test: Speed up cache creation

test/functional/test_framework/test_framework.py

@@ -29,7 +29,6 @@ from .util import (
     disconnect_nodes,
     get_datadir_path,
     initialize_datadir,
-    p2p_port,
     sync_blocks,
     sync_mempools,
 )
@@ -468,35 +467,23 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
     def _initialize_chain(self):
         """Initialize a pre-mined blockchain for use by the test.
 
-        Create a cache of a 199-block-long chain (with wallet) for MAX_NODES
+        Create a cache of a 199-block-long chain
         Afterward, create num_nodes copies from the cache."""
 
+        CACHE_NODE_ID = 0  # Use node 0 to create the cache for all other nodes
+        cache_node_dir = get_datadir_path(self.options.cachedir, CACHE_NODE_ID)
         assert self.num_nodes <= MAX_NODES
-        create_cache = False
+
-        for i in range(MAX_NODES):
+        if not os.path.isdir(cache_node_dir):
-            if not os.path.isdir(get_datadir_path(self.options.cachedir, i)):
+            self.log.debug("Creating cache directory {}".format(cache_node_dir))
-                create_cache = True
+
-                break
+            initialize_datadir(self.options.cachedir, CACHE_NODE_ID)
-
+            self.nodes.append(
-        if create_cache:
+                TestNode(
-            self.log.debug("Creating data directories from cached datadir")
+                    CACHE_NODE_ID,
-
+                    cache_node_dir,
-            # find and delete old cache directories if any exist
-            for i in range(MAX_NODES):
-                if os.path.isdir(get_datadir_path(self.options.cachedir, i)):
-                    shutil.rmtree(get_datadir_path(self.options.cachedir, i))
-
-            # Create cache directories, run bitcoinds:
-            for i in range(MAX_NODES):
-                datadir = initialize_datadir(self.options.cachedir, i)
-                args = [self.options.bitcoind, "-datadir=" + datadir, '-disablewallet']
-                if i > 0:
-                    args.append("-connect=127.0.0.1:" + str(p2p_port(0)))
-                self.nodes.append(TestNode(
-                    i,
-                    get_datadir_path(self.options.cachedir, i),
                     extra_conf=["bind=127.0.0.1"],
-                    extra_args=[],
+                    extra_args=['-disablewallet'],
                     rpchost=None,
                     timewait=self.rpc_timeout,
                     bitcoind=self.options.bitcoind,
@@ -504,12 +491,10 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                     coverage_dir=None,
                     cwd=self.options.tmpdir,
                 ))
-                self.nodes[i].args = args
+            self.start_node(CACHE_NODE_ID)
-                self.start_node(i)
 
             # Wait for RPC connections to be ready
-            for node in self.nodes:
+            self.nodes[CACHE_NODE_ID].wait_for_rpc_connection()
-                node.wait_for_rpc_connection()
 
             # Create a 199-block-long chain; each of the 4 first nodes
             # gets 25 mature blocks and 25 immature.
@@ -518,29 +503,29 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
             # This is needed so that we are out of IBD when the test starts,
             # see the tip age check in IsInitialBlockDownload().
             for i in range(8):
-                self.nodes[0].generatetoaddress(25 if i != 7 else 24, self.nodes[i % 4].get_deterministic_priv_key().address)
+                self.nodes[CACHE_NODE_ID].generatetoaddress(
-            self.sync_blocks()
+                    nblocks=25 if i != 7 else 24,
+                    address=TestNode.PRIV_KEYS[i % 4].address,
+                )
 
-            for n in self.nodes:
+            assert_equal(self.nodes[CACHE_NODE_ID].getblockchaininfo()["blocks"], 199)
-                assert_equal(n.getblockchaininfo()["blocks"], 199)
 
-            # Shut them down, and clean up cache directories:
+            # Shut it down, and clean up cache directories:
             self.stop_nodes()
             self.nodes = []
 
-            def cache_path(n, *paths):
+            def cache_path(*paths):
-                return os.path.join(get_datadir_path(self.options.cachedir, n), "regtest", *paths)
+                return os.path.join(cache_node_dir, "regtest", *paths)
 
-            for i in range(MAX_NODES):
+            os.rmdir(cache_path('wallets'))  # Remove empty wallets dir
-                os.rmdir(cache_path(i, 'wallets'))  # Remove empty wallets dir
+            for entry in os.listdir(cache_path()):
-                for entry in os.listdir(cache_path(i)):
+                if entry not in ['chainstate', 'blocks']:  # Only keep chainstate and blocks folder
-                    if entry not in ['chainstate', 'blocks']:
+                    os.remove(cache_path(entry))
-                        os.remove(cache_path(i, entry))
 
         for i in range(self.num_nodes):
-            from_dir = get_datadir_path(self.options.cachedir, i)
+            self.log.debug("Copy cache directory {} to node {}".format(cache_node_dir, i))
             to_dir = get_datadir_path(self.options.tmpdir, i)
-            shutil.copytree(from_dir, to_dir)
+            shutil.copytree(cache_node_dir, to_dir)
             initialize_datadir(self.options.tmpdir, i)  # Overwrite port/rpcport in bitcoin.conf
 
     def _initialize_chain_clean(self):

test/functional/test_framework/test_node.py

@@ -111,8 +111,6 @@ class TestNode():
 
         self.p2ps = []
 
-    def get_deterministic_priv_key(self):
-        """Return a deterministic priv key in base58, that only depends on the node's index"""
     AddressKeyPair = collections.namedtuple('AddressKeyPair', ['address', 'key'])
     PRIV_KEYS = [
             # address , privkey
@@ -129,8 +127,11 @@ class TestNode():
             AddressKeyPair('mpFAHDjX7KregM3rVotdXzQmkbwtbQEnZ6', 'cT7qK7g1wkYEMvKowd2ZrX1E5f6JQ7TM246UfqbCiyF7kZhorpX3'),
             AddressKeyPair('mzRe8QZMfGi58KyWCse2exxEFry2sfF2Y7', 'cPiRWE8KMjTRxH1MWkPerhfoHFn5iHPWVK5aPqjW8NxmdwenFinJ'),
     ]
-        assert len(PRIV_KEYS) == MAX_NODES
+
-        return PRIV_KEYS[self.index]
+    def get_deterministic_priv_key(self):
+        """Return a deterministic priv key in base58, that only depends on the node's index"""
+        assert len(self.PRIV_KEYS) == MAX_NODES
+        return self.PRIV_KEYS[self.index]
 
     def get_mem_rss_kilobytes(self):
         """Get the memory usage (RSS) per `ps`.