wallet/spkm: make GetOldestKeyPoolTime() const

The method checks the oldest key time for key pools and returns the oldest. It does no modifications.

Author: kallewoof

src/wallet/scriptpubkeyman.cpp

@@ -441,7 +441,7 @@ static int64_t GetOldestKeyTimeInPool(const std::set<int64_t>& setKeyPool, Walle
     return keypool.nTime;
 }
 
-int64_t LegacyScriptPubKeyMan::GetOldestKeyPoolTime()
+int64_t LegacyScriptPubKeyMan::GetOldestKeyPoolTime() const
 {
     LOCK(cs_KeyStore);
 

src/wallet/scriptpubkeyman.h

@@ -194,7 +194,7 @@ class ScriptPubKeyMan
     //! The action to do when the DB needs rewrite
     virtual void RewriteDB() {}
 
-    virtual int64_t GetOldestKeyPoolTime() { return GetTime(); }
+    virtual int64_t GetOldestKeyPoolTime() const { return GetTime(); }
 
     virtual size_t KeypoolCountExternalKeys() const { return 0; }
     virtual unsigned int GetKeyPoolSize() const { return 0; }
@@ -336,7 +336,7 @@ class LegacyScriptPubKeyMan : public ScriptPubKeyMan, public FillableSigningProv
 
     void RewriteDB() override;
 
-    int64_t GetOldestKeyPoolTime() override;
+    int64_t GetOldestKeyPoolTime() const override;
     size_t KeypoolCountExternalKeys() const override;
     unsigned int GetKeyPoolSize() const override;
 

src/wallet/wallet.cpp

@@ -3177,7 +3177,7 @@ bool CWallet::GetNewChangeDestination(const OutputType type, CTxDestination& des
     return true;
 }
 
-int64_t CWallet::GetOldestKeyPoolTime()
+int64_t CWallet::GetOldestKeyPoolTime() const
 {
     LOCK(cs_wallet);
     int64_t oldestKey = std::numeric_limits<int64_t>::max();

src/wallet/wallet.h

@@ -971,7 +971,7 @@ class CWallet final : public WalletStorage, private interfaces::Chain::Notificat
     size_t KeypoolCountExternalKeys() const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     bool TopUpKeyPool(unsigned int kpSize = 0);
 
-    int64_t GetOldestKeyPoolTime();
+    int64_t GetOldestKeyPoolTime() const;
 
     std::set<std::set<CTxDestination>> GetAddressGroupings() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     std::map<CTxDestination, CAmount> GetAddressBalances(interfaces::Chain::Lock& locked_chain);