From 6a28879bd56354483fe940c0c80d511eccb89983 Mon Sep 17 00:00:00 2001
From: eunhhu <necpition205@gmail.com>
Date: Fri, 25 Sep 2026 09:33:43 +0100
Subject: Add selected single-file persistent tree store

store-tree.c keeps every document in one append-only file as a persistent
B-tree of byte extents, with the key catalog in the same structure. A splice
writes only the changed leaf and path; unchanged extents are shared between
versions, readers take no lock, and two alternating head slots publish a
commit after its nodes are durable. Compaction rewrites reachable nodes.

On the recorded ext4 host a durable 1-byte middle insert into a 1 MiB
document took 8.58 ms against 78.51 ms for the default store, and the real
TUI's Ctrl+S after typing took 16.60 ms against 84.59 ms. check-tree runs the
store's crash/oracle tests and the unchanged runtime, splice, async and
real-PTY editor checks on it. It stays opt-in: linked code is 12.7 KB larger
and contiguous multi-leaf reads copy.
---
 .../2026-09-25-tui-ext4-linux-aarch64.json         | 285 +++++++++++++++++++++
 1 file changed, 285 insertions(+)
 create mode 100644 research/experiments/008-tree-store-edit-cost/2026-09-25-tui-ext4-linux-aarch64.json

(limited to 'research/experiments/008-tree-store-edit-cost/2026-09-25-tui-ext4-linux-aarch64.json')

diff --git a/research/experiments/008-tree-store-edit-cost/2026-09-25-tui-ext4-linux-aarch64.json b/research/experiments/008-tree-store-edit-cost/2026-09-25-tui-ext4-linux-aarch64.json
new file mode 100644
index 0000000..6bea961
--- /dev/null
+++ b/research/experiments/008-tree-store-edit-cost/2026-09-25-tui-ext4-linux-aarch64.json
@@ -0,0 +1,285 @@
+{
+  "platform": "Linux-6.18.39+rpt-rpi-2712-aarch64-with-glibc2.41",
+  "filesystem": "/dev/mmcblk0p2 ext4",
+  "document_bytes": 1048576,
+  "rounds": 3,
+  "edits_per_session": 8,
+  "median_ms": {
+    "replace": {
+      "flat": 86.32,
+      "paged": 21.31,
+      "tree": 16.97
+    },
+    "append": {
+      "flat": 84.59,
+      "paged": 93.29,
+      "tree": 16.6
+    }
+  },
+  "binaries": {
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+    },
+    "paged": {
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+      "tui_sha256": "77169c79a800881e901e5b1bba938543eed5f3f1f0914799e56c0635859af2d1"
+    },
+    "tree": {
+      "cli_sha256": "c0c783a1b30a1f8e88bfe9a09b6ae124f596bf6239b802e4aec5e56f374714b9",
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-- 
cgit v1.2.3