| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| |
| #ifndef IMPALA_UTIL_BITMAP_H |
| #define IMPALA_UTIL_BITMAP_H |
| |
| #include "util/bit-util.h" |
| #include "util/ubsan.h" |
| |
| namespace impala { |
| |
| /// Bitmap vector utility class. |
| /// TODO: investigate perf. |
| /// - Precomputed bitmap |
| /// - Explicit Set/Unset() apis |
| /// - Bigger words |
| /// - size bitmap to Mersenne prime. |
| class Bitmap { |
| public: |
| Bitmap(int64_t num_bits) { |
| DCHECK_GE(num_bits, 0); |
| buffer_.resize(BitUtil::RoundUpNumi64(num_bits)); |
| num_bits_ = num_bits; |
| } |
| |
| /// Resize bitmap and set all bits to zero. |
| void Reset(int64_t num_bits) { |
| DCHECK_GE(num_bits, 0); |
| buffer_.resize(BitUtil::RoundUpNumi64(num_bits)); |
| num_bits_ = num_bits; |
| SetAllBits(false); |
| } |
| |
| /// Compute memory usage of a bitmap, not including the Bitmap object itself. |
| static int64_t MemUsage(int64_t num_bits) { |
| DCHECK_GE(num_bits, 0); |
| return BitUtil::RoundUpNumi64(num_bits) * sizeof(int64_t); |
| } |
| |
| /// Compute memory usage of this bitmap, not including the Bitmap object itself. |
| int64_t MemUsage() const { return MemUsage(num_bits_); } |
| |
| /// Sets the bit at 'bit_index' to v. |
| void Set(int64_t bit_index, bool v) { |
| int64_t word_index = bit_index >> NUM_OFFSET_BITS; |
| bit_index &= BIT_INDEX_MASK; |
| DCHECK_LT(word_index, buffer_.size()); |
| if (v) { |
| buffer_[word_index] |= (1LL << bit_index); |
| } else { |
| buffer_[word_index] &= ~(1LL << bit_index); |
| } |
| } |
| |
| /// Returns true if the bit at 'bit_index' is set. |
| bool Get(int64_t bit_index) const { |
| int64_t word_index = bit_index >> NUM_OFFSET_BITS; |
| bit_index &= BIT_INDEX_MASK; |
| DCHECK_LT(word_index, buffer_.size()); |
| return (buffer_[word_index] & (1LL << bit_index)) != 0; |
| } |
| |
| void SetAllBits(bool b) { |
| Ubsan::MemSet(buffer_.data(), 255 * b, buffer_.size() * sizeof(uint64_t)); |
| } |
| |
| int64_t num_bits() const { return num_bits_; } |
| |
| /// If 'print_bits' prints 0/1 per bit, otherwise it prints the int64_t value. |
| std::string DebugString(bool print_bits) const; |
| |
| private: |
| std::vector<uint64_t> buffer_; |
| int64_t num_bits_; |
| |
| /// Used for bit shifting and masking for the word and offset calculation. |
| static const int64_t NUM_OFFSET_BITS = 6; |
| static const int64_t BIT_INDEX_MASK = 63; |
| }; |
| |
| } |
| |
| #endif |