Merge pull request #5021 from jkseppan/json-font-cache

mdboom · mdboom · commit fef412e9fd88 · 2015-10-06T13:32:41.000-04:00
Use json for the font cache instead of pickle
diff --git a/lib/matplotlib/font_manager.py b/lib/matplotlib/font_manager.py
@@ -23,7 +23,6 @@
                         unicode_literals)
 
 from matplotlib.externals import six
-from matplotlib.externals.six.moves import cPickle as pickle
 
 """
 KNOWN ISSUES
@@ -47,6 +46,7 @@
             see license/LICENSE_TTFQUERY.
 """
 
+import json
 import os, sys, warnings
 try:
     set
@@ -947,23 +947,43 @@ def ttfdict_to_fnames(d):
                             fnames.append(fname)
     return fnames
 
-def pickle_dump(data, filename):
-    """
-    Equivalent to pickle.dump(data, open(filename, 'w'))
-    but closes the file to prevent filehandle leakage.
-    """
-    with open(filename, 'wb') as fh:
-        pickle.dump(data, fh)
+class JSONEncoder(json.JSONEncoder):
+    def default(self, o):
+        if isinstance(o, FontManager):
+            return dict(o.__dict__, _class='FontManager')
+        elif isinstance(o, FontEntry):
+            return dict(o.__dict__, _class='FontEntry')
+        else:
+            return super(JSONEncoder, self).default(o)
+
+def _json_decode(o):
+    cls = o.pop('_class', None)
+    if cls is None:
+        return o
+    elif cls == 'FontManager':
+        r = FontManager.__new__(FontManager)
+        r.__dict__.update(o)
+        return r
+    elif cls == 'FontEntry':
+        r = FontEntry.__new__(FontEntry)
+        r.__dict__.update(o)
+        return r
+    else:
+        raise ValueError("don't know how to deserialize _class=%s" % cls)
 
-def pickle_load(filename):
-    """
-    Equivalent to pickle.load(open(filename, 'r'))
-    but closes the file to prevent filehandle leakage.
-    """
-    with open(filename, 'rb') as fh:
-        data = pickle.load(fh)
-    return data
+def json_dump(data, filename):
+    """Dumps a data structure as JSON in the named file.
+    Handles FontManager and its fields."""
+
+    with open(filename, 'w') as fh:
+        json.dump(data, fh, cls=JSONEncoder, indent=2)
 
+def json_load(filename):
+    """Loads a data structure as JSON from the named file.
+    Handles FontManager and its fields."""
+
+    with open(filename, 'r') as fh:
+        return json.load(fh, object_hook=_json_decode)
 
 class TempCache(object):
     """
@@ -1388,10 +1408,7 @@ def findfont(prop, fontext='ttf'):
     if not 'TRAVIS' in os.environ:
         cachedir = get_cachedir()
         if cachedir is not None:
-            if six.PY3:
-                _fmcache = os.path.join(cachedir, 'fontList.py3k.cache')
-            else:
-                _fmcache = os.path.join(cachedir, 'fontList.cache')
+            _fmcache = os.path.join(cachedir, 'fontList.json')
 
     fontManager = None
 
@@ -1404,12 +1421,12 @@ def _rebuild():
         global fontManager
         fontManager = FontManager()
         if _fmcache:
-            pickle_dump(fontManager, _fmcache)
+            json_dump(fontManager, _fmcache)
         verbose.report("generated new fontManager")
 
     if _fmcache:
         try:
-            fontManager = pickle_load(_fmcache)
+            fontManager = json_load(_fmcache)
             if (not hasattr(fontManager, '_version') or
                 fontManager._version != FontManager.__version__):
                 _rebuild()
diff --git a/lib/matplotlib/tests/test_font_manager.py b/lib/matplotlib/tests/test_font_manager.py
@@ -5,8 +5,11 @@
 from matplotlib.externals import six
 
 import os
+import tempfile
+import warnings
 
-from matplotlib.font_manager import findfont, FontProperties
+from matplotlib.font_manager import (
+    findfont, FontProperties, fontManager, json_dump, json_load)
 from matplotlib import rc_context
 
 
@@ -17,3 +20,17 @@ def test_font_priority():
         font = findfont(
             FontProperties(family=["sans-serif"]))
     assert_equal(os.path.basename(font), 'cmmi10.ttf')
+
+
+def test_json_serialization():
+    with tempfile.NamedTemporaryFile() as temp:
+        json_dump(fontManager, temp.name)
+        copy = json_load(temp.name)
+    with warnings.catch_warnings():
+        warnings.filterwarnings('ignore', 'findfont: Font family.*not found')
+        for prop in ({'family': 'STIXGeneral'},
+                     {'family': 'Bitstream Vera Sans', 'weight': 700},
+                     {'family': 'no such font family'}):
+            fp = FontProperties(**prop)
+            assert_equal(fontManager.findfont(fp, rebuild_if_missing=False),
+                         copy.findfont(fp, rebuild_if_missing=False))
