Update constants #774

steemit · Feb 28, 2017 · 3e46cf2 · 3e46cf2
1 parent db378d8
commit 3e46cf2
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Showing 3 changed files with 21 additions and 9 deletions.
diff --git a/libraries/chain/database.cpp b/libraries/chain/database.cpp
@@ -3853,7 +3853,7 @@ void database::apply_hardfork( uint32_t hardfork )
          {
             rfo.name = STEEMIT_POST_REWARD_FUND_NAME;
             rfo.last_update = head_block_time();
-            rfo.content_constant = STEEMIT_CONTENT_CONSTANT_HF17;
+            rfo.content_constant = STEEMIT_CONTENT_CONSTANT_S_HF17;
             rfo.percent_curation_rewards = STEEMIT_1_PERCENT * 25;
             rfo.percent_content_rewards = 0;
          });
@@ -3862,7 +3862,7 @@ void database::apply_hardfork( uint32_t hardfork )
          {
             rfo.name = STEEMIT_COMMENT_REWARD_FUND_NAME;
             rfo.last_update = head_block_time();
-            rfo.content_constant = STEEMIT_CONTENT_CONSTANT_HF17;
+            rfo.content_constant = STEEMIT_CONTENT_CONSTANT_S_HF17;
             rfo.percent_curation_rewards = STEEMIT_1_PERCENT * 25;
             rfo.percent_content_rewards = 0;
          });

diff --git a/libraries/chain/util/reward.cpp b/libraries/chain/util/reward.cpp
@@ -93,11 +93,21 @@ uint128_t calculate_claims( const uint128_t& rshares, const reward_fund_object&
    uint128_t result = 0;
    if( rf.name == STEEMIT_POST_REWARD_FUND_NAME || rf.name == STEEMIT_COMMENT_REWARD_FUND_NAME )
    {
-      // ( ( r + a )^2 - a^2 ) / ( r + g )
-      // In this implementation g = 40a
-      uint128_t rshares_plus_a = rshares + rf.content_constant;
-      uint128_t rshares_plus_g = rshares + rf.content_constant * STEEMIT_CONTENT_G_CONST;
-      result = ( rshares_plus_a * rshares_plus_a - rf.content_constant * rf.content_constant ) / rshares_plus_g;
+      //
+      // s = rf.content_constant
+      // alpha = beta * s
+      // gamma = 2 alpha beta mu
+      //
+      uint64_t s = rf.content_constant;
+      uint64_t two_alpha = (2 * STEEMIT_CONTENT_CONSTANT_BETA_HF17) * s;
+      uint64_t gamma = (2 * STEEMIT_CONTENT_CONSTANT_BETA_HF17 * STEEMIT_CONTENT_CONSTANT_BETA_HF17 * STEEMIT_CONTENT_CONSTANT_MU_HF17) * s;
+
+      // rshares is uint128_t so we don't have to upcast
+      uint128_t r_squared = rshares * rshares;
+      uint128_t two_alpha_r = rshares * two_alpha;
+      uint128_t beta_r_plus_gamma = STEEMIT_CONTENT_CONSTANT_BETA_HF17 * rshares + gamma;
+
+      result = ( r_squared + two_alpha_r ) / beta_r_plus_gamma;
    }
    else
    {

diff --git a/libraries/protocol/include/steemit/protocol/config.hpp b/libraries/protocol/include/steemit/protocol/config.hpp
@@ -162,8 +162,10 @@
 #define STEEMIT_COMMENT_REWARD_FUND_NAME        ("comment")
 #define STEEMIT_RECENT_RSHARES_DECAY_RATE       (fc::days(30))
 #define STEEMIT_CONTENT_CONSTANT_HF0            (uint128_t(uint64_t(2000000000000ll)))
-#define STEEMIT_CONTENT_CONSTANT_HF17           (uint64_t(277777777777ll)) // 1E13 / 36
-#define STEEMIT_CONTENT_G_CONST                 (40)
+// note, if redefining these constants make sure calculate_claims doesn't overflow
+#define STEEMIT_CONTENT_CONSTANT_S_HF17         (uint64_t(1900000000000ll))
+#define STEEMIT_CONTENT_CONSTANT_BETA_HF17      1
+#define STEEMIT_CONTENT_CONSTANT_MU_HF17        4
 
 // 5ccc e802 de5f
 // int(expm1( log1p( 1 ) / BLOCKS_PER_YEAR ) * 2**STEEMIT_APR_PERCENT_SHIFT_PER_BLOCK / 100000 + 0.5)