components/metrics/src/memfault_metrics_reliability.c

//! @file
//!
//! Copyright (c) Memfault, Inc.
//! See LICENSE for details
//! @brief APIs for tracking reliability metrics

#include "memfault/metrics/reliability.h"

// non-module includes below

#include "memfault/components.h"

static sMemfaultMetricsReliabilityCtx s_memfault_metrics_reliability_ctx;

//! Load optional system state on boot.
void memfault_metrics_reliability_boot(sMemfaultMetricsReliabilityCtx *ctx) {
  if (ctx != NULL) {
    s_memfault_metrics_reliability_ctx = *ctx;
  } else {
    // Set the last heartbeat time to the current time since boot. This supports
    // a system with a time-since-boot timer that counts through intentional
    // resets (for example OTA).
    s_memfault_metrics_reliability_ctx.last_heartbeat_ms =
      memfault_platform_get_time_since_boot_ms();
  }
}

sMemfaultMetricsReliabilityCtx *memfault_metrics_reliability_get_ctx(void) {
  return &s_memfault_metrics_reliability_ctx;
}

// Accumulate operational hours.
void memfault_metrics_reliability_collect(void) {
  // Accumulate ms since last heartbeat
  const uint32_t time_since_boot_ms = memfault_platform_get_time_since_boot_ms();
  const uint32_t this_interval_ms =
    time_since_boot_ms - s_memfault_metrics_reliability_ctx.last_heartbeat_ms;
  s_memfault_metrics_reliability_ctx.operational_ms += this_interval_ms;

  // Count any accumulated hours
  const uint32_t uptime_hours = s_memfault_metrics_reliability_ctx.operational_ms / 1000 / 3600;
  // Deduct the counted hours from the accumulated ms
  s_memfault_metrics_reliability_ctx.operational_ms -= uptime_hours * 3600 * 1000;
  // Reset the accumulated ms for the next heartbeat
  s_memfault_metrics_reliability_ctx.last_heartbeat_ms = time_since_boot_ms;

  // Only report uptime if it's non-zero
  if (!uptime_hours) {
    return;
  }

  MEMFAULT_METRIC_ADD(operational_hours, (int32_t)uptime_hours);

  bool unexpected_reboot = false;
  if (!s_memfault_metrics_reliability_ctx.counted_unexpected_reboot) {
    s_memfault_metrics_reliability_ctx.counted_unexpected_reboot = true;
    (void)memfault_reboot_tracking_get_unexpected_reboot_occurred(&unexpected_reboot);
  }
  // Deduct an hour from the crashfree hours count if there was an unexpected
  // reboot. This only applies to the first hour of uptime, which is where the
  // crash is counted.
  MEMFAULT_METRIC_ADD(operational_crashfree_hours,
                      (int32_t)(uptime_hours - (uint32_t)unexpected_reboot));
}