gaspipe

A service to estimate gas for multiple dependent Ethereum transactions.

Many user flows in Ethereum nowadays involve sending multiple transactions together (i.e. approve, then deposit). A nice UX would have the user sign them all at once and broadcast them together, ideally confirming in a single block. One challenge with this currently is that it's often difficult to estimate the gas cost for the second transaction given it depends on the first. gaspipe solves this problem by executing transactions on a light fork, so each subsequent transaction benefits from the state changes of the last.

Usage

$ FORK_URL=https://mainnet.infura.io/v3/<key> gaspipe    

Querying

For example, if you want to estimate an approve followed by a transfer:

$ curl -X POST -H "content-type: application/json" localhost:8000/estimate -d '
[
{
    "from": "0x28c6c06298d514db089934071355e5743bf21d60",
    "to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "value": "0",
    "data": "0x095ea7b3000000000000000000000000111111111111111111111111111111111111111100000000000000000000000000000000000000000000000000000000000f4240"
},
{
    "from": "0x1111111111111111111111111111111111111111",
    "to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "value": "0",
    "data": "0x23b872dd00000000000000000000000028c6c06298d514db089934071355e5743bf21d60000000000000000000000000111111111111111111111111111111111111111100000000000000000000000000000000000000000000000000000000000f4240"
}
]'

[{"gas":59963,"reverted":false},{"gas":50056,"reverted": false}] 

Performance

Current average time to estimate the above example: ~1.7s. Local fork caching allows for faster times on subsequent calls against the same block (~2.9s on fresh block, ~1.2s on repeat block).

$ for x in {1..10}; do time curl <estimate>; done

curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.00s user 0.00s system 0% cpu 2.936 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.01s user 0.00s system 0% cpu 1.223 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.00s user 0.01s system 0% cpu 1.186 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.00s user 0.01s system 0% cpu 1.180 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.00s user 0.00s system 0% cpu 1.286 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.01s user 0.00s system 0% cpu 1.195 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.01s user 0.00s system 0% cpu 1.206 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.00s user 0.01s system 0% cpu 1.176 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.00s user 0.01s system 0% cpu 1.207 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.00s user 0.01s system 0% cpu 2.867 total
curl -X POST -H "content-type: application/json" localhost:8000/estimate -d   0.01s user 0.00s system 0% cpu 1.213 total

Future Improvements

• Add an RPC eth_estimateGas style endpoint for simpler migration
• Improve latency