From f3a4f773687ee6e29eff4801e9880f6c4282827d Mon Sep 17 00:00:00 2001
From: DenioD <41270280+DenioD@users.noreply.github.com>
Date: Tue, 19 May 2020 10:03:53 +0200
Subject: [PATCH] port expired transaction notify from Zcash. Issue #110

---
 src/init.cpp       | 11 +++++++++++
 src/main.cpp       |  6 +++++-
 src/txmempool.cpp  |  5 ++++-
 src/txmempool.h    |  2 +-
 src/ui_interface.h |  3 +++
 5 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/src/init.cpp b/src/init.cpp
index ac15db192..fd0303786 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -399,6 +399,7 @@ std::string HelpMessage(HelpMessageMode mode)
 #ifndef _WIN32
     strUsage += HelpMessageOpt("-pid=<file>", strprintf(_("Specify pid file (default: %s)"), "komodod.pid"));
 #endif
+    strUsage += HelpMessageOpt("-txexpirynotify=<cmd>", _("Execute command when transaction expires (%s in cmd is replaced by transaction id)"));
     strUsage += HelpMessageOpt("-prune=<n>", strprintf(_("Reduce storage requirements by pruning (deleting) old blocks. This mode disables wallet support and is incompatible with -txindex. "
             "Warning: Reverting this setting requires re-downloading the entire blockchain. "
             "(default: 0 = disable pruning blocks, >%u = target size in MiB to use for block files)"), MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024));
@@ -618,6 +619,14 @@ static void BlockNotifyCallback(const uint256& hashNewTip)
     boost::thread t(runCommand, strCmd); // thread runs free
 }
 
+static void TxExpiryNotifyCallback(const uint256& txid)
+{
+    std::string strCmd = GetArg("-txexpirynotify", "");
+
+    boost::replace_all(strCmd, "%s", txid.GetHex());
+    boost::thread t(runCommand, strCmd); // thread runs free
+}
+
 struct CImportingNow
 {
     CImportingNow() {
@@ -2114,6 +2123,8 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
     if (mapArgs.count("-blocknotify"))
         uiInterface.NotifyBlockTip.connect(BlockNotifyCallback);
+     if (mapArgs.count("-txexpirynotify"))
+        uiInterface.NotifyTxExpiration.connect(TxExpiryNotifyCallback);
     if ( KOMODO_REWIND >= 0 )
     {
         uiInterface.InitMessage(_("Activating best chain..."));
diff --git a/src/main.cpp b/src/main.cpp
index 17b89a76b..3426facd7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4210,7 +4210,11 @@ bool static ConnectTip(CValidationState &state, CBlockIndex *pindexNew, CBlock *
     mempool.removeForBlock(pblock->vtx, pindexNew->GetHeight(), txConflicted, !IsInitialBlockDownload());
 
     // Remove transactions that expire at new block height from mempool
-    mempool.removeExpired(pindexNew->GetHeight());
+    auto ids = mempool.removeExpired(pindexNew->GetHeight());
+
+       for (auto id : ids) {
+        uiInterface.NotifyTxExpiration(id);
+    }
 
     // Update chainActive & related variables.
     UpdateTip(pindexNew);
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 8a99a99e6..307be723e 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -513,7 +513,7 @@ void CTxMemPool::removeConflicts(const CTransaction &tx, std::list<CTransaction>
 int32_t komodo_validate_interest(const CTransaction &tx,int32_t txheight,uint32_t nTime,int32_t dispflag);
 extern char ASSETCHAINS_SYMBOL[];
 
-void CTxMemPool::removeExpired(unsigned int nBlockHeight)
+std::vector<uint256> CTxMemPool::removeExpired(unsigned int nBlockHeight)
 {
     CBlockIndex *tipindex;
     // Remove expired txs from the mempool
@@ -528,11 +528,14 @@ void CTxMemPool::removeExpired(unsigned int nBlockHeight)
             transactionsToRemove.push_back(tx);
         }
     }
+    std::vector<uint256> ids;
     for (const CTransaction& tx : transactionsToRemove) {
         list<CTransaction> removed;
         remove(tx, removed, true);
+        ids.push_back(tx.GetHash());
         LogPrint("mempool", "Removing expired txid: %s\n", tx.GetHash().ToString());
     }
+    return ids;
 }
 
 /**
diff --git a/src/txmempool.h b/src/txmempool.h
index f8aa0e9a7..59eeb0d98 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -218,7 +218,7 @@ public:
     void removeWithAnchor(const uint256 &invalidRoot, ShieldedType type);
     void removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMemPoolHeight, int flags);
     void removeConflicts(const CTransaction &tx, std::list<CTransaction>& removed);
-    void removeExpired(unsigned int nBlockHeight);
+    std::vector<uint256> removeExpired(unsigned int nBlockHeight);
     void removeForBlock(const std::vector<CTransaction>& vtx, unsigned int nBlockHeight,
                         std::list<CTransaction>& conflicts, bool fCurrentEstimate = true);
     void removeWithoutBranchId(uint32_t nMemPoolBranchId);
diff --git a/src/ui_interface.h b/src/ui_interface.h
index ee0fd9113..59a549a9d 100644
--- a/src/ui_interface.h
+++ b/src/ui_interface.h
@@ -98,6 +98,9 @@ public:
 
     /** New block has been accepted */
     boost::signals2::signal<void (const uint256& hash)> NotifyBlockTip;
+
+    /** Transaction expired */
+    boost::signals2::signal<void (const uint256& txid)> NotifyTxExpiration;
 };
 
 extern CClientUIInterface uiInterface;