Use sccache for CPU builds. (#5208)

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

2 files changed, 45 insertions, 3 deletions

diff --git a/.jenkins/build.sh b/.jenkins/build.sh
index c73f4c2564..5d2a3b870e 100755
--- a/.jenkins/build.sh
+++ b/.jenkins/build.sh
@@ -16,8 +16,16 @@ export PATH=/opt/conda/bin:$PATH
 if [[ "$JOB_NAME" != *cuda* ]]; then
    export PATH=/opt/python/${PYTHON_VERSION}/bin:$PATH
    export LD_LIBRARY_PATH=/opt/python/${PYTHON_VERSION}/lib:$LD_LIBRARY_PATH
-   export CC="ccache /usr/bin/gcc-${GCC_VERSION}"
-   export CXX="ccache /usr/bin/g++-${GCC_VERSION}"
+   export CC="sccache /usr/bin/gcc-${GCC_VERSION}"
+   export CXX="sccache /usr/bin/g++-${GCC_VERSION}"
+
+   sccache --show-stats
+
+   function sccache_epilogue() {
+      sccache --show-stats
+   }
+   trap_add sccache_epilogue EXIT
+
 else
    # CMake should use ccache symlink for nvcc
    export CUDA_NVCC_EXECUTABLE=/usr/local/bin/nvcc
diff --git a/.jenkins/common.sh b/.jenkins/common.sh
index 25ca0ccbdb..5a3c891ae6 100644
--- a/.jenkins/common.sh
+++ b/.jenkins/common.sh
@@ -25,7 +25,41 @@ set -ex
 # system; to find out more, grep for this string in ossci-job-dsl.
 echo "ENTERED_USER_LAND"
 
-trap cleanup EXIT
+# compositional trap taken from https://stackoverflow.com/a/7287873/23845
+
+# note: printf is used instead of echo to avoid backslash
+# processing and to properly handle values that begin with a '-'.
+
+log() { printf '%s\n' "$*"; }
+error() { log "ERROR: $*" >&2; }
+fatal() { error "$@"; exit 1; }
+
+# appends a command to a trap
+#
+# - 1st arg:  code to add
+# - remaining args:  names of traps to modify
+#
+trap_add() {
+    trap_add_cmd=$1; shift || fatal "${FUNCNAME} usage error"
+    for trap_add_name in "$@"; do
+        trap -- "$(
+            # helper fn to get existing trap command from output
+            # of trap -p
+            extract_trap_cmd() { printf '%s\n' "$3"; }
+            # print existing trap command with newline
+            eval "extract_trap_cmd $(trap -p "${trap_add_name}")"
+            # print the new trap command
+            printf '%s\n' "${trap_add_cmd}"
+        )" "${trap_add_name}" \
+            || fatal "unable to add to trap ${trap_add_name}"
+    done
+}
+# set the trace attribute for the above function.  this is
+# required to modify DEBUG or RETURN traps because functions don't
+# inherit them unless the trace attribute is set
+declare -f -t trap_add
+
+trap_add cleanup EXIT
 
 # Converts:
 # pytorch-builds/pytorch-macos-10.13-py3-build-test ==> pytorch-macos-10.13-py3-build-test