Interesting idea!
[Q]: how to collect the instantiations that happen within the contracts (-> new)?
One option is to inspect transaction traces. Geth provides traceTransaction API https://github.com/ethereum/go-ethereum/wiki/Management-APIs#debug_tracetransaction which is available only for transactions executed while running in full archival node mode. You would need to look for CREATE
opcode, the address of the newly created account will be on top of the stack
in the next opcode for the same call depth (or 0x0 if CREATE
was unsuccessful). Then look up its bytecode in the leveldb database.
Another options is to use callTracer
introduced in geth 1.8, which can extract internal calls including CREATE
https://github.com/ethereum/go-ethereum/pull/15516. They give an example where you can create a subscription via ipc and get internal transactions from multiple blocks:
$ nc -U /work/temp/rinkeby/geth.ipc
{"id": 1, "method": "debug_subscribe", "params": ["traceChain", "0x0",
"0xffff", {"tracer": "callTracer"}]}
{"jsonrpc":"2.0","id":1,"result":"0xe1deecc4b399e5fd2b2a8abbbc4624e2"}
{"jsonrpc":"2.0","method":"debug_subscription","params":{"subscription":"0xe1deecc4b399e5fd2b2a8abbbc4624e2","result":{"block":"0x37","hash":"0xdb16f0d4465f2fd79f10ba539b169404a3e026db1be082e7fd6071b4c5f37db7","traces":[{"from":"0x31b98d14007bdee637298086988a0bbd31184523","gas":"0x0","gasUsed":"0x0","input":"0x","output":"0x","time":"1.077µs","to":"0x2ed530faddb7349c1efdbf4410db2de835a004e4","type":"CALL","value":"0xde0b6b3a7640000"}]}}}
{"jsonrpc":"2.0","method":"debug_subscription","params":{"subscription":"0xe1deecc4b399e5fd2b2a8abbbc4624e2","result":{"block":"0xf43","hash":"0xacb74aa08838896ad60319bce6e07c92edb2f5253080eb3883549ed8f57ea679","traces":[{"from":"0x31b98d14007bdee637298086988a0bbd31184523","gas":"0x0","gasUsed":"0x0","input":"0x","output":"0x","time":"1.568µs","to":"0xbedcf417ff2752d996d2ade98b97a6f0bef4beb9","type":"CALL","value":"0xde0b6b3a7640000"}]}}}
{"jsonrpc":"2.0","method":"debug_subscription","params":{"subscription":"0xe1deecc4b399e5fd2b2a8abbbc4624e2","result":{"block":"0xf47","hash":"0xea841221179e37ca9cc23424b64201d8805df327c3296a513e9f1fe6faa5ffb3","traces":[{"from":"0xbedcf417ff2752d996d2ade98b97a6f0bef4beb9","gas":"0x4687a0","gasUsed":"0x12e0d","input":"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","output":"0x60606040526000357c0100000000000000000000000000000000000000000000000000000000900463ffffffff168063230925601461003b575bfe5b341561004357fe5b61008360048080356000191690602001909190803560ff1690602001909190803560001916906020019091908035600019169060200190919050506100c5565b604051808273ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200191505060405180910390f35b6000600185858585604051806000526020016040526000604051602001526040518085600019166000191681526020018460ff1660ff1681526020018360001916600019168152602001826000191660001916815260200194505050505060206040516020810390808403906000866161da5a03f1151561014257fe5b50506020604051035190505b9493505050505600a165627a7a7230582054abc8e7b2d8ea0972823aa9f0df23ecb80ca0b58be9f31b7348d411aaf585be0029","time":"658.529µs","to":"0x5481c0fe170641bd2e0ff7f04161871829c1902d","type":"CREATE","value":"0x0"}]}}}
{"jsonrpc":"2.0","method":"debug_subscription","params":{"subscription":"0xe1deecc4b399e5fd2b2a8abbbc4624e2","result":{"block":"0xfff","hash":"0x254ccbc40eeeb183d8da11cf4908529f45d813ef8eefd0fbf8a024317561ac6b"}}}
[Q]: traversing the complete trie block by block is most probably inefficient. Is there a way to traverse only the paths that changed since the last block?
I think it's possible to efficiently compute the diff of 2 Patricia Merkle Tries. The general idea is you take 2 roots, check their nibbles, go down the trie only for nibbles that are different in both roots. Repeat it recursively for the lower level nodes. There will be some complications related to leaf/extension nodes but I think they are solvable.
Another option is to keep track of the Patricia Trie nodes that you already traversed in previous blocks, and skip them for further blocks.