diff options
Diffstat (limited to '')
-rw-r--r-- | src/rocksdb/java/rocksjni/cplusplus_to_java_convert.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/src/rocksdb/java/rocksjni/cplusplus_to_java_convert.h b/src/rocksdb/java/rocksjni/cplusplus_to_java_convert.h new file mode 100644 index 000000000..0eea6fa2c --- /dev/null +++ b/src/rocksdb/java/rocksjni/cplusplus_to_java_convert.h @@ -0,0 +1,37 @@ +// Copyright (c) 2011-present, Facebook, Inc. All rights reserved. +// This source code is licensed under both the GPLv2 (found in the +// COPYING file in the root directory) and Apache 2.0 License +// (found in the LICENSE.Apache file in the root directory). + +#pragma once + +/* + * This macro is used for 32 bit OS. In 32 bit OS, the result number is a + negative number if we use reinterpret_cast<jlong>(pointer). + * For example, jlong ptr = reinterpret_cast<jlong>(pointer), ptr is a negative + number in 32 bit OS. + * If we check ptr using ptr > 0, it fails. For example, the following code is + not correct. + * if (jblock_cache_handle > 0) { + std::shared_ptr<ROCKSDB_NAMESPACE::Cache> *pCache = + reinterpret_cast<std::shared_ptr<ROCKSDB_NAMESPACE::Cache> *>( + jblock_cache_handle); + options.block_cache = *pCache; + } + * But the result number is positive number if we do + reinterpret_cast<size_t>(pointer) first and then cast it to jlong. size_t is 4 + bytes long in 32 bit OS and 8 bytes long in 64 bit OS. + static_cast<jlong>(reinterpret_cast<size_t>(_pointer)) is also working in 64 + bit OS. + * + * We don't need an opposite cast because it works from jlong to c++ pointer in + both 32 bit and 64 bit OS. + * For example, the following code is working in both 32 bit and 64 bit OS. + jblock_cache_handle is jlong. + * std::shared_ptr<ROCKSDB_NAMESPACE::Cache> *pCache = + reinterpret_cast<std::shared_ptr<ROCKSDB_NAMESPACE::Cache> *>( + jblock_cache_handle); +*/ + +#define GET_CPLUSPLUS_POINTER(_pointer) \ + static_cast<jlong>(reinterpret_cast<size_t>(_pointer)) |