Add transparent caching, --cache-create, --cache-delete and --cache-q… (

#155)

* Add transparent caching, --cache-create, --cache-delete and --cache-query options

* Update version to 3.4.0; put rebuild_initramfs call back during --reset; update README

* Fixes #79 - tests passing for all mode transitions

* Address review comments

* Simplify cache object schema per review comment

README.md

@@ -80,6 +80,9 @@ options:
   --use-nvidia-current  Use nvidia-current instead of nvidia for kernel modules
   --reset-sddm          Restore default Xsetup file
   --reset               Revert changes made by EnvyControl
+  --cache-create        Create cache used by EnvyControl; only works in hybrid mode
+  --cache-delete        Delete cache created by EnvyControl
+  --cache-query         Show cache created by EnvyControl
   --verbose             Enable verbose mode
 ```
 
@@ -121,6 +124,55 @@ Revert all changes made by EnvyControl:
 sudo envycontrol --reset
 ```
 
+### Caching added with 3.4.0
+A cache was added in version 3.4.0. The main purpose is to cache the Nvidia PCI bus ID so that a transition from integrated mode directly to nvidia mode is possible.
+
+#### Cache file location
+
+```python
+CACHE_FILE_PATH = '/var/cache/envycontrol/cache.json'
+```
+
+#### File format
+
+```json
+{
+  "nvidia_gpu_pci_bus": "PCI:1:0:0"
+}
+```
+
+The cache is automatically re-created whenever a switch from hybrid mode is performed.
+
+#### Caching command line examples
+
+Create cache used by EnvyControl; only works in hybrid mode
+
+```
+sudo envycontrol --cache-create
+```
+
+When create cache is called when the system is in integrated or nvidia modes
+
+```
+sudo envycontrol --cache-create
+...
+ValueError: --cache-create requires that the system be in the hybrid Optimus mode
+```
+
+
+Delete cache created by EnvyControl
+
+```
+sudo envycontrol --cache-delete
+```
+
+Show cache created by EnvyControl
+
+```
+sudo envycontrol --cache-query
+```
+
+
 ## ⬇️ Getting EnvyControl
 
 ### Arch Linux ([AUR](https://aur.archlinux.org/packages/envycontrol))

envycontrol.py

@@ -1,14 +1,18 @@
 #!/usr/bin/env python3
 import argparse
-import sys
+import logging
 import os
 import re
 import subprocess
-import logging
+import sys
+from contextlib import contextmanager
 
 # begin constants definition
 
-VERSION = '3.3.1'
+VERSION = '3.4.0'
+
+# Note: Do NOT remove this in cleanup!
+CACHE_FILE_PATH = '/var/cache/envycontrol/cache.json'
 
 BLACKLIST_PATH = '/etc/modprobe.d/blacklist-nvidia.conf'
 
@@ -216,9 +220,12 @@ def graphics_mode_switcher(graphics_mode, user_display_manager, enable_force_com
     if graphics_mode == 'integrated':
 
         if logging.getLogger().level == logging.DEBUG:
-            service = subprocess.run(["systemctl", "disable", "nvidia-persistenced.service"])
+            service = subprocess.run(
+                ["systemctl", "disable", "nvidia-persistenced.service"])
         else:
-            service = subprocess.run(["systemctl", "disable", "nvidia-persistenced.service"],stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+            service = subprocess.run(
+                ["systemctl", "disable", "nvidia-persistenced.service"],
+                stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
         if service.returncode == 0:
             print('Successfully disabled nvidia-persistenced.service')
         else:
@@ -239,9 +246,12 @@ def graphics_mode_switcher(graphics_mode, user_display_manager, enable_force_com
         cleanup()
 
         if logging.getLogger().level == logging.DEBUG:
-            service = subprocess.run(["systemctl", "enable", "nvidia-persistenced.service"])
+            service = subprocess.run(
+                ["systemctl", "enable", "nvidia-persistenced.service"])
         else:
-            service = subprocess.run(["systemctl", "enable", "nvidia-persistenced.service"],stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+            service = subprocess.run(
+                ["systemctl", "enable", "nvidia-persistenced.service"],
+                stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
         if service.returncode == 0:
             print('Successfully enabled nvidia-persistenced.service')
         else:
@@ -255,7 +265,8 @@ def graphics_mode_switcher(graphics_mode, user_display_manager, enable_force_com
         else:
             # setup rtd3
             if use_nvidia_current:
-                create_file(MODESET_PATH, MODESET_CURRENT_RTD3.format(rtd3_value))
+                create_file(
+                    MODESET_PATH, MODESET_CURRENT_RTD3.format(rtd3_value))
             else:
                 create_file(MODESET_PATH, MODESET_RTD3.format(rtd3_value))
             create_file(UDEV_PM_PATH, UDEV_PM_CONTENT)
@@ -266,9 +277,12 @@ def graphics_mode_switcher(graphics_mode, user_display_manager, enable_force_com
         print(f"Enable Coolbits: {coolbits_value or False}")
 
         if logging.getLogger().level == logging.DEBUG:
-            service = subprocess.run(["systemctl", "enable", "nvidia-persistenced.service"])
+            service = subprocess.run(
+                ["systemctl", "enable", "nvidia-persistenced.service"])
         else:
-            service = subprocess.run(["systemctl", "enable", "nvidia-persistenced.service"],stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+            service = subprocess.run(
+                ["systemctl", "enable", "nvidia-persistenced.service"],
+                stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
         if service.returncode == 0:
             print('Successfully enabled nvidia-persistenced.service')
         else:
@@ -522,6 +536,12 @@ def main():
                         help='Restore default Xsetup file')
     parser.add_argument('--reset', action='store_true',
                         help='Revert changes made by EnvyControl')
+    parser.add_argument('--cache-create', action='store_true',
+                        help='Create cache used by EnvyControl; only works in hybrid mode')
+    parser.add_argument('--cache-delete', action='store_true',
+                        help='Delete cache created by EnvyControl')
+    parser.add_argument('--cache-query', action='store_true',
+                        help='Show cache created by EnvyControl')
     parser.add_argument('--verbose', default=False, action='store_true',
                         help='Enable verbose mode')
 
@@ -540,26 +560,128 @@ def main():
         logging.getLogger().setLevel(logging.DEBUG)
 
     if args.query:
-        if os.path.exists(BLACKLIST_PATH) and os.path.exists(UDEV_INTEGRATED_PATH):
-            mode = 'integrated'
-        elif os.path.exists(XORG_PATH) and os.path.exists(MODESET_PATH):
-            mode = 'nvidia'
-        else:
-            mode = 'hybrid'
+        mode = get_current_mode()
         print(mode)
-    elif args.switch:
-        assert_root()
-        graphics_mode_switcher(args.switch, args.dm,
-                               args.force_comp, args.coolbits, args.rtd3, args.use_nvidia_current)
-    elif args.reset_sddm:
+        return
+    elif args.cache_create:
         assert_root()
-        create_file(SDDM_XSETUP_PATH, SDDM_XSETUP_CONTENT, True)
-        print('Operation completed successfully')
-    elif args.reset:
+        CachedConfig(args).create_cache_file()
+        return
+    elif args.cache_delete:
         assert_root()
-        cleanup()
-        rebuild_initramfs()
-        print('Operation completed successfully')
+        CachedConfig.delete_cache_file()
+        return
+    elif args.cache_query:
+        CachedConfig.show_cache_file()
+        return
+
+    if args.switch or args.reset_sddm or args.reset:
+        with CachedConfig(args).adapter():
+            if args.switch:
+                assert_root()
+                graphics_mode_switcher(
+                    args.switch, args.dm,
+                    args.force_comp, args.coolbits, args.rtd3, args.use_nvidia_current
+                )
+            elif args.reset_sddm:
+                assert_root()
+                create_file(SDDM_XSETUP_PATH, SDDM_XSETUP_CONTENT, True)
+                print('Operation completed successfully')
+            elif args.reset:
+                assert_root()
+                cleanup()
+                CachedConfig.delete_cache_file()
+                rebuild_initramfs()
+                print('Operation completed successfully')
+
+
+class CachedConfig:
+    '''Adapter for config from CACHE_FILE_PATH'''
+
+    def __init__(self, app_args) -> None:
+        self.app_args = app_args
+        self.current_mode = get_current_mode()
+
+    @contextmanager
+    def adapter(self):
+        global get_nvidia_gpu_pci_bus
+        use_cache = os.path.exists(CACHE_FILE_PATH)
+
+        if self.is_hybrid():  # recreate cache file when in hybrid mode
+            self.create_cache_file()
+
+        if use_cache:
+            self.read_cache_file()  # might not be in hybrid mode
+
+            # rebind function to use cached value instead of detection
+            get_nvidia_gpu_pci_bus = self.get_nvidia_gpu_pci_bus
+
+        yield  # back to main ...
+
+    def create_cache_file(self):
+        if not self.is_hybrid():
+            raise ValueError(
+                '--cache-create requires that the system be in the hybrid Optimus mode')
+
+        self.nvidia_gpu_pci_bus = get_nvidia_gpu_pci_bus()
+        self.obj = self.create_cache_obj(self.nvidia_gpu_pci_bus)
+        self.write_cache_file()
+
+    def create_cache_obj(self, nvidia_gpu_pci_bus):
+        return {
+            'nvidia_gpu_pci_bus': nvidia_gpu_pci_bus
+        }
+
+    def is_hybrid(self):
+        return 'hybrid' == self.current_mode
+
+    def get_nvidia_gpu_pci_bus(self):
+        return self.nvidia_gpu_pci_bus
+
+    @staticmethod
+    def delete_cache_file():
+        os.remove(CACHE_FILE_PATH)
+        os.removedirs(os.path.dirname(CACHE_FILE_PATH))
+        logging.debug(f"Removed file {CACHE_FILE_PATH}")
+
+    def read_cache_file(self):
+        from json import loads
+        if os.path.exists(CACHE_FILE_PATH):
+            with open(CACHE_FILE_PATH, 'r', encoding='utf-8') as f:
+                content = f.read()
+            self.obj = loads(content)
+            self.nvidia_gpu_pci_bus = self.obj['nvidia_gpu_pci_bus']
+        elif self.is_hybrid():
+            self.nvidia_gpu_pci_bus = get_nvidia_gpu_pci_bus()
+        else:
+            raise ValueError(
+                'No cache present. Operation requires that the system be in the hybrid Optimus mode')
+
+    @staticmethod
+    def show_cache_file():
+        content = f'ERROR: Could not read {CACHE_FILE_PATH}'
+        if os.path.exists(CACHE_FILE_PATH):
+            with open(CACHE_FILE_PATH, 'r', encoding='utf-8') as f:
+                content = f.read()
+        print(content)
+
+    def write_cache_file(self):
+        from json import dump
+        os.makedirs(os.path.dirname(CACHE_FILE_PATH), exist_ok=True)
+
+        with open(CACHE_FILE_PATH, 'w', encoding='utf-8') as f:
+            dump(self.obj, fp=f, indent=4, sort_keys=False)
+
+        logging.debug(f"Created file {CACHE_FILE_PATH}")
+
+
+def get_current_mode():
+    mode = 'hybrid'
+    if os.path.exists(BLACKLIST_PATH) and os.path.exists(UDEV_INTEGRATED_PATH):
+        mode = 'integrated'
+    elif os.path.exists(XORG_PATH) and os.path.exists(MODESET_PATH):
+        mode = 'nvidia'
+    return mode
 
 
 if __name__ == '__main__':