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Inside Bitcoin

The code behind the network, with room to understand it.

Stable release v32.1bitcoin/bitcoin · f0de87f04062 ↗3,020 source files · 47.5 MB stored on the server440 file guides

Release published 2026-10-28 · Snapshot fetched 2026-11-01. Latest stable release at fetch time; development branches and Git history are excluded. Only the selected code window and visible folders load here.

bitcoin / bitcoinstable

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▤ benchmark.html

▤ log_format.md

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bitcoin / src / leveldb / doc / log_format.md

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2,921 bytes · SHA-256 1796ccc965e1ca2f… · View upstream ↗

1leveldb Log format
2==================
3The log file contents are a sequence of 32KB blocks.  The only exception is that
4the tail of the file may contain a partial block.
5
6Each block consists of a sequence of records:
7
8    block := record* trailer?
9    record :=
10      checksum: uint32     // crc32c of type and data[] ; little-endian
11      length: uint16       // little-endian
12      type: uint8          // One of FULL, FIRST, MIDDLE, LAST
13      data: uint8[length]
14
15A record never starts within the last six bytes of a block (since it won't fit).
16Any leftover bytes here form the trailer, which must consist entirely of zero
17bytes and must be skipped by readers.
18
19Aside: if exactly seven bytes are left in the current block, and a new non-zero
20length record is added, the writer must emit a FIRST record (which contains zero
21bytes of user data) to fill up the trailing seven bytes of the block and then
22emit all of the user data in subsequent blocks.
23
24More types may be added in the future.  Some Readers may skip record types they
25do not understand, others may report that some data was skipped.
26
27    FULL == 1
28    FIRST == 2
29    MIDDLE == 3
30    LAST == 4
31
32The FULL record contains the contents of an entire user record.
33
34FIRST, MIDDLE, LAST are types used for user records that have been split into
35multiple fragments (typically because of block boundaries).  FIRST is the type
36of the first fragment of a user record, LAST is the type of the last fragment of
37a user record, and MIDDLE is the type of all interior fragments of a user
38record.
39
40Example: consider a sequence of user records:
41
42    A: length 1000
43    B: length 97270
44    C: length 8000
45
46**A** will be stored as a FULL record in the first block.
47
48**B** will be split into three fragments: first fragment occupies the rest of
49the first block, second fragment occupies the entirety of the second block, and
50the third fragment occupies a prefix of the third block.  This will leave six
51bytes free in the third block, which will be left empty as the trailer.
52
53**C** will be stored as a FULL record in the fourth block.
54
55----
56
57## Some benefits over the recordio format:
58
591. We do not need any heuristics for resyncing - just go to next block boundary
60   and scan.  If there is a corruption, skip to the next block.  As a
61   side-benefit, we do not get confused when part of the contents of one log
62   file are embedded as a record inside another log file.
63
642. Splitting at approximate boundaries (e.g., for mapreduce) is simple: find the
65   next block boundary and skip records until we hit a FULL or FIRST record.
66
673. We do not need extra buffering for large records.
68
69## Some downsides compared to recordio format:
70
711. No packing of tiny records.  This could be fixed by adding a new record type,
72   so it is a shortcoming of the current implementation, not necessarily the
73   format.
74
752. No compression.  Again, this could be fixed by adding new record types.
76

A READING COMPANION

Source available. Guide coming next.

This file is included in the stable source snapshot. A file-specific guide has not been published yet.

440 guided files · 2,580 pending. Guides cover key sections, not every line.

cmake/bitcoin-build-config.h.in src/consensus/amount.h src/consensus/consensus.h src/primitives/block.h src/primitives/transaction.h src/crypto/sha256.h src/util/moneystr.h src/clientversion.h src/uint256.h src/script/script.h src/policy/policy.h CMakeLists.txt README.md COPYING src/consensus/tx_check.cpp src/consensus/tx_verify.cpp src/consensus/merkle.cpp src/pow.cpp src/validation.cpp src/script/interpreter.cpp src/script/solver.cpp src/script/sign.cpp src/key_io.cpp src/net.cpp src/net_processing.cpp src/netaddress.cpp src/protocol.h src/wallet/wallet.cpp src/wallet/spend.cpp

Code page 1

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/wallet/fees.cpp

src/wallet/load.cpp

src/txmempool.cpp

src/node/miner.cpp

src/chainparams.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/crypto/sha256.cpp

src/serialize.h

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/arith_uint256.h

src/blockencodings.h

src/blockfilter.h

src/crypto/siphash.h

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/compressor.h

src/compressor.cpp

src/flatfile.cpp

src/dbwrapper.h

src/util/chaintype.h

src/util/chaintype.cpp

src/scheduler.h

src/scheduler.cpp

src/checkqueue.h

src/threadsafety.h

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/blockfilter.cpp

src/merkleblock.cpp

src/merkleblock.h

src/addrman.cpp

src/netgroup.cpp

src/net_permissions.cpp

src/netbase.cpp

src/torcontrol.cpp

src/net_types.h

src/net_types.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/server.cpp

src/rpc/mempool.cpp

src/rpc/mining.cpp

src/rpc/net.cpp

src/rpc/node.cpp

src/rpc/blockchain.h

src/rpc/client.h

src/rpc/mempool.h

src/rpc/mining.h

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/abort.cpp

src/node/abort.h

src/node/caches.cpp

src/node/caches.h

src/kernel/caches.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/util/rbf.cpp

src/util/thread.h

src/common/netif.h

src/common/url.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/util/thread.cpp

src/kernel/types.h

src/interfaces/rpc.h

src/util/fees.cpp

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

src/attributes.h

src/chainparams.h

src/clientversion.cpp

src/common/signmessage.cpp

src/compat/assumptions.h

src/compat/byteswap.h

src/compat/cpuid.h

src/compat/endian.h

src/compat/stdin.cpp

src/compat/stdin.h

src/core_memusage.h

src/crypto/common.h

src/deploymentinfo.cpp

src/deploymentinfo.h

src/deploymentstatus.cpp

src/deploymentstatus.h

src/dummywallet.cpp

src/external_signer.h

src/indirectmap.h

src/init/basic.cpp

src/init/bitcoin-gui.cpp

src/init/bitcoin-node.cpp

src/init/bitcoin-qt.cpp

src/init/bitcoin-wallet.cpp

src/init/bitcoind.cpp

src/init/common.h

src/interfaces/init.h

src/interfaces/ipc.h

src/logging/categories.h

src/logging/timer.h

src/net_permissions.h

src/netmessagemaker.h

src/node/chainstatemanager_args.cpp

src/node/connection_types.h

src/node/context.h

src/node/interface_ui.h

src/node/mempool_args.cpp

src/node/mining_args.cpp

src/node/minisketchwrapper.cpp

src/node/txreconciliation.h

src/node/warnings.h

src/outputtype.cpp

src/outputtype.h

src/policy/fees/estimator_args.cpp

src/policy/fees/estimator_args.h

src/policy/fees/estimator_man.cpp

src/policy/fees/estimator_man.h

src/policy/packages.h

src/policy/rbf.h

src/policy/truc_policy.h

src/primitives/block.cpp

src/randomenv.h

src/script/keyorigin.h

src/script/parsing.cpp

src/script/parsing.h

src/script/script_error.h

src/script/sigcache.cpp

src/script/sigcache.h

src/script/solver.h

src/script/verify_flags.h

src/semaphore_grant.h

src/support/allocators/secure.h

src/support/allocators/zeroafterfree.h

src/uint256.cpp

src/util/bip32.cpp

src/util/fees.h

src/util/fs.cpp

src/util/result.h

src/util/string.cpp

src/util/tokenpipe.cpp

src/util/translation.h

src/util/vector.h

src/versionbits.h

src/versionbits_impl.h

src/wallet/external_signer_scriptpubkeyman.h

src/wallet/fees.h

src/wallet/load.h

src/wallet/receive.h

src/wallet/rpc/wallet.h

src/wallet/types.h

src/walletinitinterface.h

src/zmq/zmqabstractnotifier.cpp

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