Merge #17383: Refactor: Move consts to their correct translation units

e9ea95a30d3c0f62b0df0b29744fb5d68687f97f [net processing] Move all const declarations to top of net_processing.cpp (John Newbery)
507b36dd1bf867cd20e4312b95c68b494c9bb7b8 [validation] Move all const declarations to top of validation.h (John Newbery)
0109622b08887ed01a30911477ce4b8f266d4b4a [validation] Move validation-only consts to validation.cpp (John Newbery)
b8580cacc70764ba5a48e3defb864d75e6c28626 [net processing] Move net processing consts to net_processing.cpp (John Newbery)

Pull request description:

  Following the main.cpp split, there are still some constants in the wrong places, eg net_processing constants in validation.h. Move them all to their rightful homes. At the same time, make them constexpr.

  Also move all const declarations to the top of their files, and ensure that they all have doxygen comments.

ACKs for top commit:
  practicalswift:
    ACK e9ea95a30d3c0f62b0df0b29744fb5d68687f97f -- patch looks correct
  MarcoFalke:
    ACK e9ea95a30d3c0f62b0df0b29744fb5d68687f97f 🚉

Tree-SHA512: 44d81da73c7be01e1d36b939789d793f297d3b94f84ea4e7ac853c621cc7054b5a05c7c9e7b83db506db44c16f344541be8f240d955694211e53a84c32b0d2c5

4 files changed, 79 insertions, 88 deletions

diff --git a/src/net.h b/src/net.h
index cec31bfd80..0d79efbba7 100644
--- a/src/net.h
+++ b/src/net.h
@@ -45,16 +45,10 @@ static const bool DEFAULT_WHITELISTRELAY = true;
 /** Default for -whitelistforcerelay. */
 static const bool DEFAULT_WHITELISTFORCERELAY = false;
 
-/** Time between pings automatically sent out for latency probing and keepalive (in seconds). */
-static const int PING_INTERVAL = 2 * 60;
 /** Time after which to disconnect, after waiting for a ping response (or inactivity). */
 static const int TIMEOUT_INTERVAL = 20 * 60;
 /** Run the feeler connection loop once every 2 minutes or 120 seconds. **/
 static const int FEELER_INTERVAL = 120;
-/** The maximum number of entries in an 'inv' protocol message */
-static const unsigned int MAX_INV_SZ = 50000;
-/** The maximum number of entries in a locator */
-static const unsigned int MAX_LOCATOR_SZ = 101;
 /** The maximum number of new addresses to accumulate before announcing. */
 static const unsigned int MAX_ADDR_TO_SEND = 1000;
 /** Maximum length of incoming protocol messages (no message over 4 MB is currently acceptable). */
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 96e9178b6e..26327ac6eb 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -64,6 +64,12 @@ static constexpr int STALE_RELAY_AGE_LIMIT = 30 * 24 * 60 * 60;
 /// Age after which a block is considered historical for purposes of rate
 /// limiting block relay. Set to one week, denominated in seconds.
 static constexpr int HISTORICAL_BLOCK_AGE = 7 * 24 * 60 * 60;
+/** Time between pings automatically sent out for latency probing and keepalive (in seconds). */
+static const int PING_INTERVAL = 2 * 60;
+/** The maximum number of entries in a locator */
+static const unsigned int MAX_LOCATOR_SZ = 101;
+/** The maximum number of entries in an 'inv' protocol message */
+static const unsigned int MAX_INV_SZ = 50000;
 /** Maximum number of in-flight transactions from a peer */
 static constexpr int32_t MAX_PEER_TX_IN_FLIGHT = 100;
 /** Maximum number of announced transactions from a peer */
@@ -80,7 +86,47 @@ static_assert(INBOUND_PEER_TX_DELAY >= MAX_GETDATA_RANDOM_DELAY,
 "To preserve security, MAX_GETDATA_RANDOM_DELAY should not exceed INBOUND_PEER_DELAY");
 /** Limit to avoid sending big packets. Not used in processing incoming GETDATA for compatibility */
 static const unsigned int MAX_GETDATA_SZ = 1000;
-
+/** Number of blocks that can be requested at any given time from a single peer. */
+static const int MAX_BLOCKS_IN_TRANSIT_PER_PEER = 16;
+/** Timeout in seconds during which a peer must stall block download progress before being disconnected. */
+static const unsigned int BLOCK_STALLING_TIMEOUT = 2;
+/** Number of headers sent in one getheaders result. We rely on the assumption that if a peer sends
+ *  less than this number, we reached its tip. Changing this value is a protocol upgrade. */
+static const unsigned int MAX_HEADERS_RESULTS = 2000;
+/** Maximum depth of blocks we're willing to serve as compact blocks to peers
+ *  when requested. For older blocks, a regular BLOCK response will be sent. */
+static const int MAX_CMPCTBLOCK_DEPTH = 5;
+/** Maximum depth of blocks we're willing to respond to GETBLOCKTXN requests for. */
+static const int MAX_BLOCKTXN_DEPTH = 10;
+/** Size of the "block download window": how far ahead of our current height do we fetch?
+ *  Larger windows tolerate larger download speed differences between peer, but increase the potential
+ *  degree of disordering of blocks on disk (which make reindexing and pruning harder). We'll probably
+ *  want to make this a per-peer adaptive value at some point. */
+static const unsigned int BLOCK_DOWNLOAD_WINDOW = 1024;
+/** Block download timeout base, expressed in millionths of the block interval (i.e. 10 min) */
+static const int64_t BLOCK_DOWNLOAD_TIMEOUT_BASE = 1000000;
+/** Additional block download timeout per parallel downloading peer (i.e. 5 min) */
+static const int64_t BLOCK_DOWNLOAD_TIMEOUT_PER_PEER = 500000;
+/** Maximum number of headers to announce when relaying blocks with headers message.*/
+static const unsigned int MAX_BLOCKS_TO_ANNOUNCE = 8;
+/** Maximum number of unconnecting headers announcements before DoS score */
+static const int MAX_UNCONNECTING_HEADERS = 10;
+/** Minimum blocks required to signal NODE_NETWORK_LIMITED */
+static const unsigned int NODE_NETWORK_LIMITED_MIN_BLOCKS = 288;
+/** Average delay between local address broadcasts */
+static constexpr std::chrono::hours AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL{24};
+/** Average delay between peer address broadcasts */
+static constexpr std::chrono::seconds AVG_ADDRESS_BROADCAST_INTERVAL{30};
+/** Average delay between trickled inventory transmissions in seconds.
+ *  Blocks and whitelisted receivers bypass this, outbound peers get half this delay. */
+static const unsigned int INVENTORY_BROADCAST_INTERVAL = 5;
+/** Maximum number of inventory items to send per transmission.
+ *  Limits the impact of low-fee transaction floods. */
+static constexpr unsigned int INVENTORY_BROADCAST_MAX = 7 * INVENTORY_BROADCAST_INTERVAL;
+/** Average delay between feefilter broadcasts in seconds. */
+static constexpr unsigned int AVG_FEEFILTER_BROADCAST_INTERVAL = 10 * 60;
+/** Maximum feefilter broadcast delay after significant change. */
+static constexpr unsigned int MAX_FEEFILTER_CHANGE_DELAY = 5 * 60;
 
 struct COrphanTx {
     // When modifying, adapt the copy of this definition in tests/DoS_tests.
@@ -97,21 +143,6 @@ void EraseOrphansFor(NodeId peer);
 /** Increase a node's misbehavior score. */
 void Misbehaving(NodeId nodeid, int howmuch, const std::string& message="") EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
-/** Average delay between local address broadcasts */
-static constexpr std::chrono::hours AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL{24};
-/** Average delay between peer address broadcasts */
-static constexpr std::chrono::seconds AVG_ADDRESS_BROADCAST_INTERVAL{30};
-/** Average delay between trickled inventory transmissions in seconds.
- *  Blocks and whitelisted receivers bypass this, outbound peers get half this delay. */
-static const unsigned int INVENTORY_BROADCAST_INTERVAL = 5;
-/** Maximum number of inventory items to send per transmission.
- *  Limits the impact of low-fee transaction floods. */
-static constexpr unsigned int INVENTORY_BROADCAST_MAX = 7 * INVENTORY_BROADCAST_INTERVAL;
-/** Average delay between feefilter broadcasts in seconds. */
-static constexpr unsigned int AVG_FEEFILTER_BROADCAST_INTERVAL = 10 * 60;
-/** Maximum feefilter broadcast delay after significant change. */
-static constexpr unsigned int MAX_FEEFILTER_CHANGE_DELAY = 5 * 60;
-
 // Internal stuff
 namespace {
     /** Number of nodes with fSyncStarted. */
diff --git a/src/validation.cpp b/src/validation.cpp
index fb635b4202..25975e3e31 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -59,6 +59,25 @@
 #define MICRO 0.000001
 #define MILLI 0.001
 
+/**
+ * An extra transaction can be added to a package, as long as it only has one
+ * ancestor and is no larger than this. Not really any reason to make this
+ * configurable as it doesn't materially change DoS parameters.
+ */
+static const unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT = 10000;
+/** Maximum kilobytes for transactions to store for processing during reorg */
+static const unsigned int MAX_DISCONNECTED_TX_POOL_SIZE = 20000;
+/** The pre-allocation chunk size for blk?????.dat files (since 0.8) */
+static const unsigned int BLOCKFILE_CHUNK_SIZE = 0x1000000; // 16 MiB
+/** The pre-allocation chunk size for rev?????.dat files (since 0.8) */
+static const unsigned int UNDOFILE_CHUNK_SIZE = 0x100000; // 1 MiB
+/** Time to wait (in seconds) between writing blocks/block index to disk. */
+static const unsigned int DATABASE_WRITE_INTERVAL = 60 * 60;
+/** Time to wait (in seconds) between flushing chainstate to disk. */
+static const unsigned int DATABASE_FLUSH_INTERVAL = 24 * 60 * 60;
+/** Maximum age of our tip in seconds for us to be considered current for fee estimation */
+static const int64_t MAX_FEE_ESTIMATION_TIP_AGE = 3 * 60 * 60;
+
 bool CBlockIndexWorkComparator::operator()(const CBlockIndex *pa, const CBlockIndex *pb) const {
     // First sort by most total work, ...
     if (pa->nChainWork > pb->nChainWork) return false;
diff --git a/src/validation.h b/src/validation.h
index dbf7aa28db..91b1ba6497 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -60,57 +60,15 @@ static const unsigned int DEFAULT_ANCESTOR_SIZE_LIMIT = 101;
 static const unsigned int DEFAULT_DESCENDANT_LIMIT = 25;
 /** Default for -limitdescendantsize, maximum kilobytes of in-mempool descendants */
 static const unsigned int DEFAULT_DESCENDANT_SIZE_LIMIT = 101;
-/**
- * An extra transaction can be added to a package, as long as it only has one
- * ancestor and is no larger than this. Not really any reason to make this
- * configurable as it doesn't materially change DoS parameters.
- */
-static const unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT = 10000;
 /** Default for -mempoolexpiry, expiration time for mempool transactions in hours */
 static const unsigned int DEFAULT_MEMPOOL_EXPIRY = 336;
-/** Maximum kilobytes for transactions to store for processing during reorg */
-static const unsigned int MAX_DISCONNECTED_TX_POOL_SIZE = 20000;
 /** The maximum size of a blk?????.dat file (since 0.8) */
 static const unsigned int MAX_BLOCKFILE_SIZE = 0x8000000; // 128 MiB
-/** The pre-allocation chunk size for blk?????.dat files (since 0.8) */
-static const unsigned int BLOCKFILE_CHUNK_SIZE = 0x1000000; // 16 MiB
-/** The pre-allocation chunk size for rev?????.dat files (since 0.8) */
-static const unsigned int UNDOFILE_CHUNK_SIZE = 0x100000; // 1 MiB
-
 /** Maximum number of dedicated script-checking threads allowed */
 static const int MAX_SCRIPTCHECK_THREADS = 15;
 /** -par default (number of script-checking threads, 0 = auto) */
 static const int DEFAULT_SCRIPTCHECK_THREADS = 0;
-/** Number of blocks that can be requested at any given time from a single peer. */
-static const int MAX_BLOCKS_IN_TRANSIT_PER_PEER = 16;
-/** Timeout in seconds during which a peer must stall block download progress before being disconnected. */
-static const unsigned int BLOCK_STALLING_TIMEOUT = 2;
-/** Number of headers sent in one getheaders result. We rely on the assumption that if a peer sends
- *  less than this number, we reached its tip. Changing this value is a protocol upgrade. */
-static const unsigned int MAX_HEADERS_RESULTS = 2000;
-/** Maximum depth of blocks we're willing to serve as compact blocks to peers
- *  when requested. For older blocks, a regular BLOCK response will be sent. */
-static const int MAX_CMPCTBLOCK_DEPTH = 5;
-/** Maximum depth of blocks we're willing to respond to GETBLOCKTXN requests for. */
-static const int MAX_BLOCKTXN_DEPTH = 10;
-/** Size of the "block download window": how far ahead of our current height do we fetch?
- *  Larger windows tolerate larger download speed differences between peer, but increase the potential
- *  degree of disordering of blocks on disk (which make reindexing and pruning harder). We'll probably
- *  want to make this a per-peer adaptive value at some point. */
-static const unsigned int BLOCK_DOWNLOAD_WINDOW = 1024;
-/** Time to wait (in seconds) between writing blocks/block index to disk. */
-static const unsigned int DATABASE_WRITE_INTERVAL = 60 * 60;
-/** Time to wait (in seconds) between flushing chainstate to disk. */
-static const unsigned int DATABASE_FLUSH_INTERVAL = 24 * 60 * 60;
-/** Block download timeout base, expressed in millionths of the block interval (i.e. 10 min) */
-static const int64_t BLOCK_DOWNLOAD_TIMEOUT_BASE = 1000000;
-/** Additional block download timeout per parallel downloading peer (i.e. 5 min) */
-static const int64_t BLOCK_DOWNLOAD_TIMEOUT_PER_PEER = 500000;
-
 static const int64_t DEFAULT_MAX_TIP_AGE = 24 * 60 * 60;
-/** Maximum age of our tip in seconds for us to be considered current for fee estimation */
-static const int64_t MAX_FEE_ESTIMATION_TIP_AGE = 3 * 60 * 60;
-
 static const bool DEFAULT_CHECKPOINTS_ENABLED = true;
 static const bool DEFAULT_TXINDEX = false;
 static const char* const DEFAULT_BLOCKFILTERINDEX = "0";
@@ -119,15 +77,21 @@ static const unsigned int DEFAULT_BANSCORE_THRESHOLD = 100;
 static const bool DEFAULT_PERSIST_MEMPOOL = true;
 /** Default for using fee filter */
 static const bool DEFAULT_FEEFILTER = true;
-
-/** Maximum number of headers to announce when relaying blocks with headers message.*/
-static const unsigned int MAX_BLOCKS_TO_ANNOUNCE = 8;
-
-/** Maximum number of unconnecting headers announcements before DoS score */
-static const int MAX_UNCONNECTING_HEADERS = 10;
-
 /** Default for -stopatheight */
 static const int DEFAULT_STOPATHEIGHT = 0;
+/** Block files containing a block-height within MIN_BLOCKS_TO_KEEP of ::ChainActive().Tip() will not be pruned. */
+static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
+static const signed int DEFAULT_CHECKBLOCKS = 6;
+static const unsigned int DEFAULT_CHECKLEVEL = 3;
+// Require that user allocate at least 550 MiB for block & undo files (blk???.dat and rev???.dat)
+// At 1MB per block, 288 blocks = 288MB.
+// Add 15% for Undo data = 331MB
+// Add 20% for Orphan block rate = 397MB
+// We want the low water mark after pruning to be at least 397 MB and since we prune in
+// full block file chunks, we need the high water mark which triggers the prune to be
+// one 128MB block file + added 15% undo data = 147MB greater for a total of 545MB
+// Setting the target to >= 550 MiB will make it likely we can respect the target.
+static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
 
 struct BlockHasher
 {
@@ -175,23 +139,6 @@ extern bool fHavePruned;
 extern bool fPruneMode;
 /** Number of MiB of block files that we're trying to stay below. */
 extern uint64_t nPruneTarget;
-/** Block files containing a block-height within MIN_BLOCKS_TO_KEEP of ::ChainActive().Tip() will not be pruned. */
-static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
-/** Minimum blocks required to signal NODE_NETWORK_LIMITED */
-static const unsigned int NODE_NETWORK_LIMITED_MIN_BLOCKS = 288;
-
-static const signed int DEFAULT_CHECKBLOCKS = 6;
-static const unsigned int DEFAULT_CHECKLEVEL = 3;
-
-// Require that user allocate at least 550 MiB for block & undo files (blk???.dat and rev???.dat)
-// At 1MB per block, 288 blocks = 288MB.
-// Add 15% for Undo data = 331MB
-// Add 20% for Orphan block rate = 397MB
-// We want the low water mark after pruning to be at least 397 MB and since we prune in
-// full block file chunks, we need the high water mark which triggers the prune to be
-// one 128MB block file + added 15% undo data = 147MB greater for a total of 545MB
-// Setting the target to >= 550 MiB will make it likely we can respect the target.
-static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
 
 /**
  * Process an incoming block. This only returns after the best known valid