1 files changed, 288 insertions, 0 deletions
diff --git a/src/core/lib/support/avl.c b/src/core/lib/support/avl.c
new file mode 100644
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+++ b/src/core/lib/support/avl.c
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+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <grpc/support/avl.h>
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+
+gpr_avl gpr_avl_create(const gpr_avl_vtable *vtable) {
+  gpr_avl out;
+  out.vtable = vtable;
+  out.root = NULL;
+  return out;
+}
+
+static gpr_avl_node *ref_node(gpr_avl_node *node) {
+  if (node) {
+    gpr_ref(&node->refs);
+  }
+  return node;
+}
+
+static void unref_node(const gpr_avl_vtable *vtable, gpr_avl_node *node) {
+  if (node == NULL) {
+    return;
+  }
+  if (gpr_unref(&node->refs)) {
+    vtable->destroy_key(node->key);
+    vtable->destroy_value(node->value);
+    unref_node(vtable, node->left);
+    unref_node(vtable, node->right);
+    gpr_free(node);
+  }
+}
+
+static long node_height(gpr_avl_node *node) {
+  return node == NULL ? 0 : node->height;
+}
+
+#ifndef NDEBUG
+static long calculate_height(gpr_avl_node *node) {
+  return node == NULL ? 0 : 1 + GPR_MAX(calculate_height(node->left),
+                                        calculate_height(node->right));
+}
+
+static gpr_avl_node *assert_invariants(gpr_avl_node *n) {
+  if (n == NULL) return NULL;
+  assert_invariants(n->left);
+  assert_invariants(n->right);
+  assert(calculate_height(n) == n->height);
+  assert(labs(node_height(n->left) - node_height(n->right)) <= 1);
+  return n;
+}
+#else
+static gpr_avl_node *assert_invariants(gpr_avl_node *n) { return n; }
+#endif
+
+gpr_avl_node *new_node(void *key, void *value, gpr_avl_node *left,
+                       gpr_avl_node *right) {
+  gpr_avl_node *node = gpr_malloc(sizeof(*node));
+  gpr_ref_init(&node->refs, 1);
+  node->key = key;
+  node->value = value;
+  node->left = assert_invariants(left);
+  node->right = assert_invariants(right);
+  node->height = 1 + GPR_MAX(node_height(left), node_height(right));
+  return node;
+}
+
+static gpr_avl_node *get(const gpr_avl_vtable *vtable, gpr_avl_node *node,
+                         void *key) {
+  long cmp;
+
+  if (node == NULL) {
+    return NULL;
+  }
+
+  cmp = vtable->compare_keys(node->key, key);
+  if (cmp == 0) {
+    return node;
+  } else if (cmp > 0) {
+    return get(vtable, node->left, key);
+  } else {
+    return get(vtable, node->right, key);
+  }
+}
+
+void *gpr_avl_get(gpr_avl avl, void *key) {
+  gpr_avl_node *node = get(avl.vtable, avl.root, key);
+  return node ? node->value : NULL;
+}
+
+static gpr_avl_node *rotate_left(const gpr_avl_vtable *vtable, void *key,
+                                 void *value, gpr_avl_node *left,
+                                 gpr_avl_node *right) {
+  gpr_avl_node *n =
+      new_node(vtable->copy_key(right->key), vtable->copy_value(right->value),
+               new_node(key, value, left, ref_node(right->left)),
+               ref_node(right->right));
+  unref_node(vtable, right);
+  return n;
+}
+
+static gpr_avl_node *rotate_right(const gpr_avl_vtable *vtable, void *key,
+                                  void *value, gpr_avl_node *left,
+                                  gpr_avl_node *right) {
+  gpr_avl_node *n = new_node(
+      vtable->copy_key(left->key), vtable->copy_value(left->value),
+      ref_node(left->left), new_node(key, value, ref_node(left->right), right));
+  unref_node(vtable, left);
+  return n;
+}
+
+static gpr_avl_node *rotate_left_right(const gpr_avl_vtable *vtable, void *key,
+                                       void *value, gpr_avl_node *left,
+                                       gpr_avl_node *right) {
+  /* rotate_right(..., rotate_left(left), right) */
+  gpr_avl_node *n = new_node(
+      vtable->copy_key(left->right->key),
+      vtable->copy_value(left->right->value),
+      new_node(vtable->copy_key(left->key), vtable->copy_value(left->value),
+               ref_node(left->left), ref_node(left->right->left)),
+      new_node(key, value, ref_node(left->right->right), right));
+  unref_node(vtable, left);
+  return n;
+}
+
+static gpr_avl_node *rotate_right_left(const gpr_avl_vtable *vtable, void *key,
+                                       void *value, gpr_avl_node *left,
+                                       gpr_avl_node *right) {
+  /* rotate_left(..., left, rotate_right(right)) */
+  gpr_avl_node *n = new_node(
+      vtable->copy_key(right->left->key),
+      vtable->copy_value(right->left->value),
+      new_node(key, value, left, ref_node(right->left->left)),
+      new_node(vtable->copy_key(right->key), vtable->copy_value(right->value),
+               ref_node(right->left->right), ref_node(right->right)));
+  unref_node(vtable, right);
+  return n;
+}
+
+static gpr_avl_node *rebalance(const gpr_avl_vtable *vtable, void *key,
+                               void *value, gpr_avl_node *left,
+                               gpr_avl_node *right) {
+  switch (node_height(left) - node_height(right)) {
+    case 2:
+      if (node_height(left->left) - node_height(left->right) == -1) {
+        return assert_invariants(
+            rotate_left_right(vtable, key, value, left, right));
+      } else {
+        return assert_invariants(rotate_right(vtable, key, value, left, right));
+      }
+    case -2:
+      if (node_height(right->left) - node_height(right->right) == 1) {
+        return assert_invariants(
+            rotate_right_left(vtable, key, value, left, right));
+      } else {
+        return assert_invariants(rotate_left(vtable, key, value, left, right));
+      }
+    default:
+      return assert_invariants(new_node(key, value, left, right));
+  }
+}
+
+static gpr_avl_node *add(const gpr_avl_vtable *vtable, gpr_avl_node *node,
+                         void *key, void *value) {
+  long cmp;
+  if (node == NULL) {
+    return new_node(key, value, NULL, NULL);
+  }
+  cmp = vtable->compare_keys(node->key, key);
+  if (cmp == 0) {
+    return new_node(key, value, ref_node(node->left), ref_node(node->right));
+  } else if (cmp > 0) {
+    return rebalance(
+        vtable, vtable->copy_key(node->key), vtable->copy_value(node->value),
+        add(vtable, node->left, key, value), ref_node(node->right));
+  } else {
+    return rebalance(vtable, vtable->copy_key(node->key),
+                     vtable->copy_value(node->value), ref_node(node->left),
+                     add(vtable, node->right, key, value));
+  }
+}
+
+gpr_avl gpr_avl_add(gpr_avl avl, void *key, void *value) {
+  gpr_avl_node *old_root = avl.root;
+  avl.root = add(avl.vtable, avl.root, key, value);
+  assert_invariants(avl.root);
+  unref_node(avl.vtable, old_root);
+  return avl;
+}
+
+static gpr_avl_node *in_order_head(gpr_avl_node *node) {
+  while (node->left != NULL) {
+    node = node->left;
+  }
+  return node;
+}
+
+static gpr_avl_node *in_order_tail(gpr_avl_node *node) {
+  while (node->right != NULL) {
+    node = node->right;
+  }
+  return node;
+}
+
+static gpr_avl_node *remove(const gpr_avl_vtable *vtable, gpr_avl_node *node,
+                            void *key) {
+  long cmp;
+  if (node == NULL) {
+    return NULL;
+  }
+  cmp = vtable->compare_keys(node->key, key);
+  if (cmp == 0) {
+    if (node->left == NULL) {
+      return ref_node(node->right);
+    } else if (node->right == NULL) {
+      return ref_node(node->left);
+    } else if (node->left->height < node->right->height) {
+      gpr_avl_node *h = in_order_head(node->right);
+      return rebalance(vtable, vtable->copy_key(h->key),
+                       vtable->copy_value(h->value), ref_node(node->left),
+                       remove(vtable, node->right, h->key));
+    } else {
+      gpr_avl_node *h = in_order_tail(node->left);
+      return rebalance(
+          vtable, vtable->copy_key(h->key), vtable->copy_value(h->value),
+          remove(vtable, node->left, h->key), ref_node(node->right));
+    }
+  } else if (cmp > 0) {
+    return rebalance(vtable, vtable->copy_key(node->key),
+                     vtable->copy_value(node->value),
+                     remove(vtable, node->left, key), ref_node(node->right));
+  } else {
+    return rebalance(vtable, vtable->copy_key(node->key),
+                     vtable->copy_value(node->value), ref_node(node->left),
+                     remove(vtable, node->right, key));
+  }
+}
+
+gpr_avl gpr_avl_remove(gpr_avl avl, void *key) {
+  gpr_avl_node *old_root = avl.root;
+  avl.root = remove(avl.vtable, avl.root, key);
+  assert_invariants(avl.root);
+  unref_node(avl.vtable, old_root);
+  return avl;
+}
+
+gpr_avl gpr_avl_ref(gpr_avl avl) {
+  ref_node(avl.root);
+  return avl;
+}
+
+void gpr_avl_unref(gpr_avl avl) { unref_node(avl.vtable, avl.root); }