From 4663618cfd774f974bbbb8f0859970907300c0b8 Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Thu, 21 Mar 2013 12:14:21 +0100
Subject: [PATCH] A poor man's profiler.

The use of this profiler is trivial:

 * #include <support/pmprof.h>

 * in the block one wants to profile, add
   PROFILE_THIS_BLOCK(some_identifier)

 * At the end of the execution, statistics will be sent to standard error.
---
 src/support/Makefile.am |  1 +
 src/support/pmprof.h    | 88 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)
 create mode 100644 src/support/pmprof.h

diff --git a/src/support/Makefile.am b/src/support/Makefile.am
index a537ff8da5..5ab3ef99ee 100644
--- a/src/support/Makefile.am
+++ b/src/support/Makefile.am
@@ -83,6 +83,7 @@ liblyxsupport_a_SOURCES = \
 	Package.cpp \
 	Package.h \
 	ProgressInterface.h \
+	pmprof.h \
 	qstring_helpers.cpp \
 	qstring_helpers.h \
 	regex.h \
diff --git a/src/support/pmprof.h b/src/support/pmprof.h
new file mode 100644
index 0000000000..f1506ec222
--- /dev/null
+++ b/src/support/pmprof.h
@@ -0,0 +1,88 @@
+// -*- C++ -*-
+/* \file pmprof.h
+ * This file is part of LyX, the document processor.
+ * Licence details can be found in the file COPYING.
+ *
+ * \author Jean-Marc Lasgouttes
+ *
+ * Full author contact details are available in file CREDITS.
+ */
+
+#ifndef PMPROF_H
+#define PMPROF_H
+
+#include <sys/time.h>
+#include <iostream>
+
+/** How to use this trivial profiler:
+ *
+ * * at the beginning of the interesting block, just add:
+ *   PROFILE_THIS_BLOCK(some_identifier);
+ *
+ * * when the program ends, statistics will be sent to standard error, like:
+ *
+ *   ##### some_identifier: 6.48475usec, count=25405
+ *
+ * The code measured by the profiler corresponds to the lifetime of a
+ * local variable declared by the PROFILE_THIS_BLOCK macro.
+ */
+
+/* Helper class for gathering data. Instantiate this as a static
+ * variable, so that its destructor will be executed when the program
+ * ends.
+ */
+class PMProfStat {
+public:
+	PMProfStat(char const * name)
+	  : name_(name), sec_(0), usec_(0), count_(0) {};
+
+	~PMProfStat() {
+		if (count_>0)
+		  std::cerr << "##### " << name_ << ": "
+			    << 1.0 * (sec_ * 1000000 + usec_)/ count_
+			    << "usec, count=" << count_ << std::endl;
+	}
+
+	void add(const long long s, const long long u) {
+		sec_ += s;
+		usec_ += u;
+		count_++;
+	}
+
+private:
+	char const * name_;
+	long long sec_, usec_;
+	unsigned long long count_;
+};
+
+
+/* Helper class which gathers data at the end of the scope. One
+ * instance of this one should be created at each execution of the
+ * block. At the end of the block, it sends statistics to the static
+ * PMProfStat object.
+ */
+class PMProfInstance {
+public:
+	PMProfInstance(PMProfStat * stat) : stat_(stat)
+	{
+		gettimeofday(&before_, 0);
+	}
+
+	~PMProfInstance() {
+		gettimeofday(&after_, 0);
+		stat_->add(after_.tv_sec - before_.tv_sec,
+			   after_.tv_usec - before_.tv_usec);
+	}
+
+private:
+	timeval before_, after_;
+	PMProfStat * stat_;
+};
+
+
+#define PROFILE_THIS_BLOCK(a) \
+	static PMProfStat PMPS_##a(#a);\
+	PMProfInstance PMPI_##a(&PMPS_##a)
+
+
+#endif
-- 
2.39.5