Support eatmydata (automatically enabled if host + distribution needs…

… match) + ccache

eatmydata support gets enabled by default if it's installed on
the host system and when building for a recent Debian/Ubuntu
version (Debian/jessie + Ubuntu/vivid or newer). Usage can be
forced via USE_EATMYDATA=true and disabled via
USE_EATMYDATA=false.

ccache support can be enabled via USE_CCACHE=true

Thanks to Franco (nextime) Lanza for the initial patch in
#125

debian/control

@@ -37,6 +37,7 @@ Depends: build-essential,
          cowbuilder,
          devscripts,
          dpkg-dev,
+         eatmydata,
          fakeroot,
          file,
          git-buildpackage,

examples/debian_glue

@@ -94,3 +94,14 @@
 # ADT_RUNNER="adt-virt-qemu /srv/adt-${distribution:-}-${architecture:-}.img"
 # Default:
 # ADT=
+
+# Control usage of eatmydata to speed up builds. If eatmydata is present on the
+# host system and when building for a recent distribution (Debian/jessie +
+# Ubuntu/vivid or newer) eatmydata is enabled automatically.
+# To force its usage (skipping any host + distribution checks) set it to 'true'.
+# To disable its usage set it to 'false'.
+# USE_EATMYDATA=true
+
+# Enable ccache (compiler cache for fast recompilation of C/C++ code)
+# to speed up builds.
+# USE_CCACHE=true

scripts/build-and-provide-package

@@ -270,6 +270,9 @@ cowbuilder_init() {
     echo "USENETWORK=yes" >> "$pbuilderrc"
   fi
 
+  use_eatmydata
+  use_ccache
+
   # allow setting main pbuilder configuration file from outside, then append data
   # as needed without actually writing anything to user-provided $PBUILDER_CONFIG
   if [ -n "${PBUILDER_CONFIG:-}" ] ; then
@@ -518,6 +521,48 @@ autopkg_run() {
   adt-run --changes $changes_file ${ADT_OPTIONS:-} --- $ADT_RUNNER || bailout $?
 }
 
+use_ccache() {
+  if [ "${USE_CCACHE:-}" = 'true' ] ; then
+    echo "*** USE_CCACHE is set to true, enabling ccache support ***"
+    echo 'CCACHEDIR="/var/cache/pbuilder/ccache"' >> "$pbuilderrc"
+  fi
+}
+
+enable_eatmydata() {
+  echo 'EXTRAPACKAGES="$EXTRAPACKAGES eatmydata"' >> "$pbuilderrc"
+  echo 'export LD_PRELOAD="${LD_PRELOAD:+$LD_PRELOAD:}libeatmydata.so"' >> "$pbuilderrc"
+}
+
+use_eatmydata() {
+  if [ "${USE_EATMYDATA:-}" = 'false' ] ; then
+    echo "*** eatmydata is disabled via USE_EATMYDATA [$USE_EATMYDATA] ***"
+    return 0
+  fi
+
+  if [ "${USE_EATMYDATA:-}" = 'true' ] ; then
+    echo "*** eatmydata is enabled via USE_EATMYDATA [$USE_EATMYDATA], forcing usage (skipping host/distribution checks) ***"
+    enable_eatmydata
+  else
+    if ! dpkg-query --show --showformat='${Status}' eatmydata | grep -q '^install' ; then
+      echo "*** eatmydata missing on host system, not considering for usage (force via USE_EATMYDATA=true) ***"
+    else
+      echo "*** eatmydata is present on host system, now checking distribution support ***"
+      case "${COWBUILDER_DIST}" in
+        etch|lenny|squeeze|wheezy)
+          echo "*** Debian release $COWBUILDER_DIST doesn't provide eatmydata >=82-6, skipping eatmydata ***"
+          ;;
+        warty|hoary|breezy|dapper|edgy|feisty|gutsy|hardy|intrepid|jaunty|karmi|lucid|maverick|natty|oneiric|quantal|raring|saucy|utopic|precise|trusty)
+          echo "*** Ubuntu release $COWBUILDER_DIST doesn't provide eatmydata >=82-6, skipping eatmydata ***"
+          ;;
+        *)
+          echo "*** Distribution ${COWBUILDER_DIST} should provide recent eatmydata support, enabling eatmydata ***"
+          enable_eatmydata
+          ;;
+      esac
+    fi
+  fi
+}
+
 autopkgtest_results() {
   if [ -n "${SKIP_AUTOPKGTEST_RESULTS:-}" ] ; then
     echo "** Skipping autopkgtest_results as requested via SKIP_AUTOPKGTEST_RESULTS ***"
@@ -602,6 +647,9 @@ EOF
     echo "USENETWORK=yes" >> "$pbuilderrc"
   fi
 
+  use_eatmydata
+  use_ccache
+
   # allow setting main pbuilder configuration file from outside, then append data
   # as needed without actually writing anything to user-provided $PBUILDER_CONFIG
   if [ -n "${PBUILDER_CONFIG:-}" ] ; then