history pull (#5047)

Co-authored-by: a <aaa@aaa.aaa>
Closes https://github.com/xonsh/xonsh/issues/5044

docs/tutorial_hist.rst

@@ -255,6 +255,13 @@ may be useful to share entries between shell sessions. In such a case, one can u
 the ``flush`` action to immediately save the session history to disk and make it
 accessible from other shell sessions.
 
+``pull`` action
+================
+Tries to pull the history from parallel sessions and add to the current session.
+
+For example if there are two parallel terminal windows the run of ``history pull``
+command from the second terminal window will get the commands from the first terminal.
+
 ``clear`` action
 ================
 Deletes the history from the current session up until this point. Later commands

news/history_pull.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* Added ``history pull`` command to SQLite history backend to pull the history from parallel sessions and add to the current session.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

xonsh/history/base.py

@@ -130,6 +130,10 @@ class History:
         """
         pass
 
+    def pull(self, **kwargs):
+        """Pull history from other parallel sessions."""
+        raise NotImplementedError
+
     def flush(self, **kwargs):
         """Flush the history items to disk from a buffer."""
         pass

xonsh/history/main.py

@@ -281,6 +281,31 @@ class HistoryAlias(xcli.ArgParserAlias):
             return
         print(str(hist.sessionid), file=_stdout)
 
+    @staticmethod
+    def pull(show_commands=False, _stdout=None):
+        """Pull history from other parallel sessions.
+
+        Parameters
+        ----------
+        show_commands: -c, --show-commands
+            show pulled commands
+        """
+
+        hist = XSH.history
+
+        if hist.pull.__module__ == "xonsh.history.base":
+            backend = XSH.env.get("XONSH_HISTORY_BACKEND", "unknown")
+            print(
+                f"Pull method is not supported in {backend} history backend.",
+                file=_stdout,
+            )
+
+        lines_added = hist.pull(show_commands)
+        if lines_added:
+            print(f"Added {lines_added} records!", file=_stdout)
+        else:
+            print(f"No records found!", file=_stdout)
+
     @staticmethod
     def flush(_stdout):
         """Flush the current history to disk"""
@@ -428,7 +453,7 @@ class HistoryAlias(xcli.ArgParserAlias):
 
         dest.flush()
 
-        self.out("done.")
+        self.out("Done")
 
     def build(self):
         parser = self.create_parser(prog="history")
@@ -436,6 +461,7 @@ class HistoryAlias(xcli.ArgParserAlias):
         parser.add_command(self.id_cmd, prog="id")
         parser.add_command(self.file)
         parser.add_command(self.info)
+        parser.add_command(self.pull)
         parser.add_command(self.flush)
         parser.add_command(self.off)
         parser.add_command(self.on)

xonsh/history/sqlite.py

@@ -204,6 +204,15 @@ def xh_sqlite_delete_items(size_to_keep, filename=None):
         return _xh_sqlite_delete_records(c, size_to_keep)
 
 
+def xh_sqlite_pull(filename, last_pull_time, current_sessionid):
+    sql = f"SELECT inp FROM xonsh_history WHERE tsb > ? AND sessionid != ? ORDER BY tsb"
+    params = [last_pull_time, current_sessionid]
+    with _xh_sqlite_get_conn(filename=filename) as conn:
+        c = conn.cursor()
+        c.execute(sql, tuple(params))
+        return c.fetchall()
+
+
 def xh_sqlite_wipe_session(sessionid=None, filename=None):
     """Wipe the current session's entries from the database."""
     sql = "DELETE FROM xonsh_history WHERE sessionid = ?"
@@ -256,6 +265,7 @@ class SqliteHistory(History):
         if filename is None:
             filename = _xh_sqlite_get_file_name()
         self.filename = filename
+        self.last_pull_time = time.time()
         self.gc = SqliteHistoryGC() if gc else None
         self._last_hist_inp = None
         self.inps = []
@@ -345,6 +355,22 @@ class SqliteHistory(History):
         data["gc options"] = envs.get("XONSH_HISTORY_SIZE")
         return data
 
+    def pull(self, show_commands=False):
+        if not hasattr(XSH.shell.shell, "prompter"):
+            print(f"Shell type {XSH.shell.shell} is not supported.")
+            return 0
+
+        cnt = 0
+        for r in xh_sqlite_pull(
+            self.filename, self.last_pull_time, str(self.sessionid)
+        ):
+            if show_commands:
+                print(r[0])
+            XSH.shell.shell.prompter.history.append_string(r[0])
+            cnt += 1
+        self.last_pull_time = time.time()
+        return cnt
+
     def run_gc(self, size=None, blocking=True):
         self.gc = SqliteHistoryGC(wait_for_shell=False, size=size)
         if blocking: