Merge bitcoin/bitcoin#26251: refactor: add kernel/cs_main.h

282019c refactor: add kernel/cs_main.* (fanquake)

Pull request description:

  One place to find / include `cs_main`.
  No more:
  > // Actually declared in validation.cpp; can't include because of circular dependency.
  > extern RecursiveMutex cs_main;

  Ultimately, no more need to include `validation.h` (which also includes (heavy/boost filled) `txmempool.h`) everywhere for `cs_main`. See #26087 for another example of why that is useful.

ACKs for top commit:
  ajtowns:
    ACK 282019c

Tree-SHA512: 142835b794873e7a09c3246d6101843ae81ec0c6295e6873130c98a2abfa5f7282748d0f1a37237a779cc71c3bc0a75d03b20313ef5398c83d4814215cbc8287

Author: MarcoFalke

src/Makefile.am

@@ -177,6 +177,7 @@ BITCOIN_CORE_H = \
   kernel/checks.h \
   kernel/coinstats.h \
   kernel/context.h \
+  kernel/cs_main.h \
   kernel/mempool_entry.h \
   kernel/mempool_limits.h \
   kernel/mempool_options.h \
@@ -375,6 +376,7 @@ libbitcoin_node_a_SOURCES = \
   kernel/checks.cpp \
   kernel/coinstats.cpp \
   kernel/context.cpp \
+  kernel/cs_main.cpp \
   kernel/mempool_persist.cpp \
   mapport.cpp \
   net.cpp \
@@ -906,6 +908,7 @@ libbitcoinkernel_la_SOURCES = \
   kernel/checks.cpp \
   kernel/coinstats.cpp \
   kernel/context.cpp \
+  kernel/cs_main.cpp \
   kernel/mempool_persist.cpp \
   key.cpp \
   logging.cpp \

src/bench/rpc_mempool.cpp

@@ -4,6 +4,7 @@
 
 #include <bench/bench.h>
 #include <chainparamsbase.h>
+#include <kernel/cs_main.h>
 #include <kernel/mempool_entry.h>
 #include <rpc/mempool.h>
 #include <test/util/setup_common.h>

src/chain.h

@@ -9,6 +9,7 @@
 #include <arith_uint256.h>
 #include <consensus/params.h>
 #include <flatfile.h>
+#include <kernel/cs_main.h>
 #include <primitives/block.h>
 #include <sync.h>
 #include <uint256.h>
@@ -38,8 +39,6 @@ static constexpr int64_t TIMESTAMP_WINDOW = MAX_FUTURE_BLOCK_TIME;
  */
 static constexpr int64_t MAX_BLOCK_TIME_GAP = 90 * 60;
 
-extern RecursiveMutex cs_main;
-
 class CBlockFileInfo
 {
 public:

src/kernel/cs_main.cpp

@@ -0,0 +1,7 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <sync.h>
+
+RecursiveMutex cs_main;

src/kernel/cs_main.h

@@ -0,0 +1,22 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_KERNEL_CS_MAIN_H
+#define BITCOIN_KERNEL_CS_MAIN_H
+
+#include <sync.h>
+
+/**
+ * Mutex to guard access to validation specific variables, such as reading
+ * or changing the chainstate.
+ *
+ * This may also need to be locked when updating the transaction pool, e.g. on
+ * AcceptToMemoryPool. See CTxMemPool::cs comment for details.
+ *
+ * The transaction pool has a separate lock to allow reading from it and the
+ * chainstate at the same time.
+ */
+extern RecursiveMutex cs_main;
+
+#endif // BITCOIN_KERNEL_CS_MAIN_H

src/node/blockstorage.h

@@ -8,6 +8,7 @@
 #include <attributes.h>
 #include <chain.h>
 #include <fs.h>
+#include <kernel/cs_main.h>
 #include <protocol.h>
 #include <sync.h>
 #include <txdb.h>
@@ -17,8 +18,6 @@
 #include <unordered_map>
 #include <vector>
 
-extern RecursiveMutex cs_main;
-
 class ArgsManager;
 class BlockValidationState;
 class CBlock;

src/rpc/blockchain.h

@@ -16,8 +16,6 @@
 #include <stdint.h>
 #include <vector>
 
-extern RecursiveMutex cs_main;
-
 class CBlock;
 class CBlockIndex;
 class Chainstate;

src/rpc/node.cpp

@@ -12,6 +12,7 @@
 #include <interfaces/echo.h>
 #include <interfaces/init.h>
 #include <interfaces/ipc.h>
+#include <kernel/cs_main.h>
 #include <node/context.h>
 #include <rpc/server.h>
 #include <rpc/server_util.h>

src/test/mempool_tests.cpp

@@ -64,7 +64,7 @@ BOOST_AUTO_TEST_CASE(MempoolRemoveTest)
 
 
     CTxMemPool& testPool = *Assert(m_node.mempool);
-    LOCK2(cs_main, testPool.cs);
+    LOCK2(::cs_main, testPool.cs);
 
     // Nothing in pool, remove should do nothing:
     unsigned int poolSize = testPool.size();

src/test/txvalidationcache_tests.cpp

@@ -117,7 +117,7 @@ BOOST_FIXTURE_TEST_CASE(tx_mempool_block_doublespend, Dersig100Setup)
 // should fail.
 // Capture this interaction with the upgraded_nop argument: set it when evaluating
 // any script flag that is implemented as an upgraded NOP code.
-static void ValidateCheckInputsForAllFlags(const CTransaction &tx, uint32_t failing_flags, bool add_to_cache, CCoinsViewCache& active_coins_tip) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+static void ValidateCheckInputsForAllFlags(const CTransaction &tx, uint32_t failing_flags, bool add_to_cache, CCoinsViewCache& active_coins_tip) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
 {
     PrecomputedTransactionData txdata;