From cb1e319fe9e198c9c5cf5236fe9af5a3d748b9e8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jorge=20Tim=C3=B3n?= <jtimon@jtimon.cc>
Date: Fri, 12 Jan 2018 21:38:48 +0100
Subject: [PATCH] Bugfix: RPC: savemempool: Don't save until LoadMempool() is
 finished

---
 src/init.cpp           | 5 ++---
 src/rpc/blockchain.cpp | 6 +++++-
 src/validation.cpp     | 1 +
 src/validation.h       | 1 +
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/init.cpp b/src/init.cpp
index b0ba0cb83..348af4b13 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -116,7 +116,6 @@ static const char* FEE_ESTIMATES_FILENAME="fee_estimates.dat";
 //
 
 std::atomic<bool> fRequestShutdown(false);
-std::atomic<bool> fDumpMempoolLater(false);
 
 void StartShutdown()
 {
@@ -208,7 +207,7 @@ void Shutdown()
     threadGroup.interrupt_all();
     threadGroup.join_all();
 
-    if (fDumpMempoolLater && gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
+    if (g_is_mempool_loaded && gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
         DumpMempool();
     }
 
@@ -692,8 +691,8 @@ void ThreadImport(std::vector<fs::path> vImportFiles)
     } // End scope of CImportingNow
     if (gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
         LoadMempool();
-        fDumpMempoolLater = !fRequestShutdown;
     }
+    g_is_mempool_loaded = !fRequestShutdown;
 }
 
 /** Sanity checks
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index e15dad2f0..31cbec4c8 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1607,13 +1607,17 @@ UniValue savemempool(const JSONRPCRequest& request)
     if (request.fHelp || request.params.size() != 0) {
         throw std::runtime_error(
             "savemempool\n"
-            "\nDumps the mempool to disk.\n"
+            "\nDumps the mempool to disk. It will fail until the previous dump is fully loaded.\n"
             "\nExamples:\n"
             + HelpExampleCli("savemempool", "")
             + HelpExampleRpc("savemempool", "")
         );
     }
 
+    if (!g_is_mempool_loaded) {
+        throw JSONRPCError(RPC_MISC_ERROR, "The mempool was not loaded yet");
+    }
+
     if (!DumpMempool()) {
         throw JSONRPCError(RPC_MISC_ERROR, "Unable to dump mempool to disk");
     }
diff --git a/src/validation.cpp b/src/validation.cpp
index 839b24814..d6848a3ac 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -227,6 +227,7 @@ CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
 
 CBlockPolicyEstimator feeEstimator;
 CTxMemPool mempool(&feeEstimator);
+std::atomic_bool g_is_mempool_loaded{false};
 
 /** Constant stuff for coinbase transactions we create: */
 CScript COINBASE_FLAGS;
diff --git a/src/validation.h b/src/validation.h
index 0a7807531..4031989f0 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -158,6 +158,7 @@ extern CScript COINBASE_FLAGS;
 extern CCriticalSection cs_main;
 extern CBlockPolicyEstimator feeEstimator;
 extern CTxMemPool mempool;
+extern std::atomic_bool g_is_mempool_loaded;
 typedef std::unordered_map<uint256, CBlockIndex*, BlockHasher> BlockMap;
 extern BlockMap& mapBlockIndex;
 extern uint64_t nLastBlockTx;