Load only the current product config makefile.

To reduce the start time.
With the change and previous change of doing clean step in only given paths,
start time of mm/mmm is reduced from ~5s to about 1s;
lunch time is reduced from ~40s to 3.5s.

(cherry-pick of 157a5e1695593f935c3223430f4530e21f990378.)

Bug: 7186768,7169854
Change-Id: I0be5e2721efa66a80f112acf8f95e177ebc2f65b

8 files changed, 70 insertions, 29 deletions

diff --git a/core/base_rules.mk b/core/base_rules.mk
index deb73ea..6724c22 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -50,9 +50,6 @@ endif
 #$(shell rm -f tag-list.csv)
 #tag-list-first-time := false
 #endif
-#comma := ,
-#empty :=
-#space := $(empty) $(empty)
 #$(shell echo $(lastword $(filter-out config/% out/%,$(MAKEFILE_LIST))),$(LOCAL_MODULE),$(strip $(LOCAL_MODULE_CLASS)),$(subst $(space),$(comma),$(sort $(LOCAL_MODULE_TAGS))) >> tag-list.csv)
 
 LOCAL_UNINSTALLABLE_MODULE := $(strip $(LOCAL_UNINSTALLABLE_MODULE))
diff --git a/core/config.mk b/core/config.mk
index 03e4245..a894444 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -14,6 +14,11 @@ else
 SHELL := /bin/bash
 endif
 
+# Utility variables.
+empty :=
+space := $(empty) $(empty)
+comma := ,
+
 # Tell python not to spam the source tree with .pyc files.  This
 # only has an effect on python 2.6 and above.
 export PYTHONDONTWRITEBYTECODE := 1
diff --git a/core/definitions.mk b/core/definitions.mk
index 9d55197..d5c83d5 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -574,10 +574,6 @@ endef
 ###########################################################
 ## Convert "a b c" into "a:b:c"
 ###########################################################
-
-empty :=
-space := $(empty) $(empty)
-
 define normalize-path-list
 $(subst $(space),:,$(strip $(1)))
 endef
diff --git a/core/droiddoc.mk b/core/droiddoc.mk
index e312965..9f42933 100644
--- a/core/droiddoc.mk
+++ b/core/droiddoc.mk
@@ -85,8 +85,6 @@ full_java_libs += $(addprefix $(LOCAL_PATH)/,$(LOCAL_STATIC_JAVA_LIBRARIES)) $(L
 full_java_lib_deps += $(addprefix $(LOCAL_PATH)/,$(LOCAL_STATIC_JAVA_LIBRARIES)) $(LOCAL_CLASSPATH)
 endif
 
-empty :=
-space := $(empty) $(empty)
 $(full_target): PRIVATE_CLASSPATH := $(subst $(space),:,$(full_java_libs))
 
 endif # !LOCAL_IS_HOST_MODULE
diff --git a/core/node_fns.mk b/core/node_fns.mk
index 40abff7..ccfcc25 100644
--- a/core/node_fns.mk
+++ b/core/node_fns.mk
@@ -94,8 +94,6 @@ endef
 # - Replace "|||" with spaces, breaking haystack back into
 #   individual words.
 #
-empty :=
-space := $(empty) $(empty)
 define uniq-word
 $(strip \
   $(if $(filter-out 0 1,$(words $(filter $(2),$(1)))), \
diff --git a/core/product.mk b/core/product.mk
index d9e4186..81042a1 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -16,7 +16,12 @@
 
 #
 # Functions for including AndroidProducts.mk files
-#
+# PRODUCT_MAKEFILES is set up in AndroidProducts.mks.
+# Format of PRODUCT_MAKEFILES:
+# <product_name>:<path_to_the_product_makefile>
+# If the <product_name> is the same as the base file name (without dir
+# and the .mk suffix) of the product makefile, "<product_name>:" can be
+# omitted.
 
 #
 # Returns the list of all AndroidProducts.mk files.
diff --git a/core/product_config.mk b/core/product_config.mk
index 9c85d2c..de1c863 100644
--- a/core/product_config.mk
+++ b/core/product_config.mk
@@ -181,17 +181,54 @@ include $(BUILD_SYSTEM)/product.mk
 include $(BUILD_SYSTEM)/device.mk
 
 ifneq ($(strip $(TARGET_BUILD_APPS)),)
-  # An unbundled app build needs only the core product makefiles.
-  $(call import-products,$(call get-product-makefiles,\
-      $(SRC_TARGET_DIR)/product/AndroidProducts.mk))
+# An unbundled app build needs only the core product makefiles.
+all_product_configs := $(call get-product-makefiles,\
+    $(SRC_TARGET_DIR)/product/AndroidProducts.mk)
 else
-  # Read in all of the product definitions specified by the AndroidProducts.mk
-  # files in the tree.
-  #
-  #TODO: when we start allowing direct pointers to product files,
-  #    guarantee that they're in this list.
-  $(call import-products, $(get-all-product-makefiles))
-endif # TARGET_BUILD_APPS
+# Read in all of the product definitions specified by the AndroidProducts.mk
+# files in the tree.
+all_product_configs := $(get-all-product-makefiles)
+endif
+
+# Find the product config makefile for the current product.
+# all_product_configs consists items like:
+# <product_name>:<path_to_the_product_makefile>
+# or just <path_to_the_product_makefile> in case the product name is the
+# same as the base filename of the product config makefile.
+current_product_makefile :=
+all_product_makefiles :=
+$(foreach f, $(all_product_configs),\
+    $(eval _cpm_words := $(subst :,$(space),$(f)))\
+    $(eval _cpm_word1 := $(word 1,$(_cpm_words)))\
+    $(eval _cpm_word2 := $(word 2,$(_cpm_words)))\
+    $(if $(_cpm_word2),\
+        $(eval all_product_makefiles += $(_cpm_word2))\
+        $(if $(filter $(TARGET_PRODUCT),$(_cpm_word1)),\
+            $(eval current_product_makefile += $(_cpm_word2)),),\
+        $(eval all_product_makefiles += $(f))\
+        $(if $(filter $(TARGET_PRODUCT),$(basename $(notdir $(f)))),\
+            $(eval current_product_makefile += $(f)),)))
+_cpm_words :=
+_cpm_word1 :=
+_cpm_word2 :=
+current_product_makefile := $(strip $(current_product_makefile))
+all_product_makefiles := $(strip $(all_product_makefiles))
+
+ifneq (,$(filter product-graph dump-products, $(MAKECMDGOALS)))
+# Import all product makefiles.
+$(call import-products, $(all_product_makefiles))
+else
+# Import just the current product.
+ifndef current_product_makefile
+$(error Can not locate config makefile for product "$(TARGET_PRODUCT)")
+endif
+ifneq (1,$(words $(current_product_makefile)))
+$(error Product "$(TARGET_PRODUCT)" ambiguous: matches $(current_product_makefile))
+endif
+$(call import-products, $(current_product_makefile))
+endif  # Import all or just the current product makefile
+
+# Sanity check
 $(check-all-products)
 
 ifneq ($(filter dump-products, $(MAKECMDGOALS)),)
@@ -199,17 +236,16 @@ $(dump-products)
 $(error done)
 endif
 
-ifeq (a,b)
-$(info PRODUCTS -----------)
-$(foreach product, $(PRODUCTS), $(info $(PRODUCTS.$(product).PRODUCT_NAME)))# $(product)))
-$(error stop)
-endif
-
 # Convert a short name like "sooner" into the path to the product
 # file defining that product.
 #
 INTERNAL_PRODUCT := $(call resolve-short-product-name, $(TARGET_PRODUCT))
-#$(error TARGET_PRODUCT $(TARGET_PRODUCT) --> $(INTERNAL_PRODUCT))
+ifneq ($(current_product_makefile),$(INTERNAL_PRODUCT))
+$(error PRODUCT_NAME inconsistent in $(current_product_makefile) and $(INTERNAL_PRODUCT))
+endif
+current_product_makefile :=
+all_product_makefiles :=
+all_product_configs :=
 
 # Find the device that this product maps to.
 TARGET_DEVICE := $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_DEVICE)
diff --git a/target/product/AndroidProducts.mk b/target/product/AndroidProducts.mk
index 9279633..e8ce9df 100644
--- a/target/product/AndroidProducts.mk
+++ b/target/product/AndroidProducts.mk
@@ -18,6 +18,12 @@
 # This file should set PRODUCT_MAKEFILES to a list of product makefiles
 # to expose to the build system.  LOCAL_DIR will already be set to
 # the directory containing this file.
+# PRODUCT_MAKEFILES is set up in AndroidProducts.mks.
+# Format of PRODUCT_MAKEFILES:
+# <product_name>:<path_to_the_product_makefile>
+# If the <product_name> is the same as the base file name (without dir
+# and the .mk suffix) of the product makefile, "<product_name>:" can be
+# omitted.
 #
 # This file may not rely on the value of any variable other than
 # LOCAL_DIR; do not use any conditionals, and do not look up the