From 6deec513842ada3fdd5e5a544e1535cd5a05abf4 Mon Sep 17 00:00:00 2001
From: Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>
Date: Sun, 8 Aug 2021 10:12:51 +0000
Subject: round-robin.sh: Share ccache between builds on different executors

Change-Id: Ib5ae287428eca03b72825e419688affb59c60989
---
 jenkins-helpers.sh | 10 +++++-----
 round-robin.sh     | 14 ++++++++++----
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/jenkins-helpers.sh b/jenkins-helpers.sh
index f862a4ab..2b089799 100644
--- a/jenkins-helpers.sh
+++ b/jenkins-helpers.sh
@@ -817,17 +817,17 @@ print_volume_mounts ()
 	    # Add ccache volume for tcwg_* jobs.
 	    # These jobs depend on ccache for fast rebuilds of LLVM and GCC with
 	    # the host compiler.
-	    # tcwg_* jobs use per-executor WORKSPACES, and ccache uses separate
-	    # cache entries for different paths.  Therefore we need to use
-	    # separate caches for different $WORKSPACES.  Otherwise we get
-	    # a lot of cache polution on high-executor machines, e.g., for
-	    # tcwg_bmk builds on tcwg-x86_64-dev-01 node.
 	    local prefix
 	    if [ x"${WORKSPACE+set}" = x"set" ]; then
 		prefix=$(basename $WORKSPACE)
 	    else
 		prefix=$(echo $job | cut -d- -f 1)
 	    fi
+	    # tcwg_* jobs use per-executor WORKSPACES, and we configure ccache
+	    # to use CCACHE_BASEDIR=$WORKSPACE so that ccache sees same paths
+	    # for builds on different executors.
+	    # Strip "_$EXECUTOR_NUMBER" from the job/workspace ID.
+	    prefix="${prefix%_[0-9]*}"
 	    volume_id=$(print_docker_name "$prefix$suffix")
 	    mounts+=(ccache-"$volume_id":"$HOME"/.ccache)
 	    ;;
diff --git a/round-robin.sh b/round-robin.sh
index de33c873..48834ce8 100644
--- a/round-robin.sh
+++ b/round-robin.sh
@@ -184,6 +184,9 @@ prepare_abe ()
 
     clone_or_update_repo abe tested https://git-us.linaro.org/toolchain/abe.git > /dev/null
 
+    local workspace
+    workspace=$(pwd)
+
     cd abe
 
     # Add ccache wrappers.
@@ -193,14 +196,14 @@ prepare_abe ()
 
     cat > "$(pwd)/bin/gcc" <<EOF
 #!/bin/sh
-exec ccache /usr/bin/gcc "\$@"
+CCACHE_BASEDIR=$workspace exec ccache /usr/bin/gcc "\$@"
 EOF
     chmod +x "$(pwd)/bin/gcc"
     cp "$(pwd)/bin/gcc" "$(pwd)/bin/cc"
 
     cat > "$(pwd)/bin/g++" <<EOF
 #!/bin/sh
-exec ccache /usr/bin/g++ "\$@"
+CCACHE_BASEDIR=$workspace exec ccache /usr/bin/g++ "\$@"
 EOF
     chmod +x "$(pwd)/bin/g++"
     cp "$(pwd)/bin/g++" "$(pwd)/bin/c++"
@@ -479,6 +482,9 @@ build_llvm ()
 
     sanity_check_pwd
 
+    local workspace
+    workspace=$(pwd)
+
     # Setup ccache and ninja wrappers.
     # shellcheck disable=SC2115
     rm -rf "$(pwd)/bin"
@@ -486,13 +492,13 @@ build_llvm ()
 
     cat > "$(pwd)/bin/cc" <<EOF
 #!/bin/sh
-exec ccache /usr/bin/gcc "\$@"
+CCACHE_BASEDIR=$workspace exec ccache /usr/bin/gcc "\$@"
 EOF
     chmod +x "$(pwd)/bin/cc"
 
     cat > "$(pwd)/bin/c++" <<EOF
 #!/bin/sh
-exec ccache /usr/bin/g++ "\$@"
+CCACHE_BASEDIR=$workspace exec ccache /usr/bin/g++ "\$@"
 EOF
     chmod +x "$(pwd)/bin/c++"
 
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