It recalculates m_best_header by looping over the entire
block index. Even though this is not very performant, it
will only be used in rare situations that cannot be
triggered by others without a cost:
As part of to invalidateblock / reconsiderblock rpcs, or when a
block with an accepted header with valid PoW turns out to be invalid
later during full validation.
Because AssumeUTXO nodes prioritize tip synchronization, they relay their local
address through the network before completing the background chain sync.
This, combined with the advertising of full-node service (NODE_NETWORK), can
result in an honest peer in IBD connecting to the AssumeUTXO node (while syncing)
and requesting an historical block the node does not have. This behavior leads to
an abrupt disconnection due to perceived unresponsiveness (lack of response)
from the AssumeUTXO node.
This lack of response occurs because nodes ignore getdata requests when they do
not have the block data available (further discussion can be found in PR 30385).
Fix this by refraining from signaling full-node service support while the
background chain is being synced. During this period, the node will only
signal 'NODE_NETWORK_LIMITED' support. Then, full-node ('NODE_NETWORK')
support will be re-enabled once the background chain sync is completed.
a2955f0979 validation: Use span for ImportBlocks paths (TheCharlatan)
20515ea3f5 validation: Use span for CalculateClaimedHeadersWork (TheCharlatan)
52575e96e7 validation: Use span for ProcessNewBlockHeaders (TheCharlatan)
Pull request description:
Makes it friendlier for potential future users of the kernel library if they do not store the headers in a std::vector, but can guarantee contiguous memory.
Take this opportunity to also change the argument of ImportBlocks previously taking a `std::vector` to a `std::span`.
ACKs for top commit:
stickies-v:
re-ACK a2955f0979 - no changes except further walking the ~file~ path of modernizing variable names.
maflcko:
ACK a2955f0979🕑
achow101:
ACK a2955f0979
danielabrozzoni:
ACK a2955f0979
Tree-SHA512: 8b07f4ad26e270b65600d1968cd78847b85caca5bfbb83fd9860389f26656b1d9a40b85e0990339f50403d18cedcd2456990054f3b8b0bedce943e50222d2709
When the tracepoint was introduced in 8f37f5c2a5,
the connect_block duration was passed in microseconds `µs`.
By starting to use steady clock in fabf1cdb20
this changed to nanoseconds `ns`. As the test only checked if the
duration value is `> 0` as a plausibility check, this went unnoticed.
I detected this when setting up monitoring for block validation time
as part of the Great Consensus Cleanup Revival discussion.
This change casts the duration explicitly to nanoseconds (as it has been
nanoseconds for the last three releases; switching back now would 'break'
the broken API again; there don't seem to be many users affected), updates
the documentation and adds a check for an upper bound to the tracepoint
interface tests. The upper bound is quite lax as mining the block takes
much longer than connecting the empty test block. It's however able to
detect incorrect duration units passed.
Makes it friendlier for potential future users of the kernel library if
they do not store the headers in a std::vector, but can guarantee
contiguous memory.
Makes it friendlier for potential future users of the kernel library if
they do not store the headers in a std::vector, but can guarantee
contiguous memory.
In 6bfa26048d the testnet4 timewarp
attack fix block time variation was increased from the Great
Consensus Cleanup value of 600s to 7200s on the thesis that this
allows miners to always create blocks with the current time. Sadly,
doing so does allow for some nonzero inflation, even if not a huge
amount.
While it could be that some hardware ignores the timestamp provided
to it over Stratum and forces the block header timestamp to the
current time, I'm not aware of any such hardware, and it would also
likely suffer from random invalid blocks due to relying on NTP
anyway, making its existence highly unlikely.
This leaves the only concern being pools, but most of those rely on
work generated by Bitcoin Core (in one way or another, though when
spy mining possibly not), and it seems likely that they will also
not suffer any lost work. While its possible that a pool does
generate invalid work due to spy mining or otherwise custom logic,
it seems unlikely that a substantial portion of hashrate would do
so, making the difference somewhat academic (any pool that screws
this up will only do so once and the network would come out just
fine).
Further, while we may end up deciding these assumptions were
invalid and we should instead use 7200s, it seems prudent to try
with the value we "want" on testnet4, giving us the ability to
learn if the compatibility concerns are an issue before we go to
mainnet.
00618e8745 assumeutxo: Drop block height from metadata (Fabian Jahr)
Pull request description:
Fixes https://github.com/bitcoin/bitcoin/issues/30514 which has more context and shows how the issue can be reproduced. Since the value in question is removed, there is no test to add to reproduce anything.
This is an alternative approach to #30516 with much of the [code being suggested there](https://github.com/bitcoin/bitcoin/pull/30516#discussion_r1689146902).
ACKs for top commit:
maflcko:
re-ACK 00618e8745🎌
achow101:
ACK 00618e8745
theStack:
Code-review ACK 00618e8745
ismaelsadeeq:
Re-ACK 00618e8745
mzumsande:
ACK 00618e8745
Tree-SHA512: db9575247bae838ad7742a27a216faaf55bb11e022f9afdd05752bb09bbf9614717d0ad64304ff5722a16bf41d8dea888af544e4ae26dcaa528c1add0269a4a8
92c1d7d1f8 validation: Use MAX_TIMEWARP constant as testnet4 timewarp defense delta (Fabian Jahr)
4b2fad502e doc: Add release notes for 29775 (Fabian Jahr)
f7cc97313b doc: Align deprecation warnings (Fabian Jahr)
1163b08378 chainparams: Add initial minimum chain work for Testnet4 (Fabian Jahr)
Pull request description:
This completes follow-ups left open in #29775.
- Adds release notes
- Addresses the [misalignment](https://github.com/bitcoin/bitcoin/pull/29775#discussion_r1706982102) in deprecation warnings and hints at the intention to remove support for Testnet3.
- Adds initial minimum chainwork for Testnet4.
- Use the `MAX_TIMEWARP` constant as the timewarp defense delta, equal to `MAX_FUTURE_BLOCK_TIME`.
ACKs for top commit:
Sjors:
ACK 92c1d7d1f8
achow101:
ACK 92c1d7d1f8
tdb3:
re ACK 92c1d7d1f8
Tree-SHA512: 7ebdac7809f96231f75ca62706af59cd1ed27f713a4c7be5e2ad69fae95832b146b3ea23c712fb03b412da1deda7e8a5dae55bb2bbd2dcfd9f926e85c2a72666
2925bd537c refactor: use c++20 std::views::reverse instead of reverse_iterator.h (stickies-v)
Pull request description:
C++20 introduces [`std::ranges::views::reverse`](https://en.cppreference.com/w/cpp/ranges/reverse_view), which allows us to drop our own `reverse_iterator.h` implementation and also makes it easier to chain views (even though I think we currently don't use this).
ACKs for top commit:
achow101:
ACK 2925bd537c
maflcko:
ACK 2925bd537c🎷
Tree-SHA512: 567666ec44af5d1beb7a271836bcc89c4c577abc77f522fcc18bc6d4de516ae9b0df766d0bfa6dd217569e6878331c2aee1d9815620860375e3510dad7fed476
589db872e1 validation: don't erase coins cache on prune flushes (Andrew Toth)
0e8918755f Add linked-list test to CCoinsViewCache::SanityCheck (Pieter Wuille)
05cf4e1875 coins: move Sync logic to CoinsViewCacheCursor (Andrew Toth)
7825b8b9ae coins: pass linked list of flagged entries to BatchWrite (Andrew Toth)
a14edada8a test: add cache entry linked list tests (Andrew Toth)
24ce37cb86 coins: track flagged cache entries in linked list (Andrew Toth)
58b7ed156d coins: call ClearFlags in CCoinsCacheEntry destructor (Andrew Toth)
8bd3959fea refactor: require self and sentinel parameters for AddFlags (Andrew Toth)
75f36d241d refactor: add CoinsCachePair alias (Andrew Toth)
f08faeade2 refactor: move flags to private uint8_t and rename to m_flags (Andrew Toth)
4e4fb4cbab refactor: disallow setting flags in CCoinsCacheEntry constructors (Andrew Toth)
8737c0cefa refactor: encapsulate flags setting with AddFlags and ClearFlags (Andrew Toth)
9715d3bf1e refactor: encapsulate flags get access for all other checks (Andrew Toth)
df34a94e57 refactor: encapsulate flags access for dirty and fresh checks (Andrew Toth)
Pull request description:
Since https://github.com/bitcoin/bitcoin/pull/17487 we no longer need to clear the coins cache when syncing to disk. A warm coins cache significantly speeds up block connection, and only needs to be fully flushed when nearing the `dbcache` limit.
For frequent pruning flushes there's no need to empty the cache and kill connect block speed. However, simply using `Sync` in place of `Flush` actually slows down a pruned full IBD with a high `dbcache` value. This is because as the cache grows, sync takes longer since every coin in the cache is scanned to check if it's dirty. For frequent prune flushes and a large cache this constant scanning starts to really slow IBD down, and just emptying the cache on every prune becomes faster.
To fix this, we can add two pointers to each cache entry and construct a doubly linked list of dirty entries. We can then only iterate through all dirty entries on each `Sync`, and simply clear the pointers after.
With this approach a full IBD with `dbcache=16384` and `prune=550` was 32% faster than master. For default `dbcache=450` speedup was ~9%. All benchmarks were run with `stopatheight=800000`.
| | prune | dbcache | time | max RSS | speedup |
|-----------:|----------:|------------:|--------:|-------------:|--------------:|
| master | 550 | 16384 | 8:52:57 | 2,417,464k | - |
| branch | 550 | 16384 | 6:01:00 | 16,216,736k | 32% |
| branch | 550 | 450 | 8:05:08 | 2,818,072k | 8.8% |
| master | 10000 | 5000 | 8:19:59 | 2,962,752k | - |
| branch | 10000 | 5000| 5:56:39 | 6,179,764k | 28.8% |
| master | 0 | 16384 | 4:51:53 | 14,726,408k | - |
| branch | 0 | 16384 | 4:43:11 | 16,526,348k | 2.7% |
| master | 0 | 450 | 7:08:07 | 3,005,892k | - |
| branch | 0 | 450 | 6:57:24 | 3,013,556k |2.6%|
While the 2 pointers add memory to each cache entry, it did not slow down IBD. For non-pruned IBD results were similar for this branch and master. When I performed the initial IBD, the full UTXO set could be held in memory when using the max `dbcache` value. For non-pruned IBD with max `dbcache` to tip ended up using 12% more memory, but it was also 2.7% faster somehow. For smaller `dbcache` values the `dbcache` limit is respected so does not consume more memory, and the potentially more frequent flushes were not significant enough to cause any slowdown.
For reviewers, the commits in order do the following:
First 4 commits encapsulate all accesses to `flags` on cache entries, and then the 5th makes `flags` private.
Commits `refactor: add CoinsCachePair alias` to `coins: call ClearFlags in CCoinsCacheEntry destructor` create the linked list head nodes and cache entry self references and pass them into `AddFlags`.
Commit `coins: track flagged cache entries in linked list` actually adds the entries into a linked list when they are flagged DIRTY or FRESH and removes them from the linked list when they are destroyed or the flags are cleared manually. However, the linked list is not yet used anywhere.
Commit `test: add cache entry linked list tests` adds unit tests for the linked list.
Commit `coins: pass linked list of flagged entries to BatchWrite` uses the linked list to iterate through DIRTY entries instead of using the entire coins cache.
Commit `validation: don't erase coins cache on prune flushes` uses `Sync` instead of `Flush` for pruning flushes, so the cache is no longer cleared.
Inspired by [this comment](https://github.com/bitcoin/bitcoin/pull/15265#issuecomment-457720636).
Fixes https://github.com/bitcoin/bitcoin/issues/11315.
ACKs for top commit:
paplorinc:
ACK 589db872e1
sipa:
reACK 589db872e1
achow101:
ACK 589db872e1
mzumsande:
re-ACK 589db872e1
Tree-SHA512: 23b2bc01c83edacb5b39aa60bb0b766de9a74ce17f0c59bf13b97b4328a7b758ad9aff6581c3ca88e2973f7658380651530d497444f48d6e22ea0bfc51cc921d
fa530ec543 rpc: Return precise loadtxoutset error messages (MarcoFalke)
faa5c86dbf refactor: Use untranslated error message in ActivateSnapshot (MarcoFalke)
Pull request description:
The error messages should never happen in normal operation. However, if
they do, they are helpful to return to the user to debug the issue. For
example, to notice a truncated file.
This fixes https://github.com/bitcoin/bitcoin/issues/28621
Also includes a minor refactor commit.
ACKs for top commit:
fjahr:
Code review ACK fa530ec543
ryanofsky:
Code review ACK fa530ec543, just adjusting error messages a little since last review. (Thanks!)
Tree-SHA512: 224968c9b13d082ca2ed1f6a8fcc5f51ff16d6c96bd38c3679699505b54337b99cccaf7a8474391f6b11f9ccb101977b4e626898c1217eae95802e290cf105f1
The error messages should never happen in normal operation. However, if
they do, they are helpful to return to the user to debug the issue. For
example, to notice a truncated file.
c85accecaf [refactor] delete EraseTxNoLock, just use EraseTx (glozow)
6ff84069a5 remove obsoleted TxOrphanage::m_mutex (glozow)
61745c7451 lock m_recent_confirmed_transactions using m_tx_download_mutex (glozow)
723ea0f9a5 remove obsoleted hashRecentRejectsChainTip (glozow)
18a4355250 update recent_rejects filters on ActiveTipChange (glozow)
36f170d879 add ValidationInterface::ActiveTipChange (glozow)
3eb1307df0 guard TxRequest and rejection caches with new mutex (glozow)
Pull request description:
See #27463 for full project tracking.
This contains the first few commits of #30110, which require some thinking about thread safety in review.
- Introduce a new `m_tx_download_mutex` which guards the transaction download data structures including `m_txrequest`, the rolling bloom filters, and `m_orphanage`. Later this should become the mutex guarding `TxDownloadManager`.
- `m_txrequest` doesn't need to be guarded using `cs_main` anymore
- `m_recent_confirmed_transactions` doesn't need its own lock anymore
- `m_orphanage` doesn't need its own lock anymore
- Adds a new `ValidationInterface` event, `ActiveTipChanged`, which is a synchronous callback whenever the tip of the active chainstate changes.
- Flush `m_recent_rejects` and `m_recent_rejects_reconsiderable` on `ActiveTipChanged` just once instead of checking the tip every time `AlreadyHaveTx` is called. This should speed up calls to that function (no longer comparing a block hash each time) and removes the need to lock `cs_main` every time it is called.
Motivation:
- These data structures need synchronization. While we are holding `m_tx_download_mutex`, these should hold:
- a tx hash in `m_txrequest` is not also in `m_orphanage`
- a tx hash in `m_txrequest` is not also in `m_recent_rejects` or `m_recent_confirmed_transactions`
- In the future, orphan resolution tracking should also be synchronized. If a tx has an entry in the orphan resolution tracker, it is also in `m_orphanage`, and not in `m_txrequest`, etc.
- Currently, `cs_main` is used to e.g. sync accesses to `m_txrequest`. We should not broaden the scope of things it locks.
- Currently, we need to know the current chainstate every time we call `AlreadyHaveTx` so we can decide whether we should update it. Every call compares the current tip hash with `hashRecentRejectsChainTip`. It is more efficient to have a validation interface callback that updates the rejection filters whenever the chain tip changes.
ACKs for top commit:
instagibbs:
reACK c85accecaf
dergoegge:
Code review ACK c85accecaf
theStack:
Light code-review ACK c85accecaf
hebasto:
ACK c85accecaf, I have reviewed the code and it looks OK.
Tree-SHA512: c3bd524b5de1cafc9a10770dadb484cc479d6d4c687d80dd0f176d339fd95f73b85cb44cb3b6b464d38a52e20feda00aa2a1da5a73339e31831687e4bd0aa0c5
55b6d7be68 validation: Don't load a snapshot if it's not in the best header chain. (Martin Zumsande)
Pull request description:
This was suggested by me in the discussion of #30288, which has more context.
If the snapshot is not an ancestor of the most-work header (`m_best_header`), syncing from that alternative chain leading to `m_best_header` should be prioritised. Therefore it's not useful loading the snapshot in this situation.
If the other chain turns out to be invalid or the chain with the snapshot retrieves additional headers so that it's the most-work one again (see functional test), `m_best_header` will change and loading the snapshot will be possible again.
Because of the work required to generate a conflicting headers chain, a situation with two conflicting chains should only be possible under extreme circumstances, such as major forks.
ACKs for top commit:
fjahr:
re-ACK 55b6d7be68
achow101:
ACK 55b6d7be68
alfonsoromanz:
Re ACK 55b6d7be68
Tree-SHA512: 4fbea5ab1038ae353fc949a186041cf9b397e7ce4ac59ff36f881c9437b4f22ada922490ead5b2661389eb1ca0f3d1e7e7e6a4261057678643e71594a691ac36
51fa26239a refactor: Mark some static global vars as const (TheCharlatan)
39f9b80fba refactor: De-globalize last notified header index (TheCharlatan)
3443943f86 refactor: De-globalize validation benchmark timekeeping (TheCharlatan)
Pull request description:
In future, users of the kernel library might run multiple chainstates in parallel, or create and destroy multiple chainstates over the lifetime of a process. Having static, mutable variables could lead to state inconsistencies in these scenarios.
---
This pull request is part of the [libbitcoinkernel project](https://github.com/bitcoin/bitcoin/issues/27587).
ACKs for top commit:
dergoegge:
Code review ACK 51fa26239a
maflcko:
ACK 51fa26239a🍚
tdb3:
code review ACK 51fa26239a
Tree-SHA512: da91aa7ffa343325cabb8764ef03c8358845662cf0ba8a6cc1dd38e40e5462d88734f2b459c2de8e7a041551eda9143d92487842609f7f30636f61a0cd3c57ee
This is a synchronous callback notifying clients of all tip changes.
It allows clients to respond to a new block immediately after it is
connected. The synchronicity is important for things like
m_recent_rejects, in which a transaction's validity can change (rejected
vs accepted) when this event is processed. For example, the transaction
might have a timelock condition that has just been met. This is distinct
from something like m_recent_confirmed_transactions, in which the
validation outcome is the same (valid vs already-have), so it does not
need to be reset immediately.
If the snapshot is not an ancestor of the most-work header (m_best_header),
syncing from that alternative chain should be prioritised.
Therefore don't accept loading a snapshot in this situation.
If that other chain turns out to be invalid, m_best_header
would be reset and loading the snapshot should be possible again.
Because of the work required to generate a conflicting headers chain,
this should only be possible under extreme circumstances, such as major forks.
In future, users of the kernel library might run multiple chainstates in
parallel, or create and destroy multiple chainstates over the lifetime
of a process. Having static, mutable variables could lead to state
inconsistencies in these scenarios.
In future, users of the kernel library might run multiple chainstates in
parallel, or create and destroy multiple chainstates over the lifetime
of a process. Having static, mutable variables could lead to state
inconsistencies in these scenarios.
606a7ab862 kernel: De-globalize signature cache (TheCharlatan)
66d74bfc45 Expose CSignatureCache class in header (TheCharlatan)
021d38822c kernel: De-globalize script execution cache hasher (TheCharlatan)
13a3661aba kernel: De-globalize script execution cache (TheCharlatan)
ab14d1d6a4 validation: Don't error if maxsigcachesize exceeds uint32::max (TheCharlatan)
Pull request description:
The validation caches are currently setup independently from where the rest of the validation code is initialized. This makes their ownership semantics unclear. There is also no clear enforcement on when and in what order they need to be initialized. The caches are always initialized in the `BasicTestingSetup` although a number of tests don't actually need them.
Solve this by moving the caches from global scope into the `ChainstateManager` class. This simplifies the usage of the kernel library by no longer requiring manual setup of the caches prior to using the `ChainstateManager`. Tests that need to access the caches can instantiate them independently.
---
This pull request is part of the [libbitcoinkernel project](https://github.com/bitcoin/bitcoin/issues/27587).
ACKs for top commit:
stickies-v:
re-ACK 606a7ab862
glozow:
reACK 606a7ab
ryanofsky:
Code review ACK 606a7ab862. Just small formatting, include, and static_assert changes since last review.
Tree-SHA512: e7f3ee41406e3b233832bb67dc3a63c4203b5367e5daeed383df9cb590f227fcc62eae31311029c077d5e81b273a37a88a364db3dee2efe91bb3b9c9ddc8a42e
Move its ownership to the ChainstateManager class.
Next to simplifying usage of the kernel library by no longer requiring
manual setup of the cache prior to using validation code, it also slims
down the amount of memory allocated by BasicTestingSetup.
Use this opportunity to make SignatureCache RAII styled
Co-authored-by: Ryan Ofsky <ryan@ofsky.org>
Move its ownership to the ChainstateManager class.
Next to simplifying usage of the kernel library by no longer requiring
manual setup of the cache prior to using validation code, it also slims
down the amount of memory allocated by BasicTestingSetup.
33c48c106c validation: Check if mempool exists before asserting in ActivateSnapshot (TheCharlatan)
Pull request description:
The mempool is an optional component of the chainstate manager, so don't assume its presence and instead check if it is there first.
ACKs for top commit:
maflcko:
re-ACK 33c48c106c
fjahr:
ACK 33c48c106c
Tree-SHA512: 7a3568d5b7af45efa7bf54bae7bac1f00dc99bc9d47a744d73594f283c952be9500168f680d72f4aee09761da4e878ddca83ba675cdea8ee9e44eeff00ac09da
ce8094246e random: replace construct/assign with explicit Reseed() (Pieter Wuille)
2ae392d561 random: use LogError for init failure (Pieter Wuille)
97e16f5704 tests: make fuzz tests (mostly) deterministic with fixed seed (Pieter Wuille)
2c91330dd6 random: cleanup order, comments, static (Pieter Wuille)
8e31cf9c9b net, net_processing: use existing RNG objects more (Pieter Wuille)
d5fcbe966b random: improve precision of MakeExponentiallyDistributed (Pieter Wuille)
cfb0dfe2cf random: convert GetExponentialRand into rand_exp_duration (Pieter Wuille)
4eaa239dc3 random: convert GetRand{Micros,Millis} into randrange (Pieter Wuille)
82de1b80d9 net: use GetRandMicros for cache expiration (Pieter Wuille)
ddc184d999 random: get rid of GetRand by inlining (Pieter Wuille)
e2d1f84858 random: make GetRand() support entire range (incl. max) (Pieter Wuille)
810cdf6b4e tests: overhaul deterministic test randomness (Pieter Wuille)
6cfdc5b104 random: convert XoRoShiRo128PlusPlus into full RNG (Pieter Wuille)
8cc2f45065 random: move XoRoShiRo128PlusPlus into random module (Pieter Wuille)
8f5ac0d0b6 xoroshiro128plusplus: drop comment about nonexisting copy() (Pieter Wuille)
8924f5120f random: modernize XoRoShiRo128PlusPlus a bit (Pieter Wuille)
ddb7d26cfd random: add RandomMixin::randbits with compile-known bits (Pieter Wuille)
21ce9d8658 random: Improve RandomMixin::randbits (Pieter Wuille)
9b14d3d2da random: refactor: move rand* utilities to RandomMixin (Pieter Wuille)
40dd86fc3b random: use BasicByte concept in randbytes (Pieter Wuille)
27cefc7fd6 random: add a few noexcepts to FastRandomContext (Pieter Wuille)
b3b382dde2 random: move rand256() and randbytes() to .h file (Pieter Wuille)
493a2e024e random: write rand256() in function of fillrand() (Pieter Wuille)
Pull request description:
This PR contains a number of vaguely-related improvements to the random module.
The specific changes and more detailed rationale is in the commit messages, but the highlights are:
* `XoRoShiRo128PlusPlus` (previously a test-only RNG) moves to random.h and becomes `InsecureRandomContext`, which is even faster than `FastRandomContext` but non-cryptographic. It also gets all helper randomness functions (`randrange`, `fillrand`, ...), making it a lot more succinct to use.
* During tests, **all** randomness is made deterministic (except for `GetStrongRandBytes`) but non-repeating (like `GetRand()` used to be when `g_mock_deterministic_tests` was used), either fixed, or from a random seed (overridden by env var).
* Several infrequently used top-level functions (`GetRandMillis`, `GetRandMicros`, `GetExponentialRand`) are converted into member functions of `FastRandomContext` (and `InsecureRandomContext`).
* `GetRand<T>()` (without argument) can now return the maximum value of the type (previously e.g. `GetRand<uint32_t>()` would never return 0xffffffff).
ACKs for top commit:
achow101:
ACK ce8094246e
maflcko:
re-ACK ce8094246e🐈
hodlinator:
ACK ce8094246e
dergoegge:
utACK ce8094246e
Tree-SHA512: 79bc0cbafaf27e95012c1ce2947a8ca6f9a3c78af5f1f16e69354b6fc9b987a28858adf4cd356dc5baf21163e9af8dcc24e70f8d7173be870e8a3ddcdd47c02c
