1 files changed, 197 insertions, 0 deletions
diff --git a/src/rocksdb/util/dynamic_bloom.h b/src/rocksdb/util/dynamic_bloom.h
new file mode 100644
index 00000000..654bc9ad
--- /dev/null
+++ b/src/rocksdb/util/dynamic_bloom.h
@@ -0,0 +1,197 @@
+// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <string>
+
+#include "rocksdb/slice.h"
+
+#include "port/port.h"
+#include "util/hash.h"
+
+#include <atomic>
+#include <memory>
+
+namespace rocksdb {
+
+class Slice;
+class Allocator;
+class Logger;
+
+class DynamicBloom {
+ public:
+  // allocator: pass allocator to bloom filter, hence trace the usage of memory
+  // total_bits: fixed total bits for the bloom
+  // num_probes: number of hash probes for a single key
+  // locality:  If positive, optimize for cache line locality, 0 otherwise.
+  // hash_func:  customized hash function
+  // huge_page_tlb_size:  if >0, try to allocate bloom bytes from huge page TLB
+  //                      within this page size. Need to reserve huge pages for
+  //                      it to be allocated, like:
+  //                         sysctl -w vm.nr_hugepages=20
+  //                     See linux doc Documentation/vm/hugetlbpage.txt
+  explicit DynamicBloom(Allocator* allocator,
+                        uint32_t total_bits, uint32_t locality = 0,
+                        uint32_t num_probes = 6,
+                        size_t huge_page_tlb_size = 0,
+                        Logger* logger = nullptr);
+
+  explicit DynamicBloom(uint32_t num_probes = 6);
+
+  void SetTotalBits(Allocator* allocator, uint32_t total_bits,
+                    uint32_t locality, size_t huge_page_tlb_size,
+                    Logger* logger);
+
+  ~DynamicBloom() {}
+
+  // Assuming single threaded access to this function.
+  void Add(const Slice& key);
+
+  // Like Add, but may be called concurrent with other functions.
+  void AddConcurrently(const Slice& key);
+
+  // Assuming single threaded access to this function.
+  void AddHash(uint32_t hash);
+
+  // Like AddHash, but may be called concurrent with other functions.
+  void AddHashConcurrently(uint32_t hash);
+
+  // Multithreaded access to this function is OK
+  bool MayContain(const Slice& key) const;
+
+  // Multithreaded access to this function is OK
+  bool MayContainHash(uint32_t hash) const;
+
+  void Prefetch(uint32_t h);
+
+  uint32_t GetNumBlocks() const { return kNumBlocks; }
+
+  Slice GetRawData() const {
+    return Slice(reinterpret_cast<char*>(data_), GetTotalBits() / 8);
+  }
+
+  void SetRawData(unsigned char* raw_data, uint32_t total_bits,
+                  uint32_t num_blocks = 0);
+
+  uint32_t GetTotalBits() const { return kTotalBits; }
+
+  bool IsInitialized() const { return kNumBlocks > 0 || kTotalBits > 0; }
+
+ private:
+  uint32_t kTotalBits;
+  uint32_t kNumBlocks;
+  const uint32_t kNumProbes;
+
+  std::atomic<uint8_t>* data_;
+
+  // or_func(ptr, mask) should effect *ptr |= mask with the appropriate
+  // concurrency safety, working with bytes.
+  template <typename OrFunc>
+  void AddHash(uint32_t hash, const OrFunc& or_func);
+};
+
+inline void DynamicBloom::Add(const Slice& key) { AddHash(BloomHash(key)); }
+
+inline void DynamicBloom::AddConcurrently(const Slice& key) {
+  AddHashConcurrently(BloomHash(key));
+}
+
+inline void DynamicBloom::AddHash(uint32_t hash) {
+  AddHash(hash, [](std::atomic<uint8_t>* ptr, uint8_t mask) {
+    ptr->store(ptr->load(std::memory_order_relaxed) | mask,
+               std::memory_order_relaxed);
+  });
+}
+
+inline void DynamicBloom::AddHashConcurrently(uint32_t hash) {
+  AddHash(hash, [](std::atomic<uint8_t>* ptr, uint8_t mask) {
+    // Happens-before between AddHash and MaybeContains is handled by
+    // access to versions_->LastSequence(), so all we have to do here is
+    // avoid races (so we don't give the compiler a license to mess up
+    // our code) and not lose bits.  std::memory_order_relaxed is enough
+    // for that.
+    if ((mask & ptr->load(std::memory_order_relaxed)) != mask) {
+      ptr->fetch_or(mask, std::memory_order_relaxed);
+    }
+  });
+}
+
+inline bool DynamicBloom::MayContain(const Slice& key) const {
+  return (MayContainHash(BloomHash(key)));
+}
+
+#if defined(_MSC_VER)
+#pragma warning(push)
+// local variable is initialized but not referenced
+#pragma warning(disable : 4189) 
+#endif
+inline void DynamicBloom::Prefetch(uint32_t h) {
+  if (kNumBlocks != 0) {
+    uint32_t b = ((h >> 11 | (h << 21)) % kNumBlocks) * (CACHE_LINE_SIZE * 8);
+    PREFETCH(&(data_[b / 8]), 0, 3);
+  }
+}
+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+
+inline bool DynamicBloom::MayContainHash(uint32_t h) const {
+  assert(IsInitialized());
+  const uint32_t delta = (h >> 17) | (h << 15);  // Rotate right 17 bits
+  if (kNumBlocks != 0) {
+    uint32_t b = ((h >> 11 | (h << 21)) % kNumBlocks) * (CACHE_LINE_SIZE * 8);
+    for (uint32_t i = 0; i < kNumProbes; ++i) {
+      // Since CACHE_LINE_SIZE is defined as 2^n, this line will be optimized
+      //  to a simple and operation by compiler.
+      const uint32_t bitpos = b + (h % (CACHE_LINE_SIZE * 8));
+      uint8_t byteval = data_[bitpos / 8].load(std::memory_order_relaxed);
+      if ((byteval & (1 << (bitpos % 8))) == 0) {
+        return false;
+      }
+      // Rotate h so that we don't reuse the same bytes.
+      h = h / (CACHE_LINE_SIZE * 8) +
+          (h % (CACHE_LINE_SIZE * 8)) * (0x20000000U / CACHE_LINE_SIZE);
+      h += delta;
+    }
+  } else {
+    for (uint32_t i = 0; i < kNumProbes; ++i) {
+      const uint32_t bitpos = h % kTotalBits;
+      uint8_t byteval = data_[bitpos / 8].load(std::memory_order_relaxed);
+      if ((byteval & (1 << (bitpos % 8))) == 0) {
+        return false;
+      }
+      h += delta;
+    }
+  }
+  return true;
+}
+
+template <typename OrFunc>
+inline void DynamicBloom::AddHash(uint32_t h, const OrFunc& or_func) {
+  assert(IsInitialized());
+  const uint32_t delta = (h >> 17) | (h << 15);  // Rotate right 17 bits
+  if (kNumBlocks != 0) {
+    uint32_t b = ((h >> 11 | (h << 21)) % kNumBlocks) * (CACHE_LINE_SIZE * 8);
+    for (uint32_t i = 0; i < kNumProbes; ++i) {
+      // Since CACHE_LINE_SIZE is defined as 2^n, this line will be optimized
+      // to a simple and operation by compiler.
+      const uint32_t bitpos = b + (h % (CACHE_LINE_SIZE * 8));
+      or_func(&data_[bitpos / 8], (1 << (bitpos % 8)));
+      // Rotate h so that we don't reuse the same bytes.
+      h = h / (CACHE_LINE_SIZE * 8) +
+          (h % (CACHE_LINE_SIZE * 8)) * (0x20000000U / CACHE_LINE_SIZE);
+      h += delta;
+    }
+  } else {
+    for (uint32_t i = 0; i < kNumProbes; ++i) {
+      const uint32_t bitpos = h % kTotalBits;
+      or_func(&data_[bitpos / 8], (1 << (bitpos % 8)));
+      h += delta;
+    }
+  }
+}
+
+}  // rocksdb