Merge #19550: rpc: Add getindexinfo RPC

124e1ee134 doc: Add release notes for getindexinfo RPC (Fabian Jahr)
c447b09458 test: Add tests for getindexinfo RPC (Fabian Jahr)
667bc7a7f7 rpc: Add getindexinfo RPC (Fabian Jahr)

Pull request description:

  As I was playing with indices a I was missing an RPC that gives information about the active indices in the node. I think this can be helpful for many users, especially since there are some new index candidates coming up (#14053, #18000) that can give a quick overview without the user having to parse the logs.

  Feature summary:
  - Adds new RPC `listindices` (placed in Util section)
  - That RPC only lists the actively running indices
  - For each index it gives the name, whether it is synced and up to which block height it is synced

ACKs for top commit:
  laanwj:
    Re-ACK 124e1ee134
  jonatack:
    Code review re-ACK 124e1ee per `git range-diff a57af89 47a5372 124e1ee` no change since my last re-ACK, rebase only

Tree-SHA512: 3b7174c87951e6457fef099f530337803906baf32fb64261410b8def2c0917853d6a1bf3059cd590b1cc1523608f8916dafb327a431d27ecbf8d7454406b5b35

src/index/base.cpp

@@ -319,3 +319,12 @@ void BaseIndex::Stop()
         m_thread_sync.join();
     }
 }
+
+IndexSummary BaseIndex::GetSummary() const
+{
+    IndexSummary summary{};
+    summary.name = GetName();
+    summary.synced = m_synced;
+    summary.best_block_height = m_best_block_index.load()->nHeight;
+    return summary;
+}

src/index/base.h

@@ -13,6 +13,12 @@
 
 class CBlockIndex;
 
+struct IndexSummary {
+    std::string name;
+    bool synced{false};
+    int best_block_height{0};
+};
+
 /**
  * Base class for indices of blockchain data. This implements
  * CValidationInterface and ensures blocks are indexed sequentially according
@@ -106,6 +112,9 @@ public:
 
     /// Stops the instance from staying in sync with blockchain updates.
     void Stop();
+
+    /// Get a summary of the index and its state.
+    IndexSummary GetSummary() const;
 };
 
 #endif // BITCOIN_INDEX_BASE_H