wallet: descriptors setup, batch db operations

Instead of doing one db transaction per descriptor setup,
batch all descriptors' setup writes in a single db txn.

Speeding up the process and preventing the wallet from entering
an inconsistent state if any of the intermediate transactions
fail.

src/wallet/scriptpubkeyman.cpp

@@ -2275,7 +2275,7 @@ bool DescriptorScriptPubKeyMan::AddDescriptorKeyWithDB(WalletBatch& batch, const
     }
 }
 
-bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(const CExtKey& master_key, OutputType addr_type, bool internal)
+bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(WalletBatch& batch, const CExtKey& master_key, OutputType addr_type, bool internal)
 {
     LOCK(cs_desc_man);
     assert(m_storage.IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS));
@@ -2336,9 +2336,6 @@ bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(const CExtKey& master_
     m_wallet_descriptor = w_desc;
 
     // Store the master private key, and descriptor
-    WalletBatch batch(m_storage.GetDatabase());
-    if (!batch.TxnBegin()) throw std::runtime_error(std::string(__func__) + ": cannot start db transaction");
-
     if (!AddDescriptorKeyWithDB(batch, master_key.key, master_key.key.GetPubKey())) {
         throw std::runtime_error(std::string(__func__) + ": writing descriptor master private key failed");
     }
@@ -2350,8 +2347,6 @@ bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(const CExtKey& master_
     TopUpWithDB(batch);
 
     m_storage.UnsetBlankWalletFlag(batch);
-
-    if (!batch.TxnCommit()) throw std::runtime_error(std::string(__func__) + ": error committing db transaction");
     return true;
 }
 

src/wallet/scriptpubkeyman.h

@@ -621,7 +621,7 @@ public:
     bool IsHDEnabled() const override;
 
     //! Setup descriptors based on the given CExtkey
-    bool SetupDescriptorGeneration(const CExtKey& master_key, OutputType addr_type, bool internal);
+    bool SetupDescriptorGeneration(WalletBatch& batch, const CExtKey& master_key, OutputType addr_type, bool internal);
 
     /** Provide a descriptor at setup time
     * Returns false if already setup or setup fails, true if setup is successful

src/wallet/wallet.cpp

@@ -3535,6 +3535,10 @@ void CWallet::SetupDescriptorScriptPubKeyMans(const CExtKey& master_key)
 {
     AssertLockHeld(cs_wallet);
 
+    // Create single batch txn
+    WalletBatch batch(GetDatabase());
+    if (!batch.TxnBegin()) throw std::runtime_error("Error: cannot create db transaction for descriptors setup");
+
     for (bool internal : {false, true}) {
         for (OutputType t : OUTPUT_TYPES) {
             auto spk_manager = std::unique_ptr<DescriptorScriptPubKeyMan>(new DescriptorScriptPubKeyMan(*this, m_keypool_size));
@@ -3542,16 +3546,19 @@ void CWallet::SetupDescriptorScriptPubKeyMans(const CExtKey& master_key)
                 if (IsLocked()) {
                     throw std::runtime_error(std::string(__func__) + ": Wallet is locked, cannot setup new descriptors");
                 }
-                if (!spk_manager->CheckDecryptionKey(vMasterKey) && !spk_manager->Encrypt(vMasterKey, nullptr)) {
+                if (!spk_manager->CheckDecryptionKey(vMasterKey) && !spk_manager->Encrypt(vMasterKey, &batch)) {
                     throw std::runtime_error(std::string(__func__) + ": Could not encrypt new descriptors");
                 }
             }
-            spk_manager->SetupDescriptorGeneration(master_key, t, internal);
+            spk_manager->SetupDescriptorGeneration(batch, master_key, t, internal);
             uint256 id = spk_manager->GetID();
             AddScriptPubKeyMan(id, std::move(spk_manager));
-            AddActiveScriptPubKeyMan(id, t, internal);
+            AddActiveScriptPubKeyManWithDb(batch, id, t, internal);
         }
     }
+
+    // Ensure information is committed to disk
+    if (!batch.TxnCommit()) throw std::runtime_error("Error: cannot commit db transaction for descriptors setup");
 }
 
 void CWallet::SetupDescriptorScriptPubKeyMans()
@@ -3606,6 +3613,11 @@ void CWallet::SetupDescriptorScriptPubKeyMans()
 void CWallet::AddActiveScriptPubKeyMan(uint256 id, OutputType type, bool internal)
 {
     WalletBatch batch(GetDatabase());
+    return AddActiveScriptPubKeyManWithDb(batch, id, type, internal);
+}
+
+void CWallet::AddActiveScriptPubKeyManWithDb(WalletBatch& batch, uint256 id, OutputType type, bool internal)
+{
     if (!batch.WriteActiveScriptPubKeyMan(static_cast<uint8_t>(type), id, internal)) {
         throw std::runtime_error(std::string(__func__) + ": writing active ScriptPubKeyMan id failed");
     }

src/wallet/wallet.h

@@ -419,6 +419,9 @@ private:
     // Must be the only method adding data to it.
     void AddScriptPubKeyMan(const uint256& id, std::unique_ptr<ScriptPubKeyMan> spkm_man);
 
+    // Same as 'AddActiveScriptPubKeyMan' but designed for use within a batch transaction context
+    void AddActiveScriptPubKeyManWithDb(WalletBatch& batch, uint256 id, OutputType type, bool internal);
+
     /**
      * Catch wallet up to current chain, scanning new blocks, updating the best
      * block locator and m_last_block_processed, and registering for