Uniswap V4.

V4 keeps every pool inside a single PoolManager. ObolLadderManagerV4 adds and removes liquidity inside an unlock callback and settles once per currency.

Ladder manager

0x761F…Fe05

PoolManager

0x8366…0951

StateView

0xF333…673b

Positions per ladder

One position per bin, owner = the manager, salt = keccak256(ladderId, bin)

Native ETH

Supported (currency0 = address(0)); send ETH as msg.value

#Pools are identified by a PoolKey

A V4 pool is defined by its PoolKey: both currencies (sorted), fee, tick spacing and hooks contract. Its id is keccak256(abi.encode(key)). The app resolves the key of each pool from the PoolManager's Initialize event.

struct PoolKey {
    Currency currency0;   // address(0) = native ETH
    Currency currency1;
    uint24 fee;           // hundredths of a bip, 0x800000 = dynamic
    int24 tickSpacing;
    address hooks;
}

#Unlock and flash accounting

1. unlock

   The manager calls poolManager.unlock(data); the PoolManager calls back unlockCallback, which only accepts calls from the PoolManager.

2. modifyLiquidity per bin

   Each bin is a modifyLiquidity call. The resulting deltas are summed per currency.

3. settle or take

   Negative deltas are paid (sync → transfer → settle, or settle with ETH for the native currency); positive deltas are withdrawn with take. The pool must end fully settled.

Read more: flash accounting.

#Fees on V4

modifyLiquidity returns both callerDelta (principal + fees) and feesAccrued, so the manager knows exactly which part is fees and applies the 7.5% only to it. pendingFees is computed from StateView.getFeeGrowthInside and each position's last fee growth.

#Learn more