tracer.cc

// -*- mode: c++; c-file-style: "k&r"; c-basic-offset: 4 -*-
// vim: set ts=4 sw=4:
/***********************************************************************
 *
 * tracer.cc:
 *   latency tracing functions
 *
 **********************************************************************/

#include "tracer.h"

using namespace std;

void
Trace_Init(const string &name, Request_Trace *trace)
{
    trace->is_tracing = false;
    trace->start_time = -1;
    trace->curr_stage = -1;
    trace->max_stage = 0;
    for (int i = 0; i < 16; i++) {
        trace->stage[i] = 0;
    }
    trace->n_traces = 0;

    // Add to mapping.
    trace_map[name] = trace;
}

void
Trace_Flush(const string &name)
{
    Request_Trace *trace = trace_map[name];

    fprintf(stderr, "## Latency Stats for %s\n", name.c_str());
    fprintf(stderr, "## Number of samples: %u\n", trace->n_traces);
    fprintf(stderr, "## Number of stages: %u\n", trace->max_stage);
    fprintf(stderr, "## %s Stage Breakdown:", name.c_str());
    for (int i = 0; i < trace->max_stage; i++) {
        trace->stage[i] = trace->stage[i]/trace->n_traces;
        if (i > 0) {
            fprintf(stderr, " %u", trace->stage[i] - trace->stage[i-1]);
        } else {
            fprintf(stderr, " %u", trace->stage[i]);
        }
    }
    fprintf(stderr, "\n");
}

void
Trace_Start(const string &name)
{
    Request_Trace *trace = trace_map[name];

    trace->is_tracing = true;

    struct timeval t;
    gettimeofday(&t, NULL);
    trace->start_time = t.tv_sec * 1000000 + t.tv_usec;

    trace->curr_stage = 0;
}

void
Trace_Save(const string &name, const uint32_t index)
{
    Request_Trace *trace = trace_map[name];

    struct timeval t;
    gettimeofday(&t, NULL);
    
    trace->stage[trace->curr_stage] +=
        (t.tv_sec * 1000000 + t.tv_usec) - trace->start_time;

    trace->curr_stage++;

    if (index > 0 && index != trace->curr_stage) {
        fprintf(stderr, "Mismatch index on %u, %u\n", index,
        trace->curr_stage);
    }
}

void
Trace_Stop(const string &name)
{
    Request_Trace *trace = trace_map[name];

    struct timeval t;
    gettimeofday(&t, NULL);

    trace->stage[trace->curr_stage] +=
        (t.tv_sec * 1000000 + t.tv_usec) - trace->start_time;

    if (trace->curr_stage >= trace->max_stage) {
        trace->max_stage = trace->curr_stage + 1;
    }
    trace->n_traces++;
    trace->is_tracing = false;
}