From 0b716730b069645c20a9a83ca708f22451c5338b Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Thu, 30 May 2024 11:19:03 -0700
Subject: [PATCH] [mdns] use `NextFireTime` class (#10304)

This commit updates the mDNS module to use the recently introduced
general-purpose `NextFireTime` class, replacing the module-specific
`TimerContext` class.
---
 src/core/net/mdns.cpp | 59 +++++++++++--------------------------------
 src/core/net/mdns.hpp | 39 +++++++++++-----------------
 2 files changed, 30 insertions(+), 68 deletions(-)

diff --git a/src/core/net/mdns.cpp b/src/core/net/mdns.cpp
index df0a61fdd..84c0cd199 100644
--- a/src/core/net/mdns.cpp
+++ b/src/core/net/mdns.cpp
@@ -305,10 +305,7 @@ void Core::HandleEntryTimer(void)
 
     RemoveEmptyEntries();
 
-    if (context.GetNextTime() != context.GetNow().GetDistantFuture())
-    {
-        mEntryTimer.FireAtIfEarlier(context.GetNextTime());
-    }
+    mEntryTimer.FireAtIfEarlier(context.GetNextFireTime());
 }
 
 void Core::RemoveEmptyEntries(void)
@@ -823,6 +820,14 @@ void Core::FireTime::ScheduleFireTimeOn(TimerMilli &aTimer)
     }
 }
 
+void Core::FireTime::UpdateNextFireTimeOn(NextFireTime &aNextFireTime) const
+{
+    if (mHasFireTime)
+    {
+        aNextFireTime.UpdateIfEarlier(mFireTime);
+    }
+}
+
 //----------------------------------------------------------------------------------------------------------------------
 // Core::Entry
 
@@ -1199,10 +1204,7 @@ template <typename EntryType> void Core::Entry::HandleTimer(EntryTimerContext &a
     thisAsEntryType->DetermineNextFireTime();
 
 exit:
-    if (HasFireTime())
-    {
-        aContext.UpdateNextTime(GetFireTime());
-    }
+    UpdateNextFireTimeOn(aContext.GetNextFireTime());
 }
 
 void Core::Entry::AppendQuestionTo(TxMessage &aTxMessage) const
@@ -2673,10 +2675,7 @@ void Core::ServiceType::HandleTimer(EntryTimerContext &aContext)
     mServicesPtr.UpdateFireTimeOn(*this);
 
 exit:
-    if (HasFireTime())
-    {
-        aContext.UpdateNextTime(GetFireTime());
-    }
+    UpdateNextFireTimeOn(aContext.GetNextFireTime());
 }
 
 void Core::ServiceType::PrepareResponse(TxMessage &aResponse, TimeMilli aNow)
@@ -3211,33 +3210,11 @@ bool Core::TxMessage::ShouldClearAppendStateOnReinit(const Entry &aEntry) const
     return shouldClear;
 }
 
-//----------------------------------------------------------------------------------------------------------------------
-// Core::TimerContext
-
-Core::TimerContext::TimerContext(Instance &aInstance)
-    : InstanceLocator(aInstance)
-    , mNow(TimerMilli::GetNow())
-    , mNextTime(mNow.GetDistantFuture())
-{
-}
-
-void Core::TimerContext::UpdateNextTime(TimeMilli aTime)
-{
-    if (aTime <= mNow)
-    {
-        mNextTime = mNow;
-    }
-    else
-    {
-        mNextTime = Min(mNextTime, aTime);
-    }
-}
-
 //----------------------------------------------------------------------------------------------------------------------
 // Core::EntryTimerContext
 
 Core::EntryTimerContext::EntryTimerContext(Instance &aInstance)
-    : TimerContext(aInstance)
+    : InstanceLocator(aInstance)
     , mProbeMessage(aInstance, TxMessage::kMulticastProbe)
     , mResponseMessage(aInstance, TxMessage::kMulticastResponse)
 {
@@ -4339,10 +4316,7 @@ void Core::HandleCacheTimer(void)
 
     context.GetQueryMessage().Send();
 
-    if (context.GetNextTime() != context.GetNow().GetDistantFuture())
-    {
-        mCacheTimer.FireAtIfEarlier(context.GetNextTime());
-    }
+    mCacheTimer.FireAtIfEarlier(context.GetNextFireTime());
 }
 
 void Core::HandleCacheTask(void)
@@ -4448,7 +4422,7 @@ void Core::ResultCallback::Invoke(Instance &aInstance, const AddressResult &aRes
 // Core::CacheTimerContext
 
 Core::CacheTimerContext::CacheTimerContext(Instance &aInstance)
-    : TimerContext(aInstance)
+    : InstanceLocator(aInstance)
     , mQueryMessage(aInstance, TxMessage::kMulticastQuery)
 {
 }
@@ -4811,10 +4785,7 @@ void Core::CacheEntry::HandleTimer(CacheTimerContext &aContext)
     DetermineNextFireTime();
 
 exit:
-    if (HasFireTime())
-    {
-        aContext.UpdateNextTime(GetFireTime());
-    }
+    UpdateNextFireTimeOn(aContext.GetNextFireTime());
 }
 
 Core::ResultCallback *Core::CacheEntry::FindCallbackMatching(const ResultCallback &aCallback)
diff --git a/src/core/net/mdns.hpp b/src/core/net/mdns.hpp
index 6001e8f58..33f848870 100644
--- a/src/core/net/mdns.hpp
+++ b/src/core/net/mdns.hpp
@@ -790,6 +790,7 @@ private:
 
     protected:
         void ScheduleFireTimeOn(TimerMilli &aTimer);
+        void UpdateNextFireTimeOn(NextFireTime &aNextFireTime) const;
 
     private:
         TimeMilli mFireTime;
@@ -1189,32 +1190,19 @@ private:
 
     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-    class TimerContext : public InstanceLocator
-    {
-    public:
-        TimerContext(Instance &aInstance);
-
-        TimeMilli GetNow(void) const { return mNow; }
-        TimeMilli GetNextTime(void) const { return mNextTime; }
-        void      UpdateNextTime(TimeMilli aTime);
-
-    private:
-        TimeMilli mNow;
-        TimeMilli mNextTime;
-    };
-
-    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-    class EntryTimerContext : public TimerContext // Used by `HandleEntryTimer`.
+    class EntryTimerContext : public InstanceLocator // Used by `HandleEntryTimer`.
     {
     public:
         EntryTimerContext(Instance &aInstance);
-        TxMessage &GetProbeMessage(void) { return mProbeMessage; }
-        TxMessage &GetResponseMessage(void) { return mResponseMessage; }
+        TimeMilli     GetNow(void) const { return mNextFireTime.GetNow(); }
+        NextFireTime &GetNextFireTime(void) { return mNextFireTime; }
+        TxMessage    &GetProbeMessage(void) { return mProbeMessage; }
+        TxMessage    &GetResponseMessage(void) { return mResponseMessage; }
 
     private:
-        TxMessage mProbeMessage;
-        TxMessage mResponseMessage;
+        NextFireTime mNextFireTime;
+        TxMessage    mProbeMessage;
+        TxMessage    mResponseMessage;
     };
 
     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -1440,14 +1428,17 @@ private:
 
     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-    class CacheTimerContext : public TimerContext
+    class CacheTimerContext : public InstanceLocator
     {
     public:
         CacheTimerContext(Instance &aInstance);
-        TxMessage &GetQueryMessage(void) { return mQueryMessage; }
+        TimeMilli     GetNow(void) const { return mNextFireTime.GetNow(); }
+        NextFireTime &GetNextFireTime(void) { return mNextFireTime; }
+        TxMessage    &GetQueryMessage(void) { return mQueryMessage; }
 
     private:
-        TxMessage mQueryMessage;
+        NextFireTime mNextFireTime;
+        TxMessage    mQueryMessage;
     };
 
     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -