Add support for task expiration (#3546)

src/Context.cpp

@@ -118,6 +118,7 @@ std::string configurationDefaults =
   "json.array=1                                   # Enclose JSON output in [ ]\n"
   "abbreviation.minimum=2                         # Shortest allowed abbreviation\n"
   "news.version=                                  # Latest version highlights read by the user\n"
+  "expiration.on-sync=0                           # Expire old tasks on sync\n"
   "\n"
   "# Dates\n"
   "dateformat=Y-M-D                               # Preferred input and display date format\n"
@@ -853,13 +854,8 @@ int Context::dispatch (std::string &out)
     // The command know whether they need a GC.
     if (c->needs_gc ())
     {
-      run_gc = config.getBoolean ("gc");
       tdb2.gc ();
     }
-    else
-    {
-      run_gc = false;
-    }
 
     // This is something that is only needed for write commands with no other
     // filter processing.

src/Context.h

@@ -98,7 +98,6 @@ public:
   Hooks                               hooks               {};
   bool                                determine_color_use {true};
   bool                                use_color           {true};
-  bool                                run_gc              {true};
   bool                                verbosity_legacy    {false};
   std::set <std::string>              verbosity           {};
   std::vector <std::string>           headers             {};

src/TDB2.cpp

@@ -303,6 +303,7 @@ void TDB2::show_diff (
   }
 }
 
+////////////////////////////////////////////////////////////////////////////////
 void TDB2::gc ()
 {
   Timer timer;
@@ -316,6 +317,12 @@ void TDB2::gc ()
   Context::getContext ().time_gc_us += timer.total_us ();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void TDB2::expire_tasks ()
+{
+  replica.expire_tasks ();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Latest ID is that of the last pending task.
 int TDB2::latest_id ()

src/TDB2.h

@@ -56,6 +56,7 @@ public:
   void get_changes (std::vector <Task>&);
   void revert ();
   void gc ();
+  void expire_tasks ();
   int  latest_id ();
 
   // Generalized task accessors.

src/commands/CmdNews.cpp

@@ -172,6 +172,7 @@ std::vector<NewsItem> NewsItem::all () {
   std::vector<NewsItem> items;
   version2_6_0(items);
   version3_0_0(items);
+  version3_1_0(items);
   return items;
 }
 
@@ -537,6 +538,27 @@ void NewsItem::version3_0_0 (std::vector<NewsItem>& items) {
   items.push_back(sync);
 }
 
+void NewsItem::version3_1_0 (std::vector<NewsItem>& items) {
+  Version version("3.1.0");
+  NewsItem sync {
+    version,
+    /*title=*/"Purging and Expiring Tasks",
+    /*bg_title=*/"",
+    /*background=*/"",
+    /*punchline=*/
+    "Support for `task purge` has been restored, and new support added for automatically expiring\n"
+    "old tasks.\n\n"
+    /*update=*/
+    "The `task purge` command removes tasks entirely, in contrast to `task delete` which merely sets\n"
+    "the task status to 'Deleted'. This functionality existed in versions 2.x but was temporarily\n"
+    "removed in 3.0.\n\n"
+    "The new `expiration.on-sync` configuration parameter controls automatic expiration of old tasks.\n"
+    "An old task is one with status 'Deleted' that has not been modified in 180 days. This\n"
+    "functionality is optional and not enabled by default."
+  };
+  items.push_back(sync);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 int CmdNews::execute (std::string& output)
 {

src/commands/CmdNews.h

@@ -49,6 +49,7 @@ public:
   static std::vector<NewsItem> all();
   static void version2_6_0 (std::vector<NewsItem>&);
   static void version3_0_0 (std::vector<NewsItem>&);
+  static void version3_1_0 (std::vector<NewsItem>&);
 
 private:
   NewsItem (

src/commands/CmdShow.cpp

@@ -160,6 +160,7 @@ int CmdShow::execute (std::string& output)
     " due"
     " editor"
     " exit.on.missing.db"
+    " expiration.on-sync"
     " expressions"
     " fontunderline"
     " gc"

src/commands/CmdSync.cpp

@@ -106,7 +106,12 @@ int CmdSync::execute (std::string& output)
         << '\n';
   }
 
-  Context::getContext ().tdb2.sync(std::move(server), false);
+  Context &context = Context::getContext ();
+  context.tdb2.sync(std::move(server), false);
+
+  if (context.config.getBoolean ("expiration.on-sync")) {
+    context.tdb2.expire_tasks ();
+  }
 
   output = out.str ();
   return status;

src/tc/Replica.cpp

@@ -144,6 +144,15 @@ tc::Task tc::Replica::import_task_with_uuid (const std::string &uuid)
   return Task (tctask);
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void tc::Replica::expire_tasks ()
+{
+  auto res = tc_replica_expire_tasks (&*inner);
+  if (res != TC_RESULT_OK) {
+    throw replica_error ();
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void tc::Replica::sync (Server server, bool avoid_snapshots)
 {

src/tc/Replica.h

@@ -92,6 +92,7 @@ namespace tc {
     tc::Task new_task (Status status, const std::string &description);
     tc::Task import_task_with_uuid (const std::string &uuid);
 // TODO: struct TCTask *tc_replica_import_task_with_uuid(struct TCReplica *rep, struct TCUuid tcuuid);
+    void expire_tasks();
     void sync(Server server, bool avoid_snapshots);
     tc::ffi::TCReplicaOpList get_undo_ops ();
     void commit_undo_ops (tc::ffi::TCReplicaOpList tc_undo_ops, int32_t *undone_out);

src/tc/lib/src/replica.rs

@@ -533,6 +533,31 @@ pub unsafe extern "C" fn tc_replica_sync(
     )
 }
 
+#[ffizz_header::item]
+#[ffizz(order = 902)]
+/// Expire old, deleted tasks.
+///
+/// Expiration entails removal of tasks from the replica. Any modifications that occur after
+/// the deletion (such as operations synchronized from other replicas) will do nothing.
+///
+/// Tasks are eligible for expiration when they have status Deleted and have not been modified
+/// for 180 days (about six months). Note that completed tasks are not eligible.
+///
+/// ```c
+/// EXTERN_C TCResult tc_replica_expire_tasks(struct TCReplica *rep);
+/// ```
+#[no_mangle]
+pub unsafe extern "C" fn tc_replica_expire_tasks(rep: *mut TCReplica) -> TCResult {
+    wrap(
+        rep,
+        |rep| {
+            rep.expire_tasks()?;
+            Ok(TCResult::Ok)
+        },
+        TCResult::Error,
+    )
+}
+
 #[ffizz_header::item]
 #[ffizz(order = 902)]
 /// Return undo local operations until the most recent UndoPoint.

src/tc/lib/taskchampion.h

@@ -552,6 +552,15 @@ EXTERN_C TCResult tc_replica_commit_undo_ops(struct TCReplica *rep, TCReplicaOpL
 // free the returned string.
 EXTERN_C struct TCString tc_replica_error(struct TCReplica *rep);
 
+// Expire old, deleted tasks.
+//
+// Expiration entails removal of tasks from the replica. Any modifications that occur after
+// the deletion (such as operations synchronized from other replicas) will do nothing.
+//
+// Tasks are eligible for expiration when they have status Deleted and have not been modified
+// for 180 days (about six months). Note that completed tasks are not eligible.
+EXTERN_C TCResult tc_replica_expire_tasks(struct TCReplica *rep);
+
 // Get an existing task by its UUID.
 //
 // Returns NULL when the task does not exist, and on error.  Consult tc_replica_error