[OE-core] [PATCH v2 3/3] cmake.bbclass: enable usage of ccache

[Yannick Gicquel]

This allows ccache usage for recipes which inherit cmake.bbclass.
Since cmake v3.4, it can be enabled using some "-D" options.

Here below are some metrics while using it for webkitgtk recipe.
(machine is a 4x core i7 @ 3.4GHz)

$ bitbake -c fetchall webkitgtk
$ time bitbake webkitgtk
<snip>
real	56m25.191s
user	359m32.003s
sys	34m49.356s

$ bitbake -c clean webkitgtk
$ bitbake -c cleansstate webkitgtk
$ time bitbake webkitgtk
<snip>
real	25m19.298s
user	17m57.861s
sys	6m20.157s

Signed-off-by: Yannick Gicquel <yannick.gicquel at iot.bzh>
---
 meta/classes/cmake.bbclass | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/meta/classes/cmake.bbclass b/meta/classes/cmake.bbclass
index 9e74599..737a4e0 100644
--- a/meta/classes/cmake.bbclass
+++ b/meta/classes/cmake.bbclass
@@ -4,12 +4,9 @@ OECMAKE_SOURCEPATH ?= "${S}"
 DEPENDS_prepend = "cmake-native "
 B = "${WORKDIR}/build"
 
-# We need to unset CCACHE otherwise cmake gets too confused
-CCACHE = ""
-
 # C/C++ Compiler (without cpu arch/tune arguments)
-OECMAKE_C_COMPILER ?= "`echo ${CC} | sed 's/^\([^ ]*\).*/\1/'`"
-OECMAKE_CXX_COMPILER ?= "`echo ${CXX} | sed 's/^\([^ ]*\).*/\1/'`"
+OECMAKE_C_COMPILER ?= "${@'${CC}'.replace('${CCACHE}','',1).split(' ')[0]}"
+OECMAKE_CXX_COMPILER ?= "${@'${CXX}'.replace('${CCACHE}','',1).split(' ')[0]}"
 OECMAKE_AR ?= "${AR}"
 
 # Compiler flags
@@ -108,9 +105,16 @@ cmake_do_configure() {
 		OECMAKE_SITEFILE=""
 	fi
 
+	if [ -n "${CCACHE}" ]; then
+		OECMAKE_CCACHE="-DCMAKE_C_COMPILER_LAUNCHER=${CCACHE} -DCMAKE_CXX_COMPILER_LAUNCHER=${CCACHE}"
+	else
+		OECMAKE_CCACHE=""
+	fi
+
 	cmake \
 	  ${OECMAKE_SITEFILE} \
 	  ${OECMAKE_SOURCEPATH} \
+	  ${OECMAKE_CCACHE} \
 	  -DCMAKE_INSTALL_PREFIX:PATH=${prefix} \
 	  -DCMAKE_INSTALL_BINDIR:PATH=${@os.path.relpath(d.getVar('bindir'), d.getVar('prefix'))} \
 	  -DCMAKE_INSTALL_SBINDIR:PATH=${@os.path.relpath(d.getVar('sbindir'), d.getVar('prefix'))} \
-- 
1.9.1