Merge #16443: refactor: have CCoins* data managed under CChainState

582d2cd74754d6b9a2394616a9c82a89d2d71976 Cover UTXO set access with lock annotations (James O'Beirne)
569353068568444a25b301bbd6513bb510157dc9 refactor: have CCoins* data managed under CChainState (James O'Beirne)
fae6ab6aed3b9fdc9201bb19a307dfc3d9b89891 refactor: pcoinsTip -> CChainState::CoinsTip() (James O'Beirne)

Pull request description:

  This is part of the [assumeutxo project](https://github.com/bitcoin/bitcoin/projects/11):

  Parent PR: #15606
  Issue: #15605
  Specification: https://github.com/jamesob/assumeutxo-docs/tree/2019-04-proposal/proposal

  ---

  This change encapsulates UTXO set data within CChainState instances, removing global data `pcoinsTip` and `pcoinsviewdb`. This is necessary if we want to maintain multiple chainstates with their own rendering of the UTXO set.

  We introduce a class CoinsViews which consolidates the construction of a CCoins* hierarchy.

  This commit could be broken into smaller pieces, but it would require more ephemeral diffs to, e.g., temporarily change CCoinsViewDB's constructor invocations.

ACKs for top commit:
  Sjors:
    reACK 582d2cd74754d6b9a2394616a9c82a89d2d71976
  MarcoFalke:
    ACK 582d2cd747

Tree-SHA512: ec9d904fe5dca8cd2dc4b7916daa5d8bab30856dd4645987300f905e0a19f9919fce4f9d1ff03eda982943ca73e6e9a746be6cf53b46510de36e8c81a1eafba1

1 files changed, 28 insertions, 21 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 25c964205a..8870f379fb 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -15,7 +15,6 @@
 #include <blockfilter.h>
 #include <chain.h>
 #include <chainparams.h>
-#include <coins.h>
 #include <compat/sanity.h>
 #include <consensus/validation.h>
 #include <fs.h>
@@ -150,7 +149,6 @@ NODISCARD static bool CreatePidFile()
 // shutdown thing.
 //
 
-static std::unique_ptr<CCoinsViewErrorCatcher> pcoinscatcher;
 static std::unique_ptr<ECCVerifyHandle> globalVerifyHandle;
 
 static boost::thread_group threadGroup;
@@ -235,8 +233,14 @@ void Shutdown(InitInterfaces& interfaces)
     }
 
     // FlushStateToDisk generates a ChainStateFlushed callback, which we should avoid missing
-    if (pcoinsTip != nullptr) {
-        ::ChainstateActive().ForceFlushStateToDisk();
+    //
+    // g_chainstate is referenced here directly (instead of ::ChainstateActive()) because it
+    // may not have been initialized yet.
+    {
+        LOCK(cs_main);
+        if (g_chainstate && g_chainstate->CanFlushToDisk()) {
+            g_chainstate->ForceFlushStateToDisk();
+        }
     }
 
     // After there are no more peers/RPC left to give us new data which may generate
@@ -251,12 +255,10 @@ void Shutdown(InitInterfaces& interfaces)
 
     {
         LOCK(cs_main);
-        if (pcoinsTip != nullptr) {
-            ::ChainstateActive().ForceFlushStateToDisk();
+        if (g_chainstate && g_chainstate->CanFlushToDisk()) {
+            g_chainstate->ForceFlushStateToDisk();
+            g_chainstate->ResetCoinsViews();
         }
-        pcoinsTip.reset();
-        pcoinscatcher.reset();
-        pcoinsdbview.reset();
         pblocktree.reset();
     }
     for (const auto& client : interfaces.chain_clients) {
@@ -1467,10 +1469,10 @@ bool AppInitMain(InitInterfaces& interfaces)
             bool is_coinsview_empty;
             try {
                 LOCK(cs_main);
+                // This statement makes ::ChainstateActive() usable.
+                g_chainstate = MakeUnique<CChainState>();
                 UnloadBlockIndex();
-                pcoinsTip.reset();
-                pcoinsdbview.reset();
-                pcoinscatcher.reset();
+
                 // new CBlockTreeDB tries to delete the existing file, which
                 // fails if it's still open from the previous loop. Close it first:
                 pblocktree.reset();
@@ -1521,9 +1523,12 @@ bool AppInitMain(InitInterfaces& interfaces)
                 // At this point we're either in reindex or we've loaded a useful
                 // block tree into BlockIndex()!
 
-                pcoinsdbview.reset(new CCoinsViewDB(nCoinDBCache, false, fReset || fReindexChainState));
-                pcoinscatcher.reset(new CCoinsViewErrorCatcher(pcoinsdbview.get()));
-                pcoinscatcher->AddReadErrCallback([]() {
+                ::ChainstateActive().InitCoinsDB(
+                    /* cache_size_bytes */ nCoinDBCache,
+                    /* in_memory */ false,
+                    /* should_wipe */ fReset || fReindexChainState);
+
+                ::ChainstateActive().CoinsErrorCatcher().AddReadErrCallback([]() {
                     uiInterface.ThreadSafeMessageBox(
                         _("Error reading from database, shutting down.").translated,
                         "", CClientUIInterface::MSG_ERROR);
@@ -1531,23 +1536,25 @@ bool AppInitMain(InitInterfaces& interfaces)
 
                 // If necessary, upgrade from older database format.
                 // This is a no-op if we cleared the coinsviewdb with -reindex or -reindex-chainstate
-                if (!pcoinsdbview->Upgrade()) {
+                if (!::ChainstateActive().CoinsDB().Upgrade()) {
                     strLoadError = _("Error upgrading chainstate database").translated;
                     break;
                 }
 
                 // ReplayBlocks is a no-op if we cleared the coinsviewdb with -reindex or -reindex-chainstate
-                if (!ReplayBlocks(chainparams, pcoinsdbview.get())) {
+                if (!ReplayBlocks(chainparams, &::ChainstateActive().CoinsDB())) {
                     strLoadError = _("Unable to replay blocks. You will need to rebuild the database using -reindex-chainstate.").translated;
                     break;
                 }
 
                 // The on-disk coinsdb is now in a good state, create the cache
-                pcoinsTip.reset(new CCoinsViewCache(pcoinscatcher.get()));
+                ::ChainstateActive().InitCoinsCache();
+                assert(::ChainstateActive().CanFlushToDisk());
 
-                is_coinsview_empty = fReset || fReindexChainState || pcoinsTip->GetBestBlock().IsNull();
+                is_coinsview_empty = fReset || fReindexChainState ||
+                    ::ChainstateActive().CoinsTip().GetBestBlock().IsNull();
                 if (!is_coinsview_empty) {
-                    // LoadChainTip sets ::ChainActive() based on pcoinsTip's best block
+                    // LoadChainTip sets ::ChainActive() based on CoinsTip()'s best block
                     if (!LoadChainTip(chainparams)) {
                         strLoadError = _("Error initializing block database").translated;
                         break;
@@ -1589,7 +1596,7 @@ bool AppInitMain(InitInterfaces& interfaces)
                         break;
                     }
 
-                    if (!CVerifyDB().VerifyDB(chainparams, pcoinsdbview.get(), gArgs.GetArg("-checklevel", DEFAULT_CHECKLEVEL),
+                    if (!CVerifyDB().VerifyDB(chainparams, &::ChainstateActive().CoinsDB(), gArgs.GetArg("-checklevel", DEFAULT_CHECKLEVEL),
                                   gArgs.GetArg("-checkblocks", DEFAULT_CHECKBLOCKS))) {
                         strLoadError = _("Corrupted block database detected").translated;
                         break;