Discussion-0001 : Ordering in Parallel TX Processing

[StuartFarmer]

Assume the following:

token.balance_of('stu') = 10

def transfer(from, to, amount):
    from_balance = get_balance_row(from)
    to_balance = get_balance_row(to)

    if from_balance >= amount:
        write_balance_row(to, to_balance + amount)
        write_balance_row(from, from_balance - amount)

rows affected in order:
[
    (READ, from),
    (READ, to),
    (WRITE, to),
    (WRITE, from)
]

Subtree block from MN-Africa:

transfer('raghu', 'stu', 1)

[
    (READ, 'raghu'),
    (READ, 'stu'),
    (WRITE, 'stu'),
    (WRITE, 'raghu')
]

Subtree block from MN-Asia:

transfer('stu', 'davis', 1)

[
    (READ, 'stu'),
    (READ, 'davis'),
    (WRITE, 'davis'),
    (WRITE, 'stu')
]

Subtree block from MN-America:

def funky_town(from, to_1, to_2, to_3):
    from_balance = get_balance_row(from)

    if from_balance < 10:
        transfer(from, to_1)
    elif from_balance > 10:
        transfer(from, to_2)
    else: # balance == 10
        transfer(from, to_3)

funky_town('stuart', 'raghu', 'davis', 'falcon'

Delegate Africa gets subtrees in order:

transfer('raghu', 'stu', 10)
transfer('stu', 'davis', 1)
funky_town('stuart', 'raghu', 'davis', 'falcon'

rows affected:

[
    (READ, 'raghu'),
    (READ, 'stu'),
    (WRITE, 'stu'),
    (WRITE, 'raghu')
],
[
    (READ, 'stu'),
    (READ, 'davis'),
    (WRITE, 'davis'),
    (WRITE, 'stu')
],
[ # funky_town
    (READ, 'stu'), # balance == 19, transfer to falcon
    
    (READ, 'stu'),
    (READ, 'raghu'),
    (WRITE, 'raghu'),
    (WRITE, 'stu')
]

Delegate Asia gets subtrees in order:

transfer('stu', 'davis', 1)
funky_town('stuart', 'raghu', 'davis', 'falcon'
transfer('raghu', 'stu', 10)

rows affected:
[
    (READ, 'stu'),
    (READ, 'davis'),
    (WRITE, 'davis'),
    (WRITE, 'stu')
],
[ # funky_town
    (READ, 'stu'), # balance == 9, transfer to davis
    
    (READ, 'stu'),
    (READ, 'davis'),
    (WRITE, 'davis'),
    (WRITE, 'stu')
],
[
    (READ, 'raghu'),
    (READ, 'stu'),
    (WRITE, 'stu'),
    (WRITE, 'raghu')
]

Delegate America gets subtrees in order:

funky_town('stuart', 'raghu', 'davis', 'falcon'
transfer('raghu', 'stu', 1)
transfer('stu', 'davis', 1)

rows affected:
[ # funky_town
    (READ, 'stu'), # balance == 10, transfer to falcon
    
    (READ, 'stu'),
    (READ, 'falcon'),
    (WRITE, 'falcon'),
    (WRITE, 'stu')
],
[
    (READ, 'raghu'),
    (READ, 'stu'),
    (WRITE, 'stu'),
    (WRITE, 'raghu')
],
[
    (READ, 'stu'),
    (READ, 'davis'),
    (WRITE, 'davis'),
    (WRITE, 'stu')
]

Under this system, by describing smart contracts as READs and WRITEs, we can find the collisions and rerun them.

[JeffWScott]

Unless I'm not understanding, I think you mixed up in your funkytown results.