[cli] Remove internal keystore address dict for direct cached CLI calls

Instead of syncing an internal address dict, it now always calls the
CLI for the list of account keys in its keystore. To reduce needless
calls, all account related gets are cached based on last modified
times of keystore directory

pyhmy/cli.py

@@ -6,7 +6,7 @@ import re
 
 from .util import get_bls_build_variables, get_gopath
 
-_addresses = {}  # Internal address keystore, not guaranteed to be up-to-date unless needed.
+_account_keystore_path = "~/.hmy/account-keys"
 _binary_path = "hmy"  # Internal binary path.
 _environment = os.environ.copy()  # Internal environment dict for Subprocess & Pexpect.
 
@@ -25,11 +25,43 @@ def _get_default_hmy_binary_path(file_name="hmy"):
     return ""
 
 
-def _sync_addresses():
+def _set_account_keystore_path():
     """
-    Internal function to sync address with the binary's keystore addresses.
+    Internal function to set the account keystore path according to the binary.
+    """
+    global _account_keystore_path
+    response = single_call("hmy keys location").strip()
+    if not os.path.exists(response):
+        os.mkdir(response)
+    _account_keystore_path = response
+
+
+def _cache_account_function(fn):
+    """
+    Internal decorator to cache account related functions. The cached value gets
+    removed as soon as the account keystore directory gets changed or edited.
+    """
+    cache = {}
+    last_mod_hash = None
+
+    def wrap(*args, **kwargs):
+        nonlocal last_mod_hash
+        key = (args, frozenset(kwargs.items()))
+        mod_hash = hash(_account_keystore_path + str(os.path.getmtime(_account_keystore_path)))
+        if last_mod_hash is None or mod_hash != last_mod_hash or key not in cache.keys():
+            last_mod_hash = mod_hash
+            cache[key] = fn(*args, **kwargs)
+        return cache[key]
+
+    return wrap
+
+
+@_cache_account_function
+def get_accounts_keystore():
+    """
+    :returns A dictionary where the keys are the account names/aliases and the
+             values are their 'one1...' addresses.
     """
-    global _addresses
     curr_addresses = {}
     response = single_call("hmy keys list")
     lines = response.split("\n")
@@ -43,7 +75,7 @@ def _sync_addresses():
             break  # Done iterating through all of the addresses.
         name, address = columns
         curr_addresses[name.strip()] = address
-    _addresses = curr_addresses
+    return curr_addresses
 
 
 def set_binary_path(path):
@@ -53,7 +85,14 @@ def set_binary_path(path):
     global _binary_path
     assert os.path.isfile(path), f"`{path}` is not a file"
     _binary_path = path
-    _sync_addresses()
+    _set_account_keystore_path()
+
+
+def get_binary_path():
+    """
+    :return: The absolute path of the CLI binary.
+    """
+    return os.path.abspath(_binary_path)
 
 
 def get_version():
@@ -71,52 +110,36 @@ def get_version():
 
 def get_account_keystore_path():
     """
-    :return: The account keystore path of the CLI binary.
+    :return: The absolute path to the account keystore of the CLI binary.
     """
-    response = single_call("hmy keys location").strip()
-    if not os.path.exists(response):
-        os.mkdir(response)
-    return response
+    return os.path.abspath(_account_keystore_path)
 
 
+@_cache_account_function
 def check_address(address):
     """
     :param address: A 'one1...' address.
     :return: Boolean of if the address is in the CLI's keystore.
     """
-    if address in _addresses.values():
-        return True
-    else:
-        _sync_addresses()
-        return address in _addresses.values()
-
-
-def get_binary_path():
-    """
-    :return: The absolute path of the CLI binary.
-    """
-    return os.path.abspath(_binary_path)
+    return address in get_accounts_keystore().values()
 
 
+@_cache_account_function
 def get_address(name):
     """
     :param name: The alias of a key used in the CLI's keystore.
     :return: The associated 'one1...' address.
     """
-    if name in _addresses:
-        return _addresses[name]
-    else:
-        _sync_addresses()
-        return _addresses.get(name, None)
+    return get_accounts_keystore().get(name, None)
 
 
+@_cache_account_function
 def get_accounts(address):
     """
     :param address: The 'one1...' address
     :return: A list of account names associated with the param
     """
-    _sync_addresses()
-    return [acc for acc, addr in _addresses.items() if address == addr]
+    return [acc for acc, addr in get_accounts_keystore().items() if address == addr]
 
 
 def remove_account(name):
@@ -135,7 +158,6 @@ def remove_account(name):
     except (shutil.Error, FileNotFoundError) as err:
         raise RuntimeError(f"Failed to delete dir: {keystore_path}\n"
                            f"\tException: {err}") from err
-    del _addresses[name]
 
 
 def remove_address(address):
@@ -160,7 +182,7 @@ def single_call(command, timeout=60):
     try:
         response = subprocess.check_output(command_toks, env=_environment, timeout=timeout).decode()
     except (subprocess.CalledProcessError, subprocess.TimeoutExpired) as err:
-        raise RuntimeError(f"Bad arguments for CLI.\n "
+        raise RuntimeError(f"Bad CLI args: `{command}`\n "
                            f"\tException: {err}") from err
     return response
 
@@ -178,12 +200,12 @@ def expect_call(command, timeout=60):
     try:
         proc = pexpect.spawn(f"{_binary_path}", command_toks, env=_environment, timeout=timeout)
     except (pexpect.ExceptionPexpect, pexpect.TIMEOUT) as err:
-        raise RuntimeError(f"Bad arguments for CLI.\n "
+        raise RuntimeError(f"Bad CLI args: `{command}`\n "
                            f"\tException: {err}") from err
     return proc
 
 
-_binary_path = _get_default_hmy_binary_path()
 if os.path.exists(f"{get_gopath()}/src/github.com/harmony-one/bls") \
-        and os.path.exists(f"{get_gopath()}/src/github.com/harmony-one/mcl"):  # Check prevents needless import fail.
+        and os.path.exists(f"{get_gopath()}/src/github.com/harmony-one/mcl"):  # Check prevents needless import fails.
     _environment.update(get_bls_build_variables())  # Needed if using dynamically linked CLI binary.
+set_binary_path(_get_default_hmy_binary_path())