Default to use cached remote index and also take repo details from

environment variables. In support of #59.

Author: bnahill

cmdebug/svd_fetcher.py

@@ -25,12 +25,19 @@
 import json
 import os
 import dataclasses
+import time
+
+
+def _str_or_env(default: str, env_var: str) -> str:
+    env = os.getenv(env_var)
+    return default if env is None else env
+
 
 _REPO_OWNER = "cmsis-svd"
 _REPO_NAME = "cmsis-svd-data"
-_BRANCH = "main"
-_BASE_API_URL = f"https://api.github.com/repos/{_REPO_OWNER}/{_REPO_NAME}"
-_DEFAULT_CACHE_PATH = Path.home() / ".cache" / "cmsis-svd"
+_BRANCH = _str_or_env("main", "SVD_BRANCH")
+_BASE_API_URL = _str_or_env(f"https://api.github.com/repos/{_REPO_OWNER}/{_REPO_NAME}", "SVD_API_URL")
+_DEFAULT_CACHE_PATH = Path(_str_or_env(str(Path.home() / ".cache" / "cmsis-svd"), "SVD_CACHE_PATH"))
 
 _VERBOSE = True
 
@@ -68,6 +75,7 @@ def __init__(self, cache_dir: Optional[Path] = None):
             cache_dir = _DEFAULT_CACHE_PATH
         self.cache_dir = Path(cache_dir)
         self.cache_dir.mkdir(parents=True, exist_ok=True)
+        self.cache_file = self.cache_dir / "devices.json"
 
         self.session = requests.Session()
         # Add GitHub token if available via environment variable
@@ -76,20 +84,30 @@ def __init__(self, cache_dir: Optional[Path] = None):
             self.session.headers["Authorization"] = f"token {token}"
 
     def save(self, vendors: Dict[str, List[RemoteSVDFile]]):
-        cache_file = self.cache_dir / "devices.json"
-
         all_tuples = [(vendor, [c.as_dict() for c in chips]) for vendor, chips in vendors.items()]
         serializable_dict: Dict[str, List[Dict[str, str]]] = {}
         for (vendor, chips) in all_tuples:
             serializable_dict[vendor] = chips
 
-        open(str(cache_file), "w").write(json.dumps(serializable_dict))
+        open(str(self.cache_file), "w").write(json.dumps(serializable_dict))
 
-    def restore(self) -> Optional[Dict[str, List[RemoteSVDFile]]]:
-        cache_file = self.cache_dir / "devices.json"
+    def cache_age_seconds(self) -> Optional[int]:
+        """Get approximate time since cache file was modified
 
-        if cache_file.exists():
-            raw: Dict[str, List[Dict[str, str]]] = json.loads(open(str(cache_file)).read())
+        Returns:
+            Optional[int]: seconds since modification or None if nonexistent
+        """
+        if not self.cache_file.exists():
+            return None
+        mtime = os.path.getmtime(str(self.cache_file.absolute()))
+
+        return int(time.time() - mtime)
+
+
+    def restore(self) -> Optional[Dict[str, List[RemoteSVDFile]]]:
+        if self.cache_file.exists():
+            _log(f"Restoring cached index from {self.cache_file}")
+            raw: Dict[str, List[Dict[str, str]]] = json.loads(open(str(self.cache_file)).read())
             good_dict: Dict[str, List[RemoteSVDFile]] = dict()
             # Raw _should_ be dict of vendors with a list of chips under each
             for (vendor, chips_dicts) in raw.items():

cmdebug/svd_gdb.py

@@ -20,13 +20,13 @@
 import math
 import sys
 import struct
-
+import os
 
 from typing import Optional, Dict, List
 
-sys.path.append('.')
+sys.path.append(os.path.realpath(os.path.dirname(__file__) + "/.."))
 from cmdebug.svd import SVDFile
-from cmdebug import svd_fetcher
+from cmdebug.svd_fetcher import SVDFetcher, RemoteSVDFile
 
 BITS_TO_UNPACK_FORMAT = {
     8: "B",
@@ -82,12 +82,19 @@ class LoadSVDRemote(gdb.Command):
     """
 
     def __init__(self) -> None:
-        self.fetcher = svd_fetcher.SVDFetcher()
-        self.vendors: Optional[Dict[str, List[svd_fetcher.RemoteSVDFile]]] = None
+        self.fetcher = SVDFetcher()
+        self.vendors: Optional[Dict[str, List[RemoteSVDFile]]] = None
 
         gdb.Command.__init__(self, "svd_load_remote", gdb.COMMAND_USER)
 
     def try_to_get_vendors(self) -> bool:
+        MAX_DAYS = 1
+        if self.vendors == None:
+            # First, check if we have a fresh-enough cache file
+            cache_age = self.fetcher.cache_age_seconds()
+            if cache_age is not None and cache_age < (MAX_DAYS * 24 * 60 * 60):
+                self.vendors = self.fetcher.restore()
+
         if self.vendors == None:
             try:
                 # Get the vendors and cache them