Description

This PR provides another way to persist TrieJournal by write it into a log file instead of a kv database.

Use --journalFile flag to enable/disable the journal file feature.

Rationale

Persisting TrieJournal to KV database will cause problems below

• Additional WAL and compaction overhead in pebble/leveldb
• Big kv (>= 2GB) not supported by pebbledb. (Size out of bounds when write kv >= 2GB)

Changes:

Data Format

Journal Version
Disk Root
Disk Layer
-- **Layer Length**
-- Root
-- State ID
-- Buffer Nodes
-- **Layer Checksum**
Diff Layer
-- **Layer Length**
-- Root
-- Block
-- Trie Nodes
-- Journal Accounts
-- **Layer Checksum**

Journal Path: geth/chaindata/ancient/state.journal
Checksum: SHA256

Testing

Function test

• Normal Scenario:
  • When starting up for the first time, if the journal does not exist, blocks are appended normally.
  • Upon receiving a kill -15 signal, the journal is persisted with a size consistent with the file.
  • After the normal startup, blocks are appended normally.

The loaded diff layer matches the persistence saved as described above.

• Abnormal Scenario: Manually truncate a portion of the snap file (geth/chaindata/ancient/state.journal) and restart.
  • When the number of blocks appended is less than 460,000 ("Rewound to block with state" number=0), the blockchain rewinds to block 0 and resumes appending blocks once completed.
  • When the number of blocks appended is greater than 460,000, the blockchain rewinds to a position slightly behind the head number, and resumes appending blocks once completed.
    

Performance test

Scenario: Using TestJournal, each layer has 4K and 8K account operations.

Conclusion: The use of Journal WAL and storing trieJournalKey directly into kvdb results in nearly identical WAL write times during shutdown and WAL read/parsing times during startup.