graph-revs-log-for-path: Optimize label name lookup

• .label_name() needs to bisect through a large file
• UTF-8 decoding takes a linear time in the file name size
• comparing strings is slower (also linear time) than comparing integers

This requires swh-graph >= 6.7.0, as it fixed a major soundness bug in label_name_id.

cc @anlambert

requested review from @anlambert

Indeed the performance are much better, thanks !

Before:

$ time ./target/release/graph-revs-log-for-path ~/swh/graph_datasets/2024-08-23-popular-500-python/graph --start-rev-swhid swh:1:rev:3de092b82f5aa02fa293cd654c2ab26556ecf703 --path Modules > /dev/null
[2025-03-10T14:44:25Z INFO  graph_revs_log_for_path] Loading graph
[2025-03-10T14:44:25Z INFO  graph_revs_log_for_path] Graph loaded

real    0m0,428s
user    0m0,384s
sys     0m0,044s

After:

$ time ./target/release/graph-revs-log-for-path ~/swh/graph_datasets/2024-08-23-popular-500-python/graph --start-rev-swhid swh:1:rev:3de092b82f5aa02fa293cd654c2ab26556ecf703 --path Modules > /dev/null
[2025-03-10T14:45:44Z INFO  graph_revs_log_for_path] Loading graph
[2025-03-10T14:45:44Z INFO  graph_revs_log_for_path] Graph loaded

real    0m0,234s
user    0m0,189s
sys     0m0,044s

Could you also update the Cargo.lock file ?

approved this merge request

merged