contrib: Add caching of build

This is a primitive way of caching builds of contrib.  Basically, a hash entry
is created from all the *.mak files in contrib.  This include all rules.mak of
individual packages and config.mak generated by the bootstrap script.

When caching is enabled, the installation is done in the cache and a symbolic
link is created to it.

Caching can be enabled with `--cache-dir=/tmp/jami-contrib-cache --cache-builds'
or any other path for cache-dir.  Not providing the `cache-builds` option will
bypass the cache.

Change-Id: I58aa0295664113792518851ede1c568495a33e59

contrib/bootstrap

@@ -37,6 +37,7 @@ HOST=
 PREFIX=
 PKGS_ENABLE=
 PKGS_DISABLE=
+CACHE_BUILD=
 CONF_TARBALLS=
 
 if test ! -f "../src/main.mak"
@@ -62,7 +63,11 @@ do
 			DISABLE_CONTRIB_DOWNLOADS="TRUE"
 			;;
 		--cache-dir=*)
-			CONF_TARBALLS="${1#--cache-dir=}"
+			CACHE_DIR="${1#--cache-dir=}"
+			CONF_TARBALLS="${CACHE}"
+			;;
+		--cache-builds)
+			CACHE_BUILD=1
 			;;
 		--enable-debug)
 			ENABLE_DEBUG=1
@@ -128,6 +133,8 @@ PKGS_ENABLE := $PKGS_ENABLE
 DISABLE_CONTRIB_DOWNLOADS := $DISABLE_CONTRIB_DOWNLOADS
 DISABLE_CONTRIB_CHECKSUMS := $DISABLE_CONTRIB_CHECKSUMS
 CONF_TARBALLS := $CONF_TARBALLS
+CACHE_DIR := $CACHE_DIR
+CACHE_BUILD := $CACHE_BUILD
 ENABLE_DEBUG := $ENABLE_DEBUG
 EOF
 

contrib/src/main.mak

@@ -435,7 +435,37 @@ convert-static:
 	for p in $(PREFIX)/lib/pkgconfig/*.pc; do $(SRC)/pkg-static.sh $$p; done
 fetch: $(PKGS:%=.sum-%)
 fetch-all: $(PKGS_ALL:%=.sum-%)
+
+ifdef CACHE_BUILD
+
+ENTRY=$(CACHE_DIR)/contrib/$(shell cat $(MAKEFILE_LIST) | sha256sum | cut -d ' ' -f 1)
+CACHE_PREFIX=$(ENTRY)/$(shell basename $(PREFIX))
+
+install: $(PREFIX)
+
+ifneq ($(PREFIX),$(CACHE_PREFIX))
+$(PREFIX): $(CACHE_PREFIX)
+	ln --symbolic $^ $@
+endif
+
+$(CACHE_PREFIX): $(ENTRY)/.build
+
+ifeq ($(MAKELEVEL), 0)
+$(ENTRY)/.build:
+	unlink $(PREFIX) || true
+	mkdir --parents $(CACHE_PREFIX)
+	$(FLOCK) $(ENTRY) $(MAKE) PREFIX=$(CACHE_PREFIX)
+	touch $@
+else
+$(ENTRY)/.build: $(PKGS:%=.%) convert-static
+$(PKGS:%=.%): FORCE
+FORCE:
+endif
+
+else
 install: $(PKGS:%=.%) convert-static
+endif
+
 
 mostlyclean:
 	-$(RM) $(foreach p,$(PKGS_ALL),.$(p) .sum-$(p) .dep-$(p))