Test 2

SConstruct

@@ -1124,3 +1124,5 @@ def purge_flaky_files():
 
 
 atexit.register(purge_flaky_files)
+
+methods.clean_cache(env)

methods.py

@@ -892,7 +892,6 @@ def show_progress(env):
         # Has its own progress/tracking tool that clashes with ours
         return
 
-    import atexit
     import sys
 
     from SCons.Script import AlwaysBuild, Command, Progress
@@ -921,7 +920,6 @@ def __init__(self, path=None, limit=1073741824, half_life=43200):
                         self.convert_size(limit), self.convert_size(self.get_size(path))
                     )
                 )
-            # self.delete(self.file_list())
 
         def __call__(self, node, *args, **kw):
             nonlocal node_count, node_count_max, node_count_interval, node_count_fname, show_progress
@@ -946,7 +944,7 @@ def delete(self, files):
                 screen.write("\rPurging %d %s from cache...\n" % (len(files), len(files) > 1 and "files" or "file"))
             [os.remove(f) for f in files]
 
-        def file_list(self, limit_mult=1.0):
+        def file_list(self):
             if self.path is None:
                 # Nothing to do
                 return []
@@ -969,7 +967,7 @@ def file_list(self, limit_mult=1.0):
             sum, mark = 0, None
             for i, x in enumerate(file_stat):
                 sum += x[1]
-                if sum > self.limit * limit_mult:
+                if sum > self.limit:
                     mark = i
                     break
             if mark is None:
@@ -999,7 +997,6 @@ def progress_finish(target, source, env):
         try:
             with open(node_count_fname, "w", encoding="utf-8", newline="\n") as f:
                 f.write("%d\n" % node_count)
-            progressor.delete(progressor.file_list(1.1))
         except Exception:
             pass
 
@@ -1019,13 +1016,72 @@ def progress_finish(target, source, env):
     progress_finish_command = Command("progress_finish", [], progress_finish)
     AlwaysBuild(progress_finish_command)
 
+
+def clean_cache(env):
+    import atexit
+    import time
+
+    class cache_clean:
+        def __init__(self, path=None, limit=1073741824):
+            self.path = path
+            self.limit = limit
+
+        def clean(self):
+            self.delete(self.file_list())
+
+        def delete(self, files):
+            if len(files) == 0:
+                return
+            if env["verbose"]:
+                # Utter something
+                print("Purging %d %s from cache..." % (len(files), len(files) > 1 and "files" or "file"))
+            [os.remove(f) for f in files]
+
+        def file_list(self):
+            if self.path is None:
+                # Nothing to do
+                return []
+            # Gather a list of (filename, (size, atime)) within the
+            # cache directory
+            file_stat = [(x, os.stat(x)[6:8]) for x in glob.glob(os.path.join(self.path, "*", "*"))]
+            if file_stat == []:
+                # Nothing to do
+                return []
+            # Weight the cache files by size (assumed to be roughly
+            # proportional to the recompilation time) times an exponential
+            # decay since the ctime, and return a list with the entries
+            # (filename, size, weight).
+            current_time = time.time()
+            file_stat = [(x[0], x[1][0], (current_time - x[1][1])) for x in file_stat]
+            # Sort by the most recently accessed files (most sensible to keep) first
+            file_stat.sort(key=lambda x: x[2])
+            # Search for the first entry where the storage limit is
+            # reached
+            sum, mark = 0, None
+            for i, x in enumerate(file_stat):
+                sum += x[1]
+                if sum > self.limit:
+                    mark = i
+                    break
+            if mark is None:
+                return []
+            else:
+                return [x[0] for x in file_stat[mark:]]
+
     def progress_finally():
-        nonlocal node_count, progressor
+        nonlocal cleaner
         try:
-            progressor.delete(progressor.file_list())
+            cleaner.clean()
+            print("Final")
         except Exception:
             pass
 
+    cache_directory = os.environ.get("SCONS_CACHE")
+    # Simple cache pruning, attached to SCons' progress callback. Trim the
+    # cache directory to a size not larger than cache_limit.
+    cache_limit = float(os.getenv("SCONS_CACHE_LIMIT", 1024)) * 1024 * 1024
+    cleaner = cache_clean(cache_directory, cache_limit)
+
     atexit.register(progress_finally)