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

test/functional/rpc_misc.py

@@ -61,6 +61,34 @@ class RpcMiscTest(BitcoinTestFramework):
         node.logging(include=['qt'])
         assert_equal(node.logging()['qt'], True)
 
+        self.log.info("test getindexinfo")
+        # Without any indices running the RPC returns an empty object
+        assert_equal(node.getindexinfo(), {})
+
+        # Restart the node with indices and wait for them to sync
+        self.restart_node(0, ["-txindex", "-blockfilterindex"])
+        self.wait_until(lambda: all(i["synced"] for i in node.getindexinfo().values()))
+
+        # Returns a list of all running indices by default
+        assert_equal(
+            node.getindexinfo(),
+            {
+                "txindex": {"synced": True, "best_block_height": 200},
+                "basic block filter index": {"synced": True, "best_block_height": 200}
+            }
+        )
+
+        # Specifying an index by name returns only the status of that index
+        assert_equal(
+            node.getindexinfo("txindex"),
+            {
+                "txindex": {"synced": True, "best_block_height": 200},
+            }
+        )
+
+        # Specifying an unknown index name returns an empty result
+        assert_equal(node.getindexinfo("foo"), {})
+
 
 if __name__ == '__main__':
     RpcMiscTest().main()