v2.5.0 - Constantinople, Consensus, StateManager

This is the first release of the VM with full support for all Constantinople EIPs. It further comes along with huge improvements on consensus conformity and introduces the Beta version of a new StateManager API.

Constantinople Support

For running the VM with Constantinople hardfork rules, set the option in the VM constructor opts.hardfork to constantinople. Supported hardforks are byzantium and constantinople, default setting will stay on byzantium for now but this will change in a future release.

Changes related to Constantinople:

• EIP 1283 SSTORE, see PR #367
• EIP 1014 CREATE2, see PR #329
• EIP 1052 EXTCODEHASH, see PR #324
• Constantinople ready versions of ethereumjs-block and ethereumjs-blockchain dependencies (difficulty bomb delay), see PRs #371, #325

Consensus Conformity

This release is making a huge leap forward regarding consensus conformity, and even if you are not interested in Constantinople support at all, you should upgrade just for this reason. Some context: we couldn't run blockchain tests for a long time on a steady basis due to performance constraints and when we re-triggered a test run after quite some time with PR #341 the result was a bit depressing with over 300 failing tests. Thanks to joined efforts from the community and core team members we could bring this down far quicker than expected and this is the first release for a long time which practically comes with complete consensus conformity - with just three recently added tests failing (see skipBroken list in tests/tester.js) and otherwise passing all blockchain tests and all state tests for both Constantinople and Byzantium rules. 🏆 🏆 🏆

Consensus Conformity related changes:

• Reset selfdestruct on REVERT, see PR #392
• Undo Bloom filter changes from PR #295, see PR #384
• Fixes broken BLOCKHASH opcode, see PR #381
• Fix failing blockchain test GasLimitHigherThan2p63m1, see PR #380
• Stop adding account to cache when checking if it is empty, see PR #375

State Manager Interface

The StateManager (lib/stateManager.js) - providing a high-level interface to account and contract data from the underlying state trie structure - has been completely reworked and there is now a close-to-being finalized API (currently marked as Beta) coming with its own documentation.

This comes along with larger refactoring work throughout more-or-less the whole code base and the StateManager now completely encapsulates the trie structure and the cache backend used, see issue #268 and associated PRs for reference. This will make it much easier in the future to bring along an own state manager serving special needs (optimized for memory and performance, run on mobile,...) by e.g. using a different trie implementation, cache or underlying storage or database backend.

We plan to completely separate the currently still integrated state manager into its own repository in one of the next releases, this will then be a breaking v3.0.0 release. Discussion around a finalized interface (we might e.g. drop all genesis-releated methods respectively methods implemented in the DefaultStateManager) is still ongoing and you are very much invited to jump in and articulate your needs, just take e.g. the issue mentioned above as an entry point.

Change related to the new StateManager interface:

• StateManager interface simplification, see PR #388
• Make StateManager cache and trie private, see PR #385
• Remove vm accesses to StateManager trie and cache, see PR #376
• Remove explicit direct cache interactions, see PR #366
• Remove contract specific commit, see PR #335
• Fixed incorrect references to trie in tests, see PR #345
• Added StateManager API documentation, see PR #393

New Features

• New emitFreeLogs option, allowing any contract to emit an unlimited quantity of events without modifying the block gas limit (default: false) which can be used in debugging contexts, see PRs #378, #379

Testing and Documentation

Beyond the reintegrated blockchain tests there is now a separate test suite to test the API of the library, see tests/api. This should largely reduce the risk of introducing new bugs on the API level on future changes, generally ease the development process by being able to develop against the specific tests and also allows using the tests as a reference for examples on how to use the API.

On the documentation side the API documentation has also been consolidated and there is now a unified and auto-generated API documentation (previously being manually edited (and too often forgotten) in README).

• Added API tests for index.js, StateManager, see PR #364
• Added API Tests for runJit and fakeBlockchain, see PR #331
• Added API tests for runBlockchain, see PR #336
• Added runBlock API tests, see PR #360
• Added runTx API tests, see PR #352
• Added API Tests for the Bloom module, see PR #330
• New consistent auto-generated API documentation, see PR #377
• Blockchain tests now run by default on CI, see PR #374
• Switched from istanbul to nyc, see PR #334
• Usage of sealEngine in blockchain tests, see PR #373
• New tap-spec option to get a formatted test run result summary, see README, see PR #363
• Updates/fixes on the JSDoc comments, see PRs #362, #361

Bug Fixes and Maintenance

Some bug fix and maintenance updates:

• Fix error handling in fakeBlockChain, see PR #320
• Update of ethereumjs-util to v6.0.0, see PR #369

Thank You

Special thanks to:

• @mattdean-digicatapult for his indefatigable work on the new StateManager interface and for fixing a large portion of the failing blockchain tests
• @rmeissner for the work on Constantinople
• @vpulim for jumping in so quickly and doing a reliable SSTORE implementation within 4 days
• @s1na for the new API test suite

Beyond this release contains contributions from the following people:
@jwasinger, @Agusx1211, @holgerd77, @danjm, @whymarrh, @seesemichaelj, @kn

Thank you all very much, and thanks @axic for keeping an ongoing eye on overall library quality!