Adding Timestamps and minor refactor

README.md

@@ -119,12 +119,15 @@ uses
   Prometheus.Collectors.Histogram;
 
 begin
-  LHistogram := THistogram.Create('Name of histogram metric', 'Help text for histogram metric');
-  // If buckets argument is not supplied, the default values will be used:
-  // [0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10, INFINITE].
-  LHistogram.Observe(0.01);
-  LHistogram.Observe(0.04);
-  LHistogram.Observe(1);
+  lHistogram := TCollectorRegistry.DefaultRegistry.GetCollector<THistogram>('Name of histogram metric');
+  if not Assigned(lHistogram) then begin
+    lHistogram := THistogram.Create('Name of histogram metric', 'Help text for histogram metric');
+    // if Buckets argument is not supplied, the default values will be used
+    //[0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10, INFINITE]
+    lHistogram.Register;
+  end;
+
+  lHistogram.Observe(lRequestTimeDec);
 end.
 ```
 
@@ -197,4 +200,3 @@ You can find official **Prometheus Client middlewares** into these separate repo
 
 + [Prometheus Official Page](https://prometheus.io)
 + [Using Delphi with Prometheus and Grafana (in Italian language)](https://www.youtube.com/watch?v=-bPDl6MP6jo)
-

Samples/Starter-DMVC/WebModules.App.pas

@@ -10,8 +10,6 @@ interface
 
 type
 
-{ TAppWebModule }
-
   TAppWebModule = class(TWebModule)
     procedure WebModuleCreate(Sender: TObject);
     procedure WebModuleDestroy(Sender: TObject);
@@ -28,13 +26,13 @@ implementation
 
 uses
   MVCFramework.Commons,
+  MVCFramework.Middleware.Metrics,
   Prometheus.Collectors.Counter,
   Prometheus.Collectors.Histogram,
   Prometheus.Registry,
   Controllers.Demo;
-
+  
 { TAppWebModule }
-
 procedure TAppWebModule.WebModuleCreate(Sender: TObject);
 begin
   // Creates the Delphi MVC Framework server application engine.
@@ -43,17 +41,18 @@ procedure TAppWebModule.WebModuleCreate(Sender: TObject);
   // Add a sample controller.
   FEngine.AddController(TDemoController);
 
-  // Configure some sample metrics...
+  // Add the metrics middleware! It will export all values using the
+  // default endpoint '/metrics' but you can change it as shown below:
+  FEngine.AddMiddleware(GetMetricsMiddleware('/metrics'));
 
+  // Configure some sample metrics...
   // ... a simple counter
   TCounter.Create('http_requests_count', 'Received HTTP request count').Register();
-
   // ... A request time histogram with two labels for path and status
   THistogram.Create(
     'request_duration_seconds', 'Time taken to process request- in seconds',
     [0.05, 0.1, 0.25, 0.5, 1, 2, 10], ['path', 'status'])
     .Register();
-
   // .. A request time histogram with no labels and an increasing bucket sequence
   THistogram.Create('response_length', 'Number of bytes sent in response', 10, 3, 10, []).Register();
 
@@ -63,19 +62,19 @@ procedure TAppWebModule.WebModuleCreate(Sender: TObject);
     var
       LNextValue: Double;
     const
-      StartValue = 10;
-      ValueCount = 5;
-      StepValue = 5;
+       Start = 10;
+       Count = 5;
+       Step = 5;
     begin
-      SetLength(Result, ValueCount);
-      LNextValue := StartValue;
-      for var LIndex := 0 to ValueCount - 1 do
+      SetLength(result, Count);
+      LNextValue := Start;
+      for var I := 0 to Count - 1 do
       begin
-        Result[LIndex] := LNextValue;
-        LNextValue := LNextValue + StepValue;
+        Result[I] := lNextValue;
+        lNextValue := lNextValue + Step;
       end;
     end,
-    [])
+   [])
    .Register();
 
   FEngine.SetExceptionHandler(
@@ -90,6 +89,7 @@ procedure TAppWebModule.WebModuleCreate(Sender: TObject);
         .Labels([WebContext.Request.PathInfo, WebContext.Response.StatusCode.ToString])
         .Observe(AssumedDuration);
     end);
+
 end;
 
 procedure TAppWebModule.WebModuleDestroy(Sender: TObject);

Source/Prometheus.Collectors.Counter.pas

@@ -7,6 +7,9 @@ interface
   Prometheus.Samples,
   Prometheus.SimpleCollector;
 
+const
+  SECS_TO_MILLISECS = 1000;
+
 type
 
 { TCounterChild }
@@ -51,10 +54,19 @@   TCounterChild = class
   /// </remarks>
   TCounter = class (TSimpleCollector<TCounterChild>)
   strict private
+    FLock: TObject;
     function GetValue: Double;
   strict protected
     function CreateChild: TCounterChild; override;
   public
+    /// <summary>
+    ///  Creates a new instance of this counter collector.
+    /// </summary>
+    constructor Create(const AName: string; const AHelp: string = ''; const ALabelNames: TLabelNames = []); override;
+    /// <summary>
+    ///  Performs object cleanup releasing all the owned instances.
+    /// </summary>
+    destructor Destroy; override;
     /// <summary>
     ///  Collects all the metrics and the samples from this collector.
     /// </summary>
@@ -76,6 +88,7 @@   TCounter = class (TSimpleCollector<TCounterChild>)
 implementation
 
 uses
+  System.DateUtils,
   System.SysUtils,
   Prometheus.Resources;
 
@@ -108,9 +121,22 @@ procedure TCounterChild.Inc(const AAmount: Double);
 
 { TCounter }
 
+constructor TCounter.Create(const AName: string; const AHelp: string = ''; const ALabelNames: TLabelNames = []);
+begin
+  inherited Create(AName, AHelp, ALabelNames);
+  FLock := TObject.Create;
+end;
+
+destructor TCounter.Destroy;
+begin
+  if Assigned(FLock) then
+    FreeAndNil(FLock);
+  inherited Destroy;
+end;
+
 function TCounter.Collect: TArray<TMetricSamples>;
 begin
-  TMonitor.Enter(Lock);
+  TMonitor.Enter(FLock);
   try
     SetLength(Result, 1);
     var LMetric := PMetricSamples(@Result[0]);
@@ -126,12 +152,13 @@ function TCounter.Collect: TArray<TMetricSamples>;
         LSample^.MetricName := Self.Name;
         LSample^.LabelNames := Self.LabelNames;
         LSample^.LabelValues := ALabelValues;
+        LSample^.TimeStamp := DateTimeToUnix(TTimeZone.Local.ToUniversalTime(Now)) * SECS_TO_MILLISECS;
         LSample^.Value := AChild.Value;
         System.Inc(LIndex);
       end
     );
   finally
-    TMonitor.Exit(Lock);
+    TMonitor.Exit(FLock);
   end;
 end;
 

Source/Prometheus.Collectors.Gauge.pas

@@ -8,6 +8,9 @@ interface
   Prometheus.Samples,
   Prometheus.SimpleCollector;
 
+const
+  SECS_TO_MILLISECS = 1000;
+
 type
 
 { TGaugeChild }
@@ -68,10 +71,20 @@   TGaugeChild = class
   /// </remarks>
   TGauge = class (TSimpleCollector<TGaugeChild>)
   strict private
+    FLock: TObject;
     function GetValue: Double;
   strict protected
     function CreateChild: TGaugeChild; override;
   public
+    /// <summary>
+    ///  Creates a new instance of this gauge collector.
+    /// </summary>
+    constructor Create(const AName: string; const AHelp: string = '';
+      const ALabelNames: TLabelNames = []); override;
+    /// <summary>
+    ///  Performs object cleanup releasing all the owned instances.
+    /// </summary>
+    destructor Destroy; override;
     /// <summary>
     ///  Collects all the metrics and the samples from this collector.
     /// </summary>
@@ -189,9 +202,23 @@ procedure TGaugeChild.SetToCurrentTime;
 
 { TGauge }
 
+constructor TGauge.Create(const AName, AHelp: string;
+  const ALabelNames: TLabelNames);
+begin
+  inherited Create(AName, AHelp, ALabelNames);
+  FLock := TObject.Create;
+end;
+
+destructor TGauge.Destroy;
+begin
+  if Assigned(FLock) then
+    FreeAndNil(FLock);
+  inherited Destroy;
+end;
+
 function TGauge.Collect: TArray<TMetricSamples>;
 begin
-  TMonitor.Enter(Lock);
+  TMonitor.Enter(FLock);
   try
     SetLength(Result, 1);
     var LMetric := PMetricSamples(@Result[0]);
@@ -207,12 +234,13 @@ function TGauge.Collect: TArray<TMetricSamples>;
         LSample^.MetricName := Self.Name;
         LSample^.LabelNames := Self.LabelNames;
         LSample^.LabelValues := ALabelValues;
+        LSample^.TimeStamp := DateTimeToUnix(TTimeZone.Local.ToUniversalTime(Now)) * SECS_TO_MILLISECS;
         LSample^.Value := AChild.Value;
         System.Inc(LIndex);
       end
     );
   finally
-    TMonitor.Exit(Lock);
+    TMonitor.Exit(FLock);
   end;
 end;