transaction packing simulator

tx_pool_sim.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

import string
import random
import time

GAS_BLOCK_LIMIT = 8000000
GAS_UPPER_LIMIT = 300000
GAS_LOWER_LIMIT = 21000

GAS_PRICE_UPPER_LIMIT = 10 # 10GWei
GAS_PRICE_LOWER_LIMIT = 1  # 1GWei

def id_generator(size=40, chars=string.hexdigits):
    return ''.join(random.choice(chars) for _ in range(size))

def init_txs(size=5):
    txs = []
    for nonce in range(size):
        txs.append({"price": random.randint(GAS_PRICE_LOWER_LIMIT * 10, GAS_PRICE_UPPER_LIMIT * 10) / 10.0, 
                    "gas": random.randint(GAS_LOWER_LIMIT, GAS_UPPER_LIMIT),
                    "nonce": nonce})
    return txs

def init_pool(init_accounts=5):
    accounts = []
    for _ in range(init_accounts):
        num = random.randint(0, 10)
        accounts.append({"address": id_generator(),
                         "txs": init_txs(num),
                         "nonce": num})
    return accounts        

def new_txs(size, accounts):
    for _ in range(size):
        if bool(random.getrandbits(1)):
            # generate a txs belongs to existing account
            account = accounts[random.randint(0, len(accounts)-1)]
            account["txs"].append({"price":random.randint(GAS_PRICE_LOWER_LIMIT, GAS_PRICE_UPPER_LIMIT), 
                        "gas":random.randint(GAS_LOWER_LIMIT, GAS_UPPER_LIMIT),
                        "nonce": account["nonce"]})
            account["nonce"] += 1
        else:
            # create a new account
            accounts.append({"address": id_generator(),
                             "txs": init_txs(1),
                             "nonce": 1})
    return accounts

def calculate(pool):
    gasUsed = 0
    reward = 0
    counter = 0

    for account in pool:
        account["tmp"] = 0

    while gasUsed <= GAS_BLOCK_LIMIT:
        current = []
        for idx, account in enumerate(pool):
            if account["tmp"] == account["nonce"]:
                continue
            current.append((idx, account["txs"][account["tmp"]]))
        if len(current) == 0:
            break

        current.sort(key=lambda x: x[1]["price"], reverse=True)

        if gasUsed + current[0][1]["gas"] <= GAS_BLOCK_LIMIT:
            gasUsed += current[0][1]["gas"] 
            counter += 1
            reward += current[0][1]["gas"] * current[0][1]["price"]
            # print "add", current[0][1]
        pool[current[0][0]]["tmp"] += 1
    return gasUsed, counter, reward

def simluate():
    pool = init_pool(1)
    gasUsed = 0 
    reward = 0 
    counter = 0
    while True:
        # insert 2 new txs
        pool = new_txs(2, pool) 
        g, c, r = calculate(pool)

        if r < reward:
            print "=================================="
            print "gasUsed", gasUsed, "tx number", counter, "total reward", reward
            print "new gasUsed", g, "new tx number", c, "new total reward", r
        gasUsed, counter, reward = g, c, r
        
if __name__ == "__main__":
    simluate()