changeset 40300:72b94f946e90

rust: rustlazyancestors.__contains__

This changeset provides a Rust implementation of
the iteration performed by lazyancestor.__contains__

It has the advantage over the Python iteration to use
the 'seen' set encapsuled into the dedicated iterator (self._containsiter),
rather than storing emitted items in another set (self._containsseen),
and hence should reduce the memory footprint.

Also, there's no need to convert intermediate emitted revisions back into
Python integers.

At this point, it would be tempting to implement the whole lazyancestor object
in Rust, but that would lead to more C wrapping code (two objects) for
little expected benefits.

--- a/mercurial/ancestor.py	Sun Oct 14 01:39:22 2018 -0400
+++ b/mercurial/ancestor.py	Mon Oct 08 19:11:41 2018 +0200
@@ -383,7 +383,7 @@
             self._containsiter = None
             return False
 
-class rustlazyancestors(lazyancestors):
+class rustlazyancestors(object):
 
     def __init__(self, index, revs, stoprev=0, inclusive=False):
         self._index = index
@@ -395,12 +395,26 @@
         # constructor (from C code) doesn't understand anything else yet
         self._initrevs = initrevs = list(revs)
 
-        self._containsseen = set()
         self._containsiter = parsers.rustlazyancestors(
             index, initrevs, stoprev, inclusive)
 
+    def __nonzero__(self):
+        """False if the set is empty, True otherwise.
+
+        It's better to duplicate this essentially trivial method than
+        to subclass lazyancestors
+        """
+        try:
+            next(iter(self))
+            return True
+        except StopIteration:
+            return False
+
     def __iter__(self):
         return parsers.rustlazyancestors(self._index,
                                          self._initrevs,
                                          self._stoprev,
                                          self._inclusive)
+
+    def __contains__(self, target):
+        return target in self._containsiter

--- a/mercurial/cext/revlog.c	Sun Oct 14 01:39:22 2018 -0400
+++ b/mercurial/cext/revlog.c	Mon Oct 08 19:11:41 2018 +0200
@@ -2316,6 +2316,7 @@
 	int inclusive);
 void rustlazyancestors_drop(rustlazyancestorsObject *self);
 int rustlazyancestors_next(rustlazyancestorsObject *self);
+int rustlazyancestors_contains(rustlazyancestorsObject *self, long rev);
 
 /* CPython instance methods */
 static int rustla_init(rustlazyancestorsObject *self,
@@ -2395,6 +2396,24 @@
 	return PyInt_FromLong(res);
 }
 
+static int rustla_contains(rustlazyancestorsObject *self, PyObject *rev) {
+	if (!(PyInt_Check(rev))) {
+		return 0;
+	}
+	return rustlazyancestors_contains(self->iter, PyInt_AS_LONG(rev));
+}
+
+static PySequenceMethods rustla_sequence_methods = {
+	0,                       /* sq_length */
+	0,                       /* sq_concat */
+	0,                       /* sq_repeat */
+	0,                       /* sq_item */
+	0,                       /* sq_slice */
+	0,                       /* sq_ass_item */
+	0,                       /* sq_ass_slice */
+	(objobjproc)rustla_contains, /* sq_contains */
+};
+
 static PyTypeObject rustlazyancestorsType = {
 	PyVarObject_HEAD_INIT(NULL, 0) /* header */
 	"parsers.rustlazyancestors",           /* tp_name */
@@ -2407,7 +2426,7 @@
 	0,                         /* tp_compare */
 	0,                         /* tp_repr */
 	0,                         /* tp_as_number */
-	0,                         /* tp_as_sequence */
+	&rustla_sequence_methods,  /* tp_as_sequence */
 	0,                         /* tp_as_mapping */
 	0,                         /* tp_hash */
 	0,                         /* tp_call */

--- a/rust/hg-core/src/ancestors.rs	Sun Oct 14 01:39:22 2018 -0400
+++ b/rust/hg-core/src/ancestors.rs	Mon Oct 08 19:11:41 2018 +0200
@@ -80,6 +80,26 @@
         self.conditionally_push_rev(parents.1);
         Ok(())
     }
+
+    /// Consumes partially the iterator to tell if the given target
+    /// revision
+    /// is in the ancestors it emits.
+    /// This is meant for iterators actually dedicated to that kind of
+    /// purpose
+    pub fn contains(&mut self, target: Revision) -> bool {
+        if self.seen.contains(&target) && target != NULL_REVISION {
+            return true;
+        }
+        for rev in self {
+            if rev == target {
+                return true;
+            }
+            if rev < target {
+                return false;
+            }
+        }
+        false
+    }
 }
 
 /// Main implementation.
@@ -203,6 +223,18 @@
         assert_eq!(iter.next(), None)
     }
 
+    #[test]
+    fn test_contains() {
+        let mut lazy =
+            AncestorsIterator::new(Stub, vec![10, 1], 0, true).unwrap();
+        assert!(lazy.contains(1));
+        assert!(!lazy.contains(3));
+
+        let mut lazy =
+            AncestorsIterator::new(Stub, vec![0], 0, false).unwrap();
+        assert!(!lazy.contains(NULL_REVISION));
+    }
+
     /// A corrupted Graph, supporting error handling tests
     struct Corrupted;
 

--- a/rust/hg-direct-ffi/src/ancestors.rs	Sun Oct 14 01:39:22 2018 -0400
+++ b/rust/hg-direct-ffi/src/ancestors.rs	Mon Oct 08 19:11:41 2018 +0200
@@ -139,6 +139,27 @@
     as_ref.next().unwrap_or(NULL_REVISION) as c_long
 }
 
+#[no_mangle]
+pub extern "C" fn rustlazyancestors_contains(
+    raw: *mut AncestorsIterator<Index>,
+    target: c_long,
+) -> c_int {
+    raw_contains(raw, target)
+}
+
+/// Testable (for any Graph) version of rustlazayancestors_next
+#[inline]
+fn raw_contains<G: Graph>(
+    raw: *mut AncestorsIterator<G>,
+    target: c_long,
+) -> c_int {
+    let as_ref = unsafe { &mut *raw };
+    if as_ref.contains(target as Revision) {
+        return 1;
+    }
+    0
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -226,4 +247,18 @@
     fn test_init_err_out_of_range() {
         assert!(stub_raw_init_from_vec(vec![25], 0, 0).is_null());
     }
+
+    #[test]
+    fn test_contains() {
+        let raw = stub_raw_init_from_vec(vec![5, 6], 0, 1);
+        assert_eq!(raw_contains(raw, 5), 1);
+        assert_eq!(raw_contains(raw, 2), 1);
+    }
+
+    #[test]
+    fn test_contains_exclusive() {
+        let raw = stub_raw_init_from_vec(vec![5, 6], 0, 0);
+        assert_eq!(raw_contains(raw, 5), 0);
+        assert_eq!(raw_contains(raw, 2), 1);
+    }
 }

--- a/rust/hg-direct-ffi/src/lib.rs	Sun Oct 14 01:39:22 2018 -0400
+++ b/rust/hg-direct-ffi/src/lib.rs	Mon Oct 08 19:11:41 2018 +0200
@@ -13,4 +13,7 @@
 extern crate libc;
 
 mod ancestors;
-pub use ancestors::{rustlazyancestors_drop, rustlazyancestors_init, rustlazyancestors_next};
+pub use ancestors::{
+    rustlazyancestors_contains, rustlazyancestors_drop,
+    rustlazyancestors_init, rustlazyancestors_next,
+};