From 3576e769a4d7252aa1b4ca590d116a4913f2ba93 Mon Sep 17 00:00:00 2001
From: Spandan Das <spandandas@google.com>
Date: Wed, 3 Jan 2024 18:57:03 +0000
Subject: Handle installation rules for co-existing prebuilts

Every module belonging to a single mainline module family will be
hidden from make, except the one which has been flagged using
apex_contributions

Details
- Introduce a new `source_apex_name` property to prebuilt_apex and
  override_apex. This property will be used to identify the source
  equivalent of a prebuilt soong apex module.
- Create an N-ary tree from source to prebuilt(s). The tree wil be
  rooted at the source module.
- In a subsequent mutator, visit every node in the tree(s). Query
  apex_contributions and store the handle of the node which is "active"
  (if any)
- In the same mutator, do another pass over the tree. Invoke
  `HideFromMake` on every node which is not "active". The two-pass
  approach is needed PrebuiltSelectionInfoProvider does not know about
  the inter source-prebuilt dependency, this dependency can only be
  known by doing a graph walk of the N-ary tree.

Some tangential implementation details
- Each prebuilt apex has an internal deapxer module that is responsible
  for generating the deapex ninja rules. The name of this internal
  module uses the BaseModuleName (without the prebuilt_ prefix). Since
  we can have multiple prebuilt soong modules in trunk stable, change
  this to follow the name of the prebuilt module in order to avoid name
  collisions. Update existing unit tests accordingly

Bug: 316179314
Test: go test ./apex -run TestInstallationRulesForMultipleApexPrebuilts
Test: m nothing --no-skip-soong-tests
Test: presubmits

Change-Id: I58aa99d5e6a9859954614e6db9a8e9e2e581642d
---
 android/apex_contributions.go | 23 ++++++-----------------
 1 file changed, 6 insertions(+), 17 deletions(-)

(limited to 'android/apex_contributions.go')

diff --git a/android/apex_contributions.go b/android/apex_contributions.go
index a30964080..236abf663 100644
--- a/android/apex_contributions.go
+++ b/android/apex_contributions.go
@@ -102,7 +102,6 @@ func (a *allApexContributions) SetPrebuiltSelectionInfoProvider(ctx BaseModuleCo
 				ctx.ModuleErrorf("%s listed in apex_contributions %s does not exist\n", content, m.Name())
 			}
 			pi := &PrebuiltSelectionInfo{
-				baseModuleName:     RemoveOptionalPrebuiltPrefix(content),
 				selectedModuleName: content,
 				metadataModuleName: m.Name(),
 				apiDomain:          m.ApiDomain(),
@@ -126,7 +125,8 @@ func (a *allApexContributions) SetPrebuiltSelectionInfoProvider(ctx BaseModuleCo
 // This provider will be used in prebuilt_select mutator to redirect deps
 var PrebuiltSelectionInfoProvider = blueprint.NewMutatorProvider[PrebuiltSelectionInfoMap]("prebuilt_select")
 
-// Map of baseModuleName to the selected source or prebuilt
+// Map of selected module names to a metadata object
+// The metadata contains information about the api_domain of the selected module
 type PrebuiltSelectionInfoMap map[string]PrebuiltSelectionInfo
 
 // Add a new entry to the map with some validations
@@ -134,18 +134,10 @@ func (pm *PrebuiltSelectionInfoMap) Add(ctx BaseModuleContext, p *PrebuiltSelect
 	if p == nil {
 		return
 	}
-	// Do not allow dups. If the base module (without the prebuilt_) has been added before, raise an exception.
-	if old, exists := (*pm)[p.baseModuleName]; exists {
-		ctx.ModuleErrorf("Cannot use Soong module: %s from apex_contributions: %s because it has been added previously as: %s from apex_contributions: %s\n",
-			p.selectedModuleName, p.metadataModuleName, old.selectedModuleName, old.metadataModuleName,
-		)
-	}
-	(*pm)[p.baseModuleName] = *p
+	(*pm)[p.selectedModuleName] = *p
 }
 
 type PrebuiltSelectionInfo struct {
-	// e.g. libc
-	baseModuleName string
 	// e.g. (libc|prebuilt_libc)
 	selectedModuleName string
 	// Name of the apex_contributions module
@@ -156,12 +148,9 @@ type PrebuiltSelectionInfo struct {
 
 // Returns true if `name` is explicitly requested using one of the selected
 // apex_contributions metadata modules.
-func (p *PrebuiltSelectionInfoMap) IsSelected(baseModuleName, name string) bool {
-	if i, exists := (*p)[baseModuleName]; exists {
-		return i.selectedModuleName == name
-	} else {
-		return false
-	}
+func (p *PrebuiltSelectionInfoMap) IsSelected(name string) bool {
+	_, exists := (*p)[name]
+	return exists
 }
 
 // Return the list of soong modules selected for this api domain
-- 
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