You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: perf_context.rs
    path of file: ./repos/tikv/components/raft_log_engine/src
    
    the code of the file until where you have to start completion: // Copyright 2022 TiKV Project Authors. Licensed under Apache-2.0.

use raft_engine::get_perf_context;
use tracker::{TrackerToken, GLOBAL_TRACKERS};

#[derive(Debug)]
pub struct RaftEnginePerfContext;

impl engine_traits::PerfContext for RaftEnginePerfContext {
    fn start_observe(&mut self) {
        raft_engine::set
    
    fn report_metrics(&mut self, trackers: &[TrackerToken]) {
        let perf_context = get_perf_context();
        for token in trackers {
            GLOBAL_TRACKERS.with_tracker(*token, |t| {
                t.metrics.store_thread_wait_nanos =
                    perf_context.write_wait_duration.as_nanos() as u64;
                t.metrics.store_write_wal_nanos = (perf_context.log_write_duration
                    + perf_context.log_sync_duration
                    + perf_context.log_rotate_duration)
                    .as_nanos() as u64;
                t.metrics.store_write_memtable_nanos =
                    perf_context.apply_duration.as_nanos() as u64;
            });
        }
    }