1 files changed, 123 insertions, 0 deletions
diff --git a/methods.py b/methods.py
index 89a229e4ab..c2dd670e9c 100644
--- a/methods.py
+++ b/methods.py
@@ -630,3 +630,126 @@ def using_gcc(env):
 
 def using_clang(env):
     return "clang" in os.path.basename(env["CC"])
+
+
+def show_progress(env):
+    import sys
+    from SCons.Script import Progress, Command, AlwaysBuild
+
+    screen = sys.stdout
+    # Progress reporting is not available in non-TTY environments since it
+    # messes with the output (for example, when writing to a file)
+    show_progress = env["progress"] and sys.stdout.isatty()
+    node_count = 0
+    node_count_max = 0
+    node_count_interval = 1
+    node_count_fname = str(env.Dir("#")) + "/.scons_node_count"
+
+    import time, math
+
+    class cache_progress:
+        # The default is 1 GB cache and 12 hours half life
+        def __init__(self, path=None, limit=1073741824, half_life=43200):
+            self.path = path
+            self.limit = limit
+            self.exponent_scale = math.log(2) / half_life
+            if env["verbose"] and path != None:
+                screen.write(
+                    "Current cache limit is {} (used: {})\n".format(
+                        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
+            if show_progress:
+                # Print the progress percentage
+                node_count += node_count_interval
+                if node_count_max > 0 and node_count <= node_count_max:
+                    screen.write("\r[%3d%%] " % (node_count * 100 / node_count_max))
+                    screen.flush()
+                elif node_count_max > 0 and node_count > node_count_max:
+                    screen.write("\r[100%] ")
+                    screen.flush()
+                else:
+                    screen.write("\r[Initial build] ")
+                    screen.flush()
+
+        def delete(self, files):
+            if len(files) == 0:
+                return
+            if env["verbose"]:
+                # Utter something
+                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):
+            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 convert_size(self, size_bytes):
+            if size_bytes == 0:
+                return "0 bytes"
+            size_name = ("bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB")
+            i = int(math.floor(math.log(size_bytes, 1024)))
+            p = math.pow(1024, i)
+            s = round(size_bytes / p, 2)
+            return "%s %s" % (int(s) if i == 0 else s, size_name[i])
+
+        def get_size(self, start_path="."):
+            total_size = 0
+            for dirpath, dirnames, filenames in os.walk(start_path):
+                for f in filenames:
+                    fp = os.path.join(dirpath, f)
+                    total_size += os.path.getsize(fp)
+            return total_size
+
+    def progress_finish(target, source, env):
+        nonlocal node_count, progressor
+        with open(node_count_fname, "w") as f:
+            f.write("%d\n" % node_count)
+        progressor.delete(progressor.file_list())
+
+    try:
+        with open(node_count_fname) as f:
+            node_count_max = int(f.readline())
+    except:
+        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
+    progressor = cache_progress(cache_directory, cache_limit)
+    Progress(progressor, interval=node_count_interval)
+
+    progress_finish_command = Command("progress_finish", [], progress_finish)
+    AlwaysBuild(progress_finish_command)