Merge #14982: rpc: Add getrpcinfo command

a0ac15459a doc: Add getrpcinfo release notes (João Barbosa)
251a91c1bf qa: Add tests for getrpcinfo (João Barbosa)
d0730f5ce4 rpc: Add getrpcinfo command (João Barbosa)
068a8fc05f rpc: Track active commands (João Barbosa)
bf4383277d rpc: Remove unused PreCommand signal (João Barbosa)

Pull request description:

  The new `getrpcinfo` command exposes details of the RPC interface. The details can be configuration properties or runtime values/stats.

  This can be particular useful to coordinate concurrent functional tests (see #14958 from where this was extracted).

Tree-SHA512: 7292cb6087f4c429973d991aa2b53ffa1327d5a213df7d6ba5fc69b01b2e1a411f6d1609fed9234896293317dab05f65064da48b8f2b4a998eba532591d31882

test/functional/interface_rpc.py

@@ -5,13 +5,23 @@
 """Tests some generic aspects of the RPC interface."""
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal
+from test_framework.util import assert_equal, assert_greater_than_or_equal
 
 class RPCInterfaceTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
         self.setup_clean_chain = True
 
+    def test_getrpcinfo(self):
+        self.log.info("Testing getrpcinfo...")
+
+        info = self.nodes[0].getrpcinfo()
+        assert_equal(len(info['active_commands']), 1)
+
+        command = info['active_commands'][0]
+        assert_equal(command['method'], 'getrpcinfo')
+        assert_greater_than_or_equal(command['duration'], 0)
+
     def test_batch_request(self):
         self.log.info("Testing basic JSON-RPC batch request...")
 
@@ -39,6 +49,7 @@ class RPCInterfaceTest(BitcoinTestFramework):
         assert result_by_id[3]['result'] is not None
 
     def run_test(self):
+        self.test_getrpcinfo()
         self.test_batch_request()