From ba4b238a0029b4041f8f30ddfd812dd7b29cf97d Mon Sep 17 00:00:00 2001
From: Jonathan Hui <jonhui@nestlabs.com>
Date: Wed, 1 Aug 2018 10:33:03 -0500
Subject: [PATCH] [link-quality] explicitly clear link quality for new
 child/router (#2941)

The child/router entries are generally cleared using `memset()` to avoid
explicitly setting all fields to zero.  As a result, it is necessary to
explicitly clear the link quality state to properly initialize the last
RSSI reading.  The user-specific constructors are also removed.
---
 src/core/mac/mac.cpp             |  3 +--
 src/core/thread/link_quality.cpp | 12 +++++-------
 src/core/thread/link_quality.hpp | 17 -----------------
 src/core/thread/mle_router.cpp   |  1 +
 tests/unit/test_link_quality.cpp |  3 +++
 5 files changed, 10 insertions(+), 26 deletions(-)

diff --git a/src/core/mac/mac.cpp b/src/core/mac/mac.cpp
index ec6f791c0..21bc727c3 100644
--- a/src/core/mac/mac.cpp
+++ b/src/core/mac/mac.cpp
@@ -195,12 +195,11 @@ Mac::Mac(Instance &aInstance)
     , mTxFrame(static_cast<Frame *>(otPlatRadioGetTransmitBuffer(&aInstance)))
     , mOobFrame(NULL)
     , mKeyIdMode2FrameCounter(0)
-    , mCcaSuccessRateTracker()
     , mCcaSampleCount(0)
     , mEnabled(true)
 {
     GenerateExtAddress(&mExtAddress);
-
+    mCcaSuccessRateTracker.Reset();
     memset(&mCounters, 0, sizeof(otMacCounters));
 
     otPlatRadioEnable(&GetInstance());
diff --git a/src/core/thread/link_quality.cpp b/src/core/thread/link_quality.cpp
index 06675405c..c615b2c8c 100644
--- a/src/core/thread/link_quality.cpp
+++ b/src/core/thread/link_quality.cpp
@@ -140,18 +140,16 @@ exit:
     return string;
 }
 
-LinkQualityInfo::LinkQualityInfo(void)
-    : mLastRss(OT_RADIO_RSSI_INVALID)
-{
-    mRssAverager.Reset();
-    SetLinkQuality(0);
-}
-
 void LinkQualityInfo::Clear(void)
 {
     mRssAverager.Reset();
     SetLinkQuality(0);
     mLastRss = OT_RADIO_RSSI_INVALID;
+
+#if OPENTHREAD_CONFIG_ENABLE_TX_ERROR_RATE_TRACKING
+    mFrameErrorRate.Reset();
+    mMessageErrorRate.Reset();
+#endif
 }
 
 void LinkQualityInfo::AddRss(int8_t aNoiseFloor, int8_t aRss)
diff --git a/src/core/thread/link_quality.hpp b/src/core/thread/link_quality.hpp
index 0f905ed39..91a00c52d 100644
--- a/src/core/thread/link_quality.hpp
+++ b/src/core/thread/link_quality.hpp
@@ -67,17 +67,6 @@ public:
         kMaxRateValue = 0xffff, ///< Indicates value corresponding to maximum (failure/success) rate of 100%.
     };
 
-    /**
-     * This constructor initializes a `SuccessRateTracker` instance.
-     *
-     * After initialization the tracker starts with success rate 100% (failure rate 0%).
-     *
-     */
-    SuccessRateTracker(void)
-        : mFailureRate(0)
-    {
-    }
-
     /**
      * This method resets the tracker to its initialized state, setting success rate to 100%.
      *
@@ -241,12 +230,6 @@ public:
      */
     typedef String<kInfoStringSize> InfoString;
 
-    /**
-     * This constructor initializes the object.
-     *
-     */
-    LinkQualityInfo(void);
-
     /**
      * This method clears the all the data in the object.
      *
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index cc7e9ac83..c93e466be 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -3504,6 +3504,7 @@ void MleRouter::RestoreChildren(void)
         memset(child, 0, sizeof(*child));
 
         child->SetExtAddress(*static_cast<const Mac::ExtAddress *>(&childInfo.mExtAddress));
+        child->GetLinkInfo().Clear();
         child->SetRloc16(childInfo.mRloc16);
         child->SetTimeout(childInfo.mTimeout);
         child->SetDeviceMode(childInfo.mMode);
diff --git a/tests/unit/test_link_quality.cpp b/tests/unit/test_link_quality.cpp
index f9fa279e5..feeb73829 100644
--- a/tests/unit/test_link_quality.cpp
+++ b/tests/unit/test_link_quality.cpp
@@ -93,6 +93,7 @@ void TestLinkQualityData(RssTestData aRssData)
     size_t          i;
 
     printf("- - - - - - - - - - - - - - - - - -\n");
+    linkInfo.Clear();
     min = kMinRssValue;
     max = kMaxRssValue;
 
@@ -387,6 +388,8 @@ void TestSuccessRateTracker(void)
 
     printf("\nTesting SuccessRateTracker\n");
 
+    rateTracker.Reset();
+
     VerifyOrQuit(rateTracker.GetSuccessRate() == kMaxRate, "SuccessRateTracker: Initial value incorrect");
     VerifyOrQuit(rateTracker.GetFailureRate() == 0, "SuccessRateTracker: Initial value incorrect");