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

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