Improve map insertions

minidump/minidump_thread_id_map.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 20 matching lines @@
 
   // First, try truncating each 64-bit thread ID to 32 bits. If that’s possible
   // for each unique 64-bit thread ID, then this will be used as the mapping.
   // This preserves as much of the original thread ID as possible when feasible.
   bool collision = false;
   std::set<uint32_t> thread_ids_32;
   for (const ThreadSnapshot* thread_snapshot : thread_snapshots) {
     uint64_t thread_id_64 = thread_snapshot->ThreadID();
     if (thread_id_map->find(thread_id_64) == thread_id_map->end()) {
       uint32_t thread_id_32 = static_cast<uint32_t>(thread_id_64);
-      if (thread_ids_32.find(thread_id_32) != thread_ids_32.end()) {
+      if (!thread_ids_32.insert(thread_id_32).second) {
         collision = true;
         break;
       }
-      thread_ids_32.insert(thread_id_32);
       thread_id_map->insert(std::make_pair(thread_id_64, thread_id_32));
     }
   }
 
   if (collision) {
     // Since there was a collision, go back and assign each unique 64-bit thread
     // ID its own sequential 32-bit equivalent. The 32-bit thread IDs will not
     // bear any resemblance to the original 64-bit thread IDs.
     thread_id_map->clear();
     for (const ThreadSnapshot* thread_snapshot : thread_snapshots) {
       uint64_t thread_id_64 = thread_snapshot->ThreadID();
       if (thread_id_map->find(thread_id_64) == thread_id_map->end()) {
         uint32_t thread_id_32 =
             base::checked_cast<uint32_t>(thread_id_map->size());
         thread_id_map->insert(std::make_pair(thread_id_64, thread_id_32));
       }
     }
 
     DCHECK_LE(thread_id_map->size(), std::numeric_limits<uint32_t>::max());
   }
 }
 
 }  // namespace crashpad