feat(aio): use rocksdb APIs to re-implement the aio module (apache#1637)

apache#1575

This is a dependent work to implement encryption at rest, we can use the capacity of
rocksdb encryption after this patch.

- Use rocksdb APIs to implement class `native_linux_aio_provider`. Both of the
  implementations are using `pread()` and `pwrite()` system calls, so there isn't
  significant performance changes, see the newly added simple benchmark performance
  comparation below.
- Separate the file read and write operations for class `aio_provider`

src/aio/CMakeLists.txt

@@ -33,7 +33,7 @@ set(MY_PROJ_SRC "")
 #"GLOB" for non - recursive search
 set(MY_SRC_SEARCH_MODE "GLOB")
 
-set(MY_PROJ_LIBS dsn_runtime)
+set(MY_PROJ_LIBS dsn_runtime rocksdb)
 
 #Extra files that will be installed
 set(MY_BINPLACES "")

src/aio/aio_provider.h

@@ -27,10 +27,17 @@
 #pragma once
 
 #include <stdint.h>
+#include <memory>
+#include <string>
 
 #include "utils/error_code.h"
 #include "utils/factory_store.h"
 
+namespace rocksdb {
+class RandomAccessFile;
+class RandomRWFile;
+} // namespace rocksdb
+
 namespace dsn {
 
 class aio_context;
@@ -60,12 +67,13 @@ class aio_provider
     explicit aio_provider(disk_engine *disk);
     virtual ~aio_provider() = default;
 
-    virtual linux_fd_t open(const char *file_name, int flag, int pmode) = 0;
+    virtual std::unique_ptr<rocksdb::RandomAccessFile> open_read_file(const std::string &fname) = 0;
+    virtual error_code read(const aio_context &aio_ctx, /*out*/ uint64_t *processed_bytes) = 0;
 
-    virtual error_code close(linux_fd_t fd) = 0;
-    virtual error_code flush(linux_fd_t fd) = 0;
+    virtual std::unique_ptr<rocksdb::RandomRWFile> open_write_file(const std::string &fname) = 0;
     virtual error_code write(const aio_context &aio_ctx, /*out*/ uint64_t *processed_bytes) = 0;
-    virtual error_code read(const aio_context &aio_ctx, /*out*/ uint64_t *processed_bytes) = 0;
+    virtual error_code flush(rocksdb::RandomRWFile *rwf) = 0;
+    virtual error_code close(rocksdb::RandomRWFile *rwf) = 0;
 
     // Submits the aio_task to the underlying disk-io executor.
     // This task may not be executed immediately, call `aio_task::wait`

src/aio/disk_engine.cpp

@@ -102,22 +102,26 @@ aio_task *disk_write_queue::unlink_next_workload(void *plength)
     return first;
 }
 
-disk_file::disk_file(linux_fd_t fd) : _fd(fd) {}
+disk_file::disk_file(std::unique_ptr<rocksdb::RandomAccessFile> rf) : _read_file(std::move(rf)) {}
+disk_file::disk_file(std::unique_ptr<rocksdb::RandomRWFile> wf) : _write_file(std::move(wf)) {}
 
 aio_task *disk_file::read(aio_task *tsk)
 {
+    CHECK(_read_file, "");
     tsk->add_ref(); // release on completion, see `on_read_completed`.
     return _read_queue.add_work(tsk, nullptr);
 }
 
 aio_task *disk_file::write(aio_task *tsk, void *ctx)
 {
+    CHECK(_write_file, "");
     tsk->add_ref(); // release on completion
     return _write_queue.add_work(tsk, ctx);
 }
 
 aio_task *disk_file::on_read_completed(aio_task *wk, error_code err, size_t size)
 {
+    CHECK(_read_file, "");
     CHECK(wk->next == nullptr, "");
     auto ret = _read_queue.on_work_completed(wk, nullptr);
     wk->enqueue(err, size);
@@ -128,6 +132,7 @@ aio_task *disk_file::on_read_completed(aio_task *wk, error_code err, size_t size
 
 aio_task *disk_file::on_write_completed(aio_task *wk, void *ctx, error_code err, size_t size)
 {
+    CHECK(_write_file, "");
     auto ret = _write_queue.on_work_completed(wk, ctx);
 
     while (wk) {

src/aio/disk_engine.h

@@ -32,6 +32,7 @@
 
 #include "aio/aio_task.h"
 #include "aio_provider.h"
+#include "rocksdb/env.h"
 #include "utils/singleton.h"
 #include "utils/work_queue.h"
 
@@ -56,17 +57,21 @@ class disk_write_queue : public work_queue<aio_task>
 class disk_file
 {
 public:
-    explicit disk_file(linux_fd_t fd);
+    explicit disk_file(std::unique_ptr<rocksdb::RandomAccessFile> rf);
+    explicit disk_file(std::unique_ptr<rocksdb::RandomRWFile> wf);
     aio_task *read(aio_task *tsk);
     aio_task *write(aio_task *tsk, void *ctx);
 
     aio_task *on_read_completed(aio_task *wk, error_code err, size_t size);
     aio_task *on_write_completed(aio_task *wk, void *ctx, error_code err, size_t size);
 
-    linux_fd_t native_handle() const { return _fd; }
+    rocksdb::RandomAccessFile *rfile() const { return _read_file.get(); }
+    rocksdb::RandomRWFile *wfile() const { return _write_file.get(); }
 
 private:
-    linux_fd_t _fd;
+    // TODO(yingchun): unify to use a single RandomRWFile member variable.
+    std::unique_ptr<rocksdb::RandomAccessFile> _read_file;
+    std::unique_ptr<rocksdb::RandomRWFile> _write_file;
     disk_write_queue _write_queue;
     work_queue<aio_task> _read_queue;
 };

src/aio/file_io.cpp

@@ -26,32 +26,51 @@
 
 #include "aio/file_io.h"
 
+#include <memory>
 // IWYU pragma: no_include <algorithm>
 #include <vector>
 
 #include "aio/aio_provider.h"
 #include "disk_engine.h"
+#include "rocksdb/env.h"
+#include "utils/fmt_logging.h"
 
 namespace dsn {
 class task_tracker;
 
 namespace file {
 
-/*extern*/ disk_file *open(const char *file_name, int flag, int pmode)
+/*extern*/ disk_file *open(const std::string &fname, FileOpenType type)
 {
-    auto fd = disk_engine::provider().open(file_name, flag, pmode);
-    if (fd.is_invalid()) {
-        return nullptr;
+    switch (type) {
+    case FileOpenType::kReadOnly: {
+        auto sf = disk_engine::provider().open_read_file(fname);
+        if (!sf) {
+            return nullptr;
+        }
+        return new disk_file(std::move(sf));
     }
-
-    return new disk_file(fd);
+    case FileOpenType::kWriteOnly: {
+        auto wf = disk_engine::provider().open_write_file(fname);
+        if (!wf) {
+            return nullptr;
+        }
+        return new disk_file(std::move(wf));
+    }
+    default:
+        CHECK(false, "");
+    }
+    return nullptr;
 }
 
 /*extern*/ error_code close(disk_file *file)
 {
-    error_code result = ERR_INVALID_HANDLE;
+    error_code result = ERR_OK;
     if (file != nullptr) {
-        result = disk_engine::provider().close(file->native_handle());
+        // A read file is not needed to close.
+        if (file->wfile()) {
+            result = disk_engine::provider().close(file->wfile());
+        }
         delete file;
         file = nullptr;
     }
@@ -60,11 +79,11 @@ namespace file {
 
 /*extern*/ error_code flush(disk_file *file)
 {
-    if (nullptr != file) {
-        return disk_engine::provider().flush(file->native_handle());
-    } else {
+    if (file == nullptr || file->wfile() == nullptr) {
         return ERR_INVALID_HANDLE;
     }
+
+    return disk_engine::provider().flush(file->wfile());
 }
 
 /*extern*/ aio_task_ptr read(disk_file *file,
@@ -84,7 +103,8 @@ namespace file {
     cb->get_aio_context()->engine = &disk_engine::instance();
     cb->get_aio_context()->dfile = file;
 
-    if (!cb->spec().on_aio_call.execute(task::get_current_task(), cb, true)) {
+    if (!cb->spec().on_aio_call.execute(task::get_current_task(), cb, true) ||
+        file->rfile() == nullptr) {
         cb->enqueue(ERR_FILE_OPERATION_FAILED, 0);
         return cb;
     }
@@ -110,6 +130,10 @@ namespace file {
     cb->get_aio_context()->file_offset = offset;
     cb->get_aio_context()->type = AIO_Write;
     cb->get_aio_context()->dfile = file;
+    if (file->wfile() == nullptr) {
+        cb->enqueue(ERR_FILE_OPERATION_FAILED, 0);
+        return cb;
+    }
 
     disk_engine::instance().write(cb);
     return cb;

src/aio/file_io.h

@@ -28,6 +28,7 @@
 
 #include <stdint.h>
 #include <list>
+#include <string>
 #include <utility>
 
 #include "aio/aio_task.h"
@@ -47,6 +48,13 @@ class task_tracker;
 
 namespace file {
 
+enum class FileOpenType
+{
+    kReadOnly = 0,
+    kWriteOnly
+};
+
+// TODO(yingchun): consider to return a smart pointer
 /// open file
 ///
 /// \param file_name filename of the file.
@@ -55,7 +63,7 @@ namespace file {
 ///
 /// \return file handle
 ///
-extern disk_file *open(const char *file_name, int flag, int pmode);
+extern disk_file *open(const std::string &fname, FileOpenType type);
 
 /// close the file handle
 extern error_code close(disk_file *file);