From 6fd336eda6d012136b79ee4f1c37463d43822b96 Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Wed, 1 Dec 2021 08:01:56 +0200
Subject: perf: add benchmark script for the "many empty files" scenario

This isn't great code, but it works, which is enough for now.

Sponsored-by: author
---
 bench-manyfiles.sh | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 manyfiles.py       | 39 ++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100755 bench-manyfiles.sh
 create mode 100644 manyfiles.py

diff --git a/bench-manyfiles.sh b/bench-manyfiles.sh
new file mode 100755
index 0000000..39e6c2e
--- /dev/null
+++ b/bench-manyfiles.sh
@@ -0,0 +1,58 @@
+#!/bin/bash
+#
+# Run a simple benchmark of an incremental backup of many empty files,
+# when the live data hasn't changed.
+#
+# Edit the if-statement towards the end to get a flamegraph to see
+# where time is actually spent.
+#
+# This is very simplistic and could do with a lot of improvement. But
+# it's a start.
+
+set -euo pipefail
+
+N=100000
+
+TMP="$(mktemp -d)"
+trap 'rm -rf "$TMP"' EXIT
+
+chunks="$TMP/chunks"
+live="$TMP/live"
+
+mkdir "$chunks"
+mkdir "$live"
+python3 manyfiles.py "$live" "$N"
+
+cat <<EOF >"$TMP/server.yaml"
+address: localhost:8888
+chunks: $chunks
+tls_key: test.key
+tls_cert: test.pem
+EOF
+
+cat <<EOF >"$TMP/client.yaml"
+server_url: https://localhost:8888
+verify_tls_cert: false
+roots:
+  - $live
+log: $TMP/client.log
+EOF
+
+cargo build -q --release --all-targets
+
+OBNAM_SERVER_LOG=error cargo run -q --release --bin obnam-server -- "$TMP/server.yaml" >/dev/null &
+pid="$!"
+
+cargo run -q --release --bin obnam -- --config "$TMP/client.yaml" init --insecure-passphrase=hunter2
+
+# Initial backup.
+cargo run -q --release --bin obnam -- --config "$TMP/client.yaml" backup >/dev/null
+
+# Incremental backup.
+if true; then
+	/usr/bin/time --format=%e cargo run -q --release --bin obnam -- --config "$TMP/client.yaml" backup >/dev/null
+else
+	cargo flamegraph --bin obnam -o obnam.svg -- --config "$TMP/client.yaml" backup >/dev/null
+fi
+
+kill "$pid"
diff --git a/manyfiles.py b/manyfiles.py
new file mode 100644
index 0000000..a45d3cd
--- /dev/null
+++ b/manyfiles.py
@@ -0,0 +1,39 @@
+#!/usr/bin/python3
+#
+# Create the desired number of empty files in a directory. A thousand files per
+# subdirectory.
+
+import os
+import sys
+
+
+def subdir(dirname, dirno):
+    pathname = os.path.join(dirname, str(dirno))
+    os.mkdir(pathname)
+    return pathname
+
+
+def create(filename):
+    open(filename, "w").close()
+
+
+DIRFILES = 1000
+
+dirname = sys.argv[1]
+n = int(sys.argv[2])
+
+dirno = 0
+subdirpath = subdir(dirname, dirno)
+fileno = 0
+thisdir = 0
+
+while fileno < n:
+    filename = os.path.join(subdirpath, str(thisdir))
+    create(filename)
+
+    fileno += 1
+    thisdir += 1
+    if thisdir >= DIRFILES:
+        dirno += 1
+        subdirpath = subdir(dirname, dirno)
+        thisdir = 0
-- 
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