From 7713dd4063ed446173fd928c37a9d28bd70f8d0b Mon Sep 17 00:00:00 2001
From: Gregory Becker <becker33@llnl.gov>
Date: Thu, 3 Jun 2021 13:50:22 -0700
Subject: [PATCH] keep 5 views around by default

---
 lib/spack/spack/environment.py | 38 +++++++++++++++++++++++++++-------
 lib/spack/spack/schema/env.py  |  4 ++++
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/lib/spack/spack/environment.py b/lib/spack/spack/environment.py
index c41d567bce1..8df066d5713 100644
--- a/lib/spack/spack/environment.py
+++ b/lib/spack/spack/environment.py
@@ -453,15 +453,19 @@ def _eval_conditional(string):
     return eval(string, valid_variables)
 
 
+_default_keep = 5
+
+
 class ViewDescriptor(object):
     def __init__(self, base_path, root, projections={}, select=[], exclude=[],
-                 link=default_view_link):
+                 link=default_view_link, keep=_default_keep):
         self.base = base_path
         self.root = spack.util.path.canonicalize_path(root)
         self.projections = projections
         self.select = select
         self.exclude = exclude
         self.link = link
+        self.keep = keep
 
     def select_fn(self, spec):
         return any(spec.satisfies(s) for s in self.select)
@@ -474,7 +478,8 @@ def __eq__(self, other):
                     self.projections == other.projections,
                     self.select == other.select,
                     self.exclude == other.exclude,
-                    self.link == other.link])
+                    self.link == other.link,
+                    self.keep == other.keep])
 
     def to_dict(self):
         ret = syaml.syaml_dict([('root', self.root)])
@@ -491,6 +496,8 @@ def to_dict(self):
             ret['exclude'] = self.exclude
         if self.link != default_view_link:
             ret['link'] = self.link
+        if self.keep != _default_keep:
+            ret['keep'] = self.keep
         return ret
 
     @staticmethod
@@ -500,7 +507,8 @@ def from_dict(base_path, d):
                               d.get('projections', {}),
                               d.get('select', []),
                               d.get('exclude', []),
-                              d.get('link', default_view_link))
+                              d.get('link', default_view_link),
+                              d.get('keep', _default_keep))
 
     @property
     def _current_root(self):
@@ -636,7 +644,7 @@ def regenerate(self, all_specs, roots):
                            with_dependencies=False)
 
             # create symlink from tmpname to new_root
-            root_dirname = os.path.dirname(self.root)
+            root_dirname, root_basename = os.path.split(self.root)
             tmp_symlink_name = os.path.join(root_dirname, '._view_link')
             if os.path.exists(tmp_symlink_name):
                 os.unlink(tmp_symlink_name)
@@ -649,12 +657,26 @@ def regenerate(self, all_specs, roots):
                 raise SpackEnvironmentViewError(msg)
             os.rename(tmp_symlink_name, self.root)
 
-            # remove old_root
-            if old_root and os.path.exists(old_root):
+            # If we have more than the number of views to keep in the directory
+            # delete the oldest until the correct number remain. Do not count
+            # things that aren't named as a root would be.
+            root_impl_dir = os.path.join(root_dirname, '._%s' % root_basename)
+            roots = [os.path.join(root_impl_dir, entry)
+                     for entry in os.listdir(root_impl_dir)
+                     if re.match(r'[a-z0-9]{32}', entry)]
+
+            num_to_remove = len(roots) - self.keep
+            if num_to_remove <= 0:
+                return
+
+            # sorting by st_mtime means the oldest come first
+            oldest_roots = sorted(roots, key=lambda path: os.stat(path).st_mtime)
+            for root_to_delete in oldest_roots[:num_to_remove]:
+                # remove old_root
                 try:
-                    shutil.rmtree(old_root)
+                    shutil.rmtree(root_to_delete)
                 except (IOError, OSError) as e:
-                    msg = "Failed to remove old view at %s\n" % old_root
+                    msg = "Failed to remove old view at %s\n" % root_to_delete
                     msg += str(e)
                     tty.warn(msg)
 
diff --git a/lib/spack/spack/schema/env.py b/lib/spack/spack/schema/env.py
index 82971505e47..88b9bda4ae4 100644
--- a/lib/spack/spack/schema/env.py
+++ b/lib/spack/spack/schema/env.py
@@ -126,6 +126,10 @@
                                                 'type': 'string',
                                                 'pattern': '(roots|all)',
                                             },
+                                            'keep': {
+                                                'type': 'integer',
+                                                'minimum': 1,
+                                            },
                                             'select': {
                                                 'type': 'array',
                                                 'items': {