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: vmodule.go
    path of file: ./repos/cockroach/pkg/util/log
    
    the code of the file until where you have to start completion: // Copyright 2019 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.

package log

import (
	"bytes"
	"fmt"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"

	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
	"github.com/cockroachdb/errors"
)

type vmoduleConfig struct {
	// pcsPool maintains a set of [1]uintptr buffers to be used in V to avoid
	// allocating every time we compute the caller's PC.
	pcsPool sync.Pool

	// V logging level, the value of the --verbosity flag. Updated with
	// atomics.
	verbosity Level

	mu struct {
		// These flags are modified only under lock.
		syncutil.Mutex

		// vmap is a cache of the V Level for each V() call site, identified by PC.
		// It is wiped whenever the vmodule flag changes state.
		vmap map[uintptr]Level

		// filterLength stores the length o
    
func (c *vmoduleConfig) vDepth(l Level, depth int) bool {
	// This function tries hard to be cheap unless there's work to do.
	// The fast path is three atomic loads and compares.

	// Here is a cheap but safe test to see if V logging is enabled globally.
	if c.verbosity.get() >= l {
		return true
	}

	// It's off globally but vmodule may still be set.
	// Here is another cheap but safe test to see if vmodule is enabled.
	if atomic.LoadInt32(&c.mu.filterLength) > 0 {
		// Grab a buffer to use for reading the program counter. Keeping the
		// interface{} version around to Put back into the pool rather than
		// Put-ting the array saves an interface allocation.
		poolObj := c.pcsPool.Get()
		pcs := poolObj.([1]uintptr)
		// We prefer not to use a defer in this function, which can be used in hot
		// paths, because a defer anywhere in the body of a function causes a call
		// to runtime.deferreturn at the end of that function, which has a
		// measurable performance penalty when in a very hot path.
		// defer c.pcsPool.Put(pcs)
		if runtime.Callers(2+depth, pcs[:]) == 0 {
			c.pcsPool.Put(poolObj)
			return false
		}
		v := func() Level {
			c.mu.Lock()
			defer c.mu.Unlock()
			lvl, ok := c.mu.vmap[pcs[0]]
			if !ok {
				lvl = c.setV(pcs)
			}
			return lvl
		}()
		c.pcsPool.Put(poolObj)
		return v >= l
	}
	return false
}