tusd/metrics.go

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package tusd
import (
"sync"
"sync/atomic"
)
// Metrics provides numbers about the usage of the tusd handler. Since these may
// be accessed from multiple goroutines, it is necessary to read and modify them
// atomically using the functions exposed in the sync/atomic package, such as
// atomic.LoadUint64. In addition the maps must not be modified to prevent data
// races.
type Metrics struct {
// RequestTotal counts the number of incoming requests per method
RequestsTotal map[string]*uint64
// ErrorsTotal counts the number of returned errors by their message
ErrorsTotal ErrorsTotalMap
BytesReceived *uint64
UploadsFinished *uint64
UploadsCreated *uint64
UploadsTerminated *uint64
}
// incRequestsTotal increases the counter for this request method atomically by
// one. The method must be one of GET, HEAD, POST, PATCH, DELETE.
func (m *Metrics) incRequestsTotal(method string) {
if ptr, ok := m.RequestsTotal[method]; ok {
atomic.AddUint64(ptr, 1)
}
}
// incErrorsTotal increases the counter for this error atomically by one.
func (m *Metrics) incErrorsTotal(err HTTPError) {
m.ErrorsTotal.incError(err)
}
// incBytesReceived increases the number of received bytes atomically be the
// specified number.
func (m *Metrics) incBytesReceived(delta uint64) {
atomic.AddUint64(m.BytesReceived, delta)
}
// incUploadsFinished increases the counter for finished uploads atomically by one.
func (m *Metrics) incUploadsFinished() {
atomic.AddUint64(m.UploadsFinished, 1)
}
// incUploadsCreated increases the counter for completed uploads atomically by one.
func (m *Metrics) incUploadsCreated() {
atomic.AddUint64(m.UploadsCreated, 1)
}
// incUploadsTerminated increases the counter for completed uploads atomically by one.
func (m *Metrics) incUploadsTerminated() {
atomic.AddUint64(m.UploadsTerminated, 1)
}
func newMetrics() Metrics {
return Metrics{
RequestsTotal: map[string]*uint64{
"GET": new(uint64),
"HEAD": new(uint64),
"POST": new(uint64),
"PATCH": new(uint64),
"DELETE": new(uint64),
"OPTIONS": new(uint64),
},
ErrorsTotal: newErrorsTotalMap(),
BytesReceived: new(uint64),
UploadsFinished: new(uint64),
UploadsCreated: new(uint64),
UploadsTerminated: new(uint64),
}
}
// ErrorsTotalMap stores the counter for the different http errors.
type ErrorsTotalMap struct {
sync.RWMutex
m map[HTTPError]*uint64
}
func newErrorsTotalMap() ErrorsTotalMap {
m := make(map[HTTPError]*uint64, 20)
return ErrorsTotalMap{
m: m,
}
}
// incErrorsTotal increases the counter for this error atomically by one.
func (e *ErrorsTotalMap) incError(err HTTPError) {
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// The goal is to have a valid ptr to the counter for this err
e.RLock()
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ptr, ok := e.m[err]
e.RUnlock()
if !ok {
// The ptr does not seem to exist for this err
// Hence we create it (using a write lock)
e.Lock()
// We ensure that the ptr wasn't created in the meantime
if ptr, ok = e.m[err]; !ok {
ptr = new(uint64)
*ptr = 0
e.m[err] = ptr
}
e.Unlock()
}
// We can then increase the counter
atomic.AddUint64(e.m[err], 1)
}
// Load retrieves the map of the counter pointers atomically
func (e *ErrorsTotalMap) Load() (m map[HTTPError]*uint64) {
m = make(map[HTTPError]*uint64, len(e.m))
e.RLock()
for err, ptr := range e.m {
m[err] = ptr
}
e.RUnlock()
return
}