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https://github.com/fluencelabs/redis
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8612e6de88
We introduce the distinction between slow and fast commands since those are two different sources of latency. An O(1) or O(log N) command without side effects (can't trigger deletion of large objects as a side effect of its execution) if delayed is a symptom of inherent latency of the system. A non-fast command (commands that may run large O(N) computations) if delayed may just mean that the user is executing slow operations. The advices LATENCY should provide in this two different cases are different, so we log the two classes of commands in a separated way.
43 lines
1.4 KiB
C
43 lines
1.4 KiB
C
#ifndef __LATENCY_H
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#define __LATENCY_H
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#define LATENCY_TS_LEN 160 /* History length for every monitored event. */
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/* Representation of a latency sample: the sampling time and the latency
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* observed in milliseconds. */
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struct latencySample {
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int32_t time; /* We don't use time_t to force 4 bytes usage everywhere. */
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uint32_t latency; /* Latency in milliseconds. */
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};
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/* The latency time series for a given event. */
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struct latencyTimeSeries {
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int idx; /* Index of the next sample to store. */
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mstime_t max; /* Max latency observed for this event. */
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struct latencySample samples[LATENCY_TS_LEN]; /* Latest history. */
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};
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void latencyMonitorInit(void);
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void latencyAddSample(char *event, mstime_t latency);
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/* Latency monitoring macros. */
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/* Start monitoring an event. We just set the current time. */
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#define latencyStartMonitor(var) if (server.latency_monitor_threshold) { \
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var = mstime(); \
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}
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/* End monitoring an event, compute the difference with the current time
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* to check the amount of time elapsed. */
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#define latencyEndMonitor(var) if (server.latency_monitor_threshold) { \
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var = mstime() - var; \
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}
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/* Add the sample only if the elapsed time is >= to the configured threshold. */
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#define latencyAddSampleIfNeeded(event,var) \
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if (server.latency_monitor_threshold && \
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var >= server.latency_monitor_threshold) \
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latencyAddSample(event,var);
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#endif /* __LATENCY_H */
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