support for cluster commands limited

fox/cluster.py

@@ -29,29 +29,44 @@ def __init__(self, *hosts):
         self.hosts = hosts
         self._connections = [_get_connection(host, use_cache=False) for host in self.hosts]
 
-    def run(self, command):
-        return run_in_loop(self._run(command))
+    def run(self, command, limit=0):
+        return run_in_loop(self._run(command, limit))
 
-    async def _run(self, command):
+    async def _run(self, command, limit=0):
         bar = tqdm.tqdm(total=len(self.hosts))
         qbar = asyncio.Queue()
+        futures_done = []
+        aws = set()
 
-        results = await asyncio.gather(
-            *[self._do(qbar, connection, command) for connection in self._connections],
-            _update_bar(bar, len(self.hosts), qbar),
-            return_exceptions=True,
-        )
-        for connection, result in results[:-1]:
+        bar_task = asyncio.ensure_future(_update_bar(bar, len(self.hosts), qbar))
+
+        for connection in self._connections:
+            aws.add(asyncio.ensure_future(self._do(qbar, connection, command)))
+            if limit and len(aws) >= limit:
+                done, pending = await asyncio.wait(aws, return_when=asyncio.FIRST_COMPLETED)
+                aws = pending
+                futures_done.extend(done)
+
+        if len(aws):
+            done, pending = await asyncio.wait(aws, return_when=asyncio.ALL_COMPLETED)
+            futures_done.extend(done)
+
+        _ = await asyncio.wait({bar_task})
+
+        results = [future.result() for future in futures_done]
+        for connection, result in results:
             if isinstance(result, CommandResult):
                 print(f"output from {connection.nickname}: {result.stdout}", end="")
             else:
                 print(f"command failed on {connection.nickname}: {result}")
 
+        return results
+
     async def _do(self, queue, connection, command):
         try:
             result = await connection._run(command, echo=False)
         except Exception as exc:
-            print(f"task on {connection} failed: {exc}")
+            print(f"Task on {connection} failed: {exc}")
             result = None
 
         await queue.put(1)

fox/connection.py

@@ -363,7 +363,9 @@ def _get_connection(name=None, use_cache=True) -> Connection:
 
     # NOTE: we only cache connections created here, and maybe the tunnels.
     # maybe by default we should not re-use the tunnels, as the default behavior of SSH
-    c = Connection(ssh_options["hostname"], ssh_options["user"], ssh_options["port"], **args)
+    c = Connection(
+        ssh_options["hostname"], ssh_options["user"], ssh_options["port"], nickname=name, **args
+    )
     if use_cache:
         _connections_cache[name] = c
     return c