Expose root_cache_path setting and set it in unit tests

api/ApplicationSettings.md

@@ -32,6 +32,7 @@ Table of contents:
   * [product_version](#product_version)
   * [remote_debugging_port](#remote_debugging_port)
   * [resources_dir_path](#resources_dir_path)
+  * [root_cache_path](#root_cache_path)
   * [single_process](#single_process)
   * [string_encoding](#string_encoding)
   * [uncaught_exception_stack_size](#uncaught_exception_stack_size)
@@ -376,6 +377,27 @@ the module directory on Windows/Linux or the app bundle Resources directory
 on Mac OS X. Also configurable using the --resources-dir-path switch.
 
 
+### root_cache_path
+
+(string)
+The root directory for installation-specific data and the parent directory
+for profile-specific data. All `cache_path` values must have this parent
+directory in common. If this value is empty and `cache_path` is non-empty
+then it will default to the `cache_path` value. Any non-empty value must be
+an absolute path.
+
+If both `root_cache_path` and `cache_path` are empty then a default
+platform-specific directory will be used ("~/.config/cef_user_data" on
+Linux, "~/Library/Application Support/CEF/User Data" on Mac, and
+"AppData\Local\CEF\User Data" on Windows). Use of the default directory is
+not recommended in production applications: recent CEF/Chromium versions use
+a process singleton lock based on the `root_cache_path` value to guard
+against multiple application instances writing to the same directory, and
+relying on the default value may lead to unintended process singleton
+behavior (CEF logs a warning in this case). You should customize
+`root_cache_path` for your application.
+
+
 ### single_process
 
 (bool)

src/extern/cef/cef_types.pxd

@@ -27,6 +27,7 @@ cdef extern from "include/internal/cef_types.h":
         cef_string_t browser_subprocess_path
         int command_line_args_disabled
         cef_string_t cache_path
+        cef_string_t root_cache_path
         int enable_net_security_expiration
         int persist_session_cookies
         cef_string_t user_agent

src/settings.pyx

@@ -50,6 +50,10 @@ cdef void SetApplicationSettings(
             cefString = new CefString(&cefAppSettings.cache_path)
             PyToCefStringPointer(appSettings[key], cefString)
             del cefString
+        elif key == "root_cache_path":
+            cefString = new CefString(&cefAppSettings.root_cache_path)
+            PyToCefStringPointer(appSettings[key], cefString)
+            del cefString
         elif key == "persist_session_cookies":
             cefAppSettings.persist_session_cookies = int(appSettings[key])
         elif key == "user_agent":

unittests/_common.py

@@ -8,6 +8,7 @@
 import os
 import platform
 import sys
+import tempfile
 import time
 
 # Platforms
@@ -18,6 +19,15 @@
 LINUX = SYSTEM if SYSTEM == "LINUX" else False
 MAC = SYSTEM if SYSTEM == "MAC" else False
 
+# Issue #685: set ApplicationSettings.root_cache_path so that CEF does not
+# log a warning about using the default user-data directory which "may lead
+# to unintended process singleton behavior". A fixed directory in the
+# system temp folder is reused across runs (the tests run a single instance
+# at a time, so there is no singleton conflict).
+ROOT_CACHE_PATH = os.path.join(tempfile.gettempdir(), "cefpython_tests")
+if not os.path.isdir(ROOT_CACHE_PATH):
+    os.makedirs(ROOT_CACHE_PATH)
+
 # To show the window for an extended period of time increase this number.
 MESSAGE_LOOP_RANGE = 200  # each iteration is 0.01 sec
 

unittests/main_test.py

@@ -130,6 +130,7 @@ def test_main(self):
             "debug": False,
             "log_severity": cef.LOGSEVERITY_ERROR,
             "log_file": "",
+            "root_cache_path": ROOT_CACHE_PATH,
         }
         if not LINUX:
             # On Linux you get a lot of "X error received" messages

unittests/osr_test.py

@@ -79,7 +79,8 @@ def test_osr(self):
             "debug": False,
             "log_severity": cef.LOGSEVERITY_ERROR,
             "log_file": "",
-            "windowless_rendering_enabled": True
+            "windowless_rendering_enabled": True,
+            "root_cache_path": ROOT_CACHE_PATH,
         }
         if not LINUX:
             # On Linux you get a lot of "X error received" messages