Merge bitcoin/bitcoin#29402: mempool: Log added for dumping mempool transactions to disk

4d5b557 log: renamed disk to file so wording was more accurate (kevkevin)
b9f04be mempool: Log added for dumping mempool transactions to disk (kevkevin)

Pull request description:

  Sometimes when shutting off bitcoind it can take a while to dump the mempool transaction onto the disk so
  this change adds additional logging to the `DumpMempool` method in `kernel/mempool_persist.cpp`

  Motivated by bitcoin/bitcoin#29227 this change
   - adds a single new line for the amount of transactions being dumped and the amount of memory being dumped to file

  This is in response to bitcoin/bitcoin#29227 (comment)

  The logs will now look like this
  ```
  2024-02-09T23:41:52Z DumpAnchors: Flush 2 outbound block-relay-only peer addresses to anchors.dat completed (0.02s)
  2024-02-09T23:41:52Z scheduler thread exit
  2024-02-09T23:41:52Z Writing 29 mempool transactions to file...
  2024-02-09T23:41:52Z Writing 0 unbroadcast transactions to file.
  2024-02-09T23:41:52Z Dumped mempool: 0.000s to copy, 0.022s to dump, 0.015 MB dumped to file
  2024-02-09T23:41:52Z Flushed fee estimates to fee_estimates.dat.
  2024-02-09T23:41:53Z Shutdown: done
  ```

ACKs for top commit:
  maflcko:
    cr-ACK 4d5b557
  glozow:
    reACK 4d5b557

Tree-SHA512: 049191e140d00c1ea57debe0138f1c9eb0f9bb0ef8138e2568e6d89e64f45a5d5853ce3b9cc0b28566aab97555b47ddfb0f9199fc8cea6b81e53f50592d5ae6a

Author: glozow

src/kernel/mempool_persist.cpp

@@ -44,7 +44,7 @@ bool LoadMempool(CTxMemPool& pool, const fs::path& load_path, Chainstate& active
 
     AutoFile file{opts.mockable_fopen_function(load_path, "rb")};
     if (file.IsNull()) {
-        LogPrintf("Failed to open mempool file from disk. Continuing anyway.\n");
+        LogInfo("Failed to open mempool file. Continuing anyway.\n");
         return false;
     }
 
@@ -70,12 +70,12 @@ bool LoadMempool(CTxMemPool& pool, const fs::path& load_path, Chainstate& active
         uint64_t total_txns_to_load;
         file >> total_txns_to_load;
         uint64_t txns_tried = 0;
-        LogInfo("Loading %u mempool transactions from disk...\n", total_txns_to_load);
+        LogInfo("Loading %u mempool transactions from file...\n", total_txns_to_load);
         int next_tenth_to_report = 0;
         while (txns_tried < total_txns_to_load) {
             const int percentage_done(100.0 * txns_tried / total_txns_to_load);
             if (next_tenth_to_report < percentage_done / 10) {
-                LogInfo("Progress loading mempool transactions from disk: %d%% (tried %u, %u remaining)\n",
+                LogInfo("Progress loading mempool transactions from file: %d%% (tried %u, %u remaining)\n",
                         percentage_done, txns_tried, total_txns_to_load - txns_tried);
                 next_tenth_to_report = percentage_done / 10;
             }
@@ -138,11 +138,11 @@ bool LoadMempool(CTxMemPool& pool, const fs::path& load_path, Chainstate& active
             }
         }
     } catch (const std::exception& e) {
-        LogPrintf("Failed to deserialize mempool data on disk: %s. Continuing anyway.\n", e.what());
+        LogInfo("Failed to deserialize mempool data on file: %s. Continuing anyway.\n", e.what());
         return false;
     }
 
-    LogPrintf("Imported mempool transactions from disk: %i succeeded, %i failed, %i expired, %i already there, %i waiting for initial broadcast\n", count, failed, expired, already_there, unbroadcast);
+    LogInfo("Imported mempool transactions from file: %i succeeded, %i failed, %i expired, %i already there, %i waiting for initial broadcast\n", count, failed, expired, already_there, unbroadcast);
     return true;
 }
 
@@ -184,7 +184,9 @@ bool DumpMempool(const CTxMemPool& pool, const fs::path& dump_path, FopenFn mock
         }
         file.SetXor(xor_key);
 
-        file << (uint64_t)vinfo.size();
+        uint64_t mempool_transactions_to_write(vinfo.size());
+        file << mempool_transactions_to_write;
+        LogInfo("Writing %u mempool transactions to file...\n", mempool_transactions_to_write);
         for (const auto& i : vinfo) {
             file << TX_WITH_WITNESS(*(i.tx));
             file << int64_t{count_seconds(i.m_time)};
@@ -194,7 +196,7 @@ bool DumpMempool(const CTxMemPool& pool, const fs::path& dump_path, FopenFn mock
 
         file << mapDeltas;
 
-        LogPrintf("Writing %d unbroadcast transactions to disk.\n", unbroadcast_txids.size());
+        LogInfo("Writing %d unbroadcast transactions to file.\n", unbroadcast_txids.size());
         file << unbroadcast_txids;
 
         if (!skip_file_commit && !FileCommit(file.Get()))
@@ -205,11 +207,12 @@ bool DumpMempool(const CTxMemPool& pool, const fs::path& dump_path, FopenFn mock
         }
         auto last = SteadyClock::now();
 
-        LogPrintf("Dumped mempool: %.3fs to copy, %.3fs to dump\n",
+        LogInfo("Dumped mempool: %.3fs to copy, %.3fs to dump, %d bytes dumped to file\n",
                   Ticks<SecondsDouble>(mid - start),
-                  Ticks<SecondsDouble>(last - mid));
+                  Ticks<SecondsDouble>(last - mid),
+                  fs::file_size(dump_path));
     } catch (const std::exception& e) {
-        LogPrintf("Failed to dump mempool: %s. Continuing anyway.\n", e.what());
+        LogInfo("Failed to dump mempool: %s. Continuing anyway.\n", e.what());
         return false;
     }
     return true;