Introduce reader_test_should_cancel

This centralizes the logic around cancellation due to either sigint or a
stale threaded operation.

src/complete.cpp

@@ -1278,9 +1278,7 @@ bool completer_t::try_complete_user(const wcstring &str) {
     setpwent();
     // cppcheck-suppress getpwentCalled
     while (struct passwd *pw = getpwent()) {
-        bool interrupted =
-            is_main_thread() ? reader_test_and_clear_interrupted() : reader_thread_job_is_stale();
-        if (interrupted) {
+        if (reader_test_should_cancel()) {
             break;
         }
         const wcstring pw_name_str = str2wcstring(pw->pw_name);
@@ -1670,9 +1668,7 @@ static void append_switch(wcstring &out, const wcstring opt, const wcstring arg)
     if (arg.empty()) return;
     append_format(out, L" --%ls %ls", opt.c_str(), escape_string(arg, ESCAPE_ALL).c_str());
 }
-static void append_switch(wcstring &out, wchar_t opt) {
-    append_format(out, L" -%lc", opt);
-}
+static void append_switch(wcstring &out, wchar_t opt) { append_format(out, L" -%lc", opt); }
 static void append_switch(wcstring &out, const wcstring opt) {
     append_format(out, L" --%ls", opt.c_str());
 }

src/history.cpp

@@ -579,11 +579,10 @@ bool history_search_t::go_backwards() {
     const size_t max_index = (size_t)-1;
 
     if (current_index_ == max_index) return false;
-    const bool main_thread = is_main_thread();
 
     size_t index = current_index_;
     while (++index < max_index) {
-        if (main_thread ? reader_test_and_clear_interrupted() : reader_thread_job_is_stale()) {
+        if (reader_test_should_cancel()) {
             return false;
         }
 

src/reader.cpp

@@ -836,7 +836,13 @@ void reader_data_t::repaint_if_needed() {
 
 void reader_reset_interrupted() { interrupted = 0; }
 
-bool reader_test_interrupted() { return interrupted != 0; }
+bool reader_test_should_cancel() {
+    if (is_main_thread()) {
+        return interrupted;
+    } else {
+        return read_generation_count() != s_thread_generation;
+    }
+}
 
 bool reader_test_and_clear_interrupted() {
     int res = interrupted;
@@ -846,11 +852,6 @@ bool reader_test_and_clear_interrupted() {
     return res != 0;
 }
 
-bool reader_thread_job_is_stale() {
-    ASSERT_IS_BACKGROUND_THREAD();
-    return read_generation_count() != s_thread_generation;
-}
-
 void reader_write_title(const wcstring &cmd, parser_t &parser, bool reset_cursor_position) {
     if (!term_supports_setting_title()) return;
 
@@ -1275,7 +1276,7 @@ static std::function<autosuggestion_result_t(void)> get_autosuggestion_performer
         }
 
         history_search_t searcher(*history, search_string, HISTORY_SEARCH_TYPE_PREFIX);
-        while (!reader_thread_job_is_stale() && searcher.go_backwards()) {
+        while (!reader_test_should_cancel() && searcher.go_backwards()) {
             history_item_t item = searcher.current_item();
 
             // Skip items with newlines because they make terrible autosuggestions.
@@ -1288,7 +1289,7 @@ static std::function<autosuggestion_result_t(void)> get_autosuggestion_performer
         }
 
         // Maybe cancel here.
-        if (reader_thread_job_is_stale()) return nothing;
+        if (reader_test_should_cancel()) return nothing;
 
         // Here we do something a little funny. If the line ends with a space, and the cursor is not
         // at the end, don't use completion autosuggestions. It ends up being pretty weird seeing

src/reader.h

@@ -115,8 +115,10 @@ size_t reader_get_cursor_pos();
 /// selection, true otherwise.
 bool reader_get_selection(size_t *start, size_t *len);
 
-/// Return the value of the interrupted flag, which is set by the sigint handler.
-bool reader_test_interrupted();
+/// Return whether we have been interrupted and should cancel the current operation.
+/// This may be because we received a sigint, or because we are in a background thread
+/// and the job is now stale.
+bool reader_test_should_cancel();
 
 /// Return the value of the interrupted flag, which is set by the sigint handler, and clear it if it
 /// was set.
@@ -131,11 +133,6 @@ void reader_reset_interrupted();
 /// was set. If the current reader is interruptible, call \c reader_exit().
 int reader_reading_interrupted();
 
-/// Returns true if the current reader generation count does not equal the generation count the
-/// current thread was started with. Note 1: currently only valid for autocompletion threads! Other
-/// threads don't set the threadlocal generation count when they start up.
-bool reader_thread_job_is_stale();
-
 /// Read one line of input. Before calling this function, reader_push() must have been called in
 /// order to set up a valid reader environment. If nchars > 0, return after reading that many
 /// characters even if a full line has not yet been read. Note: the returned value may be longer

src/wildcard.cpp

@@ -499,10 +499,7 @@ class wildcard_expander_t {
 
     /// Indicate whether we should cancel wildcard expansion. This latches 'interrupt'.
     bool interrupted() {
-        if (!did_interrupt) {
-            did_interrupt = (is_main_thread() ? reader_test_and_clear_interrupted()
-                                              : reader_thread_job_is_stale());
-        }
+        did_interrupt = did_interrupt || reader_test_should_cancel();
         return did_interrupt;
     }