File indexing completed on 2024-11-17 04:55:18

 /*
     SPDX-License-Identifier: MPL-2.0
 */
 
 /* Copyright (c) 2015 Brian R. Bondy. Distributed under the MPL2 license.
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // You should probably not be using this.  This is only useful in environments
 // without std lib and having specific serialization and memory requirements.
 // Instead consider using `hash_set` which is a more generic implementation
 // with templates.
 
 #ifndef HASH_SET_H_
 #define HASH_SET_H_
 
 #include <stdint.h>
 #include <math.h>
 #include <string.h>
 #include <stdio.h>
 #include <vector>
 
 #include "./base.h"
 #include "./hash_item.h"
 
 template<class T>
 class HashSet {
  public:
   typedef uint64_t (*HashSetFnPtr)(const T *hash_item);
 
   /**
    * @param bucket_count The number of buckets to create for the hash set
    * @param multi_set Allow multiple items with the same hash to be added.
    */
   explicit HashSet(uint32_t bucket_count, bool multi_set)
       : multi_set_(multi_set) {
     Init(bucket_count);
   }
 
   ~HashSet() {
     Cleanup();
   }
 
   /**
    * Adds the specified data if it doesn't exist
    * A copy of the data will be created, so the memory used to do the add
    * doesn't need to stick around.
    *
    * @param item_to_add The node to add
    * @param update_if_exists true if the item should be updated if it is already there
    *   false if the add should fail if it is alraedy there. If multi_set is true and
    *   upate_if_exists is false than the same hash'ed item will be added again.
    * @return true if the data was added
    */
   bool Add(const T &item_to_add, bool update_if_exists = true) {
     uint64_t hash = item_to_add.GetHash();
     HashItem<T> *hash_item = buckets_[hash % bucket_count_];
     if (!hash_item) {
       hash_item = new HashItem<T>();
       hash_item->hash_item_storage_ = new T(item_to_add);
       buckets_[hash % bucket_count_] = hash_item;
       size_++;
       return true;
     }
 
     while (true) {
       if (*hash_item->hash_item_storage_ == item_to_add) {
         if (update_if_exists) {
           hash_item->hash_item_storage_->Update(item_to_add);
           return false;
         } else if (!multi_set_) {
           return false;
         }
       }
       if (!hash_item->next_) {
         HashItem<T> *created_hash_item = new HashItem<T>();
         created_hash_item->hash_item_storage_ = new T(item_to_add);
         hash_item->next_ = created_hash_item;
         break;
       }
       hash_item = hash_item->next_;
     }
 
     size_++;
     return true;
   }
 
   /**
    * Determines if the specified data exists in the set or not`
    * @param data_to_check The data to check
    * @return true if the data found
    */
   bool Exists(const T &data_to_check) {
     uint64_t hash = data_to_check.GetHash();
     HashItem<T> *hash_item = buckets_[hash % bucket_count_];
     if (!hash_item) {
       return false;
     }
 
     while (hash_item) {
       if (*hash_item->hash_item_storage_ == data_to_check) {
         return true;
       }
       hash_item = hash_item->next_;
     }
 
     return false;
   }
 
   /**
    * Determines if the specified data exists in the set or not`
    * @param data_to_check The data to check
    * @return true if the data found
    */
   size_t GetMatchingCount(const T &data_to_check) {
     size_t count = 0;
     uint64_t hash = data_to_check.GetHash();
     HashItem<T> *hash_item = buckets_[hash % bucket_count_];
     if (!hash_item) {
       return count;
     }
 
     while (hash_item) {
       if (*hash_item->hash_item_storage_ == data_to_check) {
         count++;
       }
       hash_item = hash_item->next_;
     }
 
     return count;
   }
 
   /**
    * Finds the specific data in the hash set.
    * This is useful because sometimes it contains more context
    * than the object used for the lookup.
    * @param data_to_check The data to check
    * @return The data stored in the hash set or nullptr if none is found.
    */
   T * Find(const T &data_to_check) {
     uint64_t hash = data_to_check.GetHash();
     HashItem<T> *hash_item = buckets_[hash % bucket_count_];
     if (!hash_item) {
       return nullptr;
     }
 
     while (hash_item) {
       if (*hash_item->hash_item_storage_ == data_to_check) {
         return hash_item->hash_item_storage_;
       }
       hash_item = hash_item->next_;
     }
 
     return nullptr;
   }
 
   /**
    * Finds the specific data in the hash set.
    * This is useful because sometimes it contains more context
    * than the object used for the lookup.
    * @param data_to_check The data to check
    * @return The data stored in the hash set or nullptr if none is found.
    */
   void FindAll(const T &data_to_check, std::vector<T*> *result) {
     uint64_t hash = data_to_check.GetHash();
     HashItem<T> *hash_item = buckets_[hash % bucket_count_];
     if (!hash_item) {
       return;
     }
 
     while (hash_item) {
       if (*hash_item->hash_item_storage_ == data_to_check) {
         result->push_back(hash_item->hash_item_storage_);
       }
       hash_item = hash_item->next_;
     }
   }
 
   /**
    * Removes the specific data in the hash set.
    * @param data_to_check The data to remove
    * @return true if an item matching the data was removed
    */
   bool Remove(const T &data_to_check) {
     uint64_t hash = data_to_check.GetHash();
     HashItem<T> *hash_item = buckets_[hash % bucket_count_];
     if (!hash_item) {
       return false;
     }
 
     HashItem<T> *last_item = nullptr;
     while (hash_item) {
       if (*hash_item->hash_item_storage_ == data_to_check) {
         if (last_item) {
           last_item->next_ = hash_item->next_;
           delete hash_item;
         } else {
           buckets_[hash % bucket_count_] = hash_item->next_;
           delete hash_item;
         }
         size_--;
         return true;
       }
 
       last_item = hash_item;
       hash_item = hash_item->next_;
     }
 
     return false;
   }
 
 
   /**
    * Obtains the number of items in the Hash Set
    */
   uint32_t GetSize() {
     return size_;
   }
 
   /**
    * Serializes the parsed data and bloom filter data into a single buffer.
    * @param size The size is returned in the out parameter if it's needed to
    * write to a file.
    * @return The returned buffer should be deleted by the caller.
    */
   char * Serialize(uint32_t *size) {
      *size = 0;
      *size += SerializeBuckets(nullptr);
      char *buffer = new char[*size];
      memset(buffer, 0, *size);
      SerializeBuckets(buffer);
      return buffer;
   }
 
   /**
    * Deserializes the buffer.
    * Memory passed in will be used by this instance directly without copying
    * it in.
    * @param buffer The serialized data to deserialize
    * @param buffer_size the size of the buffer to deserialize
    * @return true if the operation was successful
    */
   bool Deserialize(char *buffer, uint32_t buffer_size) {
     Cleanup();
     uint32_t pos = 0;
     if (!HasNewlineBefore(buffer, buffer_size)) {
       return false;
     }
 
     uint32_t multi_set = 0;
     sscanf(buffer + pos, "%x,%x", &bucket_count_, &multi_set);
     multi_set_ = multi_set != 0;
     buckets_ = new HashItem<T> *[bucket_count_];
     memset(buckets_, 0, sizeof(HashItem<T>*) * bucket_count_);
     pos += static_cast<uint32_t>(strlen(buffer + pos)) + 1;
     if (pos >= buffer_size) {
       return false;
     }
     for (uint32_t i = 0; i < bucket_count_; i++) {
       HashItem<T> *last_hash_item = nullptr;
       while (*(buffer + pos) != '\0') {
         if (pos >= buffer_size) {
           return false;
         }
 
         HashItem<T> *hash_item = new HashItem<T>();
         hash_item->hash_item_storage_ = new T();
         uint32_t deserialize_size =
           hash_item->hash_item_storage_->Deserialize(buffer + pos,
               buffer_size - pos);
         pos += deserialize_size;
         if (pos >= buffer_size || deserialize_size == 0) {
           return false;
         }
 
         size_++;
 
         if (last_hash_item) {
           last_hash_item->next_ = hash_item;
         } else {
           buckets_[i] = hash_item;
         }
         last_hash_item = hash_item;
       }
       pos++;
     }
     return true;
   }
 
   /**
    * Clears the HashSet back to the original dimensions but
    * with no data.
    */
   void Clear() {
     auto old_bucket_count = bucket_count_;
     Cleanup();
     Init(old_bucket_count);
   }
 
   /**
    * Returns true if the hash_set is a multi_set
    */
   bool IsMultiSet() const {
     return multi_set_;
   }
 
  private:
   bool HasNewlineBefore(char *buffer, uint32_t buffer_size) {
     char *p = buffer;
     for (uint32_t i = 0; i < buffer_size; ++i) {
       if (*p == '\0')
         return true;
       p++;
     }
     return false;
   }
 
   void Init(uint32_t num_buckets) {
     bucket_count_ = num_buckets;
     buckets_ = nullptr;
     size_ = 0;
     if (bucket_count_ != 0) {
       buckets_ = new HashItem<T>*[bucket_count_];
       memset(buckets_, 0, sizeof(HashItem<T>*) * bucket_count_);
     }
   }
 
   void Cleanup() {
     if (buckets_) {
       for (uint32_t i = 0; i < bucket_count_; i++) {
         HashItem<T> *hash_item = buckets_[i];
         while (hash_item) {
           HashItem<T> *temp_hash_item = hash_item;
           hash_item = hash_item->next_;
           delete temp_hash_item;
         }
       }
       delete[] buckets_;
       buckets_ = nullptr;
       bucket_count_ = 0;
       size_ = 0;
     }
   }
 
   uint32_t SerializeBuckets(char *buffer) {
     uint32_t total_size = 0;
     char sz[512];
     total_size += 1 + snprintf(sz, sizeof(sz), "%x,%x",
         bucket_count_, multi_set_ ? 1 : 0);
     if (buffer) {
       memcpy(buffer, sz, total_size);
     }
     for (uint32_t i = 0; i < bucket_count_; i++) {
       HashItem<T> *hash_item = buckets_[i];
       while (hash_item) {
         if (buffer) {
           total_size +=
             hash_item->hash_item_storage_->Serialize(buffer + total_size);
         } else {
           total_size += hash_item->hash_item_storage_->Serialize(nullptr);
         }
         hash_item = hash_item->next_;
       }
       if (buffer) {
         buffer[total_size] = '\0';
       }
       // Second null terminator to show next bucket
       total_size++;
     }
     return total_size;
   }
 
  protected:
   bool multi_set_;
   uint32_t bucket_count_;
   HashItem<T> **buckets_;
   uint32_t size_;
 };
 
 #endif  // HASH_SET_H_