Implement ticker.

Implement ticker, which provides a simple API for ticking off some
number of events before indicating that the ticker has hit its limit.

include/jemalloc/internal/ticker.h

@@ -0,0 +1,75 @@
+/******************************************************************************/
+#ifdef JEMALLOC_H_TYPES
+
+typedef struct ticker_s ticker_t;
+
+#endif /* JEMALLOC_H_TYPES */
+/******************************************************************************/
+#ifdef JEMALLOC_H_STRUCTS
+
+struct ticker_s {
+	int32_t	tick;
+	int32_t	nticks;
+};
+
+#endif /* JEMALLOC_H_STRUCTS */
+/******************************************************************************/
+#ifdef JEMALLOC_H_EXTERNS
+
+#endif /* JEMALLOC_H_EXTERNS */
+/******************************************************************************/
+#ifdef JEMALLOC_H_INLINES
+
+#ifndef JEMALLOC_ENABLE_INLINE
+void	ticker_init(ticker_t *ticker, int32_t nticks);
+void	ticker_copy(ticker_t *ticker, const ticker_t *other);
+int32_t	ticker_read(const ticker_t *ticker);
+bool	ticker_ticks(ticker_t *ticker, int32_t nticks);
+bool	ticker_tick(ticker_t *ticker);
+#endif
+
+#if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_TICKER_C_))
+JEMALLOC_INLINE void
+ticker_init(ticker_t *ticker, int32_t nticks)
+{
+
+	ticker->tick = nticks;
+	ticker->nticks = nticks;
+}
+
+JEMALLOC_INLINE void
+ticker_copy(ticker_t *ticker, const ticker_t *other)
+{
+
+	*ticker = *other;
+}
+
+JEMALLOC_INLINE int32_t
+ticker_read(const ticker_t *ticker)
+{
+
+	return (ticker->tick);
+}
+
+JEMALLOC_INLINE bool
+ticker_ticks(ticker_t *ticker, int32_t nticks)
+{
+
+	if (unlikely(ticker->tick < nticks)) {
+		ticker->tick = ticker->nticks;
+		return (true);
+	}
+	ticker->tick -= nticks;
+	return(false);
+}
+
+JEMALLOC_INLINE bool
+ticker_tick(ticker_t *ticker)
+{
+
+	return (ticker_ticks(ticker, 1));
+}
+#endif
+
+#endif /* JEMALLOC_H_INLINES */
+/******************************************************************************/