From 5af6fc0f9db49d60fee70d6ee14dac926d8a7191 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Thu, 22 Dec 2022 20:53:49 -0500
Subject: [PATCH] reconfigure() only needs to restart the node if something
 changed

---
 integration/test_vectors.py |  2 +-
 integration/util.py         | 45 ++++++++++++++++++++++++++-----------
 2 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/integration/test_vectors.py b/integration/test_vectors.py
index 042421e6f..252360fa2 100644
--- a/integration/test_vectors.py
+++ b/integration/test_vectors.py
@@ -87,7 +87,7 @@ async def test_chk_capability(reactor, request, alice, params_idx, convergence_i
     data = OBJECT_DATA[data_idx]
 
     # rewrite alice's config to match params and convergence
-    await reconfigure(reactor, request, alice, params, convergence)
+    await reconfigure(reactor, request, alice, (1,) + params, convergence)
 
     # upload data as a CHK
     actual = upload(alice, "chk", data)
diff --git a/integration/util.py b/integration/util.py
index 0dc63b2d5..2db6ac391 100644
--- a/integration/util.py
+++ b/integration/util.py
@@ -651,31 +651,50 @@ def insert(item: tuple[α, β], d: dict[α, β]) -> dict[α, β]:
     return d
 
 
-async def reconfigure(reactor, request, node: TahoeProcess, params: tuple[int, int], convergence: bytes) -> None:
+async def reconfigure(reactor, request, node: TahoeProcess, params: tuple[int, int, int], convergence: bytes) -> None:
     """
     Reconfigure a Tahoe-LAFS node with different ZFEC parameters and
     convergence secret.
 
+    If the current configuration is different from the specified
+    configuration, the node will be restarted so it takes effect.
+
     :param reactor: A reactor to use to restart the process.
     :param request: The pytest request object to use to arrange process
         cleanup.
     :param node: The Tahoe-LAFS node to reconfigure.
-    :param params: The ``needed`` and ``total`` ZFEC encoding parameters.
+    :param params: The ``happy``, ``needed``, and ``total`` ZFEC encoding
+      parameters.
     :param convergence: The convergence secret.
 
     :return: ``None`` after the node configuration has been rewritten, the
         node has been restarted, and the node is ready to provide service.
     """
-    needed, total = params
+    happy, needed, total = params
     config = node.get_config()
-    config.set_config("client", "shares.happy", str(1))
-    config.set_config("client", "shares.needed", str(needed))
-    config.set_config("client", "shares.total", str(total))
-    config.write_private_config("convergence", base32.b2a(convergence))
 
-    # restart the node
-    print(f"Restarting {node.node_dir} for ZFEC reconfiguration")
-    await node.restart_async(reactor, request)
-    print("Restarted.  Waiting for ready state.")
-    await_client_ready(node)
-    print("Ready.")
+    changed = False
+    cur_happy = int(config.get_config("client", "shares.happy"))
+    cur_needed = int(config.get_config("client", "shares.needed"))
+    cur_total = int(config.get_config("client", "shares.total"))
+
+    if (happy, needed, total) != (cur_happy, cur_needed, cur_total):
+        changed = True
+        config.set_config("client", "shares.happy", str(happy))
+        config.set_config("client", "shares.needed", str(needed))
+        config.set_config("client", "shares.total", str(total))
+
+    cur_convergence = config.get_private_config("convergence").encode("ascii")
+    if base32.a2b(cur_convergence) != convergence:
+        changed = True
+        config.write_private_config("convergence", base32.b2a(convergence))
+
+    if changed:
+        # restart the node
+        print(f"Restarting {node.node_dir} for ZFEC reconfiguration")
+        await node.restart_async(reactor, request)
+        print("Restarted.  Waiting for ready state.")
+        await_client_ready(node)
+        print("Ready.")
+    else:
+        print("Config unchanged, not restarting.")