[PATCH v2 1/2] meta: Support for ccache for custom packages in buildchroot

[Uladzimir Bely <ubely@ilbers.de>]

Add `INHERIT += "ccache"` to local.conf or package recipe
to globally activate the ccache functionality.
Add `CCACHE_DISABLE = '1'` to the recipe to disable ccache for it.

Signed-off-by: Uladzimir Bely <ubely@ilbers.de>
---
 meta-isar/conf/local.conf.sample              |  5 ++++
 meta/classes/buildchroot.bbclass              |  6 +++++
 meta/classes/ccache.bbclass                   | 23 +++++++++++++++++++
 meta/classes/dpkg.bbclass                     |  3 ++-
 .../buildchroot/buildchroot.inc               |  1 +
 .../buildchroot/files/build.sh                |  6 +++++
 .../buildchroot/files/common.sh               |  1 +
 7 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 meta/classes/ccache.bbclass

diff --git a/meta-isar/conf/local.conf.sample b/meta-isar/conf/local.conf.sample
index 88a8175..f180f5a 100644
--- a/meta-isar/conf/local.conf.sample
+++ b/meta-isar/conf/local.conf.sample
@@ -224,3 +224,8 @@ USER_isar[flags] += "clear-text-password"
 
 # Uncomment the below line to debug WIC.
 # WIC_CREATE_EXTRA_ARGS += "-D"
+
+# Uncomment this to use ccache for custom packages
+#INHERIT += "ccache"
+# Uncomment and set own top level ccache directory to share between builds
+#CCACHE_TOP_DIR ?= "${TMPDIR}/ccache"
diff --git a/meta/classes/buildchroot.bbclass b/meta/classes/buildchroot.bbclass
index e9eb9af..274ebdc 100644
--- a/meta/classes/buildchroot.bbclass
+++ b/meta/classes/buildchroot.bbclass
@@ -32,6 +32,12 @@ buildchroot_do_mounts() {
             mount --bind '${REPO_ISAR_DIR}/${DISTRO}' '${BUILDCHROOT_DIR}/isar-apt'
         mountpoint -q '${BUILDCHROOT_DIR}/downloads' ||
             mount --bind '${DL_DIR}' '${BUILDCHROOT_DIR}/downloads'
+        if [ "${USE_CCACHE}" = "1" ]
+        then
+            mkdir -p '${BUILDCHROOT_DIR}/ccache'
+            mountpoint -q '${BUILDCHROOT_DIR}/ccache' ||
+                mount --bind '${CCACHE_DIR}' '${BUILDCHROOT_DIR}/ccache'
+        fi
         mountpoint -q '${BUILDCHROOT_DIR}/dev' ||
             mount --rbind /dev '${BUILDCHROOT_DIR}/dev'
         mount --make-rslave '${BUILDCHROOT_DIR}/dev'
diff --git a/meta/classes/ccache.bbclass b/meta/classes/ccache.bbclass
new file mode 100644
index 0000000..0053dfa
--- /dev/null
+++ b/meta/classes/ccache.bbclass
@@ -0,0 +1,23 @@
+#
+# Usage:
+# - Enable ccache
+#   Add the following line to a conffile such as conf/local.conf:
+#   INHERIT += "ccache"
+#
+# - Disable ccache for a recipe
+#   Add the following line to the recipe if it can't be built with ccache:
+#   USE_CCACHE = "0"
+#
+# - Share ccache files between different builds
+#   Set CCACHE_TOP_DIR to a shared dir
+#   CCACHE_TOP_DIR = /path/to/shared_ccache/
+
+CCACHE_TOP_DIR ?= "${TMPDIR}/ccache"
+CCACHE_DIR ?= "${CCACHE_TOP_DIR}/${DISTRO}-${DISTRO_ARCH}"
+
+USE_CCACHE ?= "1"
+
+do_init_ccache[dirs] = "${CCACHE_DIR}"
+do_init_ccache() {
+}
+addtask do_init_ccache before do_rootfs
diff --git a/meta/classes/dpkg.bbclass b/meta/classes/dpkg.bbclass
index 4e7c2f7..4269364 100644
--- a/meta/classes/dpkg.bbclass
+++ b/meta/classes/dpkg.bbclass
@@ -4,6 +4,7 @@
 inherit dpkg-base
 
 PACKAGE_ARCH ?= "${DISTRO_ARCH}"
+USE_CCACHE ??= "0"
 
 # Install build dependencies for package
 do_install_builddeps() {
@@ -33,5 +34,5 @@ dpkg_runbuild() {
     E="${@ isar_export_proxies(d)}"
     export PARALLEL_MAKE="${PARALLEL_MAKE}"
     sudo -E chroot --userspec=$( id -u ):$( id -g ) ${BUILDCHROOT_DIR} \
-         /isar/build.sh ${PP}/${PPS} ${PACKAGE_ARCH}
+         /isar/build.sh ${PP}/${PPS} ${PACKAGE_ARCH} ${USE_CCACHE}
 }
diff --git a/meta/recipes-devtools/buildchroot/buildchroot.inc b/meta/recipes-devtools/buildchroot/buildchroot.inc
index 31524a1..726c7bb 100644
--- a/meta/recipes-devtools/buildchroot/buildchroot.inc
+++ b/meta/recipes-devtools/buildchroot/buildchroot.inc
@@ -32,6 +32,7 @@ BUILDCHROOT_PREINSTALL_COMMON = " \
     make \
     debhelper \
     autotools-dev \
+    ccache \
     dpkg \
     locales \
     docbook-to-man \
diff --git a/meta/recipes-devtools/buildchroot/files/build.sh b/meta/recipes-devtools/buildchroot/files/build.sh
index 101581d..b642f42 100644
--- a/meta/recipes-devtools/buildchroot/files/build.sh
+++ b/meta/recipes-devtools/buildchroot/files/build.sh
@@ -14,4 +14,10 @@ for i in configure aclocal.m4 Makefile.am Makefile.in; do
     fi
 done
 
+if [ "$use_ccache" == "1" ]
+then
+    export CCACHE_DIR=/ccache
+    export PATH=/usr/lib/ccache:$PATH
+fi
+
 ${GBP_PREFIX}dpkg-buildpackage -a$target_arch -d --source-option=-I
diff --git a/meta/recipes-devtools/buildchroot/files/common.sh b/meta/recipes-devtools/buildchroot/files/common.sh
index 0063a38..7085f44 100644
--- a/meta/recipes-devtools/buildchroot/files/common.sh
+++ b/meta/recipes-devtools/buildchroot/files/common.sh
@@ -17,6 +17,7 @@ fi
 
 # Create human-readable names
 target_arch=$2
+use_ccache=$3
 
 set_arch="--host-arch $target_arch"
 
-- 
2.20.1