diff options
Diffstat (limited to 'include/leveldb/env.h')
| -rw-r--r-- | include/leveldb/env.h | 80 |
1 files changed, 55 insertions, 25 deletions
diff --git a/include/leveldb/env.h b/include/leveldb/env.h index 112fe96..e00895a 100644 --- a/include/leveldb/env.h +++ b/include/leveldb/env.h @@ -13,30 +13,26 @@ #ifndef STORAGE_LEVELDB_INCLUDE_ENV_H_ #define STORAGE_LEVELDB_INCLUDE_ENV_H_ -#include <stdarg.h> -#include <stdint.h> - +#include <cstdarg> +#include <cstdint> #include <string> #include <vector> #include "leveldb/export.h" #include "leveldb/status.h" +// This workaround can be removed when leveldb::Env::DeleteFile is removed. #if defined(_WIN32) -// The leveldb::Env class below contains a DeleteFile method. -// At the same time, <windows.h>, a fairly popular header -// file for Windows applications, defines a DeleteFile macro. +// On Windows, the method name DeleteFile (below) introduces the risk of +// triggering undefined behavior by exposing the compiler to different +// declarations of the Env class in different translation units. // -// Without any intervention on our part, the result of this -// unfortunate coincidence is that the name of the -// leveldb::Env::DeleteFile method seen by the compiler depends on -// whether <windows.h> was included before or after the LevelDB -// headers. +// This is because <windows.h>, a fairly popular header file for Windows +// applications, defines a DeleteFile macro. So, files that include the Windows +// header before this header will contain an altered Env declaration. // -// To avoid headaches, we undefined DeleteFile (if defined) and -// redefine it at the bottom of this file. This way <windows.h> -// can be included before this file (or not at all) and the -// exported method will always be leveldb::Env::DeleteFile. +// This workaround ensures that the compiler sees the same Env declaration, +// independently of whether <windows.h> was included. #if defined(DeleteFile) #undef DeleteFile #define LEVELDB_DELETEFILE_UNDEFINED @@ -54,7 +50,7 @@ class WritableFile; class LEVELDB_EXPORT Env { public: - Env() = default; + Env(); Env(const Env&) = delete; Env& operator=(const Env&) = delete; @@ -122,15 +118,48 @@ class LEVELDB_EXPORT Env { // Original contents of *results are dropped. virtual Status GetChildren(const std::string& dir, std::vector<std::string>* result) = 0; - // Delete the named file. - virtual Status DeleteFile(const std::string& fname) = 0; + // + // The default implementation calls DeleteFile, to support legacy Env + // implementations. Updated Env implementations must override RemoveFile and + // ignore the existence of DeleteFile. Updated code calling into the Env API + // must call RemoveFile instead of DeleteFile. + // + // A future release will remove DeleteDir and the default implementation of + // RemoveDir. + virtual Status RemoveFile(const std::string& fname); + + // DEPRECATED: Modern Env implementations should override RemoveFile instead. + // + // The default implementation calls RemoveFile, to support legacy Env user + // code that calls this method on modern Env implementations. Modern Env user + // code should call RemoveFile. + // + // A future release will remove this method. + virtual Status DeleteFile(const std::string& fname); // Create the specified directory. virtual Status CreateDir(const std::string& dirname) = 0; // Delete the specified directory. - virtual Status DeleteDir(const std::string& dirname) = 0; + // + // The default implementation calls DeleteDir, to support legacy Env + // implementations. Updated Env implementations must override RemoveDir and + // ignore the existence of DeleteDir. Modern code calling into the Env API + // must call RemoveDir instead of DeleteDir. + // + // A future release will remove DeleteDir and the default implementation of + // RemoveDir. + virtual Status RemoveDir(const std::string& dirname); + + // DEPRECATED: Modern Env implementations should override RemoveDir instead. + // + // The default implementation calls RemoveDir, to support legacy Env user + // code that calls this method on modern Env implementations. Modern Env user + // code should call RemoveDir. + // + // A future release will remove this method. + virtual Status DeleteDir(const std::string& dirname); // Store the size of fname in *file_size. virtual Status GetFileSize(const std::string& fname, uint64_t* file_size) = 0; @@ -271,7 +300,7 @@ class LEVELDB_EXPORT Logger { virtual ~Logger(); // Write an entry to the log file with the specified format. - virtual void Logv(const char* format, va_list ap) = 0; + virtual void Logv(const char* format, std::va_list ap) = 0; }; // Identifies a locked file. @@ -333,14 +362,14 @@ class LEVELDB_EXPORT EnvWrapper : public Env { std::vector<std::string>* r) override { return target_->GetChildren(dir, r); } - Status DeleteFile(const std::string& f) override { - return target_->DeleteFile(f); + Status RemoveFile(const std::string& f) override { + return target_->RemoveFile(f); } Status CreateDir(const std::string& d) override { return target_->CreateDir(d); } - Status DeleteDir(const std::string& d) override { - return target_->DeleteDir(d); + Status RemoveDir(const std::string& d) override { + return target_->RemoveDir(d); } Status GetFileSize(const std::string& f, uint64_t* s) override { return target_->GetFileSize(f, s); @@ -375,7 +404,8 @@ class LEVELDB_EXPORT EnvWrapper : public Env { } // namespace leveldb -// Redefine DeleteFile if necessary. +// This workaround can be removed when leveldb::Env::DeleteFile is removed. +// Redefine DeleteFile if it was undefined earlier. #if defined(_WIN32) && defined(LEVELDB_DELETEFILE_UNDEFINED) #if defined(UNICODE) #define DeleteFile DeleteFileW |