64);
+  uint8x16_t x[4]; // GCOVR_EXCL_LINE
+  for (int i = 0; i < 4; ++i) {
+    x[i] = vceqq_u8(vld1q_u8(ap + i * 16), vld1q_u8(bp + i * 16));
+  }
+  auto results = vreinterpretq_u16_u8(
+      vandq_u8(vandq_u8(x[0], x[1]), vandq_u8(x[2], x[3])));
+  bool eq = vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(results, 4)), 0) ==
+            uint64_t(-1);
+#elif defined(HAS_AVX)
+  static_assert(kStride == 64);
+  __m128i x[4]; // GCOVR_EXCL_LINE
+  for (int i = 0; i < 4; ++i) {
+    x[i] = _mm_cmpeq_epi8(_mm_loadu_si128((__m128i *)(ap + i * 16)),
+                          _mm_loadu_si128((__m128i *)(bp + i * 16)));
+  }
+  auto eq =
+      _mm_movemask_epi8(_mm_and_si128(_mm_and_si128(x[0], x[1]),
+                                      _mm_and_si128(x[2], x[3]))) == 0xffff;
+#else
+  // Hope it gets vectorized
+  auto eq = memcmp(ap, bp, kStride) == 0;
+#endif
+  return eq;
+}
+
+// Precondition: ap[:kStride] != bp[:kStride]
+inline int firstNeqStride(const uint8_t *ap, const uint8_t *bp) {
+#if defined(HAS_AVX)
+  static_assert(kStride == 64);
+  uint64_t c[kStride / 16]; // GCOVR_EXCL_LINE
+  for (int i = 0; i < kStride; i += 16) {
+    const auto a = _mm_loadu_si128((__m128i *)(ap + i));
+    const auto b = _mm_loadu_si128((__m128i *)(bp + i));
+    const auto compared = _mm_cmpeq_epi8(a, b);
+    c[i / 16] = _mm_movemask_epi8(compared) & 0xffff;
+  }
+  return std::countr_zero(~(c[0] | c[1] << 16 | c[2] << 32 | c[3] << 48));
+#elif defined(HAS_ARM_NEON)
+  static_assert(kStride == 64);
+  for (int i = 0; i < kStride; i += 16) {
+    // 0xff for each match
+    uint16x8_t results =
+        vreinterpretq_u16_u8(vceqq_u8(vld1q_u8(ap + i), vld1q_u8(bp + i)));
+    // 0xf for each mismatch
+    uint64_t bitfield =
+        ~vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(results, 4)), 0);
+    if (bitfield) {
+      return i + (std::countr_zero(bitfield) >> 2);
+    }
+  }
+  __builtin_unreachable(); // GCOVR_EXCL_LINE
+#else
+  int i = 0;
+  for (; i < kStride - 1; ++i) {
+    if (*ap++ != *bp++) {
+      break;
+    }
+  }
+  return i;
+#endif
+}
+
+// This gets covered in local development
+// GCOVR_EXCL_START
+#if defined(HAS_AVX) && !defined(__SANITIZE_THREAD__)
+__attribute__((target("avx512f,avx512bw"))) inline int
+longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
+  int i = 0;
+  int end = cl & ~63;
+  while (i < end) {
+    const uint64_t eq =
+        _mm512_cmpeq_epi8_mask(_mm512_loadu_epi8(ap), _mm512_loadu_epi8(bp));
+    if (eq != uint64_t(-1)) {
+      return i + std::countr_one(eq);
+    }
+    i += 64;
+    ap += 64;
+    bp += 64;
+  }
+  if (i < cl) {
+    const uint64_t mask = (uint64_t(1) << (cl - i)) - 1;
+    const uint64_t eq = _mm512_cmpeq_epi8_mask(
+        _mm512_maskz_loadu_epi8(mask, ap), _mm512_maskz_loadu_epi8(mask, bp));
+    return i + std::countr_one(eq & mask);
+  }
+  assert(i == cl);
+  return i;
+}
+__attribute__((target("default")))
+#endif
+// GCOVR_EXCL_STOP
+
+inline int
+longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
+  if (!(cl >= 0)) {
+    __builtin_unreachable();
+  }
+
+  int i = 0;
+  int end;
+
+  // kStride * kUnrollCount at a time
+  end = cl & ~(kStride * kUnrollFactor - 1);
+  while (i < end) {
+    for (int j = 0; j < kUnrollFactor; ++j) {
+      if (!compareStride(ap, bp)) {
+        return i + firstNeqStride(ap, bp);
+      }
+      i += kStride;
+      ap += kStride;
+      bp += kStride;
+    }
+  }
+
+  // kStride at a time
+  end = cl & ~(kStride - 1);
+  while (i < end) {
+    if (!compareStride(ap, bp)) {
+      return i + firstNeqStride(ap, bp);
+    }
+    i += kStride;
+    ap += kStride;
+    bp += kStride;
+  }
+
+  // word at a time
+  end = cl & ~(sizeof(uint64_t) - 1);
+  while (i < end) {
+    uint64_t a; // GCOVR_EXCL_LINE
+    uint64_t b; // GCOVR_EXCL_LINE
+    memcpy(&a, ap, 8);
+    memcpy(&b, bp, 8);
+    const auto mismatched = a ^ b;
+    if (mismatched) {
+      return i + std::countr_zero(mismatched) / 8;
+    }
+    i += 8;
+    ap += 8;
+    bp += 8;
+  }
+
+  // byte at a time
+  while (i < cl) {
+    if (*ap != *bp) {
+      break;
+    }
+    ++ap;
+    ++bp;
+    ++i;
+  }
+
+  return i;
+}

ServerBench.cpp

@@ -76,6 +76,14 @@ void workload(weaselab::ConflictSet *cs) {
       } else {
         w.begin.len = k.size();
         cs->addWrites(&w, 1, version);
+        int64_t beginN = version - kWindowSize + rand() % kWindowSize;
+        auto b = numToKey(beginN);
+        auto e = numToKey(beginN + 1000);
+        w.begin.p = b.data();
+        w.begin.len = b.size();
+        w.end.p = e.data();
+        w.end.len = e.size();
+        cs->addWrites(&w, 1, version);
       }
     }
     // GC

corpus/2ae810daa467ba2bd354e835491a8b3026525764

@@ -0,0 +1 @@
+:<15><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>:::::