1 | // Copyright 2012 Google Inc. All Rights Reserved. |
2 | // |
3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
4 | // you may not use this file except in compliance with the License. |
5 | // You may obtain a copy of the License at |
6 | // |
7 | // http://www.apache.org/licenses/LICENSE-2.0 |
8 | // |
9 | // Unless required by applicable law or agreed to in writing, software |
10 | // distributed under the License is distributed on an "AS IS" BASIS, |
11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
12 | // See the License for the specific language governing permissions and |
13 | // limitations under the License. |
14 | |
15 | #include "build_log.h" |
16 | |
17 | #include <algorithm> |
18 | |
19 | #include <stdlib.h> |
20 | #include <time.h> |
21 | |
22 | using namespace std; |
23 | |
24 | int random(int low, int high) { |
25 | return int(low + (rand() / double(RAND_MAX)) * (high - low) + 0.5); |
26 | } |
27 | |
28 | void RandomCommand(char** s) { |
29 | int len = random(5, 100); |
30 | *s = new char[len+1]; |
31 | for (int i = 0; i < len; ++i) |
32 | (*s)[i] = (char)random(32, 127); |
33 | (*s)[len] = '\0'; |
34 | } |
35 | |
36 | int main() { |
37 | const int N = 20 * 1000 * 1000; |
38 | |
39 | // Leak these, else 10% of the runtime is spent destroying strings. |
40 | char** commands = new char*[N]; |
41 | pair<uint64_t, int>* hashes = new pair<uint64_t, int>[N]; |
42 | |
43 | srand((int)time(NULL)); |
44 | |
45 | for (int i = 0; i < N; ++i) { |
46 | RandomCommand(&commands[i]); |
47 | hashes[i] = make_pair(BuildLog::LogEntry::HashCommand(commands[i]), i); |
48 | } |
49 | |
50 | sort(hashes, hashes + N); |
51 | |
52 | int collision_count = 0; |
53 | for (int i = 1; i < N; ++i) { |
54 | if (hashes[i - 1].first == hashes[i].first) { |
55 | if (strcmp(commands[hashes[i - 1].second], |
56 | commands[hashes[i].second]) != 0) { |
57 | printf("collision!\n string 1: '%s'\n string 2: '%s'\n" , |
58 | commands[hashes[i - 1].second], |
59 | commands[hashes[i].second]); |
60 | collision_count++; |
61 | } |
62 | } |
63 | } |
64 | printf("\n\n%d collisions after %d runs\n" , collision_count, N); |
65 | } |
66 | |