Merge pull request #1230 from MartinNowak/aaStomper

new AA benchmark with cache stomping

benchmark/aabench/stomper.d

@@ -0,0 +1,66 @@
+/**
+ * Benchmark hash with cache stomping.
+ *
+ * Copyright: Copyright Martin Nowak 2015 - .
+ * License:   $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
+ * Authors:    Martin Nowak
+ */
+import std.file, std.algorithm, std.random, std.math;
+
+// exponential distribution around mean
+struct ExpRandom
+{
+    double mean;
+    Xorshift32 gen;
+
+    this(double mean)
+    {
+        this.mean = mean;
+        gen = Xorshift32(unpredictableSeed);
+    }
+
+    size_t front()
+    {
+        return lround(mean * -log(uniform!"()"(0.0, 1.0, gen)));
+    }
+
+    alias gen this;
+}
+
+struct CacheStomper
+{
+    ExpRandom rnd;
+    size_t i;
+    ubyte[] mem;
+
+    this(size_t avgBytesPerCall)
+    {
+        rnd = ExpRandom(avgBytesPerCall / 64.0);
+        mem = new ubyte[](32 * 1024 * 1024);
+    }
+
+    void stomp()
+    {
+        immutable n = rnd.front();
+        rnd.popFront();
+        foreach (_; 0 .. n)
+            ++mem[(i += 64) & ($ - 1)];
+    }
+}
+
+void main(string[] args)
+{
+    auto path = args.length > 1 ? args[1] : "extra-files/dante.txt";
+    auto words = splitter(cast(string) read(path), ' ');
+
+    size_t[string] aa;
+    auto stomper = CacheStomper(1000);
+    foreach (_; 0 .. 10)
+    {
+        foreach (word; words)
+        {
+            ++aa[word];
+            stomper.stomp();
+        }
+    }
+}

benchmark/aabench/string.d

@@ -5,7 +5,7 @@
  * License:   $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
  * Authors:    Martin Nowak
  */
-import std.array, std.file, std.path;
+import std.algorithm, std.file;
 
 void runTest(R)(R words)
 {