1 files changed, 69 insertions, 0 deletions
diff --git a/research/experiments/012-tail-records/run.py b/research/experiments/012-tail-records/run.py
new file mode 100755
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+++ b/research/experiments/012-tail-records/run.py
@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""Commit cost by where the head goes (see docs/research/081-tail-records.md).
+
+Runs probe.c (a small commit's sync with its head in a slot at the start, or
+just before its bytes) for 2 KiB and 8 KiB commits, and ../010-one-sync-commit
+/commits.c (tree store commit latency) built against the store of --before
+(heads in slots) and the current one (heads as records before the bytes),
+alternating their order per round so device drift reaches both alike. Prints
+one JSON document.
+"""
+import argparse
+import json
+import shutil
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+HERE = Path(__file__).resolve().parent
+ROOT = HERE.parents[2]
+PURE = ROOT / 'prototypes' / 'connections'
+COMMITS = HERE.parent / '010-one-sync-commit' / 'commits.c'
+
+
+def build(output, sources):
+    subprocess.run(['cc', '-O2', '-std=c17', f'-I{PURE}', '-o', str(output)] + [str(s) for s in sources] + ['-lpthread'],
+                   check=True)
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--directory', type=Path, default=Path('/var/tmp'), help='on the device to measure')
+    parser.add_argument('--before', default='2ef0d40', help='a revision with heads in slots')
+    parser.add_argument('--rounds', type=int, default=3)
+    parser.add_argument('--commits', type=int, default=400)
+    args = parser.parse_args()
+    with tempfile.TemporaryDirectory() as work:
+        work = Path(work)
+        before = work / 'store-tree-before.c'
+        before.write_text(subprocess.run(['git', '-C', str(ROOT), 'show', f'{args.before}:prototypes/connections/store-tree.c'],
+                                         capture_output=True, text=True, check=True).stdout)
+        build(work / 'probe', [HERE / 'probe.c'])
+        builds = {'heads in slots': work / 'commits-before', 'heads as records': work / 'commits-after'}
+        build(builds['heads in slots'], [COMMITS, before])
+        build(builds['heads as records'], [COMMITS, PURE / 'store-tree.c'])
+        results = {'rounds': []}
+        for round_ in range(args.rounds):
+            measured = {'probe': [], 'commits': {}}
+            for size in (2048, 8192):
+                probe = subprocess.run([str(work / 'probe'), str(args.directory), str(size)], capture_output=True,
+                                       text=True, check=True)
+                measured['probe'] += [json.loads(line) for line in probe.stdout.splitlines()]
+            names = list(builds) if round_ % 2 == 0 else list(builds)[::-1]
+            for name in names:
+                store = Path(tempfile.mkdtemp(dir=args.directory, prefix='pure-commit-cost-'))
+                shutil.rmtree(store)
+                try:
+                    run = subprocess.run([str(builds[name]), str(store), str(args.commits)], capture_output=True, text=True,
+                                         check=True)
+                    measured['commits'][name] = json.loads(run.stdout)
+                finally:
+                    shutil.rmtree(store, ignore_errors=True)
+            results['rounds'].append(measured)
+            print(json.dumps(measured), file=sys.stderr, flush=True)
+        print(json.dumps(results, indent=1))
+
+
+if __name__ == '__main__':
+    sys.exit(main())