libc/src/search/hsearch.cpp

   1 //===-- Implementation of hsearch -------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/search/hsearch.h"
  10 #include "src/__support/HashTable/randomness.h"
  11 #include "src/__support/HashTable/table.h"
  12 #include "src/__support/macros/config.h"
  13 #include "src/errno/libc_errno.h"
  14 #include "src/search/hsearch/global.h"
  15
  16 namespace LIBC_NAMESPACE_DECL {
  17 LLVM_LIBC_FUNCTION(ENTRY *, hsearch, (ENTRY item, ACTION action)) {
  18   ENTRY *result = nullptr;
  19   if (internal::global_hash_table == nullptr) {
  20     // If global_hash_table is null, we create a new hash table with a minimal
  21     // capacity. Such hashtable will be expanded as needed.
  22     uint64_t randomness = internal::randomness::next_random_seed();
  23     internal::global_hash_table = internal::HashTable::allocate(0, randomness);
  24   }
  25
  26   // In rare cases, the global hashtable may still fail to allocate. We treat it
  27   // as ESRCH or ENOMEM depending on the action.
  28   switch (action) {
  29   case FIND:
  30     result = internal::global_hash_table
  31                  ? internal::global_hash_table->find(item.key)
  32                  : nullptr;
  33     if (result == nullptr) {
  34       libc_errno = ESRCH;
  35     }
  36     break;
  37   case ENTER:
  38     result =
  39         internal::global_hash_table
  40             ? internal::HashTable::insert(internal::global_hash_table, item)
  41             : nullptr;
  42     if (result == nullptr) {
  43       libc_errno = ENOMEM;
  44     }
  45     break;
  46   }
  47   return result;
  48 }
  49
  50 } // namespace LIBC_NAMESPACE_DECL