Open Replica read-only when possible (#3776)

* Open Replica read-only when possible

Specifically, when either
 - the command is read-only; or
 - the command requires GC (including recurrence updates) but GC is disabled by config

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

test/CMakeLists.txt

@@ -157,6 +157,7 @@ set (pythonTests
   purge.test.py
   quotes.test.py
   rc.override.test.py
+  read-only.test.py
   recurrence.test.py
   reports.test.py
   search.test.py

test/make_tc_task.cpp

@@ -56,7 +56,7 @@ int main(int argc, char **argv) {
   }
   char *datadir = *++argv;
 
-  auto replica = tc::new_replica_on_disk(datadir, true);
+  auto replica = tc::new_replica_on_disk(datadir, /*create_if_missing=*/true, /*read_write=*/true);
   auto uuid = tc::uuid_v4();
   auto operations = tc::new_operations();
   auto task = tc::create_task(uuid, operations);

test/read-only.test.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+###############################################################################
+#
+# Copyright 2006 - 2021, Tomas Babej, Paul Beckingham, Federico Hernandez.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+#
+# https://www.opensource.org/licenses/mit-license.php
+#
+###############################################################################
+
+import sys
+import os
+import platform
+import time
+import unittest
+
+# Ensure python finds the local simpletap module
+sys.path.append(os.path.dirname(os.path.abspath(__file__)))
+
+from basetest import Task, TestCase
+
+
+class TestReadOnly(TestCase):
+    def setUp(self):
+        self.t = Task()
+        self.t("add foo")
+
+        # set the mtime of the taskdb to an hour ago, so we can see any changes
+        self.taskdb = self.t.datadir + "/taskchampion.sqlite3"
+        os.utime(self.taskdb, (time.time() - 3600,) * 2)
+
+    def assertNotModified(self):
+        self.assertLess(os.stat(self.taskdb).st_mtime, time.time() - 1800)
+
+    def assertModified(self):
+        self.assertGreater(os.stat(self.taskdb).st_mtime, time.time() - 1800)
+
+    def test_read_only_command(self):
+        code, out, err = self.t("reports")
+        self.assertNotModified()
+
+    def test_report(self):
+        code, out, err = self.t("list")
+        self.assertModified()
+
+    def test_burndown(self):
+        code, out, err = self.t("burndown")
+        self.assertModified()
+
+    def test_report_gc_0(self):
+        self.t.config("gc", "0")
+        code, out, err = self.t("list")
+        self.assertNotModified()
+
+    def test_burndown_gc_0(self):
+        self.t.config("gc", "0")
+        code, out, err = self.t("burndown")
+        self.assertNotModified()
+
+
+if __name__ == "__main__":
+    from simpletap import TAPTestRunner
+
+    unittest.main(testRunner=TAPTestRunner())
+
+# vim: ai sts=4 et sw=4 ft=python

test/tdb2_test.cpp

@@ -61,7 +61,7 @@ int TEST_NAME(int, char**) {
     context.config.set("gc", 1);
     context.config.set("debug", 1);
 
-    context.tdb2.open_replica(".", true);
+    context.tdb2.open_replica(".", /*create_if_missing=*/true, /*read_write=*/true);
 
     // Try reading an empty database.
     std::vector<Task> pending = context.tdb2.pending_tasks();
@@ -108,7 +108,7 @@ int TEST_NAME(int, char**) {
 
     // Reset for reuse.
     cleardb();
-    context.tdb2.open_replica(".", true);
+    context.tdb2.open_replica(".", /*create_if_missing=*/true, /*read_write=*/true);
 
     // TODO complete a task
     // TODO gc

test/view_test.cpp

@@ -47,6 +47,7 @@ int TEST_NAME(int, char**) {
   UnitTest t(1);
   Context context;
   Context::setContext(&context);
+  context.tdb2.open_replica_in_memory();
 
   // Ensure environment has no influence.
   unsetenv("TASKDATA");