1 files changed, 85 insertions, 0 deletions
diff --git a/research/experiments/005-storage-edit-latency/sequence.py b/research/experiments/005-storage-edit-latency/sequence.py
new file mode 100644
index 0000000..57ff835
--- /dev/null
+++ b/research/experiments/005-storage-edit-latency/sequence.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+"""Measure repeated durable edits and page-segment rebuilds on one real document."""
+import argparse
+import hashlib
+import json
+from pathlib import Path
+import platform
+import statistics
+import subprocess
+import tempfile
+
+from measure import INITIAL, PROGRAM, invoke
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--flat', type=Path, required=True)
+    parser.add_argument('--paged', type=Path, required=True)
+    parser.add_argument('--scratch-parent', type=Path, required=True)
+    parser.add_argument('--edits', type=int, default=70)
+    parser.add_argument('--output', type=Path, required=True)
+    args = parser.parse_args()
+    if args.edits < 66 or args.output.exists():
+        parser.error('at least 66 edits are needed to observe the current rebuild boundary; output must be new')
+    binaries = {'flat': args.flat.resolve(), 'paged': args.paged.resolve()}
+    args.scratch_parent.mkdir(parents=True, exist_ok=True)
+    with tempfile.TemporaryDirectory(prefix='pure-storage-sequence-',
+                                     dir=args.scratch_parent.resolve()) as name:
+        root = Path(name)
+        filesystem = subprocess.run(['findmnt', '-T', str(root), '-no', 'FSTYPE,SOURCE'],
+                                    capture_output=True, text=True, check=True).stdout.strip()
+        (root / 'initial').write_bytes(INITIAL)
+        patches = {'Y': root / 'Y', 'Z': root / 'Z'}
+        for label, file in patches.items():
+            file.write_bytes(label.encode())
+        bases = {variant: [binary, '--program', PROGRAM, '--store', root / variant]
+                 for variant, binary in binaries.items()}
+        for base in bases.values():
+            result, _ = invoke([*base, 'edit', 'document', 0, 0, 0, root / 'initial'])
+            assert json.loads(result.stdout)['revision'] == '1'
+        samples = {variant: [] for variant in binaries}
+        for edit in range(1, args.edits + 1):
+            patch = 'Z' if edit % 2 else 'Y'
+            order = ('flat', 'paged') if edit % 2 else ('paged', 'flat')
+            for variant in order:
+                base = bases[variant]
+                result, elapsed = invoke([*base, 'edit', 'document', edit,
+                                          len(INITIAL) - 1, 1, patches[patch]])
+                assert json.loads(result.stdout)['revision'] == str(edit + 1)
+                files = [file for file in (root / variant).iterdir() if file.is_file()]
+                samples[variant].append({'edit': edit, 'elapsed_ms': round(elapsed, 3),
+                                         'files': len(files),
+                                         'allocated_bytes': sum(file.stat().st_blocks * 512
+                                                                for file in files)})
+        expected = INITIAL[:-1] + patches[patch].read_bytes()
+        for base in bases.values():
+            shown, _ = invoke([*base, 'show', 'document'])
+            assert shown.stdout == expected
+            assert json.loads(shown.stderr)['revision'] == str(args.edits + 1)
+    result = {'profile': 'repeated-durable-one-mib-document-last-byte-edit',
+              'platform': platform.platform(), 'filesystem': filesystem,
+              'edits_per_variant': args.edits,
+              'final_body_sha256': hashlib.sha256(expected).hexdigest(),
+              'scope': ('Same actual source-loaded CLI and editor.pure, two persistent '
+                        'stores, alternating operation order. Timings include each '
+                        'edit process, parser, store init and fsync; creation and '
+                        'final show are not timed. Device state is uncontrolled.'),
+              'variants': {variant: {
+                  'binary_sha256': hashlib.sha256(binary.read_bytes()).hexdigest(),
+                  'median_edit_ms': round(statistics.median(row['elapsed_ms']
+                                                             for row in samples[variant]), 3),
+                  'samples': samples[variant]}
+                  for variant, binary in binaries.items()}}
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+    args.output.write_text(json.dumps(result, indent=2) + '\n')
+    print(json.dumps({variant: {'median_edit_ms': row['median_edit_ms'],
+                                'max_edit_ms': max(sample['elapsed_ms']
+                                                   for sample in row['samples']),
+                                'max_allocated_bytes': max(sample['allocated_bytes']
+                                                           for sample in row['samples'])}
+                      for variant, row in result['variants'].items()}, indent=2))
+
+
+if __name__ == '__main__':
+    main()