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pg_include/portability/instr_time.h

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+/*-------------------------------------------------------------------------
+ *
+ * instr_time.h
+ *	  portable high-precision interval timing
+ *
+ * This file provides an abstraction layer to hide portability issues in
+ * interval timing.  On Unix we use gettimeofday(), but on Windows that
+ * gives a low-precision result so we must use QueryPerformanceCounter()
+ * instead.  These macros also give some breathing room to use other
+ * high-precision-timing APIs on yet other platforms.
+ *
+ * The basic data type is instr_time, which all callers should treat as an
+ * opaque typedef.	instr_time can store either an absolute time (of
+ * unspecified reference time) or an interval.	The operations provided
+ * for it are:
+ *
+ * INSTR_TIME_IS_ZERO(t)			is t equal to zero?
+ *
+ * INSTR_TIME_SET_ZERO(t)			set t to zero (memset is acceptable too)
+ *
+ * INSTR_TIME_SET_CURRENT(t)		set t to current time
+ *
+ * INSTR_TIME_ADD(x, y)				x += y
+ *
+ * INSTR_TIME_SUBTRACT(x, y)		x -= y
+ *
+ * INSTR_TIME_ACCUM_DIFF(x, y, z)	x += (y - z)
+ *
+ * INSTR_TIME_GET_DOUBLE(t)			convert t to double (in seconds)
+ *
+ * INSTR_TIME_GET_MILLISEC(t)		convert t to double (in milliseconds)
+ *
+ * INSTR_TIME_GET_MICROSEC(t)		convert t to uint64 (in microseconds)
+ *
+ * Note that INSTR_TIME_SUBTRACT and INSTR_TIME_ACCUM_DIFF convert
+ * absolute times to intervals.  The INSTR_TIME_GET_xxx operations are
+ * only useful on intervals.
+ *
+ * When summing multiple measurements, it's recommended to leave the
+ * running sum in instr_time form (ie, use INSTR_TIME_ADD or
+ * INSTR_TIME_ACCUM_DIFF) and convert to a result format only at the end.
+ *
+ * Beware of multiple evaluations of the macro arguments.
+ *
+ *
+ * Copyright (c) 2001-2012, PostgreSQL Global Development Group
+ *
+ * src/include/portability/instr_time.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef INSTR_TIME_H
+#define INSTR_TIME_H
+
+#ifndef WIN32
+
+#include <sys/time.h>
+
+typedef struct timeval instr_time;
+
+#define INSTR_TIME_IS_ZERO(t)	((t).tv_usec == 0 && (t).tv_sec == 0)
+
+#define INSTR_TIME_SET_ZERO(t)	((t).tv_sec = 0, (t).tv_usec = 0)
+
+#define INSTR_TIME_SET_CURRENT(t)	gettimeofday(&(t), NULL)
+
+#define INSTR_TIME_ADD(x,y) \
+	do { \
+		(x).tv_sec += (y).tv_sec; \
+		(x).tv_usec += (y).tv_usec; \
+		/* Normalize */ \
+		while ((x).tv_usec >= 1000000) \
+		{ \
+			(x).tv_usec -= 1000000; \
+			(x).tv_sec++; \
+		} \
+	} while (0)
+
+#define INSTR_TIME_SUBTRACT(x,y) \
+	do { \
+		(x).tv_sec -= (y).tv_sec; \
+		(x).tv_usec -= (y).tv_usec; \
+		/* Normalize */ \
+		while ((x).tv_usec < 0) \
+		{ \
+			(x).tv_usec += 1000000; \
+			(x).tv_sec--; \
+		} \
+	} while (0)
+
+#define INSTR_TIME_ACCUM_DIFF(x,y,z) \
+	do { \
+		(x).tv_sec += (y).tv_sec - (z).tv_sec; \
+		(x).tv_usec += (y).tv_usec - (z).tv_usec; \
+		/* Normalize after each add to avoid overflow/underflow of tv_usec */ \
+		while ((x).tv_usec < 0) \
+		{ \
+			(x).tv_usec += 1000000; \
+			(x).tv_sec--; \
+		} \
+		while ((x).tv_usec >= 1000000) \
+		{ \
+			(x).tv_usec -= 1000000; \
+			(x).tv_sec++; \
+		} \
+	} while (0)
+
+#define INSTR_TIME_GET_DOUBLE(t) \
+	(((double) (t).tv_sec) + ((double) (t).tv_usec) / 1000000.0)
+
+#define INSTR_TIME_GET_MILLISEC(t) \
+	(((double) (t).tv_sec * 1000.0) + ((double) (t).tv_usec) / 1000.0)
+
+#define INSTR_TIME_GET_MICROSEC(t) \
+	(((uint64) (t).tv_sec * (uint64) 1000000) + (uint64) (t).tv_usec)
+#else							/* WIN32 */
+
+typedef LARGE_INTEGER instr_time;
+
+#define INSTR_TIME_IS_ZERO(t)	((t).QuadPart == 0)
+
+#define INSTR_TIME_SET_ZERO(t)	((t).QuadPart = 0)
+
+#define INSTR_TIME_SET_CURRENT(t)	QueryPerformanceCounter(&(t))
+
+#define INSTR_TIME_ADD(x,y) \
+	((x).QuadPart += (y).QuadPart)
+
+#define INSTR_TIME_SUBTRACT(x,y) \
+	((x).QuadPart -= (y).QuadPart)
+
+#define INSTR_TIME_ACCUM_DIFF(x,y,z) \
+	((x).QuadPart += (y).QuadPart - (z).QuadPart)
+
+#define INSTR_TIME_GET_DOUBLE(t) \
+	(((double) (t).QuadPart) / GetTimerFrequency())
+
+#define INSTR_TIME_GET_MILLISEC(t) \
+	(((double) (t).QuadPart * 1000.0) / GetTimerFrequency())
+
+#define INSTR_TIME_GET_MICROSEC(t) \
+	((uint64) (((double) (t).QuadPart * 1000000.0) / GetTimerFrequency()))
+
+static inline double
+GetTimerFrequency(void)
+{
+	LARGE_INTEGER f;
+
+	QueryPerformanceFrequency(&f);
+	return (double) f.QuadPart;
+}
+#endif   /* WIN32 */
+
+#endif   /* INSTR_TIME_H */