monero/src/cryptonote_core/blockchain_db.h

// Copyright (c) 2014, The Monero Project
// 
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#ifndef BLOCKCHAIN_DB_H
#define BLOCKCHAIN_DB_H

#include <list>
#include <string>
#include <exception>
#include "crypto/hash.h"
#include "cryptonote_core/cryptonote_basic.h"
#include "cryptonote_core/difficulty.h"

/* DB Driver Interface
 *
 * The DB interface is a store for the canonical block chain.
 * It serves as a persistent storage for the blockchain.
 *
 * For the sake of efficiency, the reference implementation will also
 * store some blockchain data outside of the blocks, such as spent
 * transfer key images, unspent transaction outputs, etc.
 *
 * Transactions are duplicated so that we don't have to fetch a whole block
 * in order to fetch a transaction from that block.  If this is deemed
 * unnecessary later, this can change.
 *
 * Spent key images are duplicated outside of the blocks so it is quick
 * to verify an output hasn't already been spent
 *
 * Unspent transaction outputs are duplicated to quickly gather random
 * outputs to use for mixins
 *
 * IMPORTANT:
 * A concrete implementation of this interface should populate these
 * duplicated members!  It is possible to have a partial implementation
 * of this interface call to private members of the interface to be added
 * later that will then populate as needed.
 *
 * General:
 *   open()
 *   close()
 *   sync()
 *   reset()
 *
 *   Lock and unlock provided for reorg externally, and for block
 *   additions internally, this way threaded reads are completely fine
 *   unless the blockchain is changing.
 *   bool lock()
 *   unlock()
 *
 * vector<str>   get_filenames()
 *
 * Blocks:
 *   bool        block_exists(hash)
 *   height      add_block(block, block_size, cumulative_difficulty, coins_generated, transactions)
 *   block       get_block(hash)
 *   height      get_block_height(hash)
 *   header      get_block_header(hash)
 *   block       get_block_from_height(height)
 *   size_t      get_block_size(height)
 *   difficulty  get_block_cumulative_difficulty(height)
 *   uint64_t    get_block_already_generated_coins(height)
 *   uint64_t    get_block_timestamp(height) 
 *   uint64_t    get_top_block_timestamp()
 *   hash        get_block_hash_from_height(height)
 *   blocks      get_blocks_range(height1, height2)
 *   hashes      get_hashes_range(height1, height2)
 *   hash        top_block_hash()
 *   block       get_top_block()
 *   height      height()
 *   void        pop_block(block&, tx_list&)
 *
 * Transactions:
 *   bool        tx_exists(hash)
 *   uint64_t    get_tx_unlock_time(hash)
 *   tx          get_tx(hash)
 *   uint64_t    get_tx_count()
 *   tx_list     get_tx_list(hash_list)
 *   height      get_tx_block_height(hash)
 *
 * Outputs:
 *   index       get_random_output(amount)
 *   uint64_t    get_num_outputs(amount)
 *   pub_key     get_output_key(amount, index)
 *   tx_out      get_output(tx_hash, index)
 *   hash,index  get_output_tx_and_index(amount, index)
 *   vec<uint64> get_tx_output_indices(tx_hash)
 *
 *
 * Spent Output Key Images:
 *   bool        has_key_image(key_image)
 *
 * Exceptions:
 *   DB_ERROR -- generic
 *   DB_OPEN_FAILURE
 *   DB_CREATE_FAILURE
 *   DB_SYNC_FAILURE
 *   BLOCK_DNE
 *   BLOCK_PARENT_DNE
 *   BLOCK_EXISTS
 *   BLOCK_INVALID -- considering making this multiple errors
 *   TX_DNE
 *   TX_EXISTS
 *   OUTPUT_DNE
 *   OUTPUT_EXISTS
 *   KEY_IMAGE_EXISTS
 */

namespace cryptonote
{

// typedef for convenience
typedef std::pair<crypto::hash, uint64_t> tx_out_index;

/***********************************
 * Exception Definitions
 ***********************************/
class DB_EXCEPTION : public std::exception
{
  private:
    std::string m;

  protected:
    DB_EXCEPTION(const char *s) : m(s) { }

  public:
    virtual ~DB_EXCEPTION() { }

    const char* what() const throw()
    {
      return m.c_str();
    }
};

class DB_ERROR : public DB_EXCEPTION
{
  public:
    DB_ERROR() : DB_EXCEPTION("Generic DB Error") { }
    DB_ERROR(const char* s) : DB_EXCEPTION(s) { }
};

class DB_OPEN_FAILURE : public DB_EXCEPTION
{
  public:
    DB_OPEN_FAILURE() : DB_EXCEPTION("Failed to open the db") { }
    DB_OPEN_FAILURE(const char* s) : DB_EXCEPTION(s) { }
};

class DB_CREATE_FAILURE : public DB_EXCEPTION
{
  public:
    DB_CREATE_FAILURE() : DB_EXCEPTION("Failed to create the db") { }
    DB_CREATE_FAILURE(const char* s) : DB_EXCEPTION(s) { }
};

class DB_SYNC_FAILURE : public DB_EXCEPTION
{
  public:
    DB_SYNC_FAILURE() : DB_EXCEPTION("Failed to sync the db") { }
    DB_SYNC_FAILURE(const char* s) : DB_EXCEPTION(s) { }
};

class BLOCK_DNE : public DB_EXCEPTION
{
  public:
    BLOCK_DNE() : DB_EXCEPTION("The block requested does not exist") { }
    BLOCK_DNE(const char* s) : DB_EXCEPTION(s) { }
};

class BLOCK_PARENT_DNE : public DB_EXCEPTION
{
  public:
    BLOCK_PARENT_DNE() : DB_EXCEPTION("The parent of the block does not exist") { }
    BLOCK_PARENT_DNE(const char* s) : DB_EXCEPTION(s) { }
};

class BLOCK_EXISTS : public DB_EXCEPTION
{
  public:
    BLOCK_EXISTS() : DB_EXCEPTION("The block to be added already exists!") { }
    BLOCK_EXISTS(const char* s) : DB_EXCEPTION(s) { }
};

class BLOCK_INVALID : public DB_EXCEPTION
{
  public:
    BLOCK_INVALID() : DB_EXCEPTION("The block to be added did not pass validation!") { }
    BLOCK_INVALID(const char* s) : DB_EXCEPTION(s) { }
};

class TX_DNE : public DB_EXCEPTION
{
  public:
    TX_DNE() : DB_EXCEPTION("The transaction requested does not exist") { }
    TX_DNE(const char* s) : DB_EXCEPTION(s) { }
};

class TX_EXISTS : public DB_EXCEPTION
{
  public:
    TX_EXISTS() : DB_EXCEPTION("The transaction to be added already exists!") { }
    TX_EXISTS(const char* s) : DB_EXCEPTION(s) { }
};

class OUTPUT_DNE : public DB_EXCEPTION
{
  public:
    OUTPUT_DNE() : DB_EXCEPTION("The output requested does not exist!") { }
    OUTPUT_DNE(const char* s) : DB_EXCEPTION(s) { }
};

class OUTPUT_EXISTS : public DB_EXCEPTION
{
  public:
    OUTPUT_EXISTS() : DB_EXCEPTION("The output to be added already exists!") { }
    OUTPUT_EXISTS(const char* s) : DB_EXCEPTION(s) { }
};

class KEY_IMAGE_EXISTS : public DB_EXCEPTION
{
  public:
    KEY_IMAGE_EXISTS() : DB_EXCEPTION("The spent key image to be added already exists!") { }
    KEY_IMAGE_EXISTS(const char* s) : DB_EXCEPTION(s) { }
};

/***********************************
 * End of Exception Definitions
 ***********************************/


class BlockchainDB
{
private:
  /*********************************************************************
   * private virtual members
   *********************************************************************/

  // tells the subclass to add the block and metadata to storage
  virtual void add_block( const block& blk
                , const size_t& block_size
                , const difficulty_type& cumulative_difficulty
                , const uint64_t& coins_generated
                ) = 0;

  // tells the subclass to remove data about the top block
  virtual void remove_block() = 0;

  // tells the subclass to store the transaction and its metadata
  virtual void add_transaction_data(const crypto::hash& blk_hash, const transaction& tx) = 0;

  // tells the subclass to remove data about a transaction
  virtual void remove_transaction_data(const crypto::hash& tx_hash) = 0;

  // tells the subclass to store an output
  virtual void add_output(const crypto::hash& tx_hash, const tx_out& tx_output, const uint64_t& local_index) = 0;

  // tells the subclass to remove an output
  virtual void remove_output(const tx_out& tx_output) = 0;

  // tells the subclass to store a spent key
  virtual void add_spent_key(const crypto::key_image& k_image) = 0;

  // tells the subclass to remove a spent key
  virtual void remove_spent_key(const crypto::key_image& k_image) = 0;


  /*********************************************************************
   * private concrete members
   *********************************************************************/ 
  // private version of pop_block, for undoing if an add_block goes tits up
  void pop_block();

  // helper function for add_transactions, to add each individual tx
  void add_transaction(const crypto::hash& blk_hash, const transaction& tx);

  // helper function to remove transaction from blockchain
  void remove_transaction(const crypto::hash& tx_hash);


public:

  // virtual dtor
  virtual ~BlockchainDB() { };


  // open the db at location <filename>, or create it if there isn't one.
  virtual void open(const std::string& filename) = 0;

  // make sure implementation has a create function as well
  virtual void create(const std::string& filename) = 0;

  // close and sync the db
  virtual void close() = 0;

  // sync the db
  virtual void sync() = 0;

  // reset the db -- USE WITH CARE
  virtual void reset() = 0;

  // get all files used by this db (if any)
  virtual std::vector<std::string> get_filenames() const = 0;


  // FIXME: these are just for functionality mocking, need to implement
  // RAII-friendly and multi-read one-write friendly locking mechanism
  //
  // acquire db lock
  virtual bool lock() = 0;

  // release db lock
  virtual void unlock() = 0;


  // adds a block with the given metadata to the top of the blockchain, returns the new height
  // NOTE: subclass implementations of this (or the functions it calls) need
  // to handle undoing any partially-added blocks in the event of a failure.
  virtual uint64_t add_block( const block& blk
                            , const size_t& block_size
                            , const difficulty_type& cumulative_difficulty
                            , const uint64_t& coins_generated
                            , const std::vector<transaction>& txs
                            );

  // return true if a block with hash <h> exists in the blockchain
  virtual bool block_exists(const crypto::hash& h) const = 0;

  // return block with hash <h>
  virtual block get_block(const crypto::hash& h) const = 0;

  // return the height of the block with hash <h> on the blockchain,
  // throw if it doesn't exist
  virtual uint64_t get_block_height(const crypto::hash& h) const = 0;

  // return header for block with hash <h>
  virtual block_header get_block_header(const crypto::hash& h) const = 0;

  // return block at height <height>
  virtual block get_block_from_height(const uint64_t& height) const = 0;

  // return timestamp of block at height <height>
  virtual uint64_t get_block_timestamp(const uint64_t& height) const = 0;

  // return timestamp of most recent block
  virtual uint64_t get_top_block_timestamp() const = 0;

  // return block size of block at height <height>
  virtual size_t get_block_size(const uint64_t& height) const = 0;

  // return cumulative difficulty up to and including block at height <height>
  virtual difficulty_type get_block_cumulative_difficulty(const uint64_t& height) const = 0;

  // return difficulty of block at height <height>
  virtual difficulty_type get_block_difficulty(const uint64_t& height) const = 0;

  // return number of coins generated up to and including block at height <height>
  virtual uint64_t get_block_already_generated_coins(const uint64_t& height) const = 0;

  // return hash of block at height <height>
  virtual crypto::hash get_block_hash_from_height(const uint64_t& height) const = 0;

  // return vector of blocks in range <h1,h2> of height (inclusively)
  virtual std::vector<block> get_blocks_range(const uint64_t& h1, const uint64_t& h2) const = 0;

  // return vector of block hashes in range <h1, h2> of height (inclusively)
  virtual std::vector<crypto::hash> get_hashes_range(const uint64_t& h1, const uint64_t& h2) const = 0;

  // return the hash of the top block on the chain
  virtual crypto::hash top_block_hash() const = 0;

  // return the block at the top of the blockchain
  virtual block get_top_block() const = 0;

  // return the index of the top block on the chain
  // NOTE: for convenience using heights as indices, this is not the total
  // size of the blockchain, but rather the index of the top block.  As the
  // chain is 0-indexed, the total size will be height() + 1.
  virtual uint64_t height() const = 0;

  // pops the top block off the blockchain.
  // Returns by reference the popped block and its associated transactions
  //
  // IMPORTANT:
  // When a block is popped, the transactions associated with it need to be
  // removed, as well as outputs and spent key images associated with
  // those transactions.
  virtual void pop_block(block& blk, std::vector<transaction>& txs);


  // return true if a transaction with hash <h> exists
  virtual bool tx_exists(const crypto::hash& h) const = 0;

  // return unlock time of tx with hash <h>
  virtual uint64_t get_tx_unlock_time(const crypto::hash& h) const = 0;

  // return tx with hash <h>
  // throw if no such tx exists
  virtual transaction get_tx(const crypto::hash& h) const = 0;

  // returns the total number of transactions in all blocks
  virtual uint64_t get_tx_count() const = 0;

  // return list of tx with hashes <hlist>.
  // TODO: decide if a missing hash means return empty list
  // or just skip that hash
  virtual std::vector<transaction> get_tx_list(const std::vector<crypto::hash>& hlist) const = 0;

  // returns height of block that contains transaction with hash <h>
  virtual uint64_t get_tx_block_height(const crypto::hash& h) const = 0;

  // return global output index of a random output of amount <amount>
  virtual uint64_t get_random_output(const uint64_t& amount) const = 0;

  // returns the total number of outputs of amount <amount>
  virtual uint64_t get_num_outputs(const uint64_t& amount) const = 0;

  // return public key for output with global output amount <amount> and index <index>
  virtual crypto::public_key get_output_key(const uint64_t& amount, const uint64_t& index) const = 0;

  // returns the output indexed by <index> in the transaction with hash <h>
  virtual tx_out get_output(const crypto::hash& h, const uint64_t& index) const = 0;

  // returns the transaction-local reference for the output with <amount> at <index>
  // return type is pair of tx hash and index
  virtual tx_out_index get_output_tx_and_index(const uint64_t& amount, const uint64_t& index) const = 0;

  // return a vector of indices corresponding to the global output index for
  // each output in the transaction with hash <h>
  virtual std::vector<uint64_t> get_tx_output_indices(const crypto::hash& h) const = 0;

  // returns true if key image <img> is present in spent key images storage
  virtual bool has_key_image(const crypto::key_image& img) const = 0;

};  // class BlockchainDB


}  // namespace cryptonote

#endif  // BLOCKCHAIN_DB_H