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diff --git a/examples/redis-unstable/src/latency.h b/examples/redis-unstable/src/latency.h
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+++ b/examples/redis-unstable/src/latency.h
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+/* latency.h -- latency monitor API header file
+ * See latency.c for more information.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2014-Present, Redis Ltd.
+ * All rights reserved.
+ *
+ * Licensed under your choice of (a) the Redis Source Available License 2.0
+ * (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
+ * GNU Affero General Public License v3 (AGPLv3).
+ */
+
+#ifndef __LATENCY_H
+#define __LATENCY_H
+
+#define LATENCY_TS_LEN 160 /* History length for every monitored event. */
+
+/* Representation of a latency sample: the sampling time and the latency
+ * observed in milliseconds. */
+struct latencySample {
+    int32_t time; /* We don't use time_t to force 4 bytes usage everywhere. */
+    uint32_t latency; /* Latency in milliseconds. */
+};
+
+/* The latency time series for a given event. */
+struct latencyTimeSeries {
+    int idx; /* Index of the next sample to store. */
+    uint32_t max; /* Max latency observed for this event. */
+    struct latencySample samples[LATENCY_TS_LEN]; /* Latest history. */
+};
+
+/* Latency statistics structure. */
+struct latencyStats {
+    uint32_t all_time_high; /* Absolute max observed since latest reset. */
+    uint32_t avg;           /* Average of current samples. */
+    uint32_t min;           /* Min of current samples. */
+    uint32_t max;           /* Max of current samples. */
+    uint32_t mad;           /* Mean absolute deviation. */
+    uint32_t samples;       /* Number of non-zero samples. */
+    time_t period;          /* Number of seconds since first event and now. */
+};
+
+void latencyMonitorInit(void);
+void latencyAddSample(const char *event, mstime_t latency);
+
+/* Latency monitoring macros. */
+
+/* Start monitoring an event. We just set the current time. */
+#define latencyStartMonitor(var) if (server.latency_monitor_threshold) { \
+    var = mstime(); \
+} else { \
+    var = 0; \
+}
+
+/* End monitoring an event, compute the difference with the current time
+ * to check the amount of time elapsed. */
+#define latencyEndMonitor(var) if (server.latency_monitor_threshold) { \
+    var = mstime() - var; \
+}
+
+/* Add the sample only if the elapsed time is >= to the configured threshold. */
+#define latencyAddSampleIfNeeded(event,var) \
+    if (server.latency_monitor_threshold && \
+        (var) >= server.latency_monitor_threshold) \
+          latencyAddSample((event),(var));
+
+/* Remove time from a nested event. */
+#define latencyRemoveNestedEvent(event_var,nested_var) \
+    event_var += nested_var;
+
+typedef struct durationStats {
+    unsigned long long cnt;
+    unsigned long long sum;
+    unsigned long long max;
+} durationStats;
+
+typedef enum {
+    EL_DURATION_TYPE_EL = 0, // cumulative time duration metric of the whole eventloop
+    EL_DURATION_TYPE_CMD,    // cumulative time duration metric of executing commands
+    EL_DURATION_TYPE_AOF,    // cumulative time duration metric of flushing AOF in eventloop
+    EL_DURATION_TYPE_CRON,   // cumulative time duration metric of cron (serverCron and beforeSleep, but excluding IO and AOF)
+    EL_DURATION_TYPE_NUM
+} DurationType;
+
+void durationAddSample(int type, monotime duration);
+
+#endif /* __LATENCY_H */