fi
}
+good_trees_file="$HOME/travis-cache/good-trees"
+
+# Save some info about the current commit's tree, so we can skip the build
+# job if we encounter the same tree again and can provide a useful info
+# message.
+save_good_tree () {
+ echo "$(git rev-parse $TRAVIS_COMMIT^{tree}) $TRAVIS_COMMIT $TRAVIS_JOB_NUMBER $TRAVIS_JOB_ID" >>"$good_trees_file"
+ # limit the file size
+ tail -1000 "$good_trees_file" >"$good_trees_file".tmp
+ mv "$good_trees_file".tmp "$good_trees_file"
+}
+
+# Skip the build job if the same tree has already been built and tested
+# successfully before (e.g. because the branch got rebased, changing only
+# the commit messages).
+skip_good_tree () {
+ if ! good_tree_info="$(grep "^$(git rev-parse $TRAVIS_COMMIT^{tree}) " "$good_trees_file")"
+ then
+ # Haven't seen this tree yet, or no cached good trees file yet.
+ # Continue the build job.
+ return
+ fi
+
+ echo "$good_tree_info" | {
+ read tree prev_good_commit prev_good_job_number prev_good_job_id
+
+ if test "$TRAVIS_JOB_ID" = "$prev_good_job_id"
+ then
+ cat <<-EOF
+ $(tput setaf 2)Skipping build job for commit $TRAVIS_COMMIT.$(tput sgr0)
+ This commit has already been built and tested successfully by this build job.
+ To force a re-build delete the branch's cache and then hit 'Restart job'.
+ EOF
+ else
+ cat <<-EOF
+ $(tput setaf 2)Skipping build job for commit $TRAVIS_COMMIT.$(tput sgr0)
+ This commit's tree has already been built and tested successfully in build job $prev_good_job_number for commit $prev_good_commit.
+ The log of that build job is available at https://travis-ci.org/$TRAVIS_REPO_SLUG/jobs/$prev_good_job_id
+ To force a re-build delete the branch's cache and then hit 'Restart job'.
+ EOF
+ fi
+ }
+
+ exit 0
+}
+
# Set 'exit on error' for all CI scripts to let the caller know that
# something went wrong.
# Set tracing executed commands, primarily setting environment variables
mkdir -p "$HOME/travis-cache"
skip_branch_tip_with_tag
+skip_good_tree
if test -z "$jobname"
then