functional_tests: speed up signature generation

Executing a new binary for each signature can get really slow

tests/functional_tests/make_test_signature.cc

@@ -33,9 +33,9 @@
 int main(int argc, const char **argv)
 {
   TRY_ENTRY();
-  if (argc > 2)
+  if (argc > 3)
   {
-    fprintf(stderr, "usage: %s <secret_key>\n", argv[0]);
+    fprintf(stderr, "usage: %s [<secret_key> [N]]\n", argv[0]);
     return 1;
   }
 
@@ -55,8 +55,22 @@ int main(int argc, const char **argv)
     fprintf(stderr, "invalid secret key\n");
     return 1;
   }
-  std::string signature = cryptonote::make_rpc_payment_signature(skey);
-  printf("%s\n", signature.c_str());
+  uint32_t count = 1;
+  if (argc == 3)
+  {
+    int i = atoi(argv[2]);
+    if (i <= 0)
+    {
+      fprintf(stderr, "invalid count\n");
+      return 1;
+    }
+    count = (uint32_t)i;
+  }
+  while (count--)
+  {
+    std::string signature = cryptonote::make_rpc_payment_signature(skey);
+    printf("%s\n", signature.c_str());
+  }
   return 0;
   CATCH_ENTRY_L0("main()", 1);
 }

tests/functional_tests/rpc_payment.py

@@ -44,6 +44,7 @@ class RPCPaymentTest():
         self.make_test_signature = os.environ['MAKE_TEST_SIGNATURE']
         assert len(self.make_test_signature) > 0
         self.secret_key, self.public_key = self.get_keys()
+        self.signatures = []
         self.reset()
         self.test_access_tracking()
         self.test_access_mining()
@@ -57,8 +58,17 @@ class RPCPaymentTest():
         assert len(fields) == 2
         return fields
 
+    def refill_signatures(self):
+        signatures = subprocess.check_output([self.make_test_signature, self.secret_key, '256']).decode('utf-8')
+        for line in signatures.split():
+            self.signatures.append(line.rstrip())
+
     def get_signature(self):
-        return subprocess.check_output([self.make_test_signature, self.secret_key]).decode('utf-8').rstrip()
+        if len(self.signatures) == 0:
+            self.refill_signatures()
+        s = self.signatures[0]
+        self.signatures = self.signatures[1:]
+        return s
 
     def reset(self):
         print('Resetting blockchain')