logging: use predictable log file names

README.md

@@ -145,7 +145,9 @@ You can run the plugin host in nvim with logging enabled to debug errors:
 NVIM_PYTHON_LOG_FILE=logfile NVIM_PYTHON_LOG_LEVEL=DEBUG nvim
 ```
 As more than one python host process might be started, the log filenames take
-the pattern `logfile_PID` where `PID` is the process id.
+the pattern `logfile_pyX_KIND` where `X` is the major python version (2 or 3)
+and `KIND` is either "rplugin" or "script" (for the `:python[3]`
+script interface).
 
 If the host cannot start at all, the error could be found in `~/.nvimlog` if
 `nvim` was compiled with logging.

neovim/__init__.py

@@ -53,7 +53,14 @@ def start_host(session=None):
         if os.path.isdir(path) and dup in plugins:
             plugins.remove(dup)
 
-    setup_logging()
+    # Special case: the legacy scripthost receives a single relative filename
+    # while the rplugin host will receive absolute paths.
+    if plugins == ["script_host.py"]:
+        name = "script"
+    else:
+        name = "rplugin"
+
+    setup_logging(name)
 
     if not session:
         session = stdio_session()
@@ -94,12 +101,13 @@ def attach(session_type, address=None, port=None,
     return Nvim.from_session(session).with_decode(decode)
 
 
-def setup_logging():
+def setup_logging(name):
     """Setup logging according to environment variables."""
     logger = logging.getLogger(__name__)
     if 'NVIM_PYTHON_LOG_FILE' in os.environ:
-        logfile = (os.environ['NVIM_PYTHON_LOG_FILE'].strip() +
-                   '_' + str(os.getpid()))
+        prefix = os.environ['NVIM_PYTHON_LOG_FILE'].strip()
+        major_version = sys.version_info[0]
+        logfile = '{0}_py{1}_{2}'.format(prefix, major_version, name)
         handler = logging.FileHandler(logfile, 'w')
         handler.formatter = logging.Formatter(
             '%(asctime)s [%(levelname)s @ '

test/test_common.py

@@ -6,7 +6,7 @@
 
 from nose.tools import eq_ as eq
 
-neovim.setup_logging()
+neovim.setup_logging("test")
 
 child_argv = os.environ.get('NVIM_CHILD_ARGV')
 listen_address = os.environ.get('NVIM_LISTEN_ADDRESS')