redict/src/latency.c

/* The latency monitor allows to easily observe the sources of latency
 * in a Redis instance using the LATENCY command. Different latency
 * sources are monitored, like disk I/O, execution of commands, fork
 * system call, and so forth.
 *
 * ----------------------------------------------------------------------------
 *
 * Copyright (c) 2014, Salvatore Sanfilippo <antirez at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "redis.h"

/* Dictionary type for latency events. Key/Val destructors are set to NULL
 * since we never delete latency time series at runtime. */
int dictStringKeyCompare(void *privdata, const void *key1, const void *key2) {
    return strcmp(key1,key2) == 0;
}

unsigned int dictStringHash(const void *key) {
    return dictGenHashFunction(key, strlen(key));
}

dictType latencyTimeSeriesDictType = {
    dictStringHash,             /* hash function */
    NULL,                       /* key dup */
    NULL,                       /* val dup */
    dictStringKeyCompare,       /* key compare */
    NULL,                       /* key destructor */
    NULL                        /* val destructor */
};

/* ---------------------------- Latency API --------------------------------- */

/* Latency monitor initialization. We just need to create the dictionary
 * of time series, each time serie is craeted on demand in order to avoid
 * having a fixed list to maintain. */
void latencyMonitorInit(void) {
    server.latency_events = dictCreate(&latencyTimeSeriesDictType,NULL);
}

/* Add the specified sample to the specified time series "event".
 * This function is usually called via latencyAddSampleIfNeeded(), that
 * is a macro that only adds the sample if the latency is higher than
 * server.latency_monitor_threshold. */
void latencyAddSample(char *event, mstime_t latency) {
    struct latencyTimeSeries *ts = dictFetchValue(server.latency_events,event);

    /* Create the time series if it does not exist. */
    if (ts == NULL) {
        ts = zmalloc(sizeof(*ts));
        ts->idx = 0;
        ts->max = 0;
        memset(ts->samples,0,sizeof(ts->samples));
        dictAdd(server.latency_events,zstrdup(event),ts);
    }

    ts->samples[ts->idx].time = time(NULL);
    ts->samples[ts->idx].latency = latency;
    if (latency > ts->max) ts->max = latency;

    ts->idx++;
    if (ts->idx == LATENCY_TS_LEN) ts->idx = 0;
}

/* ---------------------- Latency command implementation -------------------- */

void latencyCommand(redisClient *c) {
}