Patchwork [6,of,8] revlog: use the native implementation of issnapshot

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Submitter Boris Feld
Date Dec. 17, 2018, noon
Message ID <5e538853cc3267f20274.1545048048@localhost.localdomain>
Download mbox | patch
Permalink /patch/37222/
State Accepted
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Boris Feld - Dec. 17, 2018, noon
# HG changeset patch
# User Boris Feld <boris.feld@octobus.net>
# Date 1545040919 -3600
#      Mon Dec 17 11:01:59 2018 +0100
# Node ID 5e538853cc3267f20274e8eb032d40793f4a8b44
# Parent  72f9ed348875eaa260f4536885c3120ae536f373
# EXP-Topic sparse-revlog-corner-cases
# Available At https://bitbucket.org/octobus/mercurial-devel/
#              hg pull https://bitbucket.org/octobus/mercurial-devel/ -r 5e538853cc32
revlog: use the native implementation of issnapshot

In some sparserevlog case where a lot of the history has to be searched for a
snapshot, the cost of issnashot cost becomes significant. The computation done
by the method is fairly low level, a native implementation provide a very
significant speedup.

example affected manifest write
before: 0.490375s
after:  0.114989s (-76%)

Patch

diff --git a/mercurial/cext/revlog.c b/mercurial/cext/revlog.c
--- a/mercurial/cext/revlog.c
+++ b/mercurial/cext/revlog.c
@@ -1014,6 +1014,21 @@  static int index_issnapshotrev(indexObje
 	return index_issnapshotrev(self, base);
 }
 
+static PyObject *index_issnapshot(indexObject *self, PyObject *value)
+{
+	long rev;
+	int issnap;
+
+	if (!pylong_to_long(value, &rev)) {
+		return NULL;
+	}
+	issnap = index_issnapshotrev(self, (Py_ssize_t)rev);
+	if (issnap < 0) {
+		return NULL;
+	};
+	return PyBool_FromLong((long)issnap);
+}
+
 static PyObject *index_deltachain(indexObject *self, PyObject *args)
 {
 	int rev, generaldelta;
@@ -2626,6 +2641,8 @@  static PyMethodDef index_methods[] = {
      "get head revisions"}, /* Can do filtering since 3.2 */
     {"headrevsfiltered", (PyCFunction)index_headrevs, METH_VARARGS,
      "get filtered head revisions"}, /* Can always do filtering */
+    {"issnapshot", (PyCFunction)index_issnapshot, METH_O,
+     "True if the object is a snapshot"},
     {"deltachain", (PyCFunction)index_deltachain, METH_VARARGS,
      "determine revisions with deltas to reconstruct fulltext"},
     {"slicechunktodensity", (PyCFunction)index_slicechunktodensity,
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1533,6 +1533,12 @@  class revlog(object):
     def issnapshot(self, rev):
         """tells whether rev is a snapshot
         """
+        if not self._generaldelta:
+            return self.deltaparent(rev) == nullrev
+        elif util.safehasattr(self.index, 'issnapshot'):
+            # directly assign the method to cache the testing and access
+            self.issnapshot = self.index.issnapshot
+            return self.issnapshot(rev)
         if rev == nullrev:
             return True
         entry = self.index[rev]