add RPC to get a histogram of outputs of a given amount

src/wallet/wallet2.cpp

@@ -2266,6 +2266,71 @@ bool wallet2::refresh(uint64_t & blocks_fetched, bool& received_money, bool& ok)
   return ok;
 }
 //----------------------------------------------------------------------------------------------------
+bool wallet2::get_output_distribution(uint64_t &start_height, std::vector<uint64_t> &distribution)
+{
+  uint32_t rpc_version;
+  boost::optional<std::string> result = m_node_rpc_proxy.get_rpc_version(rpc_version);
+  // no error
+  if (!!result)
+  {
+    // empty string -> not connection
+    THROW_WALLET_EXCEPTION_IF(result->empty(), tools::error::no_connection_to_daemon, "getversion");
+    THROW_WALLET_EXCEPTION_IF(*result == CORE_RPC_STATUS_BUSY, tools::error::daemon_busy, "getversion");
+    if (*result != CORE_RPC_STATUS_OK)
+    {
+      MDEBUG("Cannot determine daemon RPC version, not requesting rct distribution");
+      return false;
+    }
+  }
+  else
+  {
+    if (rpc_version >= MAKE_CORE_RPC_VERSION(1, 19))
+    {
+      MDEBUG("Daemon is recent enough, requesting rct distribution");
+    }
+    else
+    {
+      MDEBUG("Daemon is too old, not requesting rct distribution");
+      return false;
+    }
+  }
+
+  cryptonote::COMMAND_RPC_GET_OUTPUT_DISTRIBUTION::request req = AUTO_VAL_INIT(req);
+  cryptonote::COMMAND_RPC_GET_OUTPUT_DISTRIBUTION::response res = AUTO_VAL_INIT(res);
+  req.amounts.push_back(0);
+  m_daemon_rpc_mutex.lock();
+  bool r = net_utils::invoke_http_json_rpc("/json_rpc", "get_output_distribution", req, res, m_http_client, rpc_timeout);
+  m_daemon_rpc_mutex.unlock();
+  if (!r)
+  {
+    MWARNING("Failed to request output distribution: no connection to daemon");
+    return false;
+  }
+  if (res.status == CORE_RPC_STATUS_BUSY)
+  {
+    MWARNING("Failed to request output distribution: daemon is busy");
+    return false;
+  }
+  if (res.status != CORE_RPC_STATUS_OK)
+  {
+    MWARNING("Failed to request output distribution: " << res.status);
+    return false;
+  }
+  if (res.distributions.size() != 1)
+  {
+    MWARNING("Failed to request output distribution: not the expected single result");
+    return false;
+  }
+  if (res.distributions[0].amount != 0)
+  {
+    MWARNING("Failed to request output distribution: results are not for amount 0");
+    return false;
+  }
+  start_height = res.distributions[0].start_height;
+  distribution = std::move(res.distributions[0].distribution);
+  return true;
+}
+//----------------------------------------------------------------------------------------------------
 void wallet2::detach_blockchain(uint64_t height)
 {
   LOG_PRINT_L0("Detaching blockchain on height " << height);

src/wallet/wallet2.h

@@ -1103,6 +1103,8 @@ namespace tools
     rct::key get_multisig_k(size_t idx, const std::unordered_set<rct::key> &used_L) const;
     void update_multisig_rescan_info(const std::vector<std::vector<rct::key>> &multisig_k, const std::vector<std::vector<tools::wallet2::multisig_info>> &info, size_t n);
 
+    bool get_output_distribution(uint64_t &start_height, std::vector<uint64_t> &distribution);
+
     cryptonote::account_base m_account;
     boost::optional<epee::net_utils::http::login> m_daemon_login;
     std::string m_daemon_address;

src/wallet/wallet_errors.h

@@ -85,6 +85,7 @@ namespace tools
     //         no_connection_to_daemon
     //         is_key_image_spent_error
     //         get_histogram_error
+    //         get_output_distribution
     //       wallet_files_doesnt_correspond
     //
     // * - class with protected ctor
@@ -757,6 +758,14 @@ namespace tools
       }
     };
     //----------------------------------------------------------------------------------------------------
+    struct get_output_distribution : public wallet_rpc_error
+    {
+      explicit get_output_distribution(std::string&& loc, const std::string& request)
+        : wallet_rpc_error(std::move(loc), "failed to get output distribution", request)
+      {
+      }
+    };
+    //----------------------------------------------------------------------------------------------------
     struct wallet_files_doesnt_correspond : public wallet_logic_error
     {
       explicit wallet_files_doesnt_correspond(std::string&& loc, const std::string& keys_file, const std::string& wallet_file)