Merge bitcoin/bitcoin#22697: addrman: Remove CAddrMan::Clear() function

4d2fa97 [addrman] Clean up ctor (John Newbery)
7e6e659 [addrman] inline Clear() into CAddrMan ctor (John Newbery)
406be5f [addrman] Remove all public uses of CAddrMan.Clear() from the tests (John Newbery)
ed9ba8a [tests] Remove CAddrMan.Clear() call from CAddrDB::Read() (John Newbery)
e8e7392 [addrman] Don't call Clear() if parsing peers.dat fails (John Newbery)
181a120 [addrman] Move peers.dat parsing to init.cpp (John Newbery)

Pull request description:

  `CAddrMan::Clear()` exists to reset the internal state of `CAddrMan`. It's currently used in two places:

  - on startup, if deserializing peers.dat fails, `Clear()` is called to reset to an empty addrman
  - in tests, `Clear()` is called to reset the addrman for more tests

  In both cases, we can simply destruct the `CAddrMan` and construct a new, empty addrman. That approach is safer - it's possible that `Clear()` could 'reset' the addrman to a state that's not equivalent to a freshly constructed addrman (one actual example of this is that `Clear()` does not clear the `m_tried_collisions` set). On the other hand, if we destruct and then construct a fresh addrman, we're guaranteed that the new object is empty.

  This wasn't possible when addrman was initially implemented, since it was a global, and so it would only be destructed on shutdown. However, addrman is now owned by `node.context`, so we have control over its destruction/construction.

ACKs for top commit:
  laanwj:
    Code review ACK 4d2fa97
  vasild:
    ACK 4d2fa97
  Zero-1729:
    crACK 4d2fa97

Tree-SHA512: f715bf2cbff4f8c3a9dbc613f8c7f11846b065d6807faf3c7d346a0b0b29cbe7ce1dc0509465c2c9b88a8ad55299c9182ea53f5f743e47502a69a0f375e09408

Author: fanquake

src/addrdb.cpp

@@ -244,12 +244,7 @@ bool CAddrDB::Read(CAddrMan& addr)
 
 bool CAddrDB::Read(CAddrMan& addr, CDataStream& ssPeers)
 {
-    bool ret = DeserializeDB(ssPeers, addr, false);
-    if (!ret) {
-        // Ensure addrman is left in a clean state
-        addr.Clear();
-    }
-    return ret;
+    return DeserializeDB(ssPeers, addr, false);
 }
 
 void DumpAnchors(const fs::path& anchors_db_path, const std::vector<CAddress>& anchors)

src/addrman.cpp

@@ -77,6 +77,23 @@ double CAddrInfo::GetChance(int64_t nNow) const
     return fChance;
 }
 
+CAddrMan::CAddrMan(bool deterministic, int32_t consistency_check_ratio)
+    : insecure_rand{deterministic}
+    , nKey{deterministic ? uint256{1} : insecure_rand.rand256()}
+    , m_consistency_check_ratio{consistency_check_ratio}
+{
+    for (auto& bucket : vvNew) {
+        for (auto& entry : bucket) {
+            entry = -1;
+        }
+    }
+    for (auto& bucket : vvTried) {
+        for (auto& entry : bucket) {
+            entry = -1;
+        }
+    }
+}
+
 CAddrInfo* CAddrMan::Find(const CNetAddr& addr, int* pnId)
 {
     AssertLockHeld(cs);

src/addrman.h

@@ -471,38 +471,7 @@ class CAddrMan
         Check();
     }
 
-    void Clear()
-        EXCLUSIVE_LOCKS_REQUIRED(!cs)
-    {
-        LOCK(cs);
-        std::vector<int>().swap(vRandom);
-        nKey = insecure_rand.rand256();
-        for (size_t bucket = 0; bucket < ADDRMAN_NEW_BUCKET_COUNT; bucket++) {
-            for (size_t entry = 0; entry < ADDRMAN_BUCKET_SIZE; entry++) {
-                vvNew[bucket][entry] = -1;
-            }
-        }
-        for (size_t bucket = 0; bucket < ADDRMAN_TRIED_BUCKET_COUNT; bucket++) {
-            for (size_t entry = 0; entry < ADDRMAN_BUCKET_SIZE; entry++) {
-                vvTried[bucket][entry] = -1;
-            }
-        }
-
-        nIdCount = 0;
-        nTried = 0;
-        nNew = 0;
-        nLastGood = 1; //Initially at 1 so that "never" is strictly worse.
-        mapInfo.clear();
-        mapAddr.clear();
-    }
-
-    explicit CAddrMan(bool deterministic, int32_t consistency_check_ratio)
-        : insecure_rand{deterministic},
-          m_consistency_check_ratio{consistency_check_ratio}
-    {
-        Clear();
-        if (deterministic) nKey = uint256{1};
-    }
+    explicit CAddrMan(bool deterministic, int32_t consistency_check_ratio);
 
     ~CAddrMan()
     {
@@ -624,17 +593,16 @@ class CAddrMan
         Check();
     }
 
-protected:
-    //! secret key to randomize bucket select with
-    uint256 nKey;
-
+private:
     //! A mutex to protect the inner data structures.
     mutable Mutex cs;
 
-private:
     //! Source of random numbers for randomization in inner loops
     mutable FastRandomContext insecure_rand GUARDED_BY(cs);
 
+    //! secret key to randomize bucket select with
+    uint256 nKey;
+
     //! Serialization versions.
     enum Format : uint8_t {
         V0_HISTORICAL = 0,    //!< historic format, before commit e6b343d88
@@ -658,7 +626,7 @@ class CAddrMan
     static constexpr uint8_t INCOMPATIBILITY_BASE = 32;
 
     //! last used nId
-    int nIdCount GUARDED_BY(cs);
+    int nIdCount GUARDED_BY(cs){0};
 
     //! table with information about all nIds
     std::unordered_map<int, CAddrInfo> mapInfo GUARDED_BY(cs);
@@ -672,19 +640,19 @@ class CAddrMan
     mutable std::vector<int> vRandom GUARDED_BY(cs);
 
     // number of "tried" entries
-    int nTried GUARDED_BY(cs);
+    int nTried GUARDED_BY(cs){0};
 
     //! list of "tried" buckets
     int vvTried[ADDRMAN_TRIED_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);
 
     //! number of (unique) "new" entries
-    int nNew GUARDED_BY(cs);
+    int nNew GUARDED_BY(cs){0};
 
     //! list of "new" buckets
     int vvNew[ADDRMAN_NEW_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);
 
-    //! last time Good was called (memory only)
-    int64_t nLastGood GUARDED_BY(cs);
+    //! last time Good was called (memory only). Initially set to 1 so that "never" is strictly worse.
+    int64_t nLastGood GUARDED_BY(cs){1};
 
     //! Holds addrs inserted into tried table that collide with existing entries. Test-before-evict discipline used to resolve these collisions.
     std::set<int> m_tried_collisions;

src/bench/addrman.cpp

@@ -72,11 +72,9 @@ static void AddrManAdd(benchmark::Bench& bench)
 {
     CreateAddresses();
 
-    CAddrMan addrman(/* deterministic */ false, /* consistency_check_ratio */ 0);
-
     bench.run([&] {
+        CAddrMan addrman{/* deterministic */ false, /* consistency_check_ratio */ 0};
         AddAddressesToAddrMan(addrman);
-        addrman.Clear();
     });
 }
 

src/init.cpp

@@ -1167,6 +1167,20 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     assert(!node.addrman);
     auto check_addrman = std::clamp<int32_t>(args.GetArg("-checkaddrman", DEFAULT_ADDRMAN_CONSISTENCY_CHECKS), 0, 1000000);
     node.addrman = std::make_unique<CAddrMan>(/* deterministic */ false, /* consistency_check_ratio */ check_addrman);
+    {
+        // Load addresses from peers.dat
+        uiInterface.InitMessage(_("Loading P2P addresses…").translated);
+        int64_t nStart = GetTimeMillis();
+        CAddrDB adb;
+        if (adb.Read(*node.addrman)) {
+            LogPrintf("Loaded %i addresses from peers.dat  %dms\n", node.addrman->size(), GetTimeMillis() - nStart);
+        } else {
+            // Addrman can be in an inconsistent state after failure, reset it
+            node.addrman = std::make_unique<CAddrMan>(/* deterministic */ false, /* consistency_check_ratio */ check_addrman);
+            LogPrintf("Recreating peers.dat\n");
+            adb.Write(*node.addrman);
+        }
+    }
     assert(!node.banman);
     node.banman = std::make_unique<BanMan>(gArgs.GetDataDirNet() / "banlist", &uiInterface, args.GetArg("-bantime", DEFAULT_MISBEHAVING_BANTIME));
     assert(!node.connman);

src/net.cpp

@@ -2534,22 +2534,6 @@ bool CConnman::Start(CScheduler& scheduler, const Options& connOptions)
         AddAddrFetch(strDest);
     }
 
-    if (m_client_interface) {
-        m_client_interface->InitMessage(_("Loading P2P addresses…").translated);
-    }
-    // Load addresses from peers.dat
-    int64_t nStart = GetTimeMillis();
-    {
-        CAddrDB adb;
-        if (adb.Read(addrman))
-            LogPrintf("Loaded %i addresses from peers.dat  %dms\n", addrman.size(), GetTimeMillis() - nStart);
-        else {
-            addrman.Clear(); // Addrman can be in an inconsistent state after failure, reset it
-            LogPrintf("Recreating peers.dat\n");
-            DumpAddresses();
-        }
-    }
-
     if (m_use_addrman_outgoing) {
         // Load addresses from anchors.dat
         m_anchors = ReadAnchors(gArgs.GetDataDirNet() / ANCHORS_DATABASE_FILENAME);