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xpcom/ds/nsStatistics.cpp

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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "MPL"); you may not use this file except in
+ * compliance with the MPL.  You may obtain a copy of the MPL at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the MPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the MPL
+ * for the specific language governing rights and limitations under the
+ * MPL.
+ *
+ * The Initial Developer of this code under the MPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1999 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ *
+ * Original Author:
+ *   Chris Waterson <waterson@netscape.com>
+ */
+
+#include "nsStatistics.h"
+#include "nsISupportsUtils.h"
+#include "nsTraceRefCnt.h" // for NS_MeanAndStdDev
+#include "plhash.h"
+
+inline PLHashNumber
+nsStatistics::HashPRInt32(const void* aKey)
+{
+    return PLHashNumber(aKey);
+}
+
+nsStatistics::nsStatistics(const char* aTopic)
+    : mTopic(aTopic),
+      mDistribution(nsnull),
+      mMinimum(0),
+      mMaximum(0),
+      mCount(0),
+      mSum(0),
+      mSumOfSquares(0)
+{
+    mDistribution = PL_NewHashTable(24, HashPRInt32, PL_CompareValues, PL_CompareValues, nsnull, nsnull);
+}
+
+nsStatistics::~nsStatistics()
+{
+    PL_HashTableDestroy(mDistribution);
+}
+
+void
+nsStatistics::Clear()
+{
+    PL_HashTableDestroy(mDistribution);
+    mCount = mMinimum = mMaximum = 0;
+    mSum = mSumOfSquares = 0.0;
+    mDistribution = PL_NewHashTable(24, HashPRInt32, PL_CompareValues, PL_CompareValues, nsnull, nsnull);
+}
+
+
+void
+nsStatistics::Record(PRInt32 aValue)
+{
+    ++mCount;
+    if (aValue < mMinimum)
+        mMinimum = aValue;
+    if (aValue > mMaximum)
+        mMaximum = aValue;
+    mSum += aValue;
+    mSumOfSquares += aValue * aValue;
+
+    PLHashEntry** hep = PL_HashTableRawLookup(mDistribution, PLHashNumber(aValue),
+                                              NS_REINTERPRET_CAST(const void*, aValue));
+
+    if (hep && *hep) {
+        PRInt32 count = NS_REINTERPRET_CAST(PRUint32, (*hep)->value);
+        (*hep)->value = NS_REINTERPRET_CAST(void*, ++count);
+    }
+    else {
+        PL_HashTableRawAdd(mDistribution, hep, PLHashNumber(aValue),
+                           NS_REINTERPRET_CAST(const void*, aValue),
+                           NS_REINTERPRET_CAST(void*, 1));
+    }
+}
+
+
+void
+nsStatistics::Print(FILE* aFile)
+{
+    double mean, stddev;
+    NS_MeanAndStdDev(mCount, mSum, mSumOfSquares, &mean, &stddev);
+    fprintf(aFile, "%s count=%d, minimum=%d, maximum=%d, mean=%0.2lf+/-%0.2lf\n",
+            mTopic, mCount, mMinimum, mMaximum, mean, stddev);
+
+    for (PRInt32 i = mMinimum; i < mMaximum; ++i) {
+        PRUint32 count = NS_REINTERPRET_CAST(PRUint32, PL_HashTableLookup(mDistribution, NS_REINTERPRET_CAST(const void*, i)));
+        if (! count)
+            continue;
+
+        fprintf(aFile, "  %d: %d\n", i, count);
+    }
+}

xpcom/ds/nsStatistics.h

@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "MPL"); you may not use this file except in
+ * compliance with the MPL.  You may obtain a copy of the MPL at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the MPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the MPL
+ * for the specific language governing rights and limitations under the
+ * MPL.
+ *
+ * The Initial Developer of this code under the MPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1999 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ *
+ * Original Author:
+ *   Chris Waterson <waterson@netscape.com>
+ */
+
+/*
+
+  An object that collects distribution data
+
+*/
+#ifndef nsStatistics_h__
+#define nsStatistics_h__
+
+#include <stdio.h>
+#include "nscore.h"
+#include "nsCom.h"
+#include "plhash.h"
+
+/**
+ * An object that collects distribution data.
+ */
+class NS_COM nsStatistics
+{
+public:
+    nsStatistics(const char* aTopic);
+    ~nsStatistics();
+
+    /**
+     * Add a value to the distribution
+     */
+    void Record(PRInt32 aValue);
+
+    /**
+     * Clear the information collected so far
+     */
+    void Clear();
+
+    /**
+     * Print the mean, standard deviation, and distribution
+     * of values reported so far
+     */
+    void Print(FILE* aStream);
+
+protected:
+    const char* mTopic;
+    PLHashTable* mDistribution;
+    PRInt32 mCount;
+    PRInt32 mMinimum;
+    PRInt32 mMaximum;
+    double mSum;
+    double mSumOfSquares;
+
+    static PLHashNumber HashPRInt32(const void* aKey);
+};
+
+
+#endif