build system: support building examples

CMakeLists.txt and Makefile have been updated to support building
examples. The Makefile now includes a variable `SCYLLA_EXAMPLES_TO_RUN`,
which lists the examples that are expected to run successfully. Those
examples will be built when the `build-examples` target is invoked.
CMakeLists.txt has been modified to conditionally add example
subdirectories based on the `CASS_EXAMPLES_WHITELIST` variable,
which is populated from the `SCYLLA_EXAMPLES_TO_RUN` variable in the
Makefile.

What is now possible after this commit is to build specific examples
using the `build-examples` target in the Makefile. Also, it's possible
to conveniently override the list of examples to build:
`make run-examples SCYLLA_EXAMPLES_TO_RUN="basic callbacks"`

Author: wprzytula

CMakeLists.txt

@@ -69,6 +69,10 @@ if(CASS_BUILD_INTEGRATION_TESTS OR CASS_BUILD_UNIT_TESTS)
   set(CASS_USE_LIBUV ON)
 endif()
 
+if(CASS_BUILD_EXAMPLES)
+  set(CASS_USE_LIBUV ON) # Some examples require libuv, e.g. "callbacks".
+endif()
+
 # Determine which driver target should be used as a dependency
 set(PROJECT_LIB_NAME_TARGET scylla-cpp-driver)
 if(CASS_USE_STATIC_LIBS OR
@@ -236,7 +240,22 @@ add_subdirectory(scylla-rust-wrapper)
 add_subdirectory(src)
 
 if(CASS_BUILD_EXAMPLES)
-  add_subdirectory(examples)
+  message(STATUS "Using CASS_EXAMPLES_WHITELIST: ${CASS_EXAMPLES_WHITELIST}")
+
+  # Get all example directories
+  file(GLOB EXAMPLE_DIRS "${CASS_ROOT_DIR}/examples/*")
+
+  foreach(EXAMPLE_DIR ${EXAMPLE_DIRS})
+    get_filename_component(EXAMPLE_NAME ${EXAMPLE_DIR} NAME)
+
+    # Check whitelist
+    if(IS_DIRECTORY ${EXAMPLE_DIR})
+      if(CASS_EXAMPLES_WHITELIST STREQUAL "" OR EXAMPLE_NAME IN_LIST CASS_EXAMPLES_WHITELIST)
+        message(STATUS "Adding example subdirectory ${EXAMPLE_DIR}, example name ${EXAMPLE_NAME}")
+        add_subdirectory(${EXAMPLE_DIR})
+      endif()
+    endif()
+  endforeach()
 endif()
 
 if(CASS_BUILD_INTEGRATION_TESTS OR CASS_BUILD_TESTS)

Makefile

@@ -120,6 +120,38 @@ CASSANDRA_NO_VALGRIND_TEST_FILTER := $(subst ${SPACE},${EMPTY},AsyncTests.Integr
 :HeartbeatTests.Integration_Cassandra_HeartbeatFailed)
 endif
 
+ifndef SCYLLA_EXAMPLES_TO_RUN
+SCYLLA_EXAMPLES_TO_RUN := \
+    async \
+	basic \
+	batch \
+	bind_by_name \
+	collections \
+	concurrent_executions \
+	date_time \
+	duration \
+	maps \
+	named_parameters \
+	paging \
+	prepared \
+	simple \
+	ssl \
+	tracing \
+	tuple \
+	udt \
+	uuids \
+
+	# auth <- unimplemented `cass_cluster_set_authenticator_callbacks()`
+	# callbacks <- panics due to bug in future management - attempting to block in async context
+	# execution_profiles <- unimplemented `cass_statement_set_keyspace()`
+	# host_listener <- unimplemented `cass_cluster_set_host_listener_callback()`
+	# logging <- unimplemented `cass_cluster_set_host_listener_callback()`
+	# perf <- unimplemented `cass_cluster_set_num_threads_io()`, `cass_cluster_set_queue_size_io()`
+	# schema_meta <- unimplemented multiple schema-related functions
+	# cloud <- out of interest for us, not related to ScyllaDB
+	# dse <- out of interest for us, not related to ScyllaDB
+endif
+
 ifndef CCM_COMMIT_ID
 	export CCM_COMMIT_ID := master
 endif
@@ -206,6 +238,16 @@ build-integration-test-bin-if-missing:
 		cmake -DCASS_BUILD_INTEGRATION_TESTS=ON -DCMAKE_BUILD_TYPE=Release .. && (make -j 4 || make);\
 	}
 
+SCYLLA_EXAMPLES_TO_RUN_SEMICOLON_SEPARATED := $(subst ${SPACE},;,${SCYLLA_EXAMPLES_TO_RUN})
+
+build-examples:
+	@{\
+		echo "Building examples to ${EXAMPLES_DIR}";\
+		mkdir "${BUILD_DIR}" >/dev/null 2>&1 || true;\
+		cd "${BUILD_DIR}";\
+		cmake -DCASS_EXAMPLES_WHITELIST="${SCYLLA_EXAMPLES_TO_RUN_SEMICOLON_SEPARATED}" -DCASS_BUILD_EXAMPLES=on -DCMAKE_BUILD_TYPE=Release .. && (make -j 4 || make);\
+	}
+
 _update-rust-tooling:
 	@echo "Run rustup update"
 	@rustup update