modulate share difficulty to prevent any node from producing more than 5% of shares

[p2pool.git] / p2pool / bitcoin / data.py

diff --git a/p2pool/bitcoin/data.py b/p2pool/bitcoin/data.py
index de6d405..88e1730 100644 (file)
--- a/p2pool/bitcoin/data.py
+++ b/p2pool/bitcoin/data.py
@@ -2,6 +2,7 @@ from __future__ import division
 
 import hashlib
 import random
+import warnings
 
 import p2pool
 from p2pool.util import math, pack
@@ -214,13 +215,23 @@ def check_merkle_link(tip_hash, link):
 # targets
 
 def target_to_average_attempts(target):
+    assert 0 <= target and isinstance(target, (int, long)), target
+    if target >= 2**256: warnings.warn('target >= 2**256!')
     return 2**256//(target + 1)
 
+def average_attempts_to_target(average_attempts):
+    assert average_attempts > 0
+    return min(int(2**256/average_attempts - 1 + 0.5), 2**256-1)
+
 def target_to_difficulty(target):
+    assert 0 <= target and isinstance(target, (int, long)), target
+    if target >= 2**256: warnings.warn('target >= 2**256!')
     return (0xffff0000 * 2**(256-64) + 1)/(target + 1)
 
 def difficulty_to_target(difficulty):
-    return (0xffff0000 * 2**(256-64) + 1)/difficulty - 1
+    assert difficulty >= 0
+    if difficulty == 0: return 2**256-1
+    return min(int((0xffff0000 * 2**(256-64) + 1)/difficulty - 1 + 0.5), 2**256-1)
 
 # human addresses