ci: Travis: improve/revisit caching (#10358)

- use CACHE_NVIM_DEPS_DIR

- do not cache pip
  This is handled through http caches in general/better, and it is not
  used much anyway.

- do not cache DEPS_DOWNLOAD_DIR
  Built deps are cached, downloads are not needed then.

- display ccache stats before clearing

- do not cache ccache stats

- improve output of `du` (do not list pages of output for "/home/travis/.cache/go-build")

3 files changed, 10 insertions, 13 deletions

diff --git a/ci/before_cache.sh b/ci/before_cache.sh
index c8a1fd5b71..c86109168e 100755
--- a/ci/before_cache.sh
+++ b/ci/before_cache.sh
@@ -7,23 +7,20 @@ CI_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "${CI_DIR}/common/build.sh"
 source "${CI_DIR}/common/suite.sh"
 
-# Don't cache pip's log and selfcheck.
-rm -rf "${HOME}/.cache/pip/log"
-rm -f "${HOME}/.cache/pip/selfcheck.json"
-
 echo "before_cache.sh: cache size"
-du -d 2 "${HOME}/.cache" | sort -n
+du -chd 1 "${HOME}/.cache" | sort -rh | head -20
 
 echo "before_cache.sh: ccache stats"
 ccache -s 2>/dev/null || true
+# Do not keep ccache stats (uploaded to cache otherwise; reset initially anyway).
+find "${HOME}/.ccache" -name stats -delete
 
 # Update the third-party dependency cache only if the build was successful.
 if ended_successfully; then
-  rm -rf "${HOME}/.cache/nvim-deps"
-  mv "${DEPS_BUILD_DIR}" "${HOME}/.cache/nvim-deps"
-
-  rm -rf "${HOME}/.cache/nvim-deps-downloads"
-  mv "${DEPS_DOWNLOAD_DIR}" "${HOME}/.cache/nvim-deps-downloads"
+  # Do not cache downloads.  They should not be needed with up-to-date deps.
+  rm -rf "${DEPS_BUILD_DIR}/build/downloads"
+  rm -rf "${CACHE_NVIM_DEPS_DIR}"
+  mv "${DEPS_BUILD_DIR}" "${CACHE_NVIM_DEPS_DIR}"
 
   touch "${CACHE_MARKER}"
   echo "Updated third-party dependencies (timestamp: $(_stat "${CACHE_MARKER}"))."
diff --git a/ci/before_script.sh b/ci/before_script.sh
index ae20eef1fc..605ecdbf66 100755
--- a/ci/before_script.sh
+++ b/ci/before_script.sh
@@ -20,6 +20,8 @@ if [[ -n "${LLVM_SYMBOLIZER}" ]] && [[ ! $(type -P "${LLVM_SYMBOLIZER}") ]]; the
   exit 1
 fi
 
+echo "before_script.sh: ccache stats (will be cleared)"
+ccache -s
 # Reset ccache stats for real results in before_cache.
 ccache --zero-stats
 
diff --git a/ci/common/build.sh b/ci/common/build.sh
index 85b141de86..bdbe012ca6 100644
--- a/ci/common/build.sh
+++ b/ci/common/build.sh
@@ -27,15 +27,13 @@ build_deps() {
   fi
 
   mkdir -p "${DEPS_BUILD_DIR}"
-  mkdir -p "${DEPS_DOWNLOAD_DIR}"
 
   # Use cached dependencies if $CACHE_MARKER exists.
   if test "${CACHE_ENABLE}" = "false" ; then
     export CCACHE_RECACHE=1
   elif test -f "${CACHE_MARKER}" ; then
     echo "Using third-party dependencies from Travis cache (last update: $(_stat "${CACHE_MARKER}"))."
-    cp -a "${HOME}/.cache/nvim-deps"/. "${DEPS_BUILD_DIR}"
-    cp -a "${HOME}/.cache/nvim-deps-downloads"/. "${DEPS_DOWNLOAD_DIR}"
+    cp -a "${CACHE_NVIM_DEPS_DIR}"/. "${DEPS_BUILD_DIR}"
   fi
 
   # Even if we're using cached dependencies, run CMake and make to