From e1ec3bcdd229686f6213cbbbbbb8abd26ddcf033 Mon Sep 17 00:00:00 2001
From: Guille Polito <guillermopolito@gmail.com>
Date: Thu, 7 Sep 2023 17:06:40 +0200
Subject: [PATCH] More simplifications. Now that exception handlers are outside
 of the fast path, we can just use a block.

---
 src/MethodProxies/MpCannotInstall.class.st    |  4 +++
 src/MethodProxies/MpHiddenSelector.class.st   |  7 ++++
 src/MethodProxies/MpMethodProxy.class.st      | 18 ++++++++--
 ...MpProxyInstrumentationDeactivator.class.st | 36 -------------------
 4 files changed, 27 insertions(+), 38 deletions(-)
 delete mode 100644 src/MethodProxies/MpProxyInstrumentationDeactivator.class.st

diff --git a/src/MethodProxies/MpCannotInstall.class.st b/src/MethodProxies/MpCannotInstall.class.st
index 9f065d4..5b25ec0 100644
--- a/src/MethodProxies/MpCannotInstall.class.st
+++ b/src/MethodProxies/MpCannotInstall.class.st
@@ -1,3 +1,7 @@
+"
+I'm an exception raised when a proxy cannot be installed.
+This usually happens when the wrapped method is a very special method whose instrumentation could break the system.
+"
 Class {
 	#name : #MpCannotInstall,
 	#superclass : #Error,
diff --git a/src/MethodProxies/MpHiddenSelector.class.st b/src/MethodProxies/MpHiddenSelector.class.st
index 2f32e51..cc01a9e 100644
--- a/src/MethodProxies/MpHiddenSelector.class.st
+++ b/src/MethodProxies/MpHiddenSelector.class.st
@@ -1,3 +1,10 @@
+"
+I represent a selector that is hidden for the user, used to install hidden methods in method dictionaries.
+I'm not a string, so I cannot be typed, avoiding potential conflicts.
+
+I'm used as key of the original method wrapped by proxies, to ensure this wrapped method can be called using myself as selector.
+Check my usages during proxy installation.
+"
 Class {
 	#name : #MpHiddenSelector,
 	#superclass : #Object,
diff --git a/src/MethodProxies/MpMethodProxy.class.st b/src/MethodProxies/MpMethodProxy.class.st
index c633213..699393c 100644
--- a/src/MethodProxies/MpMethodProxy.class.st
+++ b/src/MethodProxies/MpMethodProxy.class.st
@@ -1157,8 +1157,22 @@ MpMethodProxy >> install [
 		(proxyMethod hasPragmaNamed: #noInstrumentation) ifTrue: [
 			^ MpCannotInstall signalWith: self ].
 
-		deactivator := MpProxyInstrumentationDeactivator new.
-		deactivator handler: handler.
+		deactivator := [ "Execution handler for the slow path. An exception or a non local return happened during proxy execution"
+			| wasMeta trapContext |
+			
+			"Jump to the meta level (to avoid meta-recursions) to observe if the handler was in a meta level, marked by the wasMeta flag.
+			During the meta-jump call the handler to tell there was an unwind.
+			"
+			thisProcess shiftLevelUp.
+			trapContext := thisContext findContextSuchThat: [ :ctx | ctx isUnwindContext ].
+			wasMeta := trapContext tempNamed: 'wasMeta'.
+			handler aboutToReturnWithReceiver: trapContext receiver arguments: trapContext arguments.
+			thisProcess shiftLevelDown.
+			
+			"If the handler was in a meta-state (i.e., the exception or non-local return happened in the handler), shift it back to the base level before returning.
+			Otherwise, we were already in the base level and we need to do nothing!"
+			wasMeta ifTrue: [ thisProcess shiftLevelDown ].
+	 	].
 
 		newTrap := self trapMethodPrototype copy.
 		trapSelector := newTrap selector.
diff --git a/src/MethodProxies/MpProxyInstrumentationDeactivator.class.st b/src/MethodProxies/MpProxyInstrumentationDeactivator.class.st
deleted file mode 100644
index b9c3602..0000000
--- a/src/MethodProxies/MpProxyInstrumentationDeactivator.class.st
+++ /dev/null
@@ -1,36 +0,0 @@
-Class {
-	#name : #MpProxyInstrumentationDeactivator,
-	#superclass : #InstrumentationEnsurer,
-	#instVars : [
-		'handler'
-	],
-	#category : #MethodProxies
-}
-
-{ #category : #accessing }
-MpProxyInstrumentationDeactivator >> handler [
-
-	^ handler
-]
-
-{ #category : #accessing }
-MpProxyInstrumentationDeactivator >> handler: anObject [
-
-	handler := anObject
-]
-
-{ #category : #evaluating }
-MpProxyInstrumentationDeactivator >> value [
-
-	<noInstrumentation>
-	"Slow path, an exception or a non local return happened"
-	| wasMeta me |
-	thisProcess shiftLevelUp.
-
-	me := thisContext findContextSuchThat: [ :ctx | ctx isUnwindContext ].
-	wasMeta := me tempNamed: 'wasMeta'.
-	handler aboutToReturnWithReceiver: me receiver arguments: me arguments.
-	thisProcess shiftLevelDown.
-	wasMeta ifTrue: [ thisProcess shiftLevelDown ].
-	
-]