From d683f331cd4f67a2c304b806bb99cd9d438f4d11 Mon Sep 17 00:00:00 2001
From: Bo Zhou <2466956298@qq.com>
Date: Tue, 2 Jun 2020 20:03:25 +0800
Subject: [PATCH] ping the master before connection (#278)

* ping the master before connection

* yapf

* fix comments

* remove the useless library

* install ping for the docker environment

* remove protobuf intallation

* remove evokit test
---
 .teamcity/Dockerfile                   |  5 ++---
 .teamcity/build.sh                     | 14 -------------
 parl/algorithms/fluid/impala/vtrace.py |  2 +-
 parl/remote/client.py                  | 10 +++++++--
 parl/remote/tests/ping_master_test.py  | 29 ++++++++++++++++++++++++++
 parl/utils/communication.py            | 27 +++++++++++++++++++++++-
 6 files changed, 66 insertions(+), 21 deletions(-)
 create mode 100644 parl/remote/tests/ping_master_test.py

diff --git a/.teamcity/Dockerfile b/.teamcity/Dockerfile
index e16d09d..67e20af 100644
--- a/.teamcity/Dockerfile
+++ b/.teamcity/Dockerfile
@@ -23,6 +23,5 @@ RUN apt-get install -y libgflags-dev libgoogle-glog-dev libomp-dev unzip
 RUN apt-get install -y libgtest-dev && cd /usr/src/gtest && mkdir build \
 	&& cd build && cmake .. && make  && cp libgtest*.a /usr/local/lib
 
-RUN wget https://github.com/google/protobuf/releases/download/v2.4.1/protobuf-2.4.1.tar.gz \
-    && tar -zxvf protobuf-2.4.1.tar.gz \
-    && cd protobuf-2.4.1 && ./configure && make && make install 
+RUN apt-get update
+RUN apt-get install -y iputils-ping
diff --git a/.teamcity/build.sh b/.teamcity/build.sh
index 09d9982..3a76f48 100755
--- a/.teamcity/build.sh
+++ b/.teamcity/build.sh
@@ -134,19 +134,6 @@ EOF
     rm -rf ${REPO_ROOT}/build
 }
 
-function run_evo_kit_test {
-    cd ${REPO_ROOT}/evo_kit
-
-    cat <<EOF
-    ========================================
-    Running evo_kit test...
-    ========================================
-EOF
-    sh test/run_test.sh
-    rm -rf ${REPO_ROOT}/evo_kit/build
-    rm -rf ${REPO_ROOT}/evo_kit/libtorch
-}
-
 function main() {
     set -e
     local CMD=$1
@@ -189,7 +176,6 @@ function main() {
           /root/miniconda3/envs/empty_env/bin/pip install .
           run_import_test
           run_docs_test
-          run_evo_kit_test
           ;;
         *)
           print_usage
diff --git a/parl/algorithms/fluid/impala/vtrace.py b/parl/algorithms/fluid/impala/vtrace.py
index 9eb7595..99840bb 100644
--- a/parl/algorithms/fluid/impala/vtrace.py
+++ b/parl/algorithms/fluid/impala/vtrace.py
@@ -146,7 +146,7 @@ def from_importance_weights(behaviour_actions_log_probs,
 
 
 def recursively_scan(discounts, cs, deltas):
-    """ Recursively calculate vs_minus_v_xs according to following equation:
+    r""" Recursively calculate vs_minus_v_xs according to following equation:
     vs_minus_v_xs(t) = deltas(t) + discounts(t) * cs(t) * vs_minus_v_xs(t + 1)
 
     Args:
diff --git a/parl/remote/client.py b/parl/remote/client.py
index 0c06eff..93174d1 100644
--- a/parl/remote/client.py
+++ b/parl/remote/client.py
@@ -20,6 +20,7 @@ import sys
 import threading
 import zmq
 from parl.utils import to_str, to_byte, get_ip_address, logger
+from parl.utils.communication import ping
 from parl.remote import remote_constants
 import time
 
@@ -326,9 +327,14 @@ def connect(master_address, distributed_files=[]):
         Exception: An exception is raised if the master node is not started.
     """
 
-    assert len(master_address.split(":")) == 2, "please input address in " +\
+    assert len(master_address.split(":")) == 2, "Please input address in " +\
         "{ip}:{port} format"
     global GLOBAL_CLIENT
+    addr = master_address.split(":")[0]
+    assert ping(
+        addr
+    ) == 0, "Error occurs in connection with {}. PARL failed to ping this IP.".format(
+        master_address)
     cur_process_id = os.getpid()
     if GLOBAL_CLIENT is None:
         GLOBAL_CLIENT = Client(master_address, cur_process_id,
@@ -366,5 +372,5 @@ def disconnect():
         GLOBAL_CLIENT = None
     else:
         logger.info(
-            "No client to be released. Please make sure that you have call `parl.connect`"
+            "No client to be released. Please make sure that you have called `parl.connect`"
         )
diff --git a/parl/remote/tests/ping_master_test.py b/parl/remote/tests/ping_master_test.py
new file mode 100644
index 0000000..1d0b2a1
--- /dev/null
+++ b/parl/remote/tests/ping_master_test.py
@@ -0,0 +1,29 @@
+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import parl
+import unittest
+from parl.remote.client import disconnect
+
+
+class TestPingMaster(unittest.TestCase):
+    def tearDown(self):
+        disconnect()
+
+    def test_throw_exception(self):
+        with self.assertRaises(AssertionError):
+            parl.connect("176.2.3.4:8080")
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/parl/utils/communication.py b/parl/utils/communication.py
index ea201ba..be80de6 100644
--- a/parl/utils/communication.py
+++ b/parl/utils/communication.py
@@ -14,9 +14,14 @@
 
 import cloudpickle
 import pyarrow
+import subprocess
+import os
+from parl.utils import _IS_WINDOWS
 from parl.utils import SerializeError, DeserializeError
 
-__all__ = ['dumps_argument', 'loads_argument', 'dumps_return', 'loads_return']
+__all__ = [
+    'dumps_argument', 'loads_argument', 'dumps_return', 'loads_return', 'ping'
+]
 
 
 # Reference: https://github.com/apache/arrow/blob/f88474c84e7f02e226eb4cc32afef5e2bbc6e5b4/python/pyarrow/tests/test_serialization.py#L658-L682
@@ -115,3 +120,23 @@ def loads_return(data):
         raise DeserializeError(e)
 
     return ret
+
+
+#Reference: https://stackoverflow.com/questions/2953462/pinging-servers-in-python
+def ping(host):
+    """
+    Returns True if host (str) responds to a ping request.
+    Remember that a host may not respond to a ping (ICMP) request even if the host name is valid.
+    """
+
+    # Option for the number of packets as a function of
+    param = '-n' if _IS_WINDOWS else '-c'
+
+    # Building the command. Ex: "ping -c 1 google.com"
+    command = ['ping', param, '1', host]
+    FNULL = open(os.devnull, 'w')
+    child = subprocess.Popen(command, stdout=FNULL, stderr=subprocess.STDOUT)
+    FNULL.close()
+    child.communicate()[0]
+
+    return child.returncode
-- 
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