add WITH_EXAMPLES options to cmake and cleanups. (#6580)

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6580

Reviewed By: cheng-chang

Differential Revision: D21846336

Pulled By: ajkr

fbshipit-source-id: e5bb0152a0876061d4ff158e7144eb9cc5a88cad

CMakeLists.txt

@@ -1269,3 +1269,8 @@ if(WITH_TOOLS)
   add_custom_target(tools
     DEPENDS ${tool_deps})
 endif()
+
+option(WITH_EXAMPLES "build with examples" OFF)
+if(WITH_EXAMPLES)
+  add_subdirectory(examples)
+endif()

examples/CMakeLists.txt

@@ -0,0 +1,45 @@
+add_executable(simple_example
+  simple_example.cc)
+target_link_libraries(simple_example
+  ${ROCKSDB_LIB})
+
+add_executable(column_families_example
+  column_families_example.cc)
+target_link_libraries(column_families_example
+  ${ROCKSDB_LIB})
+
+add_executable(compact_files_example
+  compact_files_example.cc)
+target_link_libraries(compact_files_example
+  ${ROCKSDB_LIB})
+
+add_executable(c_simple_example
+  c_simple_example.c)
+target_link_libraries(c_simple_example
+  ${ROCKSDB_LIB})
+
+add_executable(optimistic_transaction_example
+  optimistic_transaction_example.cc)
+target_link_libraries(optimistic_transaction_example
+  ${ROCKSDB_LIB})
+
+add_executable(transaction_example
+  transaction_example.cc)
+target_link_libraries(transaction_example
+  ${ROCKSDB_LIB})
+
+add_executable(compaction_filter_example
+  compaction_filter_example.cc)
+target_link_libraries(compaction_filter_example
+  ${ROCKSDB_LIB})
+
+add_executable(options_file_example
+  options_file_example.cc)
+target_link_libraries(options_file_example
+  ${ROCKSDB_LIB})
+
+add_executable(multi_processes_example
+  EXCLUDE_FROM_ALL
+  multi_processes_example.cc)
+target_link_libraries(multi_processes_example
+  ${ROCKSDB_LIB})

examples/simple_example.cc

@@ -68,7 +68,7 @@ int main() {
   }
 
   PinnableSlice pinnable_val;
-  db->Get(ReadOptions(), db->DefaultColumnFamily(), "key1", &pinnable_val);
+  s = db->Get(ReadOptions(), db->DefaultColumnFamily(), "key1", &pinnable_val);
   assert(s.IsNotFound());
   // Reset PinnableSlice after each use and before each reuse
   pinnable_val.Reset();