convert: parse perforce data on-demand

We are using read-only attributes that parse the perforce data on
demand. We are reading the data only once whenever an attribute is
requested and use it throughout the import process. This is equivalent
to the previous behavior, but we are avoiding reading from perforce when
we initialize the object, but instead run it during the actual import
process, when the first attribute is requested (usually getheads(), see
`convertcmd.convert`).

hgext/convert/p4.py

@@ -56,13 +56,8 b' class p4_source(common.converter_source)'
         common.checktool('p4', abort=False)
 
         self.revmap = {}
-        self.heads = []
-        self.changeset = {}
-        self.files = {}
-        self.copies = {}
         self.encoding = self.ui.config('convert', 'p4.encoding',
                                        default=convcmd.orig_encoding)
-        self.depotname = {}           # mapping from local name to depot name
         self.re_type = re.compile(
             "([a-z]+)?(text|binary|symlink|apple|resource|unicode|utf\d+)"
             "(\+\w+)?$")
@@ -74,7 +69,6 b' class p4_source(common.converter_source)'
         if revs and len(revs) > 1:
             raise error.Abort(_("p4 source does not support specifying "
                                "multiple revisions"))
-        self._parse_once(ui, path)
 
     def setrevmap(self, revmap):
         """Sets the parsed revmap dictionary.
@@ -240,13 +234,29 b' class p4_source(common.converter_source)'
             'depotname': depotname,
         }
 
-    def _parse_once(self, ui, path):
-        d = self._parse(ui, path)
-        self.changeset = d['changeset']
-        self.heads = d['heads']
-        self.files = d['files']
-        self.copies = d['copies']
-        self.depotname = d['depotname']
+    @util.propertycache
+    def _parse_once(self):
+        return self._parse(self.ui, self.path)
+
+    @util.propertycache
+    def copies(self):
+        return self._parse_once['copies']
+
+    @util.propertycache
+    def files(self):
+        return self._parse_once['files']
+
+    @util.propertycache
+    def changeset(self):
+        return self._parse_once['changeset']
+
+    @util.propertycache
+    def heads(self):
+        return self._parse_once['heads']
+
+    @util.propertycache
+    def depotname(self):
+        return self._parse_once['depotname']
 
     def getheads(self):
         return self.heads

tests/test-convert-p4-filetypes.t

@@ -307,11 +307,11 b' check keywords in p4'
 convert
   $ hg convert -s p4 $DEPOTPATH dst
   initializing destination dst repository
+  scanning source...
   reading p4 views
   collecting p4 changelists
   1 initial
   2 keywords
-  scanning source...
   sorting...
   converting...
   1 initial

tests/test-convert-p4.t

@@ -67,12 +67,12 b' change some files'
 convert
   $ hg convert -s p4 $DEPOTPATH dst
   initializing destination dst repository
+  scanning source...
   reading p4 views
   collecting p4 changelists
   1 initial
   2 change a
   3 change b/c
-  scanning source...
   sorting...
   converting...
   2 initial
@@ -98,13 +98,10 b' change some files'
 
 convert again
   $ hg convert -s p4 $DEPOTPATH dst
+  scanning source...
   reading p4 views
   collecting p4 changelists
-  1 initial
-  2 change a
-  3 change b/c
   4 change a b/c
-  scanning source...
   sorting...
   converting...
   0 change a b/c
@@ -130,14 +127,10 b' interesting names'
 
 convert again
   $ hg convert -s p4 $DEPOTPATH dst
+  scanning source...
   reading p4 views
   collecting p4 changelists
-  1 initial
-  2 change a
-  3 change b/c
-  4 change a b/c
   5 add d e f
-  scanning source...
   sorting...
   converting...
   0 add d e f