public void FindPerformanceIsNotProportionalToKeyWordCount()
{
var stopwatch = new Stopwatch();
var keywordCounts = new[] { 1000, 100000 };
var searchTimes = new long[keywordCounts.Length];
var searchText = GenerateRandomString(100000);
for (var i = 0; i < keywordCounts.Length; i++)
{
var machine = new AhoCorasickStringMatch(GenerateKeywords(keywordCounts[i]));
machine.Find("foo"); // Burn one, to blow out the cobwebs
stopwatch.Restart();
machine.Find(searchText);
stopwatch.Stop();
var lookupTime = stopwatch.Elapsed;
searchTimes[i] = lookupTime.Ticks;
output.WriteLine($"Find time for machine with {keywordCounts[i]} keywords: {lookupTime.TotalMilliseconds}ms");
}
var smallTime = searchTimes.First();
var bigTime = searchTimes.Last();
if (bigTime > smallTime)
{
// Assert find time does not vary by more than 50%
((double)(bigTime - smallTime) / smallTime).ShouldBeLessThan(0.5);
}
}
public void TimeToConstructMachineGrowsLinearlyWithSumOfKeywordsLengths()
{
var stopwatch = new Stopwatch();
const int initialKeywordCount = 1000;
const int allowedInitialConstructionMilliseconds = 200;
var keywordCounts = new[] { initialKeywordCount, 10000, 100000, 500000 };
var constructionTimes = new long[keywordCounts.Length];
// Limit to time growth of 2n
var constructionTimesAllowed = keywordCounts
.Select(x => x == initialKeywordCount
? allowedInitialConstructionMilliseconds
: (x / initialKeywordCount) * allowedInitialConstructionMilliseconds * 2).ToArray();
for (var i = 0; i < keywordCounts.Length; i++)
{
stopwatch.Restart();
var machine = new AhoCorasickStringMatch(GenerateKeywords(keywordCounts[i]));
stopwatch.Stop();
var constructionTime = stopwatch.Elapsed;
constructionTimes[i] = constructionTime.Ticks;
var allowedConstructionTime = constructionTimesAllowed[i];
output.WriteLine($"Construction time for machine with {keywordCounts[i]} keywords: {constructionTime.TotalMilliseconds}ms");
output.WriteLine($"Allowed time: {allowedConstructionTime}ms");
constructionTime.TotalMilliseconds.ShouldBeLessThan(allowedConstructionTime);
}
}
public void ExampleFromPaperIsSuccessful()
{
var keywords = new[] { "he", "she", "his", "hers" };
var subject = new AhoCorasickStringMatch(keywords);
var result = subject.Find("ushers").ToList();
result.Count.ShouldBe(3);
result.ShouldContain("she");
result.ShouldContain("he");
result.ShouldContain("hers");
}
public void FindPerformanceIsLinearlyProportionalToSearchTextLength()
{
var stopwatch = new Stopwatch();
var keywords = GenerateKeywords(100000);
stopwatch.Start();
var machine = new AhoCorasickStringMatch(keywords);
stopwatch.Stop();
output.WriteLine($"Machine build time: {stopwatch.Elapsed.TotalMilliseconds}ms");
// Burn one, to blow out the cobwebs
machine.Find("Foo");
const int initialSearchTextLength = 1000;
const double initialSearchTextAllowedMilliseconds = 0.025;
var searchTextLengths = new[] { initialSearchTextLength, 10000, 100000, 1000000, 10000000 };
// Limit to time growth of 3n
var searchTimesAllowed = searchTextLengths
.Select(x => x == initialSearchTextLength
? initialSearchTextAllowedMilliseconds
: (x / initialSearchTextLength) * initialSearchTextAllowedMilliseconds * 3).ToArray();
for (var i = 0; i < searchTextLengths.Length; i++)
{
var searchText = GenerateRandomString(searchTextLengths[i]);
stopwatch.Restart();
machine.Find(searchText);
stopwatch.Stop();
var lookupTime = stopwatch.Elapsed;
var allowedSearchTime = searchTimesAllowed[i];
output.WriteLine($"Find time for search-text of length {searchTextLengths[i]}: {lookupTime.TotalMilliseconds}ms");
output.WriteLine($"Allowed time: {allowedSearchTime}ms");
lookupTime.TotalMilliseconds.ShouldBeLessThan(allowedSearchTime);
}
}