Merge bitcoin/bitcoin#28590: assumeutxo: change getchainstates RPC to return a list of chainstates

a9ef702a877a964bac724a56e2c0b5bee4ea7586 assumeutxo: change getchainstates RPC to return a list of chainstates (Ryan Ofsky)

Pull request description:

  Current `getchainstates` RPC returns "normal" and "snapshot" fields which are not ideal because it requires new "normal" and "snapshot" terms to be defined, and the definitions are not really consistent with internal code. (In the RPC interface, the "snapshot" chainstate becomes the "normal" chainstate after it is validated, while in internal code there is no "normal chainstate" and the "snapshot chainstate" is still called that temporarily after it is validated).

  The current `getchainstates` RPC is also awkward to use if you to want information about the most-work chainstate, because you have to look at the "snapshot" field if it exists, and otherwise fall back to the "normal" field.

  Fix these issues by having `getchainstates` just return a flat list of chainstates ordered by work, and adding a new chainstate "validated" field alongside the existing "snapshot_blockhash" field so it is explicit if a chainstate was originally loaded from a snapshot, and whether the snapshot has been validated.

  This change was motivated by comment thread in https://github.com/bitcoin/bitcoin/pull/28562#discussion_r1344154808

ACKs for top commit:
  Sjors:
    re-ACK a9ef702a877a964bac724a56e2c0b5bee4ea7586
  jamesob:
    re-ACK a9ef702
  achow101:
    ACK a9ef702a877a964bac724a56e2c0b5bee4ea7586

Tree-SHA512: b364e2e96675fb7beaaee60c4dff4b69e6bc2d8a30dea1ba094265633d1cddf9dbf1c5ce20c07d6e23222cf1e92a195acf6227e4901f3962e81a1e53a43490aa

1 files changed, 10 insertions, 12 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 0f4941b40c..abd723ee56 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -2807,6 +2807,7 @@ const std::vector<RPCResult> RPCHelpForChainstate{
     {RPCResult::Type::STR_HEX, "snapshot_blockhash", /*optional=*/true, "the base block of the snapshot this chainstate is based on, if any"},
     {RPCResult::Type::NUM, "coins_db_cache_bytes", "size of the coinsdb cache"},
     {RPCResult::Type::NUM, "coins_tip_cache_bytes", "size of the coinstip cache"},
+    {RPCResult::Type::BOOL, "validated", "whether the chainstate is fully validated. True if all blocks in the chainstate were validated, false if the chain is based on a snapshot and the snapshot has not yet been validated."},
 };
 
 static RPCHelpMan getchainstates()
@@ -2818,8 +2819,7 @@ return RPCHelpMan{
         RPCResult{
             RPCResult::Type::OBJ, "", "", {
                 {RPCResult::Type::NUM, "headers", "the number of headers seen so far"},
-                {RPCResult::Type::OBJ, "normal", /*optional=*/true, "fully validated chainstate containing blocks this node has validated starting from the genesis block", RPCHelpForChainstate},
-                {RPCResult::Type::OBJ, "snapshot", /*optional=*/true, "only present if an assumeutxo snapshot is loaded. Partially validated chainstate containing blocks this node has validated starting from the snapshot. After the snapshot is validated (when the 'normal' chainstate advances far enough to validate it), this chainstate will replace and become the 'normal' chainstate.", RPCHelpForChainstate},
+                {RPCResult::Type::ARR, "chainstates", "list of the chainstates ordered by work, with the most-work (active) chainstate last", {{RPCResult::Type::OBJ, "", "", RPCHelpForChainstate},}},
             }
         },
         RPCExamples{
@@ -2834,7 +2834,7 @@ return RPCHelpMan{
     NodeContext& node = EnsureAnyNodeContext(request.context);
     ChainstateManager& chainman = *node.chainman;
 
-    auto make_chain_data = [&](const Chainstate& cs) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
+    auto make_chain_data = [&](const Chainstate& cs, bool validated) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
         AssertLockHeld(::cs_main);
         UniValue data(UniValue::VOBJ);
         if (!cs.m_chain.Tip()) {
@@ -2852,20 +2852,18 @@ return RPCHelpMan{
         if (cs.m_from_snapshot_blockhash) {
             data.pushKV("snapshot_blockhash", cs.m_from_snapshot_blockhash->ToString());
         }
+        data.pushKV("validated", validated);
         return data;
     };
 
-    if (chainman.GetAll().size() > 1) {
-        for (Chainstate* chainstate : chainman.GetAll()) {
-            obj.pushKV(
-                chainstate->m_from_snapshot_blockhash ? "snapshot" : "normal",
-                make_chain_data(*chainstate));
-        }
-    } else {
-        obj.pushKV("normal", make_chain_data(chainman.ActiveChainstate()));
-    }
     obj.pushKV("headers", chainman.m_best_header ? chainman.m_best_header->nHeight : -1);
 
+    const auto& chainstates = chainman.GetAll();
+    UniValue obj_chainstates{UniValue::VARR};
+    for (Chainstate* cs : chainstates) {
+      obj_chainstates.push_back(make_chain_data(*cs, !cs->m_from_snapshot_blockhash || chainstates.size() == 1));
+    }
+    obj.pushKV("chainstates", std::move(obj_chainstates));
     return obj;
 }
     };