Add find-ccache.sh with find_ccache_and_export_vars

.evergreen/generated_configs/legacy-config.yml

@@ -1861,10 +1861,9 @@ tasks:
         export distro_id='${distro_id}' # Required by find_cmake_latest.
         . .evergreen/scripts/find-cmake-latest.sh
         cmake_binary="$(find_cmake_latest)"
-        # Allow reuse of ccache compilation results between different build directories.
-        export CCACHE_BASEDIR CCACHE_NOHASHDIR
-        CCACHE_BASEDIR="$(pwd)"
-        CCACHE_NOHASHDIR=1
+        # Use ccache if able.
+        . .evergreen/scripts/find-ccache.sh
+        find_ccache_and_export_vars "$(pwd)" || true
         # Compile test-awsauth. Disable unnecessary dependencies since test-awsauth is copied to a remote Ubuntu 20.04 ECS cluster for testing, which may not have all dependent libraries.
         export CC='${CC}'
         "$cmake_binary" -DENABLE_TRACING=ON -DENABLE_SASL=OFF -DENABLE_SNAPPY=OFF -DENABLE_ZSTD=OFF -DENABLE_CLIENT_SIDE_ENCRYPTION=OFF .

.evergreen/legacy_config_generator/evergreen_config_lib/tasks.py

@@ -930,10 +930,9 @@ def do_is_valid_combination(self) -> bool:
             . .evergreen/scripts/find-cmake-latest.sh
             cmake_binary="$(find_cmake_latest)"
 
-            # Allow reuse of ccache compilation results between different build directories.
-            export CCACHE_BASEDIR CCACHE_NOHASHDIR
-            CCACHE_BASEDIR="$(pwd)"
-            CCACHE_NOHASHDIR=1
+            # Use ccache if able.
+            . .evergreen/scripts/find-ccache.sh
+            find_ccache_and_export_vars "$(pwd)" || true
 
             # Compile test-awsauth. Disable unnecessary dependencies since test-awsauth is copied to a remote Ubuntu 20.04 ECS cluster for testing, which may not have all dependent libraries.
             export CC='${CC}'

.evergreen/scripts/compile-openssl-static.sh

@@ -109,10 +109,9 @@ if [[ "${OSTYPE}" == darwin* ]]; then
   }
 fi
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$(pwd)"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+. "${script_dir:?}/find-ccache.sh"
+find_ccache_and_export_vars "$(pwd)" || true
 
 "${CMAKE}" "${configure_flags[@]}" .
 "${CMAKE}" --build . -- -j "$(nproc)"

.evergreen/scripts/compile-scan-build.sh

@@ -148,10 +148,9 @@ for dir in "${scan_build_directories[@]}"; do
 done
 : "${scan_build_binary:?"could not find a scan-build binary!"}"
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$(pwd)"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+. "${script_dir:?}/find-ccache.sh"
+find_ccache_and_export_vars "$(pwd)" || true
 
 "${scan_build_binary}" --use-cc="${CC}" --use-c++="${CXX}" "${cmake_binary}" "${configure_flags[@]}" .
 

.evergreen/scripts/compile-std.sh

@@ -134,10 +134,9 @@ echo "Installing libmongocrypt... done."
 echo "CFLAGS: ${CFLAGS}"
 echo "configure_flags: ${configure_flags[*]}"
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$(pwd)"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+. "${script_dir:?}/find-ccache.sh"
+find_ccache_and_export_vars "$(pwd)" || true
 
 "${cmake_binary}" "${configure_flags[@]}" .
 "${cmake_binary}" --build .

.evergreen/scripts/compile-test-azurekms.sh

@@ -16,10 +16,9 @@ echo "Installing libmongocrypt ... begin"
 }
 echo "Installing libmongocrypt ... end"
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$(pwd)"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+. .evergreen/scripts/find-ccache.sh
+find_ccache_and_export_vars "$(pwd)" || true
 
 echo "Compile test-azurekms ... begin"
 # Disable unnecessary dependencies. test-azurekms is copied to a remote host for testing, which may not have all dependent libraries.

.evergreen/scripts/compile-test-gcpkms.sh

@@ -16,10 +16,9 @@ echo "Installing libmongocrypt ... begin"
 }
 echo "Installing libmongocrypt ... end"
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$(pwd)"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+. .evergreen/scripts/find-ccache.sh
+find_ccache_and_export_vars "$(pwd)" || true
 
 echo "Compile test-gcpkms ... begin"
 # Disable unnecessary dependencies. test-gcpkms is copied to a remote host for testing, which may not have all dependent libraries.

.evergreen/scripts/compile-unix.sh

@@ -204,10 +204,9 @@ else
   configure_flags_append "-DENABLE_CLIENT_SIDE_ENCRYPTION=OFF"
 fi
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$(pwd)"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+. "${script_dir:?}/find-ccache.sh"
+find_ccache_and_export_vars "$(pwd)" || true
 
 "${cmake_binary}" "${configure_flags[@]}" ${extra_configure_flags[@]+"${extra_configure_flags[@]}"} .
 "${cmake_binary}" --build .

.evergreen/scripts/find-ccache.sh

@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+
+find_ccache_check() {
+  : "${1:?}"
+
+  if command -v "${1:?}" >/dev/null; then
+    declare version
+    version="$("${1:?}" --version | head -n 1)"
+    echo "Found ${1:?}: ${version:-}" 1>&2
+    echo "${1:?}"
+    return 0
+  fi
+
+  return 1
+}
+
+# find_ccache
+#
+# Usage:
+#   find_ccache
+#   ccache_binary="$(find_ccache)"
+#   ccache_binary="$(find_ccache 2>/dev/null)"
+#
+# Return 0 (true) if a ccache binary is found.
+# Return a non-zero (false) value otherwise.
+#
+# If successful, print the name of the ccache binary to stdout (pipe 1).
+# Otherwise, no output is printed to stdout.
+#
+# Diagnostic messages may be printed to stderr (pipe 2). Redirect to /dev/null
+# with `2>/dev/null` to silence these messages.
+find_ccache() {
+  # Most distros provide ccache via system paths.
+  {
+    find_ccache_check ccache && return
+  } || true
+
+  # Some distros provide ccache via mongodbtoolchain.
+  {
+    find_ccache_check /opt/mongodbtoolchain/v4/bin/ccache && return
+  } || {
+    find_ccache_check /opt/mongodbtoolchain/v3/bin/ccache && return
+  } || true
+
+  # Could not find ccache.
+  echo "Could not find a ccache binary." 1>&2
+  return 1
+}
+
+# Find, export, and set ccache env vars in one command for convenience.
+# Requires base_dir as first argument.
+# Returns a non-zero (false) value if a ccache binary is not found.
+# Redirects find_ccache's stderr to stdout to avoid output sync issues on EVG.
+find_ccache_and_export_vars() {
+  declare base_dir
+  base_dir="${1:?"missing base_dir"}"
+
+  declare ccache_binary
+  ccache_binary="$(find_ccache)" 2>&1 || return
+
+  export CMAKE_C_COMPILER_LAUNCHER="${ccache_binary:?}"
+  export CMAKE_CXX_COMPILER_LAUNCHER="${ccache_binary:?}"
+
+  # Allow reuse of ccache compilation results between different build directories.
+  export CCACHE_BASEDIR="${base_dir:?}"
+  export CCACHE_NOHASHDIR=1
+}

.evergreen/scripts/install-uninstall-check.sh

@@ -13,6 +13,10 @@ CMAKE=$(find_cmake_latest)
 . $DIR/check-symlink.sh
 SRCROOT=$(pwd)
 
+# Use ccache if able.
+. $DIR/find-ccache.sh
+find_ccache_and_export_vars "$(pwd)" || true
+
 SCRATCH_DIR=$(pwd)/.scratch
 rm -rf "$SCRATCH_DIR"
 mkdir -p "$SCRATCH_DIR"
@@ -48,10 +52,11 @@ else
   BSON_ONLY_OPTION="-DENABLE_MONGOC=ON"
 fi
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$SCRATCH_DIR"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+if [[ -f $DIR/find-ccache.sh ]]; then
+  . $DIR/find-ccache.sh
+  find_ccache_and_export_vars "$SCRATCH_DIR" || true
+fi
 
 $CMAKE -DCMAKE_INSTALL_PREFIX=$INSTALL_PREFIX -DCMAKE_PREFIX_PATH=$INSTALL_DIR/lib/cmake $BSON_ONLY_OPTION "$SCRATCH_DIR"
 $CMAKE --build .

.evergreen/scripts/link-sample-program-bson.sh

@@ -44,10 +44,11 @@ mkdir -p $INSTALL_DIR
 
 cd $BUILD_DIR
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$SCRATCH_DIR"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+if [[ -f $DIR/find-ccache.sh ]]; then
+  . $DIR/find-ccache.sh
+  find_ccache_and_export_vars "$SCRATCH_DIR" || true
+fi
 
 if [ "$LINK_STATIC" ]; then
   # Our CMake system builds shared and static by default.

.evergreen/scripts/link-sample-program.sh

@@ -72,10 +72,11 @@ fi
 
 ZSTD="AUTO"
 
-# Allow reuse of ccache compilation results between different build directories.
-export CCACHE_BASEDIR CCACHE_NOHASHDIR
-CCACHE_BASEDIR="$SCRATCH_DIR"
-CCACHE_NOHASHDIR=1
+# Use ccache if able.
+if [[ -f $DIR/find-ccache.sh ]]; then
+  . $DIR/find-ccache.sh
+  find_ccache_and_export_vars "$SCRATCH_DIR" || true
+fi
 
 $CMAKE -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR -DCMAKE_PREFIX_PATH=$INSTALL_DIR/lib/cmake $SSL_CMAKE_OPTION $SNAPPY_CMAKE_OPTION $STATIC_CMAKE_OPTION -DENABLE_ZSTD=$ZSTD "$SCRATCH_DIR"
 $CMAKE --build . --parallel

CMakeLists.txt

@@ -315,9 +315,6 @@ if(ENABLE_MAINTAINER_FLAGS)
    )
 endif()
 
-# Enable CCache, if possible
-include (CCache)
-
 # Link with LLD, if possible
 if (NOT MSVC)
    include (LLDLinker)

NEWS

@@ -1,4 +1,4 @@
-libmongoc 1.28.0 (unreleased)
+libmongoc 1.28.0 (Unreleased)
 =============================
 
 New features:
@@ -10,6 +10,12 @@ Notes:
   * Bump minimum wire protocol version from 6 (MongoDB 3.6) to 7 (MongoDB 4.0).
   * Raise required version of libmongocrypt to 1.11.0 to support In-Use Encryption (corresponds to the CMake option: `ENABLE_CLIENT_SIDE_ENCRYPTION`).
 
+Build Configuration:
+
+  * Remove automatic ccache detection and usage (CCache.cmake).
+      * Set [`CMAKE_<LANG>_COMPILER_LAUNCHER`](https://cmake.org/cmake/help/latest/envvar/CMAKE_LANG_COMPILER_LAUNCHER.html) to build with ccache.
+  * Remove `MONGO_USE_CCACHE` (no longer applicable; see above).
+
 Changed:
 
   * Test and example targets are excluded from the `ALL` target.

src/libbson/NEWS

@@ -1,3 +1,13 @@
+libbson 1.28.0 (Unreleased)
+=============================
+
+Build Configuration:
+
+  * Remove automatic ccache detection and usage (CCache.cmake).
+      * Set [`CMAKE_<LANG>_COMPILER_LAUNCHER`](https://cmake.org/cmake/help/latest/envvar/CMAKE_LANG_COMPILER_LAUNCHER.html) to build with ccache.
+  * Remove `MONGO_USE_CCACHE` (no longer applicable; see above).
+
+
 libbson 1.27.5
 ==============