Remove deprecated features that are esay to replace

That's the "soft" part of the deprecation: Everything that has been
marked deprecated in v0.8 or earlier and is straight-forward to
replace by a non-deprecated way, is removed here.

Sadly, this does not include the HTTP part. We first need to provide a
replacement for HTTP instrumentation (as planned for v0.8) to then
remove the deprecated parts in v0.9.

prometheus/counter.go

@@ -30,15 +30,6 @@ type Counter interface {
 	Metric
 	Collector
 
-	// Set is used to set the Counter to an arbitrary value. It is only used
-	// if you have to transfer a value from an external counter into this
-	// Prometheus metric. Do not use it for regular handling of a
-	// Prometheus counter (as it can be used to break the contract of
-	// monotonically increasing values).
-	//
-	// Deprecated: Use NewConstMetric to create a counter for an external
-	// value. A Counter should never be set.
-	Set(float64)
 	// Inc increments the counter by 1.
 	Inc()
 	// Add adds the given value to the counter. It panics if the value is <

prometheus/http.go

@@ -62,7 +62,7 @@ func giveBuf(buf *bytes.Buffer) {
 //
 // Deprecated: Please note the issues described in the doc comment of
 // InstrumentHandler. You might want to consider using promhttp.Handler instead
-// (which is non instrumented).
+// (which is not instrumented).
 func Handler() http.Handler {
 	return InstrumentHandler("prometheus", UninstrumentedHandler())
 }
@@ -245,23 +245,46 @@ func InstrumentHandlerFuncWithOpts(opts SummaryOpts, handlerFunc func(http.Respo
 		},
 		instLabels,
 	)
+	if err := Register(reqCnt); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			reqCnt = are.ExistingCollector.(*CounterVec)
+		} else {
+			panic(err)
+		}
+	}
 
 	opts.Name = "request_duration_microseconds"
 	opts.Help = "The HTTP request latencies in microseconds."
 	reqDur := NewSummary(opts)
+	if err := Register(reqDur); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			reqDur = are.ExistingCollector.(Summary)
+		} else {
+			panic(err)
+		}
+	}
 
 	opts.Name = "request_size_bytes"
 	opts.Help = "The HTTP request sizes in bytes."
 	reqSz := NewSummary(opts)
+	if err := Register(reqSz); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			reqSz = are.ExistingCollector.(Summary)
+		} else {
+			panic(err)
+		}
+	}
 
 	opts.Name = "response_size_bytes"
 	opts.Help = "The HTTP response sizes in bytes."
 	resSz := NewSummary(opts)
-
-	regReqCnt := MustRegisterOrGet(reqCnt).(*CounterVec)
-	regReqDur := MustRegisterOrGet(reqDur).(Summary)
-	regReqSz := MustRegisterOrGet(reqSz).(Summary)
-	regResSz := MustRegisterOrGet(resSz).(Summary)
+	if err := Register(resSz); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			resSz = are.ExistingCollector.(Summary)
+		} else {
+			panic(err)
+		}
+	}
 
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		now := time.Now()
@@ -285,10 +308,10 @@ func InstrumentHandlerFuncWithOpts(opts SummaryOpts, handlerFunc func(http.Respo
 
 		method := sanitizeMethod(r.Method)
 		code := sanitizeCode(delegate.status)
-		regReqCnt.WithLabelValues(method, code).Inc()
-		regReqDur.Observe(elapsed)
-		regResSz.Observe(float64(delegate.written))
-		regReqSz.Observe(float64(<-out))
+		reqCnt.WithLabelValues(method, code).Inc()
+		reqDur.Observe(elapsed)
+		resSz.Observe(float64(delegate.written))
+		reqSz.Observe(float64(<-out))
 	})
 }
 

prometheus/http_test.go

@@ -46,7 +46,7 @@ func TestInstrumentHandler(t *testing.T) {
 		ConstLabels: Labels{"handler": "test-handler"},
 	}
 
-	reqCnt := MustRegisterOrGet(NewCounterVec(
+	reqCnt := NewCounterVec(
 		CounterOpts{
 			Namespace:   opts.Namespace,
 			Subsystem:   opts.Subsystem,
@@ -55,19 +55,51 @@ func TestInstrumentHandler(t *testing.T) {
 			ConstLabels: opts.ConstLabels,
 		},
 		instLabels,
-	)).(*CounterVec)
+	)
+	err := Register(reqCnt)
+	if err == nil {
+		t.Fatal("expected reqCnt to be registered already")
+	}
+	if are, ok := err.(AlreadyRegisteredError); ok {
+		reqCnt = are.ExistingCollector.(*CounterVec)
+	} else {
+		t.Fatal("unexpected registration error:", err)
+	}
 
 	opts.Name = "request_duration_microseconds"
 	opts.Help = "The HTTP request latencies in microseconds."
-	reqDur := MustRegisterOrGet(NewSummary(opts)).(Summary)
+	reqDur := NewSummary(opts)
+	err = Register(reqDur)
+	if err == nil {
+		t.Fatal("expected reqDur to be registered already")
+	}
+	if are, ok := err.(AlreadyRegisteredError); ok {
+		reqDur = are.ExistingCollector.(Summary)
+	} else {
+		t.Fatal("unexpected registration error:", err)
+	}
 
 	opts.Name = "request_size_bytes"
 	opts.Help = "The HTTP request sizes in bytes."
-	MustRegisterOrGet(NewSummary(opts))
+	reqSz := NewSummary(opts)
+	err = Register(reqSz)
+	if err == nil {
+		t.Fatal("expected reqSz to be registered already")
+	}
+	if _, ok := err.(AlreadyRegisteredError); !ok {
+		t.Fatal("unexpected registration error:", err)
+	}
 
 	opts.Name = "response_size_bytes"
 	opts.Help = "The HTTP response sizes in bytes."
-	MustRegisterOrGet(NewSummary(opts))
+	resSz := NewSummary(opts)
+	err = Register(resSz)
+	if err == nil {
+		t.Fatal("expected resSz to be registered already")
+	}
+	if _, ok := err.(AlreadyRegisteredError); !ok {
+		t.Fatal("unexpected registration error:", err)
+	}
 
 	reqCnt.Reset()
 

prometheus/registry.go

@@ -152,38 +152,6 @@ func MustRegister(cs ...Collector) {
 	DefaultRegisterer.MustRegister(cs...)
 }
 
-// RegisterOrGet registers the provided Collector with the DefaultRegisterer and
-// returns the Collector, unless an equal Collector was registered before, in
-// which case that Collector is returned.
-//
-// Deprecated: RegisterOrGet is merely a convenience function for the
-// implementation as described in the documentation for
-// AlreadyRegisteredError. As the use case is relatively rare, this function
-// will be removed in a future version of this package to clean up the
-// namespace.
-func RegisterOrGet(c Collector) (Collector, error) {
-	if err := Register(c); err != nil {
-		if are, ok := err.(AlreadyRegisteredError); ok {
-			return are.ExistingCollector, nil
-		}
-		return nil, err
-	}
-	return c, nil
-}
-
-// MustRegisterOrGet behaves like RegisterOrGet but panics instead of returning
-// an error.
-//
-// Deprecated: This is deprecated for the same reason RegisterOrGet is. See
-// there for details.
-func MustRegisterOrGet(c Collector) Collector {
-	c, err := RegisterOrGet(c)
-	if err != nil {
-		panic(err)
-	}
-	return c
-}
-
 // Unregister removes the registration of the provided Collector from the
 // DefaultRegisterer.
 //
@@ -201,25 +169,6 @@ func (gf GathererFunc) Gather() ([]*dto.MetricFamily, error) {
 	return gf()
 }
 
-// SetMetricFamilyInjectionHook replaces the DefaultGatherer with one that
-// gathers from the previous DefaultGatherers but then merges the MetricFamily
-// protobufs returned from the provided hook function with the MetricFamily
-// protobufs returned from the original DefaultGatherer.
-//
-// Deprecated: This function manipulates the DefaultGatherer variable. Consider
-// the implications, i.e. don't do this concurrently with any uses of the
-// DefaultGatherer. In the rare cases where you need to inject MetricFamily
-// protobufs directly, it is recommended to use a custom Registry and combine it
-// with a custom Gatherer using the Gatherers type (see
-// there). SetMetricFamilyInjectionHook only exists for compatibility reasons
-// with previous versions of this package.
-func SetMetricFamilyInjectionHook(hook func() []*dto.MetricFamily) {
-	DefaultGatherer = Gatherers{
-		DefaultGatherer,
-		GathererFunc(func() ([]*dto.MetricFamily, error) { return hook(), nil }),
-	}
-}
-
 // AlreadyRegisteredError is returned by the Register method if the Collector to
 // be registered has already been registered before, or a different Collector
 // that collects the same metrics has been registered before. Registration fails

prometheus/registry_test.go

@@ -526,20 +526,21 @@ func TestRegisterWithOrGet(t *testing.T) {
 		},
 		[]string{"foo", "bar"},
 	)
-	if err := prometheus.Register(original); err != nil {
+	var err error
+	if err = prometheus.Register(original); err != nil {
 		t.Fatal(err)
 	}
-	if err := prometheus.Register(equalButNotSame); err == nil {
+	if err = prometheus.Register(equalButNotSame); err == nil {
 		t.Fatal("expected error when registringe equal collector")
 	}
-	existing, err := prometheus.RegisterOrGet(equalButNotSame)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if existing != original {
+	if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
+		if are.ExistingCollector != original {
 			t.Error("expected original collector but got something else")
 		}
-	if existing == equalButNotSame {
+		if are.ExistingCollector == equalButNotSame {
 			t.Error("expected original callector but got new one")
 		}
+	} else {
+		t.Error("unexpected error:", err)
+	}
 }