log: show reindex progress in ImportBlocks #33353

1. 
   l0rinc commented at 7:08 pm on September 9, 2025: contributor

   Summary

   When triggering a reindex, users have no indication of progress.

   Fix

   This patch precomputes the total number of block files so progress can be shown. Instead of only displaying which block file is being processed, it now shows the percent complete.

   Reproducer + expected results

   0cmake -B build -DCMAKE_BUILD_TYPE=Release && make -C build -j && ./build/bin/bitcoind -datadir=demo -reindex
   

   Before, the block files were shown one-by-one, there’s no way to see how much work is left:

   0Reindexing block file blk00000.dat...
   1Loaded 119920 blocks from external file in 1228ms
   2Reindexing block file blk00001.dat...
   3Loaded 10671 blocks from external file in 284ms
   4Reindexing block file blk00002.dat...
   5Loaded 5459 blocks from external file in 263ms
   6Reindexing block file blk00003.dat...
   7Loaded 5595 blocks from external file in 267ms
   

   After the change we add a percentage:

   0Reindexing block file blk00000.dat (0% complete)...
   1Loaded 119920 blocks from external file in 1255ms
   2Reindexing block file blk00001.dat (1% complete)...
   3Loaded 10671 blocks from external file in 303ms
   4Reindexing block file blk00002.dat (2% complete)...
   5Loaded 5459 blocks from external file in 278ms
   6Reindexing block file blk00003.dat (3% complete)...
   7Loaded 5595 blocks from external file in 285ms
   

2. 
   DrahtBot commented at 7:08 pm on September 9, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33353.

   Reviews

   See the guideline for information on the review process. A summary of reviews will appear here.

3. l0rinc renamed this:
   logs: show reindex progress in `ImportBlocks`
   log: show reindex progress in `ImportBlocks`
   on Sep 9, 2025
4. DrahtBot added the label Utils/log/libs on Sep 9, 2025
5. logs: show reindex progress in `ImportBlocks`

   ### Summary
   
   When triggering a reindex, users had no indication of how many files remained or how far along the process was.
   
   ### Fix
   
   This patch prefetches the target file block file count to be able to show progress information.
   Instead of just displaying which block file is being processed, it now indicates how many files remain.
   
   ### Reproducer + expected results
   
   Running
   ```bash
   cmake -B build && make -C build -DCMAKE_BUILD_TYPE=Release && ./build/bin/bitcoind -datadir=demo -reindex
   ```
   Shows the block files one-by-one currently, there's no way to see how much work is left:
   ```
   Reindexing block file blk00000.dat...
   Loaded 119920 blocks from external file in 1228ms
   Reindexing block file blk00001.dat...
   Loaded 10671 blocks from external file in 284ms
   Reindexing block file blk00002.dat...
   Loaded 5459 blocks from external file in 263ms
   Reindexing block file blk00003.dat...
   Loaded 5595 blocks from external file in 267ms
   ```
   
   After the change:
   ```
   Reindexing block file blk00000.dat (0% complete)...
   Loaded 119920 blocks from external file in 1255ms
   Reindexing block file blk00001.dat (1% complete)...
   Loaded 10671 blocks from external file in 303ms
   Reindexing block file blk00002.dat (2% complete)...
   Loaded 5459 blocks from external file in 278ms
   Reindexing block file blk00003.dat (3% complete)...
   Loaded 5595 blocks from external file in 285ms
   ```

   d7de5b109f
6. l0rinc force-pushed on Sep 9, 2025

Contributors
l0rinc DrahtBot

Labels
Utils/log/libs