Merge #11099: [RPC][mempool]: Add savemempool RPC

1aa97ee08 Add savemempool RPC (Lawrence Nahum)
467cbbcbf Add return value to DumpMempool (Lawrence Nahum)

Pull request description:

  Adds a simple parameterless rpc command to dump the mempool.

  Rationale:

  Sometimes there can be a crash for whatever reason (bug, power loss, etc) causing the mempool.dat file to not be saved.

  This change allows to script/cron the rpc call to have more regular saves to the file as well as cli/ad-hoc.

  This should solve issue https://github.com/bitcoin/bitcoin/issues/11086

Tree-SHA512: e856ae9777425a4521279c9b58e69285d8e374790bebefd3284cf91931eac0e456f86224f427a087a01bf70440bf6e439fa02c8a34940eb1046ae473e98b6aaa

3 files changed, 25 insertions, 3 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 9fae9a7cd9..d131635067 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1534,6 +1534,25 @@ UniValue getchaintxstats(const JSONRPCRequest& request)
     return ret;
 }
 
+UniValue savemempool(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() != 0) {
+        throw std::runtime_error(
+            "savemempool\n"
+            "\nDumps the mempool to disk.\n"
+            "\nExamples:\n"
+            + HelpExampleCli("savemempool", "")
+            + HelpExampleRpc("savemempool", "")
+        );
+    }
+
+    if (!DumpMempool()) {
+        throw JSONRPCError(RPC_MISC_ERROR, "Unable to dump mempool to disk");
+    }
+
+    return NullUniValue;
+}
+
 static const CRPCCommand commands[] =
 { //  category              name                      actor (function)         argNames
   //  --------------------- ------------------------  -----------------------  ----------
@@ -1554,6 +1573,7 @@ static const CRPCCommand commands[] =
     { "blockchain",         "gettxout",               &gettxout,               {"txid","n","include_mempool"} },
     { "blockchain",         "gettxoutsetinfo",        &gettxoutsetinfo,        {} },
     { "blockchain",         "pruneblockchain",        &pruneblockchain,        {"height"} },
+    { "blockchain",         "savemempool",            &savemempool,            {} },
     { "blockchain",         "verifychain",            &verifychain,            {"checklevel","nblocks"} },
 
     { "blockchain",         "preciousblock",          &preciousblock,          {"blockhash"} },
diff --git a/src/validation.cpp b/src/validation.cpp
index 0edc9bc32a..d1ef11759c 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -4331,7 +4331,7 @@ bool LoadMempool(void)
     return true;
 }
 
-void DumpMempool(void)
+bool DumpMempool(void)
 {
     int64_t start = GetTimeMicros();
 
@@ -4351,7 +4351,7 @@ void DumpMempool(void)
     try {
         FILE* filestr = fsbridge::fopen(GetDataDir() / "mempool.dat.new", "wb");
         if (!filestr) {
-            return;
+            return false;
         }
 
         CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
@@ -4375,7 +4375,9 @@ void DumpMempool(void)
         LogPrintf("Dumped mempool: %gs to copy, %gs to dump\n", (mid-start)*MICRO, (last-mid)*MICRO);
     } catch (const std::exception& e) {
         LogPrintf("Failed to dump mempool: %s. Continuing anyway.\n", e.what());
+        return false;
     }
+    return true;
 }
 
 //! Guess how far we are in the verification process at the given block index
diff --git a/src/validation.h b/src/validation.h
index 214d29173c..23d4b35585 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -478,7 +478,7 @@ static const unsigned int REJECT_HIGHFEE = 0x100;
 CBlockFileInfo* GetBlockFileInfo(size_t n);
 
 /** Dump the mempool to disk. */
-void DumpMempool();
+bool DumpMempool();
 
 /** Load the mempool from disk. */
 bool LoadMempool();