Rewrite of variable_decay.py for speed improvements

This commit is contained in:
Brendon J. Brewer 2020-07-07 11:53:39 +12:00 committed by Jack Robison
parent 511a5c3f82
commit 1cdff47477
No known key found for this signature in database
GPG key ID: DF25C68FE0239BB2
2 changed files with 324 additions and 269 deletions

1
.gitignore vendored
View file

@ -11,6 +11,7 @@
lbry.egg-info
__pycache__
_trial_temp/
trending*.log
/tests/integration/blockchain/files
/tests/.coverage.*

View file

@ -1,18 +1,17 @@
"""
Delayed AR with variable decay rate.
The spike height function is also simpler.
AR-like trending with a delayed effect and a faster
decay rate for high valued claims.
"""
import copy
import math
import time
import apsw
# Half life in blocks *for lower LBC claims* (it's shorter for whale claims)
HALF_LIFE = 200
# Whale threshold (higher -> less DB writing)
WHALE_THRESHOLD = 3.0
# Whale threshold, in LBC (higher -> less DB writing)
WHALE_THRESHOLD = 10000.0
# Decay coefficient per block
DECAY = 0.5**(1.0/HALF_LIFE)
@ -38,6 +37,7 @@ def install(connection):
Install the trending algorithm.
"""
check_trending_values(connection)
trending_data.initialise(connection.cursor())
if TRENDING_LOG:
f = open("trending_variable_decay.log", "a")
@ -46,7 +46,6 @@ def install(connection):
# Stub
CREATE_TREND_TABLE = ""
def check_trending_values(connection):
"""
If the trending values appear to be based on the zscore algorithm,
@ -60,19 +59,304 @@ def check_trending_values(connection):
break
if needs_reset:
print("Resetting some columns. This might take a while...", flush=True, end="")
print("Resetting some columns. This might take a while...", flush=True,
end="")
c.execute(""" BEGIN;
UPDATE claim SET trending_group = 0;
UPDATE claim SET trending_mixed = 0;
UPDATE claim SET trending_global = 0;
UPDATE claim SET trending_local = 0;
COMMIT;""")
print("done.")
def spike_height(x, x_old):
def trending_log(s):
"""
Compute the size of a trending spike (normed - constant units).
Log a string to the log file
"""
if TRENDING_LOG:
fout = open("trending_variable_decay.log", "a")
fout.write(s)
fout.flush()
fout.close()
def trending_unit(height):
"""
Return the trending score unit at a given height.
"""
# Round to the beginning of a SAVE_INTERVAL batch of blocks.
_height = height - (height % SAVE_INTERVAL)
return 1.0/DECAY**(height % RENORM_INTERVAL)
class TrendingDB:
"""
An in-memory database of trending scores
"""
def __init__(self):
self.conn = apsw.Connection(":memory:")
self.cursor = self.conn.cursor()
self.initialised = False
self.write_needed = set()
def execute(self, query, *args, **kwargs):
return self.cursor.execute(query, *args, **kwargs)
def executemany(self, query, *args, **kwargs):
return self.cursor.executemany(query, *args, **kwargs)
def begin(self):
self.execute("BEGIN;")
def commit(self):
self.execute("COMMIT;")
def initialise(self, db):
"""
Pass in claims.db
"""
if self.initialised:
return
trending_log("Initialising trending database...")
# The need for speed
self.execute("PRAGMA JOURNAL_MODE=OFF;")
self.execute("PRAGMA SYNCHRONOUS=0;")
self.begin()
# Create the tables
self.execute("""
CREATE TABLE IF NOT EXISTS claims
(claim_hash BYTES PRIMARY KEY,
lbc REAL NOT NULL DEFAULT 0.0,
trending_score REAL NOT NULL DEFAULT 0.0)
WITHOUT ROWID;""")
self.execute("""
CREATE TABLE IF NOT EXISTS spikes
(id INTEGER PRIMARY KEY,
claim_hash BYTES NOT NULL,
height INTEGER NOT NULL,
mass REAL NOT NULL,
FOREIGN KEY (claim_hash)
REFERENCES claims (claim_hash));""")
# Clear out any existing data
self.execute("DELETE FROM claims;")
self.execute("DELETE FROM spikes;")
# Create indexes
self.execute("CREATE INDEX idx1 ON spikes (claim_hash, height, mass);")
self.execute("CREATE INDEX idx2 ON spikes (claim_hash, height, mass DESC);")
self.execute("CREATE INDEX idx3 on claims (lbc DESC, claim_hash, trending_score);")
# Import data from claims.db
for row in db.execute("""
SELECT claim_hash,
1E-8*(amount + support_amount) AS lbc,
trending_mixed
FROM claim;
"""):
self.execute("INSERT INTO claims VALUES (?, ?, ?);", row)
self.commit()
self.initialised = True
trending_log("done.\n")
def apply_spikes(self, height):
"""
Apply spikes that are due. This occurs inside a transaction.
"""
spikes = []
unit = trending_unit(height)
for row in self.execute("""
SELECT SUM(mass), claim_hash FROM spikes
WHERE height = ?
GROUP BY claim_hash;
""", (height, )):
spikes.append((row[0]*unit, row[1]))
self.write_needed.add(row[1])
self.executemany("""
UPDATE claims
SET trending_score = (trending_score + ?)
WHERE claim_hash = ?;
""", spikes)
self.execute("DELETE FROM spikes WHERE height = ?;", (height, ))
def decay_whales(self, height):
"""
Occurs inside transaction.
"""
if height % SAVE_INTERVAL != 0:
return
whales = self.execute("""
SELECT trending_score, lbc, claim_hash
FROM claims
WHERE lbc >= ?;
""", (WHALE_THRESHOLD, )).fetchall()
whales2 = []
for whale in whales:
trending, lbc, claim_hash = whale
# Overall multiplication factor for decay rate
# At WHALE_THRESHOLD, this is 1
# At 10*WHALE_THRESHOLD, it is 3
decay_rate_factor = 1.0 + 2.0*math.log10(lbc/WHALE_THRESHOLD)
# The -1 is because this is just the *extra* part being applied
factor = (DECAY**SAVE_INTERVAL)**(decay_rate_factor - 1.0)
# Decay
trending *= factor
whales2.append((trending, claim_hash))
self.write_needed.add(claim_hash)
self.executemany("UPDATE claims SET trending_score=? WHERE claim_hash=?;",
whales2)
def renorm(self, height):
"""
Renormalise trending scores. Occurs inside a transaction.
"""
if height % RENORM_INTERVAL == 0:
threshold = 1.0E-3/DECAY_PER_RENORM
for row in self.execute("""SELECT claim_hash FROM claims
WHERE ABS(trending_score) >= ?;""",
(threshold, )):
self.write_needed.add(row[0])
self.execute("""UPDATE claims SET trending_score = ?*trending_score
WHERE ABS(trending_score) >= ?;""",
(DECAY_PER_RENORM, threshold))
def write_to_claims_db(self, db, height):
"""
Write changed trending scores to claims.db.
"""
if height % SAVE_INTERVAL != 0:
return
rows = self.execute(f"""
SELECT trending_score, claim_hash
FROM claims
WHERE claim_hash IN
({','.join('?' for _ in self.write_needed)});
""", self.write_needed).fetchall()
db.executemany("""UPDATE claim SET trending_mixed = ?
WHERE claim_hash = ?;""", rows)
# Clear list of claims needing to be written to claims.db
self.write_needed = set()
def update(self, db, height, recalculate_claim_hashes):
"""
Update trending scores.
Input is a cursor to claims.db, the block height, and the list of
claims that changed.
"""
assert self.initialised
self.begin()
self.renorm(height)
# Fetch changed/new claims from claims.db
for row in db.execute(f"""
SELECT claim_hash,
1E-8*(amount + support_amount) AS lbc
FROM claim
WHERE claim_hash IN
({','.join('?' for _ in recalculate_claim_hashes)});
""", recalculate_claim_hashes):
claim_hash, lbc = row
# Insert into trending db if it does not exist
self.execute("""
INSERT INTO claims (claim_hash)
VALUES (?)
ON CONFLICT (claim_hash) DO NOTHING;""",
(claim_hash, ))
# See if it was an LBC change
old = self.execute("SELECT * FROM claims WHERE claim_hash=?;",
(claim_hash, )).fetchone()
lbc_old = old[1]
# Save new LBC value into trending db
self.execute("UPDATE claims SET lbc = ? WHERE claim_hash = ?;",
(lbc, claim_hash))
if lbc > lbc_old:
# Schedule a future spike
delay = min(int((lbc + 1E-8)**0.4), HALF_LIFE)
spike = (claim_hash, height + delay, spike_mass(lbc, lbc_old))
self.execute("""INSERT INTO spikes
(claim_hash, height, mass)
VALUES (?, ?, ?);""", spike)
elif lbc < lbc_old:
# Subtract from future spikes
penalty = spike_mass(lbc_old, lbc)
spikes = self.execute("""
SELECT * FROM spikes
WHERE claim_hash = ?
ORDER BY height ASC, mass DESC;
""", (claim_hash, )).fetchall()
for spike in spikes:
spike_id, mass = spike[0], spike[3]
if mass > penalty:
# The entire penalty merely reduces this spike
self.execute("UPDATE spikes SET mass=? WHERE id=?;",
(mass - penalty, spike_id))
penalty = 0.0
else:
# Removing this spike entirely accounts for some (or
# all) of the penalty, then move on to other spikes
self.execute("DELETE FROM spikes WHERE id=?;",
(spike_id, ))
penalty -= mass
# If penalty remains, that's a negative spike to be applied
# immediately.
if penalty > 0.0:
self.execute("""
INSERT INTO spikes (claim_hash, height, mass)
VALUES (?, ?, ?);""",
(claim_hash, height, -penalty))
self.apply_spikes(height)
self.decay_whales(height)
self.commit()
self.write_to_claims_db(db, height)
# The "global" instance to work with
# pylint: disable=C0103
trending_data = TrendingDB()
def spike_mass(x, x_old):
"""
Compute the mass of a trending spike (normed - constant units).
x_old = old LBC value
x = new LBC value
"""
# Sign of trending spike
@ -89,155 +373,16 @@ def spike_height(x, x_old):
return sign*mag
def get_time_boost(height):
"""
Return the time boost at a given height.
"""
return 1.0/DECAY**(height % RENORM_INTERVAL)
def trending_log(s):
"""
Log a string.
"""
if TRENDING_LOG:
fout = open("trending_variable_decay.log", "a")
fout.write(s)
fout.flush()
fout.close()
class TrendingData:
"""
An object of this class holds trending data
"""
def __init__(self):
# Dict from claim id to some trending info.
# Units are TIME VARIABLE in here
self.claims = {}
# Claims with >= WHALE_THRESHOLD LBC total amount
self.whales = set([])
# Have all claims been read from db yet?
self.initialised = False
# List of pending spikes.
# Units are CONSTANT in here
self.pending_spikes = []
def insert_claim_from_load(self, height, claim_hash, trending_score, total_amount):
assert not self.initialised
self.claims[claim_hash] = {"trending_score": trending_score,
"total_amount": total_amount,
"changed": False}
if trending_score >= WHALE_THRESHOLD*get_time_boost(height):
self.add_whale(claim_hash)
def add_whale(self, claim_hash):
self.whales.add(claim_hash)
def apply_spikes(self, height):
"""
Apply all pending spikes that are due at this height.
Apply with time boost ON.
"""
time_boost = get_time_boost(height)
for spike in self.pending_spikes:
if spike["height"] > height:
# Ignore
pass
if spike["height"] == height:
# Apply
self.claims[spike["claim_hash"]]["trending_score"] += time_boost*spike["size"]
self.claims[spike["claim_hash"]]["changed"] = True
if self.claims[spike["claim_hash"]]["trending_score"] >= WHALE_THRESHOLD*time_boost:
self.add_whale(spike["claim_hash"])
if spike["claim_hash"] in self.whales and \
self.claims[spike["claim_hash"]]["trending_score"] < WHALE_THRESHOLD*time_boost:
self.whales.remove(spike["claim_hash"])
# Keep only future spikes
self.pending_spikes = [s for s in self.pending_spikes \
if s["height"] > height]
def update_claim(self, height, claim_hash, total_amount):
"""
Update trending data for a claim, given its new total amount.
"""
assert self.initialised
# Extract existing total amount and trending score
# or use starting values if the claim is new
if claim_hash in self.claims:
old_state = copy.deepcopy(self.claims[claim_hash])
else:
old_state = {"trending_score": 0.0,
"total_amount": 0.0,
"changed": False}
# Calculate LBC change
change = total_amount - old_state["total_amount"]
# Modify data if there was an LBC change
if change != 0.0:
spike = spike_height(total_amount,
old_state["total_amount"])
delay = min(int((total_amount + 1E-8)**0.4), HALF_LIFE)
if change < 0.0:
# How big would the spike be for the inverse movement?
reverse_spike = spike_height(old_state["total_amount"], total_amount)
# Remove that much spike from future pending ones
for future_spike in self.pending_spikes:
if future_spike["claim_hash"] == claim_hash:
if reverse_spike >= future_spike["size"]:
reverse_spike -= future_spike["size"]
future_spike["size"] = 0.0
elif reverse_spike > 0.0:
future_spike["size"] -= reverse_spike
reverse_spike = 0.0
delay = 0
spike = -reverse_spike
self.pending_spikes.append({"height": height + delay,
"claim_hash": claim_hash,
"size": spike})
self.claims[claim_hash] = {"total_amount": total_amount,
"trending_score": old_state["trending_score"],
"changed": False}
def process_whales(self, height):
"""
Whale claims decay faster.
"""
if height % SAVE_INTERVAL != 0:
def run(db, height, final_height, recalculate_claim_hashes):
if height < final_height - 5*HALF_LIFE:
trending_log(f"Skipping trending calculations at block {height}.\n")
return
for claim_hash in self.whales:
trending_normed = self.claims[claim_hash]["trending_score"]/get_time_boost(height)
# Overall multiplication factor for decay rate
decay_rate_factor = trending_normed/WHALE_THRESHOLD
# The -1 is because this is just the *extra* part being applied
factor = (DECAY**SAVE_INTERVAL)**(decay_rate_factor - 1.0)
# print(claim_hash, trending_normed, decay_rate_factor)
self.claims[claim_hash]["trending_score"] *= factor
self.claims[claim_hash]["changed"] = True
start = time.time()
trending_log(f"Calculating variable_decay trending at block {height}.\n")
trending_data.update(db, height, recalculate_claim_hashes)
end = time.time()
trending_log(f"Trending operations took {end - start} seconds.\n\n")
def test_trending():
"""
@ -260,12 +405,12 @@ def test_trending():
COMMIT;
""")
# Initialise trending data before anything happens with the claims
trending_data.initialise(db)
# Insert initial states of claims
everything = {"huge_whale": 0.01,
"huge_whale_botted": 0.01,
"medium_whale": 0.01,
"small_whale": 0.01,
"minnow": 0.01}
everything = {"huge_whale": 0.01, "medium_whale": 0.01, "small_whale": 0.01,
"huge_whale_botted": 0.01, "minnow": 0.01}
def to_list_of_tuples(stuff):
l = []
@ -277,13 +422,17 @@ def test_trending():
INSERT INTO claim (claim_hash, amount) VALUES (?, 1E8*?);
""", to_list_of_tuples(everything))
# Process block zero
height = 0
run(db, height, height, everything.keys())
# Save trajectories for plotting
trajectories = {}
for key in trending_data.claims:
trajectories[key] = [trending_data.claims[key]["trending_score"]]
for row in trending_data.execute("""
SELECT claim_hash, trending_score
FROM claims;
"""):
trajectories[row[0]] = [row[1]/trending_unit(height)]
# Main loop
for height in range(1, 1000):
@ -312,119 +461,24 @@ def test_trending():
# Call run()
run(db, height, height, everything.keys())
for key in trending_data.claims:
trajectories[key].append(trending_data.claims[key]["trending_score"]\
/get_time_boost(height))
# Append current trending scores to trajectories
for row in db.execute("""
SELECT claim_hash, trending_mixed
FROM claim;
"""):
trajectories[row[0]].append(row[1]/trending_unit(height))
dbc.close()
# pylint: disable=C0415
import matplotlib.pyplot as plt
for key in trending_data.claims:
for key in trajectories:
plt.plot(trajectories[key], label=key)
plt.legend()
plt.show()
# One global instance
# pylint: disable=C0103
trending_data = TrendingData()
def run(db, height, final_height, recalculate_claim_hashes):
if height < final_height - 5*HALF_LIFE:
trending_log("Skipping variable_decay trending at block {h}.\n".format(h=height))
return
start = time.time()
trending_log("Calculating variable_decay trending at block {h}.\n".format(h=height))
trending_log(" Length of trending data = {l}.\n"\
.format(l=len(trending_data.claims)))
# Renormalise trending scores and mark all as having changed
if height % RENORM_INTERVAL == 0:
trending_log(" Renormalising trending scores...")
keys = trending_data.claims.keys()
trending_data.whales = set([])
for key in keys:
if trending_data.claims[key]["trending_score"] != 0.0:
trending_data.claims[key]["trending_score"] *= DECAY_PER_RENORM
trending_data.claims[key]["changed"] = True
# Tiny becomes zero
if abs(trending_data.claims[key]["trending_score"]) < 1E-3:
trending_data.claims[key]["trending_score"] = 0.0
# Re-mark whales
if trending_data.claims[key]["trending_score"] >= WHALE_THRESHOLD*get_time_boost(height):
trending_data.add_whale(key)
trending_log("done.\n")
# Regular message.
trending_log(" Reading total_amounts from db and updating"\
+ " trending scores in RAM...")
# Update claims from db
if not trending_data.initialised:
trending_log("initial load...")
# On fresh launch
for row in db.execute("""
SELECT claim_hash, trending_mixed,
(amount + support_amount)
AS total_amount
FROM claim;
"""):
trending_data.insert_claim_from_load(height, row[0], row[1], 1E-8*row[2])
trending_data.initialised = True
else:
for row in db.execute(f"""
SELECT claim_hash,
(amount + support_amount)
AS total_amount
FROM claim
WHERE claim_hash IN
({','.join('?' for _ in recalculate_claim_hashes)});
""", recalculate_claim_hashes):
trending_data.update_claim(height, row[0], 1E-8*row[1])
# Apply pending spikes
trending_data.apply_spikes(height)
trending_log("done.\n")
# Write trending scores to DB
if height % SAVE_INTERVAL == 0:
trending_log(" Finding and processing whales...")
trending_log(str(len(trending_data.whales)) + " whales found...")
trending_data.process_whales(height)
trending_log("done.\n")
trending_log(" Writing trending scores to db...")
the_list = []
keys = trending_data.claims.keys()
for key in keys:
if trending_data.claims[key]["changed"]:
the_list.append((trending_data.claims[key]["trending_score"], key))
trending_data.claims[key]["changed"] = False
trending_log("{n} scores to write...".format(n=len(the_list)))
db.executemany("UPDATE claim SET trending_mixed=? WHERE claim_hash=?;",
the_list)
trending_log("done.\n")
trending_log("Trending operations took {time} seconds.\n\n"\
.format(time=time.time() - start))
if __name__ == "__main__":