forked from LBRYCommunity/lbry-sdk
265 lines
8 KiB
Python
265 lines
8 KiB
Python
import copy
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import math
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import time
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# Half life in blocks
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HALF_LIFE = 134
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# Decay coefficient per block
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DECAY = 0.5**(1.0/HALF_LIFE)
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# How frequently to write trending values to the db
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SAVE_INTERVAL = 10
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# Renormalisation interval
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RENORM_INTERVAL = 1000
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# Assertion
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assert RENORM_INTERVAL % SAVE_INTERVAL == 0
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# Decay coefficient per renormalisation interval
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DECAY_PER_RENORM = DECAY**(RENORM_INTERVAL)
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# Log trending calculations?
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TRENDING_LOG = True
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def install(connection):
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"""
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Install the AR trending algorithm.
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"""
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check_trending_values(connection)
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if TRENDING_LOG:
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f = open("trending_ar.log", "a")
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f.close()
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# Stub
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CREATE_TREND_TABLE = ""
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def check_trending_values(connection):
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"""
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If the trending values appear to be based on the zscore algorithm,
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reset them. This will allow resyncing from a standard snapshot.
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"""
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c = connection.cursor()
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needs_reset = False
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for row in c.execute("SELECT COUNT(*) num FROM claim WHERE trending_global <> 0;"):
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if row[0] != 0:
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needs_reset = True
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break
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if needs_reset:
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print("Resetting some columns. This might take a while...", flush=True, end="")
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c.execute(""" BEGIN;
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UPDATE claim SET trending_group = 0;
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UPDATE claim SET trending_mixed = 0;
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UPDATE claim SET trending_global = 0;
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UPDATE claim SET trending_local = 0;
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COMMIT;""")
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print("done.")
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def spike_height(trending_score, x, x_old, time_boost=1.0):
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"""
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Compute the size of a trending spike.
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"""
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# Change in softened amount
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change_in_softened_amount = x**0.25 - x_old**0.25
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# Softened change in amount
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delta = x - x_old
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softened_change_in_amount = abs(delta)**0.25
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# Softened change in amount counts more for minnows
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if delta > 0.0:
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if trending_score >= 0.0:
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multiplier = 0.1/((trending_score/time_boost + softened_change_in_amount) + 1.0)
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softened_change_in_amount *= multiplier
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else:
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softened_change_in_amount *= -1.0
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return time_boost*(softened_change_in_amount + change_in_softened_amount)
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def get_time_boost(height):
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"""
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Return the time boost at a given height.
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"""
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return 1.0/DECAY**(height % RENORM_INTERVAL)
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def trending_log(s):
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"""
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Log a string.
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"""
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if TRENDING_LOG:
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fout = open("trending_ar.log", "a")
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fout.write(s)
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fout.flush()
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fout.close()
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class TrendingData:
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"""
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An object of this class holds trending data
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"""
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def __init__(self):
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self.claims = {}
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# Have all claims been read from db yet?
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self.initialised = False
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def insert_claim_from_load(self, claim_hash, trending_score, total_amount):
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assert not self.initialised
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self.claims[claim_hash] = {"trending_score": trending_score,
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"total_amount": total_amount,
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"changed": False}
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def update_claim(self, claim_hash, total_amount, time_boost=1.0):
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"""
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Update trending data for a claim, given its new total amount.
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"""
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assert self.initialised
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# Extract existing total amount and trending score
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# or use starting values if the claim is new
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if claim_hash in self.claims:
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old_state = copy.deepcopy(self.claims[claim_hash])
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else:
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old_state = {"trending_score": 0.0,
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"total_amount": 0.0,
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"changed": False}
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# Calculate LBC change
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change = total_amount - old_state["total_amount"]
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# Modify data if there was an LBC change
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if change != 0.0:
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spike = spike_height(old_state["trending_score"],
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total_amount,
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old_state["total_amount"],
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time_boost)
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trending_score = old_state["trending_score"] + spike
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self.claims[claim_hash] = {"total_amount": total_amount,
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"trending_score": trending_score,
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"changed": True}
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def test_trending():
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"""
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Quick trending test for something receiving 10 LBC per block
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"""
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data = TrendingData()
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data.insert_claim_from_load("abc", 10.0, 1.0)
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data.initialised = True
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for height in range(1, 5000):
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if height % RENORM_INTERVAL == 0:
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data.claims["abc"]["trending_score"] *= DECAY_PER_RENORM
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time_boost = get_time_boost(height)
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data.update_claim("abc", data.claims["abc"]["total_amount"] + 10.0,
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time_boost=time_boost)
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print(str(height) + " " + str(time_boost) + " " \
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+ str(data.claims["abc"]["trending_score"]))
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# One global instance
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# pylint: disable=C0103
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trending_data = TrendingData()
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def run(db, height, final_height, recalculate_claim_hashes):
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if height < final_height - 5*HALF_LIFE:
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trending_log("Skipping AR trending at block {h}.\n".format(h=height))
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return
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start = time.time()
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trending_log("Calculating AR trending at block {h}.\n".format(h=height))
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trending_log(" Length of trending data = {l}.\n"\
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.format(l=len(trending_data.claims)))
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# Renormalise trending scores and mark all as having changed
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if height % RENORM_INTERVAL == 0:
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trending_log(" Renormalising trending scores...")
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keys = trending_data.claims.keys()
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for key in keys:
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if trending_data.claims[key]["trending_score"] != 0.0:
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trending_data.claims[key]["trending_score"] *= DECAY_PER_RENORM
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trending_data.claims[key]["changed"] = True
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# Tiny becomes zero
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if abs(trending_data.claims[key]["trending_score"]) < 1E-9:
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trending_data.claims[key]["trending_score"] = 0.0
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trending_log("done.\n")
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# Regular message.
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trending_log(" Reading total_amounts from db and updating"\
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+ " trending scores in RAM...")
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# Get the value of the time boost
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time_boost = get_time_boost(height)
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# Update claims from db
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if not trending_data.initialised:
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# On fresh launch
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for row in db.execute("""
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SELECT claim_hash, trending_mixed,
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(amount + support_amount)
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AS total_amount
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FROM claim;
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"""):
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trending_data.insert_claim_from_load(row[0], row[1], 1E-8*row[2])
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trending_data.initialised = True
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else:
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for row in db.execute(f"""
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SELECT claim_hash,
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(amount + support_amount)
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AS total_amount
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FROM claim
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WHERE claim_hash IN
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({','.join('?' for _ in recalculate_claim_hashes)});
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""", recalculate_claim_hashes):
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trending_data.update_claim(row[0], 1E-8*row[1], time_boost)
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trending_log("done.\n")
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# Write trending scores to DB
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if height % SAVE_INTERVAL == 0:
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trending_log(" Writing trending scores to db...")
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the_list = []
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keys = trending_data.claims.keys()
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for key in keys:
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if trending_data.claims[key]["changed"]:
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the_list.append((trending_data.claims[key]["trending_score"],
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key))
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trending_data.claims[key]["changed"] = False
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trending_log("{n} scores to write...".format(n=len(the_list)))
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db.executemany("UPDATE claim SET trending_mixed=? WHERE claim_hash=?;",
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the_list)
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trending_log("done.\n")
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trending_log("Trending operations took {time} seconds.\n\n"\
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.format(time=time.time() - start))
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if __name__ == "__main__":
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test_trending()
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