#include <wallet2.h>

Public Member Functions
uint64_t	pick ()
	gamma_picker (const std::vector< uint64_t > &rct_offsets)
	gamma_picker (const std::vector< uint64_t > &rct_offsets, double shape, double scale)

Detailed Description

Definition at line 87 of file wallet2.h.

Constructor & Destructor Documentation

◆ gamma_picker() [1/2]

tools::gamma_picker::gamma_picker ( const std::vector< uint64_t > & rct_offsets )

Definition at line 1011 of file wallet2.cpp.

1011: gamma_picker(rct_offsets, GAMMA_SHAPE, GAMMA_SCALE) {}

tools::gamma_picker::gamma_picker

gamma_picker(const std::vector< uint64_t > &rct_offsets)

Definition wallet2.cpp:1011

GAMMA_SCALE

#define GAMMA_SCALE

Definition wallet2.cpp:135

GAMMA_SHAPE

#define GAMMA_SHAPE

Definition wallet2.cpp:134

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◆ gamma_picker() [2/2]

tools::gamma_picker::gamma_picker	(	const std::vector< uint64_t > &	rct_offsets,
		double	shape,
		double	scale )

Definition at line 996 of file wallet2.cpp.

                                                                                            :
    rct_offsets(rct_offsets)
{
  gamma = std::gamma_distribution<double>(shape, scale);
  THROW_WALLET_EXCEPTION_IF(rct_offsets.size() <= ETN_DEFAULT_TX_SPENDABLE_AGE_V8, error::wallet_internal_error, "Bad offset calculation");
  const size_t blocks_in_a_year = 86400 * 365 / DIFFICULTY_TARGET_V6;
  const size_t blocks_to_consider = std::min<size_t>(rct_offsets.size(), blocks_in_a_year);
  const size_t outputs_to_consider = rct_offsets.back() - (blocks_to_consider < rct_offsets.size() ? rct_offsets[rct_offsets.size() - blocks_to_consider - 1] : 0);
  begin = rct_offsets.data();
  end = rct_offsets.data() + rct_offsets.size() - ETN_DEFAULT_TX_SPENDABLE_AGE_V8;
  num_rct_outputs = *(end - 1);
  THROW_WALLET_EXCEPTION_IF(num_rct_outputs == 0, error::wallet_internal_error, "No rct outputs");
  average_output_time = DIFFICULTY_TARGET_V6 * blocks_to_consider / outputs_to_consider; // this assumes constant target over the whole rct range
};

Member Function Documentation

◆ pick()

uint64_t tools::gamma_picker::pick ( )

Definition at line 1013 of file wallet2.cpp.

{
  double x = gamma(engine);
  x = exp(x);
  uint64_t output_index = x / average_output_time;
  if (output_index >= num_rct_outputs)
    return std::numeric_limits<uint64_t>::max(); // bad pick
  output_index = num_rct_outputs - 1 - output_index;
 
  const uint64_t *it = std::lower_bound(begin, end, output_index);
  THROW_WALLET_EXCEPTION_IF(it == end, error::wallet_internal_error, "output_index not found");
  uint64_t index = std::distance(begin, it);
 
  const uint64_t first_rct = index == 0 ? 0 : rct_offsets[index - 1];
  const uint64_t n_rct = rct_offsets[index] - first_rct;
  if (n_rct == 0)
    return std::numeric_limits<uint64_t>::max(); // bad pick
  MTRACE("Picking 1/" << n_rct << " in block " << index);
  return first_rct + crypto::rand_idx(n_rct);
};