Enforce switchover when target state is standby AND mux mode is standby (#281)

Description of PR
Summary:
Fixes # (issue)
Enforce switchover when target state is standby AND mux mode is standby.

sign-off: Jing Zhang [email protected]

Type of change
 Bug fix
 New feature
 Doc/Design
 Unit test
Approach
What is the motivation for this PR?
Soc agent can always restart and set the forwarding state to default "active" on host side. If this happens during ToR maintenance ( mux mode != auto), we still need to correct the state to "standby".

Work item tracking
Microsoft ADO (number only):
30158450

Author: zjswhhh

src/link_manager/LinkManagerStateMachineActiveActive.cpp

@@ -1034,7 +1034,8 @@ void ActiveActiveStateMachine::switchMuxState(
     if (forceSwitch ||
         mMuxPortConfig.getMode() == common::MuxPortConfig::Mode::Auto ||
         mMuxPortConfig.getMode() == common::MuxPortConfig::Mode::Detached ||
-        (mMuxPortConfig.getMode() == common::MuxPortConfig::Mode::Active && label == mux_state::MuxState::Label::Active)) {
+        (mMuxPortConfig.getMode() == common::MuxPortConfig::Mode::Active && label == mux_state::MuxState::Label::Active) ||
+        (mMuxPortConfig.getMode() == common::MuxPortConfig::Mode::Standby && label == mux_state::MuxState::Label::Standby)) {
         MUXLOGWARNING(
             boost::format("%s: Switching MUX state to '%s'") %
             mMuxPortConfig.getPortName() %

test/LinkManagerStateMachineActiveActiveTest.cpp

@@ -384,6 +384,28 @@ TEST_F(LinkManagerStateMachineActiveActiveTest, MuxActiveConfigStandby)
     VALIDATE_STATE(Active, Active, Up);
 }
 
+TEST_F(LinkManagerStateMachineActiveActiveTest, ConfigStandbySocAgentRestart)
+{
+    setMuxActive();
+
+    handleMuxConfig("standby", 1);
+    EXPECT_EQ(mDbInterfacePtr->mSetMuxStateInvokeCount, 2);
+    EXPECT_EQ(mDbInterfacePtr->mLastSetMuxState, mux_state::MuxState::Label::Standby);
+    VALIDATE_STATE(Active, Standby, Up);
+
+    handleMuxState("standby", 3);
+    VALIDATE_STATE(Active, Standby, Up);
+
+    handleMuxState("active", 3);
+    VALIDATE_STATE(Active, Standby, Up);
+    EXPECT_EQ(mDbInterfacePtr->mSetMuxStateInvokeCount, 3);
+
+    handleMuxConfig("auto", 1);
+    EXPECT_EQ(mDbInterfacePtr->mSetMuxStateInvokeCount, 4);
+    EXPECT_EQ(mDbInterfacePtr->mLastSetMuxState, mux_state::MuxState::Label::Active);
+    VALIDATE_STATE(Active, Active, Up);
+}
+
 TEST_F(LinkManagerStateMachineActiveActiveTest, MuxActiveLinkProberPeerActive)
 {
     setMuxActive();