kernel: Remove batchpriority from kernel library

The current usage of ScheduleBatchPriority is not transparent. Once the
thread scheduling is changed, it remains unchanged for the remainder of
the thread's lifetime. So move the call from `ImportBlocks` to the init
code where it is clearer that its effect lasts for the entire lifetime
of the thread.

Users of the kernel library might not expect `ImportBlocks` to have an
influence on the thread it is called in. Particularly since it is only a
compile time option and cannot be controlled at runtime. With this patch
users of the kernel library can now choose their own scheduling policy.

Author: TheCharlatan

src/Makefile.am

@@ -975,7 +975,6 @@ libbitcoinkernel_la_SOURCES = \
   txdb.cpp \
   txmempool.cpp \
   uint256.cpp \
-  util/batchpriority.cpp \
   util/chaintype.cpp \
   util/check.cpp \
   util/feefrac.cpp \

src/init.cpp

@@ -69,6 +69,7 @@
 #include <txdb.h>
 #include <txmempool.h>
 #include <util/asmap.h>
+#include <util/batchpriority.h>
 #include <util/chaintype.h>
 #include <util/check.h>
 #include <util/fs.h>
@@ -1735,6 +1736,7 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     }
 
     chainman.m_thread_load = std::thread(&util::TraceThread, "initload", [=, &chainman, &args, &node] {
+        ScheduleBatchPriority();
         // Import blocks
         ImportBlocks(chainman, vImportFiles);
         if (args.GetBoolArg("-stopafterblockimport", DEFAULT_STOPAFTERBLOCKIMPORT)) {

src/node/blockstorage.cpp

@@ -1175,69 +1175,66 @@ class ImportingNow
 
 void ImportBlocks(ChainstateManager& chainman, std::vector<fs::path> vImportFiles)
 {
-    ScheduleBatchPriority();
-
-    {
-        ImportingNow imp{chainman.m_blockman.m_importing};
-
-        // -reindex
-        if (fReindex) {
-            int nFile = 0;
-            // Map of disk positions for blocks with unknown parent (only used for reindex);
-            // parent hash -> child disk position, multiple children can have the same parent.
-            std::multimap<uint256, FlatFilePos> blocks_with_unknown_parent;
-            while (true) {
-                FlatFilePos pos(nFile, 0);
-                if (!fs::exists(chainman.m_blockman.GetBlockPosFilename(pos))) {
-                    break; // No block files left to reindex
-                }
-                AutoFile file{chainman.m_blockman.OpenBlockFile(pos, true)};
-                if (file.IsNull()) {
-                    break; // This error is logged in OpenBlockFile
-                }
-                LogPrintf("Reindexing block file blk%05u.dat...\n", (unsigned int)nFile);
-                chainman.LoadExternalBlockFile(file, &pos, &blocks_with_unknown_parent);
-                if (chainman.m_interrupt) {
-                    LogPrintf("Interrupt requested. Exit %s\n", __func__);
-                    return;
-                }
-                nFile++;
+    ImportingNow imp{chainman.m_blockman.m_importing};
+
+    // -reindex
+    if (fReindex) {
+        int nFile = 0;
+        // Map of disk positions for blocks with unknown parent (only used for reindex);
+        // parent hash -> child disk position, multiple children can have the same parent.
+        std::multimap<uint256, FlatFilePos> blocks_with_unknown_parent;
+        while (true) {
+            FlatFilePos pos(nFile, 0);
+            if (!fs::exists(chainman.m_blockman.GetBlockPosFilename(pos))) {
+                break; // No block files left to reindex
             }
-            WITH_LOCK(::cs_main, chainman.m_blockman.m_block_tree_db->WriteReindexing(false));
-            fReindex = false;
-            LogPrintf("Reindexing finished\n");
-            // To avoid ending up in a situation without genesis block, re-try initializing (no-op if reindexing worked):
-            chainman.ActiveChainstate().LoadGenesisBlock();
+            AutoFile file{chainman.m_blockman.OpenBlockFile(pos, true)};
+            if (file.IsNull()) {
+                break; // This error is logged in OpenBlockFile
+            }
+            LogPrintf("Reindexing block file blk%05u.dat...\n", (unsigned int)nFile);
+            chainman.LoadExternalBlockFile(file, &pos, &blocks_with_unknown_parent);
+            if (chainman.m_interrupt) {
+                LogPrintf("Interrupt requested. Exit %s\n", __func__);
+                return;
+            }
+            nFile++;
         }
-
-        // -loadblock=
-        for (const fs::path& path : vImportFiles) {
-            AutoFile file{fsbridge::fopen(path, "rb")};
-            if (!file.IsNull()) {
-                LogPrintf("Importing blocks file %s...\n", fs::PathToString(path));
-                chainman.LoadExternalBlockFile(file);
-                if (chainman.m_interrupt) {
-                    LogPrintf("Interrupt requested. Exit %s\n", __func__);
-                    return;
-                }
-            } else {
-                LogPrintf("Warning: Could not open blocks file %s\n", fs::PathToString(path));
+        WITH_LOCK(::cs_main, chainman.m_blockman.m_block_tree_db->WriteReindexing(false));
+        fReindex = false;
+        LogPrintf("Reindexing finished\n");
+        // To avoid ending up in a situation without genesis block, re-try initializing (no-op if reindexing worked):
+        chainman.ActiveChainstate().LoadGenesisBlock();
+    }
+
+    // -loadblock=
+    for (const fs::path& path : vImportFiles) {
+        AutoFile file{fsbridge::fopen(path, "rb")};
+        if (!file.IsNull()) {
+            LogPrintf("Importing blocks file %s...\n", fs::PathToString(path));
+            chainman.LoadExternalBlockFile(file);
+            if (chainman.m_interrupt) {
+                LogPrintf("Interrupt requested. Exit %s\n", __func__);
+                return;
             }
+        } else {
+            LogPrintf("Warning: Could not open blocks file %s\n", fs::PathToString(path));
         }
+    }
 
-        // scan for better chains in the block chain database, that are not yet connected in the active best chain
+    // scan for better chains in the block chain database, that are not yet connected in the active best chain
 
-        // We can't hold cs_main during ActivateBestChain even though we're accessing
-        // the chainman unique_ptrs since ABC requires us not to be holding cs_main, so retrieve
-        // the relevant pointers before the ABC call.
-        for (Chainstate* chainstate : WITH_LOCK(::cs_main, return chainman.GetAll())) {
-            BlockValidationState state;
-            if (!chainstate->ActivateBestChain(state, nullptr)) {
-                chainman.GetNotifications().fatalError(strprintf(_("Failed to connect best block (%s)."), state.ToString()));
-                return;
-            }
+    // We can't hold cs_main during ActivateBestChain even though we're accessing
+    // the chainman unique_ptrs since ABC requires us not to be holding cs_main, so retrieve
+    // the relevant pointers before the ABC call.
+    for (Chainstate* chainstate : WITH_LOCK(::cs_main, return chainman.GetAll())) {
+        BlockValidationState state;
+        if (!chainstate->ActivateBestChain(state, nullptr)) {
+            chainman.GetNotifications().fatalError(strprintf(_("Failed to connect best block (%s)."), state.ToString()));
+            return;
         }
-    } // End scope of ImportingNow
+    }
+    // End scope of ImportingNow
 }
 
 std::ostream& operator<<(std::ostream& os, const BlockfileType& type) {