1 files changed, 303 insertions, 0 deletions
diff --git a/src/core/ext/census/hash_table.c b/src/core/ext/census/hash_table.c
new file mode 100644
index 0000000000..ee6fdfc6e8
--- /dev/null
+++ b/src/core/ext/census/hash_table.c
@@ -0,0 +1,303 @@
+/*
+ *
+ * Copyright 2015, 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 "src/core/ext/census/hash_table.h"
+
+#include <stddef.h>
+#include <stdio.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/port_platform.h>
+
+#define CENSUS_HT_NUM_BUCKETS 1999
+
+/* A single hash table data entry */
+typedef struct ht_entry {
+  census_ht_key key;
+  void *data;
+  struct ht_entry *next;
+} ht_entry;
+
+/* hash table bucket */
+typedef struct bucket {
+  /* NULL if bucket is empty */
+  ht_entry *next;
+  /* -1 if all buckets are empty. */
+  int32_t prev_non_empty_bucket;
+  /* -1 if all buckets are empty. */
+  int32_t next_non_empty_bucket;
+} bucket;
+
+struct unresizable_hash_table {
+  /* Number of entries in the table */
+  size_t size;
+  /* Number of buckets */
+  uint32_t num_buckets;
+  /* Array of buckets initialized at creation time. Memory consumption is
+     16 bytes per bucket on a 64-bit platform. */
+  bucket *buckets;
+  /* Index of the first non-empty bucket. -1 iff size == 0. */
+  int32_t first_non_empty_bucket;
+  /* Index of the last non_empty bucket. -1 iff size == 0. */
+  int32_t last_non_empty_bucket;
+  /* Immutable options of this hash table, initialized at creation time. */
+  census_ht_option options;
+};
+
+typedef struct entry_locator {
+  int32_t bucket_idx;
+  int is_first_in_chain;
+  int found;
+  ht_entry *prev_entry;
+} entry_locator;
+
+/* Asserts if option is not valid. */
+void check_options(const census_ht_option *option) {
+  GPR_ASSERT(option != NULL);
+  GPR_ASSERT(option->num_buckets > 0);
+  GPR_ASSERT(option->key_type == CENSUS_HT_UINT64 ||
+             option->key_type == CENSUS_HT_POINTER);
+  if (option->key_type == CENSUS_HT_UINT64) {
+    GPR_ASSERT(option->hash == NULL);
+  } else if (option->key_type == CENSUS_HT_POINTER) {
+    GPR_ASSERT(option->hash != NULL);
+    GPR_ASSERT(option->compare_keys != NULL);
+  }
+}
+
+#define REMOVE_NEXT(options, ptr) \
+  do {                            \
+    ht_entry *tmp = (ptr)->next;  \
+    (ptr)->next = tmp->next;      \
+    delete_entry(options, tmp);   \
+  } while (0)
+
+static void delete_entry(const census_ht_option *opt, ht_entry *p) {
+  if (opt->delete_data != NULL) {
+    opt->delete_data(p->data);
+  }
+  if (opt->delete_key != NULL) {
+    opt->delete_key(p->key.ptr);
+  }
+  gpr_free(p);
+}
+
+static uint64_t hash(const census_ht_option *opt, census_ht_key key) {
+  return opt->key_type == CENSUS_HT_UINT64 ? key.val : opt->hash(key.ptr);
+}
+
+census_ht *census_ht_create(const census_ht_option *option) {
+  int i;
+  census_ht *ret = NULL;
+  check_options(option);
+  ret = (census_ht *)gpr_malloc(sizeof(census_ht));
+  ret->size = 0;
+  ret->num_buckets = option->num_buckets;
+  ret->buckets = (bucket *)gpr_malloc(sizeof(bucket) * ret->num_buckets);
+  ret->options = *option;
+  /* initialize each bucket */
+  for (i = 0; i < ret->options.num_buckets; i++) {
+    ret->buckets[i].prev_non_empty_bucket = -1;
+    ret->buckets[i].next_non_empty_bucket = -1;
+    ret->buckets[i].next = NULL;
+  }
+  return ret;
+}
+
+static int32_t find_bucket_idx(const census_ht *ht, census_ht_key key) {
+  return hash(&ht->options, key) % ht->num_buckets;
+}
+
+static int keys_match(const census_ht_option *opt, const ht_entry *p,
+                      const census_ht_key key) {
+  GPR_ASSERT(opt->key_type == CENSUS_HT_UINT64 ||
+             opt->key_type == CENSUS_HT_POINTER);
+  if (opt->key_type == CENSUS_HT_UINT64) return p->key.val == key.val;
+  return !opt->compare_keys((p->key).ptr, key.ptr);
+}
+
+static entry_locator ht_find(const census_ht *ht, census_ht_key key) {
+  entry_locator loc = {0, 0, 0, NULL};
+  int32_t idx = 0;
+  ht_entry *ptr = NULL;
+  GPR_ASSERT(ht != NULL);
+  idx = find_bucket_idx(ht, key);
+  ptr = ht->buckets[idx].next;
+  if (ptr == NULL) {
+    /* bucket is empty */
+    return loc;
+  }
+  if (keys_match(&ht->options, ptr, key)) {
+    loc.bucket_idx = idx;
+    loc.is_first_in_chain = 1;
+    loc.found = 1;
+    return loc;
+  } else {
+    for (; ptr->next != NULL; ptr = ptr->next) {
+      if (keys_match(&ht->options, ptr->next, key)) {
+        loc.bucket_idx = idx;
+        loc.is_first_in_chain = 0;
+        loc.found = 1;
+        loc.prev_entry = ptr;
+        return loc;
+      }
+    }
+  }
+  /* Could not find the key */
+  return loc;
+}
+
+void *census_ht_find(const census_ht *ht, census_ht_key key) {
+  entry_locator loc = ht_find(ht, key);
+  if (loc.found == 0) {
+    return NULL;
+  }
+  return loc.is_first_in_chain ? ht->buckets[loc.bucket_idx].next->data
+                               : loc.prev_entry->next->data;
+}
+
+void census_ht_insert(census_ht *ht, census_ht_key key, void *data) {
+  int32_t idx = find_bucket_idx(ht, key);
+  ht_entry *ptr = NULL;
+  entry_locator loc = ht_find(ht, key);
+  if (loc.found) {
+    /* Replace old value with new value. */
+    ptr = loc.is_first_in_chain ? ht->buckets[loc.bucket_idx].next
+                                : loc.prev_entry->next;
+    if (ht->options.delete_data != NULL) {
+      ht->options.delete_data(ptr->data);
+    }
+    ptr->data = data;
+    return;
+  }
+
+  /* first entry in the table. */
+  if (ht->size == 0) {
+    ht->buckets[idx].next_non_empty_bucket = -1;
+    ht->buckets[idx].prev_non_empty_bucket = -1;
+    ht->first_non_empty_bucket = idx;
+    ht->last_non_empty_bucket = idx;
+  } else if (ht->buckets[idx].next == NULL) {
+    /* first entry in the bucket. */
+    ht->buckets[ht->last_non_empty_bucket].next_non_empty_bucket = idx;
+    ht->buckets[idx].prev_non_empty_bucket = ht->last_non_empty_bucket;
+    ht->buckets[idx].next_non_empty_bucket = -1;
+    ht->last_non_empty_bucket = idx;
+  }
+  ptr = (ht_entry *)gpr_malloc(sizeof(ht_entry));
+  ptr->key = key;
+  ptr->data = data;
+  ptr->next = ht->buckets[idx].next;
+  ht->buckets[idx].next = ptr;
+  ht->size++;
+}
+
+void census_ht_erase(census_ht *ht, census_ht_key key) {
+  entry_locator loc = ht_find(ht, key);
+  if (loc.found == 0) {
+    /* noop if not found */
+    return;
+  }
+  ht->size--;
+  if (loc.is_first_in_chain) {
+    bucket *b = &ht->buckets[loc.bucket_idx];
+    GPR_ASSERT(b->next != NULL);
+    /* The only entry in the bucket */
+    if (b->next->next == NULL) {
+      int prev = b->prev_non_empty_bucket;
+      int next = b->next_non_empty_bucket;
+      if (prev != -1) {
+        ht->buckets[prev].next_non_empty_bucket = next;
+      } else {
+        ht->first_non_empty_bucket = next;
+      }
+      if (next != -1) {
+        ht->buckets[next].prev_non_empty_bucket = prev;
+      } else {
+        ht->last_non_empty_bucket = prev;
+      }
+    }
+    REMOVE_NEXT(&ht->options, b);
+  } else {
+    GPR_ASSERT(loc.prev_entry->next != NULL);
+    REMOVE_NEXT(&ht->options, loc.prev_entry);
+  }
+}
+
+/* Returns NULL if input table is empty. */
+census_ht_kv *census_ht_get_all_elements(const census_ht *ht, size_t *num) {
+  census_ht_kv *ret = NULL;
+  int i = 0;
+  int32_t idx = -1;
+  GPR_ASSERT(ht != NULL && num != NULL);
+  *num = ht->size;
+  if (*num == 0) {
+    return NULL;
+  }
+
+  ret = (census_ht_kv *)gpr_malloc(sizeof(census_ht_kv) * ht->size);
+  idx = ht->first_non_empty_bucket;
+  while (idx >= 0) {
+    ht_entry *ptr = ht->buckets[idx].next;
+    for (; ptr != NULL; ptr = ptr->next) {
+      ret[i].k = ptr->key;
+      ret[i].v = ptr->data;
+      i++;
+    }
+    idx = ht->buckets[idx].next_non_empty_bucket;
+  }
+  return ret;
+}
+
+static void ht_delete_entry_chain(const census_ht_option *options,
+                                  ht_entry *first) {
+  if (first == NULL) {
+    return;
+  }
+  if (first->next != NULL) {
+    ht_delete_entry_chain(options, first->next);
+  }
+  delete_entry(options, first);
+}
+
+void census_ht_destroy(census_ht *ht) {
+  unsigned i;
+  for (i = 0; i < ht->num_buckets; ++i) {
+    ht_delete_entry_chain(&ht->options, ht->buckets[i].next);
+  }
+  gpr_free(ht->buckets);
+  gpr_free(ht);
+}
+
+size_t census_ht_get_size(const census_ht *ht) { return ht->size; }