| // Copyright 2012 Google Inc. 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, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include "build_log.h" |
| |
| #include <algorithm> |
| |
| #include <stdlib.h> |
| #include <time.h> |
| |
| using namespace std; |
| |
| int random(int low, int high) { |
| return int(low + (rand() / double(RAND_MAX)) * (high - low) + 0.5); |
| } |
| |
| void RandomCommand(char** s) { |
| int len = random(5, 100); |
| *s = new char[len+1]; |
| for (int i = 0; i < len; ++i) |
| (*s)[i] = (char)random(32, 127); |
| (*s)[len] = '\0'; |
| } |
| |
| int main() { |
| const int N = 20 * 1000 * 1000; |
| |
| // Leak these, else 10% of the runtime is spent destroying strings. |
| char** commands = new char*[N]; |
| pair<uint64_t, int>* hashes = new pair<uint64_t, int>[N]; |
| |
| srand((int)time(NULL)); |
| |
| for (int i = 0; i < N; ++i) { |
| RandomCommand(&commands[i]); |
| hashes[i] = make_pair(BuildLog::LogEntry::HashCommand(commands[i]), i); |
| } |
| |
| sort(hashes, hashes + N); |
| |
| int collision_count = 0; |
| for (int i = 1; i < N; ++i) { |
| if (hashes[i - 1].first == hashes[i].first) { |
| if (strcmp(commands[hashes[i - 1].second], |
| commands[hashes[i].second]) != 0) { |
| printf("collision!\n string 1: '%s'\n string 2: '%s'\n", |
| commands[hashes[i - 1].second], |
| commands[hashes[i].second]); |
| collision_count++; |
| } |
| } |
| } |
| printf("\n\n%d collisions after %d runs\n", collision_count, N); |
| } |