Move "hull" pointer to lineage

algorithms.py

@@ -124,10 +124,9 @@ def __init__(self, index):
         self.node = None
         self.prev = None
         self.next = None
+        self.index = index
         self.population = None
         self.label = 0
-        self.index = index
-        self.hull = None
         self.lineage = None
 
     def __repr__(self):
@@ -154,7 +153,7 @@ def get_hull(self):
         assert seg is not None
         while seg.prev is not None:
             seg = seg.prev
-        hull = seg.hull
+        hull = seg.lineage.hull
         return hull
 
     def get_left_index(self):
@@ -166,11 +165,6 @@ def get_left_index(self):
         return index
 
 
-@dataclasses.dataclass
-class Lineage:
-    head: Segment
-
-
 class Population:
     """
     Class representing a population in the simulation.
@@ -729,6 +723,12 @@ def __repr__(self):
         return f"x:{self.x}, io:{self.insertion_order}"
 
 
+@dataclasses.dataclass
+class Lineage:
+    head: Segment
+    hull: Hull = None
+
+
 class OrderStatisticsTree:
     """
     Bintrees AVL tree with added functionality to keep track of the rank
@@ -1054,15 +1054,11 @@ def change_migration_matrix_element(self, pop_i, pop_j, rate):
         self.migration_matrix[pop_i][pop_j] = rate
 
     def alloc_hull(self, left, right, lineage):
-        alpha = lineage.head
         hull = self.hull_stack.pop()
         hull.left = left
         hull.right = right
-        while alpha.prev is not None:
-            alpha = alpha.prev
-        assert alpha is not None
         hull.lineage = lineage
-        alpha.hull = hull
+        lineage.hull = hull
         return hull
 
     def alloc_segment(
@@ -1688,7 +1684,7 @@ def migration_event(self, j, k):
         index = random.randint(0, source.get_num_ancestors(label) - 1)
         lineage = source.remove(index, label)
         x = lineage.head
-        hull = x.get_hull()
+        hull = lineage.hull
         assert (self.model == "smc_k") == (hull is not None)
         dest.add(lineage, label)
         if self.model == "smc_k":

lib/msprime.c

@@ -200,7 +200,7 @@ segment_get_hull(segment_t *seg)
         seg = seg->prev;
     }
     tsk_bug_assert(seg->lineage != NULL);
-    hull = seg->hull;
+    hull = seg->lineage->hull;
     tsk_bug_assert(hull->lineage == seg->lineage);
 
     return hull;
@@ -839,7 +839,7 @@ msp_set_hull_block_size(msp_t *self, size_t block_size)
 static segment_t *MSP_WARN_UNUSED
 msp_alloc_segment(msp_t *self, double left, double right, tsk_id_t value,
     population_id_t population, label_id_t label, segment_t *prev, segment_t *next,
-    hull_t *hull)
+    hull_t *MSP_UNUSED(hull))
 {
     segment_t *seg = NULL;
 
@@ -878,7 +878,6 @@ msp_alloc_segment(msp_t *self, double left, double right, tsk_id_t value,
     seg->value = value;
     seg->population = population;
     seg->label = label;
-    seg->hull = hull;
 out:
     return seg;
 }
@@ -907,7 +906,7 @@ static segment_t *MSP_WARN_UNUSED
 msp_copy_segment(msp_t *self, const segment_t *seg)
 {
     return msp_alloc_segment(self, seg->left, seg->right, seg->value, seg->population,
-        seg->label, seg->prev, seg->next, seg->hull);
+        seg->label, seg->prev, seg->next, NULL);
 }
 
 static hull_t *MSP_WARN_UNUSED
@@ -950,7 +949,7 @@ msp_alloc_hull(msp_t *self, double left, double right, lineage_t *lineage)
     hull->count = 0;
     hull->insertion_order = UINT64_MAX;
     tsk_bug_assert(lineage->head->prev == NULL);
-    lineage->head->hull = hull;
+    lineage->hull = hull;
 out:
     return hull;
 }
@@ -1949,7 +1948,7 @@ msp_verify_hulls(msp_t *self)
             for (a = avl->head; a->next != NULL; a = a->next) {
                 lin = (lineage_t *) a->item;
                 x = lin->head;
-                hull_right = x->hull->right;
+                hull_right = lin->hull->right;
                 hull_a.left = x->left;
                 while (x->next != NULL) {
                     x = x->next;

lib/msprime.h

@@ -84,12 +84,12 @@ typedef struct segment_t_t {
     size_t id;
     struct segment_t_t *prev;
     struct segment_t_t *next;
-    struct hull_t_t *hull;
     struct lineage_t_t *lineage;
 } segment_t;
 
 typedef struct lineage_t_t {
     segment_t *head;
+    struct hull_t_t *hull;
 } lineage_t;
 
 typedef struct {