Let the node and the value holder carry a description

source/Canopy-Core-Tests/CanopyDescriptionTest.class.st

@@ -0,0 +1,35 @@
+Class {
+	#name : 'CanopyDescriptionTest',
+	#superclass : 'TestCase',
+	#category : 'Canopy-Core-Tests',
+	#package : 'Canopy-Core-Tests'
+}
+
+{ #category : 'tests' }
+CanopyDescriptionTest >> testABranchAndACellCarryADescription [
+	| branch cell |
+	branch := CanopyBranchNode new.
+	cell := CanopyCell new value: 1.
+	branch description: 'where the limits live'.
+	cell description: 'the maximum of open files'.
+	self assert: branch description equals: 'where the limits live'.
+	self assert: cell description equals: 'the maximum of open files'
+]
+
+{ #category : 'tests' }
+CanopyDescriptionTest >> testAHolderCarriesADescriptionAndLabels [
+	| holder |
+	holder := CanopyValue value: 1.
+	holder description: 'what the component says'.
+	holder labelAt: #database put: 'alpha'.
+	self assert: holder description equals: 'what the component says'.
+	self assert: (holder labels at: #database) equals: 'alpha'
+]
+
+{ #category : 'tests' }
+CanopyDescriptionTest >> testNothingIsDescribedUnlessSomeoneSaidSo [
+	self assert: CanopyBranchNode new description isNil.
+	self assert: (CanopyCell new value: 1) description isNil.
+	self assert: (CanopyValue value: 1) description isNil.
+	self assert: (CanopyValue value: 1) labels isEmpty
+]

source/Canopy-Core/CanopyNode.class.st

@@ -4,7 +4,8 @@ Class {
 	#instVars : [
 		'parent',
 		'tags',
-		'labels'
+		'labels',
+		'description'
 	],
 	#category : 'Canopy-Core',
 	#package : 'Canopy-Core'
@@ -28,6 +29,19 @@ CanopyNode >> allKeys [
 		ifNil: [ #() ]
 ]
 
+{ #category : 'accessing' }
+CanopyNode >> description [
+	"What this node is for, declared where the tree is built. Branches, cells and accessors all
+	carry one. Nil when nobody said; the export then falls back to what the value holder of a
+	leaf brings along, and last to the key."
+	^ description
+]
+
+{ #category : 'accessing' }
+CanopyNode >> description: aString [
+	description := aString
+]
+
 { #category : 'accessing' }
 CanopyNode >> fullKey [
 	^ '_' join: (self allKeys collect: [ :k | k asString ])

source/Canopy-Core/CanopyValueHolder.class.st

@@ -2,7 +2,9 @@ Class {
 	#name : 'CanopyValueHolder',
 	#superclass : 'Object',
 	#instVars : [
-		'value'
+		'value',
+		'description',
+		'labels'
 	],
 	#category : 'Canopy-Core',
 	#package : 'Canopy-Core'
@@ -22,6 +24,36 @@ CanopyValueHolder >> asCanopyValue [
 	^ self
 ]
 
+{ #category : 'accessing' }
+CanopyValueHolder >> description [
+	"What the component itself says this value is for. A description on the node wins over
+	this one - see CanopyNode>>description - so this is the fallback a component brings along."
+	^ description
+]
+
+{ #category : 'accessing' }
+CanopyValueHolder >> description: aString [
+	description := aString
+]
+
+{ #category : 'initialization' }
+CanopyValueHolder >> initialize [
+	super initialize.
+	labels := Dictionary new
+]
+
+{ #category : 'accessing' }
+CanopyValueHolder >> labelAt: aKey put: anObject [
+	"A label the component itself knows, as opposed to one the tree carries - the stage of a
+	deployment hangs at the root, the database a number belongs to is known here."
+	labels at: aKey put: anObject
+]
+
+{ #category : 'accessing' }
+CanopyValueHolder >> labels [
+	^ labels
+]
+
 { #category : 'printing' }
 CanopyValueHolder >> printOn: aStream [
 	super printOn: aStream.

source/Canopy-Metrics-Tests/CanopyDeclaredMetricTest.class.st

@@ -25,6 +25,20 @@ CanopyDeclaredMetricTest >> setUp [
 	branch := root /+ #server
 ]
 
+{ #category : 'tests' }
+CanopyDeclaredMetricTest >> testTheNodeDescriptionBeatsTheOneOfTheHolder [
+	"The node is the declaration made where the tree is built, the holder only what the component
+	brings along when it is read - so the node wins, and the holder answers only where the node
+	says nothing."
+	| described |
+	branch counter: #requests description: 'from the holder' reading: [ 3 ].
+	branch counter: #errors description: 'from the holder' reading: [ 1 ].
+	described := branch / #requests.
+	described description: 'from the node'.
+	self assert: (self scrape includesSubstring: '# HELP server_requests from the node').
+	self assert: (self scrape includesSubstring: '# HELP server_errors from the holder')
+]
+
 { #category : 'tests' }
 CanopyDeclaredMetricTest >> testACounterIsWrittenAsOne [
 	branch counter: #requests description: 'requests served' reading: [ 3 ].

source/Canopy-Metrics/CanopyMetric.class.st

@@ -2,42 +2,12 @@ Class {
 	#name : 'CanopyMetric',
 	#superclass : 'CanopyValueHolder',
 	#instVars : [
-		'type',
-		'description',
-		'labels'
+		'type'
 	],
 	#category : 'Canopy-Metrics',
 	#package : 'Canopy-Metrics'
 }
 
-{ #category : 'accessing' }
-CanopyMetric >> description [
-	^ description
-]
-
-{ #category : 'accessing' }
-CanopyMetric >> description: aString [
-	description := aString
-]
-
-{ #category : 'initialization' }
-CanopyMetric >> initialize [
-	super initialize.
-	labels := Dictionary new
-]
-
-{ #category : 'accessing' }
-CanopyMetric >> labelAt: aKey put: anObject [
-	"A label the component itself knows, as opposed to one the tree carries - the stage of a
-	deployment hangs at the root, the database a number belongs to is known here."
-	labels at: aKey put: anObject
-]
-
-{ #category : 'accessing' }
-CanopyMetric >> labels [
-	^ labels
-]
-
 { #category : 'enumerating' }
 CanopyMetric >> readingsDo: aBlock [
 	"One reading: the labels this metric knows itself, and its value. Whatever the tree adds is

source/Canopy-Metrics/CanopyPrometheusVisitor.class.st

@@ -112,7 +112,8 @@ CanopyPrometheusVisitor >> writeHelpLine: aNode holder: aMetric [
 		nextPutAll: '# HELP ';
 		nextPutAll: (self convertMetricName: aNode);
 		nextPutAll: ' '.
-	stream nextPutAll: (aMetric description ifNil: [ aNode key asString ]).
+	stream nextPutAll: (aNode description
+		ifNil: [ aMetric description ifNil: [ aNode key asString ] ]).
 	stream nextPut: Character linefeed
 ]