Add support for sccache

bin/ebuild.sh

@@ -121,7 +121,7 @@ export PORTAGE_BZIP2_COMMAND=${PORTAGE_BZIP2_COMMAND:-bzip2}
 
 # These two functions wrap sourcing and calling respectively.  At present they
 # perform a qa check to make sure eclasses and ebuilds and profiles don't mess
-# with shell opts (shopts).  Ebuilds/eclasses changing shopts should reset them 
+# with shell opts (shopts).  Ebuilds/eclasses changing shopts should reset them
 # when they are done.
 
 __qa_source() {
@@ -732,6 +732,13 @@ if [[ ${EBUILD_PHASE} != clean?(rm) ]]; then
 
 				[[ -n ${CCACHE_SIZE} ]] && ccache -M ${CCACHE_SIZE} &> /dev/null
 			fi
+
+			if contains_word sccache "${FEATURES}"; then
+				if [[ -n ${SCCACHE_DIR} ]] ; then
+					addread "${SCCACHE_DIR}"
+					addwrite "${SCCACHE_DIR}"
+				fi
+			fi
 		fi
 	fi
 fi

bin/phase-functions.sh

@@ -1087,7 +1087,8 @@ __ebuild_main() {
 
 			local x
 			for x in ASFLAGS CCACHE_DIR CCACHE_SIZE \
-				CFLAGS CXXFLAGS LDFLAGS LIBCFLAGS LIBCXXFLAGS ; do
+				CFLAGS CXXFLAGS LDFLAGS LIBCFLAGS LIBCXXFLAGS \
+				SCCACHE_DIR SCCACHE_CACHE_SIZE ; do
 				[[ ${!x+set} = set ]] && export ${x}
 			done
 			unset x

bin/save-ebuild-env.sh

@@ -162,9 +162,10 @@ __save_ebuild_env() (
 		INSTALL_MASK
 		PKG_INSTALL_MASK
 
-		# CCACHE and DISTCC configuration variables.
+		# CCACHE, DISTCC, and SCCACHE configuration variables.
 		"${!CCACHE_@}"
 		"${!DISTCC_@}"
+		"${!SCCACHE_@}"
 	)
 
 	# Unset the collected variables before moving on to functions.

lib/_emerge/EbuildPhase.py

@@ -139,6 +139,7 @@ class EbuildPhase(CompositeTask):
         "nostrip",
         "preserve-libs",
         "sandbox",
+        "sccache",
         "selinux",
         "sesandbox",
         "splitdebug",

lib/_emerge/actions.py

@@ -2075,6 +2075,23 @@ def action_info(settings, trees, myopts, myfiles):
             ccache_str += " [disabled]"
         append(ccache_str)
 
+    try:
+        proc = subprocess.Popen(
+            ["sccache", "-V"], stdout=subprocess.PIPE, stderr=subprocess.STDOUT
+        )
+    except OSError:
+        output = (1, None)
+    else:
+        output = _unicode_decode(proc.communicate()[0]).rstrip("\n")
+        output = (proc.wait(), output)
+    if output[0] == os.EX_OK:
+        sccache_str = output[1].split("\n", 1)[0]
+        if "sccache" in settings.features:
+            sccache_str += " [enabled]"
+        else:
+            sccache_str += " [disabled]"
+        append(sccache_str)
+
     myvars = [
         "dev-build/autoconf",
         "dev-build/automake",

lib/portage/const.py

@@ -223,6 +223,7 @@
         "python-trace",
         "qa-unresolved-soname-deps",
         "sandbox",
+        "sccache",
         "selinux",
         "sesandbox",
         "sfperms",

lib/portage/package/ebuild/_config/special_env_vars.py

@@ -245,7 +245,7 @@
     )
 )
 
-environ_whitelist_re = re.compile(r"^(CCACHE_|DISTCC_).*")
+environ_whitelist_re = re.compile(r"^(S?CCACHE_|DISTCC_).*")
 
 # Filter selected variables in the config.environ() method so that
 # they don't needlessly propagate down into the ebuild environment.

lib/portage/package/ebuild/doebuild.py

@@ -609,8 +609,9 @@ def doebuild_environment(
         ccache = "ccache" in mysettings.features
         distcc = "distcc" in mysettings.features
         icecream = "icecream" in mysettings.features
+        sccache = "sccache" in mysettings.features
 
-        if ccache or distcc or icecream:
+        if ccache or distcc or icecream or sccache:
             libdir = None
             default_abi = mysettings.get("DEFAULT_ABI")
             if default_abi:
@@ -628,6 +629,8 @@ def doebuild_environment(
                 masquerades.append(("icecream", "icecc"))
             if ccache:
                 masquerades.append(("ccache", "ccache"))
+            if sccache:
+                masquerades.append(("sccache", "sccache"))
 
             for feature, m in masquerades:
                 for l in possible_libexecdirs:
@@ -645,6 +648,12 @@ def doebuild_environment(
                     )
                     mysettings.features.remove(feature)
 
+        if sccache:
+            # Set to a custom default port (not the upstream default) to avoid conflicts with other users
+            # and avoid permission issue when other server has non-writable SCCACHE_DIR.
+            mysettings.setdefault("SCCACHE_SERVER_PORT", "6224")
+            mysettings["RUSTC_WRAPPER"] = "sccache"
+
         # MAKEOPTS conflicts with MAKEFLAGS, so skip this if MAKEFLAGS exists.
         if "MAKEOPTS" not in mysettings and "MAKEFLAGS" not in mysettings:
             nproc = get_cpu_count()

lib/portage/package/ebuild/prepare_build_dirs.py

@@ -216,6 +216,11 @@ def _prepare_features_dirs(mysettings):
             "subdirs": ("lock", "state"),
             "always_recurse": True,
         },
+        "sccache": {
+            "basedir_var": "SCCACHE_DIR",
+            "default_dir": os.path.join(mysettings["PORTAGE_TMPDIR"], "sccache"),
+            "always_recurse": False,
+        },
     }
     dirmode = 0o2070
     filemode = 0o60