This PR adds support for block overrides when doing debug_traceCall.
- Previously, debug_traceCall against pending erroneously used a common.Hash{} stateroot when looking up the state, meaning that a totally empty state was used -- so it always failed,
- With this change, we reject executing debug_traceCall against pending.
- And we add ability to override all evm-visible header fields.
This adds a JS tracer runtime environment based on the Goja VM. The new
runtime replaces the duktape runtime, which will be removed soon.
Goja is implemented in Go and is faster for cases where the Go <-> JS
transition overhead dominates overall performance. It is faster because
duktape is written in C, and the transition cost includes the cost of using
cgo. Another reason for using Goja is that go-duktape is not maintained
anymore.
We expect the performace of JS tracing to be at least as good or better with
this change.
Previously freezer has only been used for storing ancient chain data, while obviously it can be used more. This PR unties the chain data and freezer, keep the minimal freezer structure and move all other logic (like incrementally freezing block data) into a separate structure called ChainFreezer.
This PR also extends the database interface by adding a new ancient store function AncientDatadir which can return the root directory of ancient store. The ancient root directory can be used when we want to open some other ancient-stores (e.g. reverse diff freezer).
* core: recover the state in SetChainHead if the head state is missing
* core: disable test logging
* core: address comment from martin
* core: improve log level in case state is recovered
* core, eth, les, light: rename SetChainHead to SetCanonical
This PR fixes the flaw that @rjl493456442 found in https://github.com/ethereum/go-ethereum/pull/#issuecomment-1093817551 , namely, that the snapshot iterator uses the combined (disk + difflayers) 'view', wheres the raw iterator uses only the disk 'view'.
This PR instead splits up the work: one phase is iterating the disk layer data, another phase is loading the journalled difflayers and performing the same check there.
This adds a tools.go file to import all command packages used for
go:generate. Doing so makes it possible to execute go-based code
generators using 'go run', locking in the tool version using go.mod.
Co-authored-by: Felix Lange <fjl@twurst.com>
This PR fixes a few panics in the chain marker benchmarks. The root
cause for panic is in chain marker the genesis header/block is not
accessible, while it's expected to be obtained in tests. So this PR
avoids touching genesis header at all to avoid panic.
This commit replaces ioutil.TempDir with t.TempDir in tests. The
directory created by t.TempDir is automatically removed when the test
and all its subtests complete.
Prior to this commit, temporary directory created using ioutil.TempDir
had to be removed manually by calling os.RemoveAll, which is omitted in
some tests. The error handling boilerplate e.g.
defer func() {
if err := os.RemoveAll(dir); err != nil {
t.Fatal(err)
}
}
is also tedious, but t.TempDir handles this for us nicely.
Reference: https://pkg.go.dev/testing#T.TempDir
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
* core,eth: add empty tx logger hooks
* core,eth: add initial and remaining gas to tx hooks
* store tx gasLimit in js tracer
* use gasLimit to compute intrinsic cost for js tracer
* re-use rules in transitiondb
* rm logs
* rm logs
* Mv some fields from Start to TxStart
* simplify sender lookup in prestate tracer
* mv env to TxStart
* Revert "mv env to TxStart"
This reverts commit 656939634b9aff19f55a1cd167345faf8b1ec310.
* Revert "simplify sender lookup in prestate tracer"
This reverts commit ab65bce48007cab99e68232e7aac2fe008338d50.
* Revert "Mv some fields from Start to TxStart"
This reverts commit aa50d3d9b2559addc80df966111ef5fb5d0c1b6b.
* fix intrinsic gas for prestate tracer
* add comments
* refactor
* fix test case
* simplify consumedGas calc in prestate tracer
Trie tracer is an auxiliary tool to capture all deleted nodes
which can't be captured by trie.Committer. The deleted nodes
can be removed from the disk later.
* cmd,core: add simple legacy receipt converter
core/rawdb: use forEach in migrate
core/rawdb: batch reads in forEach
core/rawdb: make forEach anonymous fn
cmd/geth: check for legacy receipts on node startup
fix err msg
Co-authored-by: rjl493456442 <garyrong0905@gmail.com>
fix log
Co-authored-by: rjl493456442 <garyrong0905@gmail.com>
fix some review comments
add warning to cmd
drop isLegacy fn from migrateTable params
add test for windows rename
test replacing in windows case
* minor fix
* sanity check for tail-deletion
* add log before moving files around
* speed-up hack for mainnet
* fix mainnet check, use networkid instead
* check mainnet genesis
* review fixes
* resume previous migration attempt
* core/rawdb: lint fix
Co-authored-by: Martin Holst Swende <martin@swende.se>
* core/beacon: eth/catalyst: updated engine api to new version
* core: implement exchangeTransitionConfig
* core/beacon: prevRandao instead of Random
* eth/catalyst: Fix ExchangeTransitionConfig, add test
* eth/catalyst: stop external miners on TTD reached
* node: implement --authrpc.vhosts flag
* core: allow for config override on non-mainnet networks
* eth/catalyst: fix peters comments
* eth/catalyst: make stop remote sealer more explicit
* eth/catalyst: add log output
* cmd/utils: rename authrpc.host to authrpc.addr
* eth/catalyst: disable the disabling of the miner
* eth: core: remove notion of terminal pow block
* eth: les: more of peters nitpicks
We want to be able to capture StateUpdates even if the Geth snapshot
trie is in a weird state and can't offer the snapshot we're looking
for. This adds our own implementation of the Snapshot() interface
so that we can continue collecting the necessary information to make
it available to the StateUpdates hook.
* eth/downloader: implement beacon sync
* eth/downloader: fix a crash if the beacon chain is reduced in length
* eth/downloader: fix beacon sync start/stop thrashing data race
* eth/downloader: use a non-nil pivot even in degenerate sync requests
* eth/downloader: don't touch internal state on beacon Head retrieval
* eth/downloader: fix spelling mistakes
* eth/downloader: fix some typos
* eth: integrate legacy/beacon sync switchover and UX
* eth: handle UX wise being stuck on post-merge TTD
* core, eth: integrate the beacon client with the beacon sync
* eth/catalyst: make some warning messages nicer
* eth/downloader: remove Ethereum 1&2 notions in favor of merge
* core/beacon, eth: clean up engine API returns a bit
* eth/downloader: add skeleton extension tests
* eth/catalyst: keep non-kiln spec, handle mining on ttd
* eth/downloader: add beacon header retrieval tests
* eth: fixed spelling, commented failing tests out
* eth/downloader: review fixes
* eth/downloader: drop peers failing to deliver beacon headers
* core/rawdb: track beacon sync data in db inspect
* eth: fix review concerns
* internal/web3ext: nit
Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>
* core/rawdb, cmd, ethdb, eth: implement freezer tail deletion
* core/rawdb: address comments from martin and sina
* core/rawdb: fixes cornercase in tail deletion
* core/rawdb: separate metadata into a standalone file
* core/rawdb: remove unused code
* core/rawdb: add random test
* core/rawdb: polish code
* core/rawdb: fsync meta file before manipulating the index
* core/rawdb: fix typo
* core/rawdb: address comments
This change makes use of the new code generator rlp/rlpgen to improve the
performance of RLP encoding for Header and StateAccount. It also speeds up
encoding of ReceiptForStorage using the new rlp.EncoderBuffer API.
The change is much less transparent than I wanted it to be, because Header and
StateAccount now have an EncodeRLP method defined with pointer receiver. It
used to be possible to encode non-pointer values of these types, but the new
method prevents that and attempting to encode unadressable values (even if
part of another value) will return an error. The error can be surprising and may
pop up in places that previously didn't expect any errors.
To make things work, I also needed to update all code paths (mostly in unit tests)
that lead to encoding of non-pointer values, and pass a pointer instead.
Benchmark results:
name old time/op new time/op delta
EncodeRLP/legacy-header-8 328ns ± 0% 237ns ± 1% -27.63% (p=0.000 n=8+8)
EncodeRLP/london-header-8 353ns ± 0% 247ns ± 1% -30.06% (p=0.000 n=8+8)
EncodeRLP/receipt-for-storage-8 237ns ± 0% 123ns ± 0% -47.86% (p=0.000 n=8+7)
EncodeRLP/receipt-full-8 297ns ± 0% 301ns ± 1% +1.39% (p=0.000 n=8+8)
name old speed new speed delta
EncodeRLP/legacy-header-8 1.66GB/s ± 0% 2.29GB/s ± 1% +38.19% (p=0.000 n=8+8)
EncodeRLP/london-header-8 1.55GB/s ± 0% 2.22GB/s ± 1% +42.99% (p=0.000 n=8+8)
EncodeRLP/receipt-for-storage-8 38.0MB/s ± 0% 64.8MB/s ± 0% +70.48% (p=0.000 n=8+7)
EncodeRLP/receipt-full-8 910MB/s ± 0% 897MB/s ± 1% -1.37% (p=0.000 n=8+8)
name old alloc/op new alloc/op delta
EncodeRLP/legacy-header-8 0.00B 0.00B ~ (all equal)
EncodeRLP/london-header-8 0.00B 0.00B ~ (all equal)
EncodeRLP/receipt-for-storage-8 64.0B ± 0% 0.0B -100.00% (p=0.000 n=8+8)
EncodeRLP/receipt-full-8 320B ± 0% 320B ± 0% ~ (all equal)
This PR adds an addtional API called `NewBatchWithSize` for db
batcher. It turns out that leveldb batch memory allocation is
super inefficient. The main reason is the allocation step of
leveldb Batch is too small when the batch size is large. It can
take a few second to build a leveldb batch with 100MB size.
Luckily, leveldb also offers another API called MakeBatch which can
pre-allocate the memory area. So if the approximate size of batch is
known in advance, this API can be used in this case.
It's needed in new state scheme PR which needs to commit a batch of
trie nodes in a single batch. Implement the feature in a seperate PR.
* cmd/geth: add db cmd to show metadata
* cmd/geth: better output generator status
Co-authored-by: Sina Mahmoodi <1591639+s1na@users.noreply.github.com>
* cmd: minor
Co-authored-by: Sina Mahmoodi <1591639+s1na@users.noreply.github.com>
Co-authored-by: Sina Mahmoodi <itz.s1na@gmail.com>
* freezer: add readonly flag to table
* freezer: enforce readonly in table repair
* freezer: enforce readonly in newFreezer
* minor fix
* minor
* core/rawdb: test that writing during readonly fails
* rm unused log
* check readonly on batch append
* minor
* Revert "check readonly on batch append"
This reverts commit 2ddb5ec4ba7534bf6edbdfec158ea99a2eed5036.
* review fixes
* minor test refactor
* attempt at fixing windows issue
* add comment re windows sync issue
* k->kind
* open readonly db for genesis check
Co-authored-by: Martin Holst Swende <martin@swende.se>
* core: implement eip-4399 random opcode
* core: make vmconfig threadsafe
* core: miner: pass vmConfig by value not reference
* all: enable 4399 by Rules
* core: remove diff (f)
* tests: set proper difficulty (f)
* smaller diff (f)
* eth/catalyst: nit
* core: make RANDOM a pointer which is only set post-merge
* cmd/evm/internal/t8ntool: fix t8n tracing of 4399
* tests: set difficulty
* cmd/evm/internal/t8ntool: check that baserules are london before applying the merge chainrules
The loop variable changes before the defer executes, so we need to
pass it to the function to make sure the closure has the correct
version of the loop variable.
It turns out we were only notifying plugins of freezer commits and
cleaning up our record when the block being processed was greater
than MAX_UINT64.
So, uh, never.
While looking for the source of a memory leak, I decided to optimize
the metatracer to avoid encoding values when there weren't any tracers
configured to received the encoded values.
I also avoided putting the EVM into debug mode when there weren't any
tracers configured.
None of these fixed the memory leak, but they still seem like good
practices. Memory leak fix is in the next commit.
* core/vm: reverse bit order in bytes of code bitmap
This bit order is more natural for bit manipulation operations and we
can eliminate some small number of CPU instructions.
* core/vm: drop lookup table
This PR reduces the amount of work we do when answering header queries, e.g. when a peer
is syncing from us.
For some items, e.g block bodies, when we read the rlp-data from database, we plug it
directly into the response package. We didn't do that for headers, but instead read
headers-rlp, decode to types.Header, and re-encode to rlp. This PR changes that to keep it
in RLP-form as much as possible. When a node is syncing from us, it typically requests 192
contiguous headers. On master it has the following effect:
- For headers not in ancient: 2 db lookups. One for translating hash->number (even though
the request is by number), and another for reading by hash (this latter one is sometimes
cached).
- For headers in ancient: 1 file lookup/syscall for translating hash->number (even though
the request is by number), and another for reading the header itself. After this, it
also performes a hashing of the header, to ensure that the hash is what it expected. In
this PR, I instead move the logic for "give me a sequence of blocks" into the lower
layers, where the database can determine how and what to read from leveldb and/or
ancients.
There are basically four types of requests; three of them are improved this way. The
fourth, by hash going backwards, is more tricky to optimize. However, since we know that
the gap is 0, we can look up by the parentHash, and stlil shave off all the number->hash
lookups.
The gapped collection can be optimized similarly, as a follow-up, at least in three out of
four cases.
Co-authored-by: Felix Lange <fjl@twurst.com>
This PR fixes a special corner case in transaction indexing.
When the chain is rewound by SetHead to a historical point which is even lower than the transaction indexes tail, then system will report Failed to decode block body error all the time, because the relevant blocks are already deleted.
In order to avoid this "non-critical-but-annoying" issue, we can recap the indexing target to head+1(to is excluded, so it means indexing transactions from 0 to head).
* core/vm: Remove interpreter loop interruption check
* core/vm: Unit test for interpreter loop interruption
* core/vm: Check for interpreter loop abort on every jump
* core/vm: Move interpreter.ReadOnly check into the opcode implementations
Also remove the same check from the interpreter inner loop.
* core/vm: Remove obsolete operation.writes flag
* core/vm: Capture fault states in logger
Co-authored-by: Martin Holst Swende <martin@swende.se>
* core/vm: Remove panic added for testing
Co-authored-by: Martin Holst Swende <martin@swende.se>
* core/vm: break loop on any error
* core/vm: move ErrExecutionReverted to opRevert()
* core/vm: use "stop token" to stop the loop
* core/vm: unconditionally pc++ in the loop
* core/vm: set return data in instruction impls
* all: work for eth1/2 transtition
* consensus/beacon, eth: change beacon difficulty to 0
* eth: updates
* all: add terminalBlockDifficulty config, fix rebasing issues
* eth: implemented merge interop spec
* internal/ethapi: update to v1.0.0.alpha.2
This commit updates the code to the new spec, moving payloadId into
it's own object. It also fixes an issue with finalizing an empty blockhash.
It also properly sets the basefee
* all: sync polishes, other fixes + refactors
* core, eth: correct semantics for LeavePoW, EnterPoS
* core: fixed rebasing artifacts
* core: light: performance improvements
* core: use keyed field (f)
* core: eth: fix compilation issues + tests
* eth/catalyst: dbetter error codes
* all: move Merger to consensus/, remove reliance on it in bc
* all: renamed EnterPoS and LeavePoW to ReachTDD and FinalizePoS
* core: make mergelogs a function
* core: use InsertChain instead of InsertBlock
* les: drop merger from lightchain object
* consensus: add merger
* core: recoverAncestors in catalyst mode
* core: fix nitpick
* all: removed merger from beacon, use TTD, nitpicks
* consensus: eth: add docstring, removed unnecessary code duplication
* consensus/beacon: better comment
* all: easy to fix nitpicks by karalabe
* consensus/beacon: verify known headers to be sure
* core: comments
* core: eth: don't drop peers who advertise blocks, nitpicks
* core: never add beacon blocks to the future queue
* core: fixed nitpicks
* consensus/beacon: simplify IsTTDReached check
* consensus/beacon: correct IsTTDReached check
Co-authored-by: rjl493456442 <garyrong0905@gmail.com>
Co-authored-by: Péter Szilágyi <peterke@gmail.com>
* all: mv loggers to eth/tracers
* core/vm: minor
* eth/tracers: tmp comment out testStoreCapture
* eth/tracers: uncomment and fix logger test
* eth/tracers: simplify test
* core/vm: re-add license
* core/vm: minor
* rename LogConfig to Config
* cmd, core: add flag --dev.gaslimit to allow configuring initial block gas limit in dev mode
* core: use provided gaslimit
Co-authored-by: Martin Holst Swende <martin@swende.se>
The price limit is supposed to exclude transactions with too low fee
amount. Before EIP-1559, it was sufficient to check the limit against
the gas price of the transaction. After 1559, it is more complicated
because the concept of 'transaction gas price' does not really exist.
When mining, the price limit is used to exclude transactions below a
certain effective fee amount. This change makes it apply the same check
earlier, in tx validation. Transactions below the specified fee amount
cannot enter the pool.
Fixes#23837
This PR offers two more database sub commands for exporting and importing data.
Two exporters are implemented: preimage and snapshot data respectively.
The import command is generic, it can take any data export and import into leveldb.
The data format has a 'magic' for disambiguation, and a version field for future compatibility.
It is because write known block only checks block and state without snapshot, which could lead to gap between newest snapshot and newest block state. However, new blocks which would cause snapshot to become fixed were ignored, since state was already known.
Co-authored-by: Gary Rong <garyrong0905@gmail.com>
Co-authored-by: Martin Holst Swende <martin@swende.se>
We had been assuming that the `item` returned from batch.commit()
was the item committed, but it's actually the next item to be added
to the freezer, and multiple items can be committed in a single batch.
This commit finds the smallest item in the freezer and iterates from
that to the number returned by commit(), passing any tracked blocks
in that range to plugins.
* core: write test showing that TD is not stored properly at genesis
The ToBlock method applies a default value for an empty
difficulty value. This default is not carried over through the Commit
method because the TotalDifficulty database write writes the
original difficulty value (nil) instead of the defaulty value
present on the genesis Block.
Date: 2021-10-22 08:25:32-07:00
Signed-off-by: meows <b5c6@protonmail.com>
* core: write TD value from Block, not original genesis value
This an issue where a default TD value was not written to
the database, resulting in a 0 value TD at genesis.
A test for this issue was provided at 90e3ffd393
Date: 2021-10-22 08:28:00-07:00
Signed-off-by: meows <b5c6@protonmail.com>
* core: fix tests by adding GenesisDifficulty to expected result
See prior two commits.
Date: 2021-10-22 09:16:01-07:00
Signed-off-by: meows <b5c6@protonmail.com>
* les: fix test with genesis change
Co-authored-by: Martin Holst Swende <martin@swende.se>
This PR adds a new accessor method to the freezer database. This new view offers a consistent interface, guaranteeing that all individual tables (headers, bodies etc) are all on the same number, and that this number is not changes (added/truncated) while the operation is performing.
* core/state/snapshot: fix BAD BLOCK error when snapshot is generating
* core/state/snapshot: alternative fix for the snapshot generator
* add comments and minor update
Co-authored-by: Martin Holst Swende <martin@swende.se>
This commit adds a ModifyAncients hook that plugins can implement
to more accurately track what Geth is doing under the hood. We
still support the old AppendAncients interface as best we can,
though internal changes may make it so that it does not behave
as it once did.
Notes: the AppendAncient plugin hook is broken by this commit.
This adds CaptureEnter() and CaptureExit() as no-ops for interface
compliance, but these capabilities should be added for plugin tracers
soon.
This doesn't fix all go-critic warnings, just the most serious ones.
Co-authored-by: Felix Lange <fjl@twurst.com>
Co-authored-by: Martin Holst Swende <martin@swende.se>
This removes some code:
- The clique engine calculated the snapshot twice when verifying headers/blocks.
- The method GetBlockHashesFromHash in Header/Block/Lightchain was only used by tests. It
is now removed from the API.
- The method GetTdByHash internally looked up the number before calling GetTd(hash, num).
In many cases, callers already had the number, and used this method just because it has a
shorter name. I have removed the method to make the API surface smaller.
This change removes misuses of sync.WaitGroup in BlockChain. Before this change,
block insertion modified the WaitGroup counter in order to ensure that Stop would wait
for pending operations to complete. This was racy and could even lead to crashes
if Stop was called at an unfortunate time. The issue is resolved by adding a specialized
'closable' mutex, which prevents chain modifications after stopping while also
synchronizing writers with each other.
Co-authored-by: Felix Lange <fjl@twurst.com>
This resolves a long-standing TODO. The point of copying the address is
to ensure that all data referenced by types.Transaction is independent of the
data passed into the constructor.
Co-authored-by: Felix Lange <fjl@twurst.com>
* core/types: rm extranous check in test
* core/rawdb: add lightweight types for block logs
* core/rawdb,eth: use lightweight accessor for log filtering
* core/rawdb: add bench for decoding into rlpLogs
This change introduces 2 new optional methods; `enter()` and `exit()` for js tracers, and makes `step()` optiona. The two new methods are invoked when entering and exiting a call frame (but not invoked for the outermost scope, which has it's own methods). Currently these are the data fields passed to each of them:
enter: type (opcode), from, to, input, gas, value
exit: output, gasUsed, error
The PR also comes with a re-write of the callTracer. As a backup we keep the previous tracing script under the name `callTracerLegacy`. Behaviour of both tracers are equivalent for the most part, although there are some small differences (improvements), where the new tracer is more correct / has more information.
This makes several updates to support the blockupdates plugin.
I had to update several hooks that were using the wrong types, and
provide a way to get event.Feed objects into plugins without importing
event.Feed (which I did by having the plugin loader make them
available).
This change is a rewrite of the freezer code.
When writing ancient chain data to the freezer, the previous version first encoded each
individual item to a temporary buffer, then wrote the buffer. For small item sizes (for
example, in the block hash freezer table), this strategy causes a lot of system calls for
writing tiny chunks of data. It also allocated a lot of temporary []byte buffers.
In the new version, we instead encode multiple items into a re-useable batch buffer, which
is then written to the file all at once. This avoids performing a system call for every
inserted item.
To make the internal batching work, the ancient database API had to be changed. While
integrating this new API in BlockChain.InsertReceiptChain, additional optimizations were
also added there.
Co-authored-by: Felix Lange <fjl@twurst.com>
* core/rawdb: implement sequential reads in freezer_table
* core/rawdb, ethdb: add sequential reader to db interface
* core/rawdb: lint nitpicks
* core/rawdb: fix some nitpicks
* core/rawdb: fix flaw with deferred reads not being performed
* core/rawdb: better documentation
This adds a check to verify that a sender-account does not have code, which means that the codehash is either `emptyCodeHash` _OR_ not present. The latter occurs IFF the sender did not previously exist, a situation which can only occur with zero cost gasprices.
* internal/ethapi: revert + fix properly in al tracer
* internal/ethapi: use toMessage instead of creating new message
* internal/ethapi: remove ineffassign
* core: fix invalid unmarshalling, fix test
Co-authored-by: Martin Holst Swende <martin@swende.se>
When processing a transaction with London fork rules, EIP-1559 mandates
checking that the sender must have sufficient balance to cover gas * gasFeeCap.
In the EIP's pseudocode, this check happens after the value transferred by the
transaction has already been deducted. However, in go-ethereum, the balance
has not yet been updated when the check happens, and therefore needs to be
added explicitly.
Co-authored-by: Martin Holst Swende <martin@swende.se>
The encoding of Log and LogForStorage is exactly the same
now. After tracking it down it seems like #17106 changed the
storage schema of logs to be the same as the consensus
encoding.
Support for the legacy format was dropped in #22852 and if
I'm not wrong there's no reason anymore to have these two
equivalent types.
Since the RLP encoding simply contains the first three fields
of Log, we can also avoid creating a temporary struct for
encoding/decoding, and use the rlp:"-" tag in Log instead.
Note: this is an API change in core/types. We decided it's OK
to make this change because LogForStorage is an implementation
detail of go-ethereum and the type has zero uses outside of
package core/types.
Co-authored-by: Felix Lange <fjl@twurst.com>
When the plugin loader itself had to know the types in the arguments
and return values of the plugin functions, it was very difficult to
avoid import loops, given that the types were often defined in the
same package that needed to invoke the plugins.
Under this model, the plugin loader has much less knowledge of the
plugins themselves, and within each package we define functions to
interact with the plugins.
Things are currently broken because of import cycles. I'm going to
need to revisit how the plugin loader works, but I wanted to make
a checkpoint before I start breaking things again.
This change increases the cache size from 64 to 256 Mb for block bodies.
Benchmarks have shown this to be one bottleneck when trying to achieve
higher download speeds.
The commit also includes a minor optimization for header inserts in package
core: previously, the presence of headers in the database was checked for
every header before writing it. With the change, if one header fails the
presence check, all subsequent headers are also assumed to be missing.
This is an improvement because in practice, the headers are almost always
missing during sync.
Copy the CliqueConfig instead of reusing the pointer.
This makes DeveloperGenesisBlock thread safe and prevents it from
changing params.AllCliqueProtocolChanges.Clique.Epoch.
