UDF based on existing function infra (#4804)

Added UDF support using C++.

---------

Co-authored-by: zhaojunnan <zhaojunnan@kanzhun.com>
Co-authored-by: Wey Gu <weyl.gu@gmail.com>
Co-authored-by: Cheng Xuntao <7731943+xtcyclist@users.noreply.github.com>

conf/nebula-graphd.conf.default

@@ -97,6 +97,12 @@
 # if use balance data feature, only work if enable_experimental_feature is true
 --enable_data_balance=true
 
+# enable udf, written in c++ only for now
+--enable_udf=true
+
+# set the directory where the .so files of udf are stored, when enable_udf is true
+--udf_path=/home/nebula/dev/nebula/udf/
+
 ########## session ##########
 # Maximum number of sessions that can be created per IP and per user
 --max_sessions_per_ip_per_user=300
@@ -116,3 +122,4 @@
 --memory_purge_enabled=true
 # memory background purge interval in seconds
 --memory_purge_interval_seconds=10
+

src/common/function/CMakeLists.txt

@@ -6,6 +6,8 @@ nebula_add_library(
     function_manager_obj OBJECT
     FunctionManager.cpp
     ../geo/GeoFunction.cpp
+    FunctionUdfManager.cpp
+    GraphFunction.h
 )
 
 nebula_add_library(

src/common/function/FunctionManager.cpp

@@ -10,6 +10,7 @@
 #include <boost/algorithm/string/replace.hpp>
 #include <cstdint>
 
+#include "FunctionUdfManager.h"
 #include "common/base/Base.h"
 #include "common/datatypes/DataSet.h"
 #include "common/datatypes/Edge.h"
@@ -28,12 +29,18 @@
 #include "common/thrift/ThriftTypes.h"
 #include "common/time/TimeUtils.h"
 #include "common/time/WallClock.h"
+#include "graph/service/GraphFlags.h"
+
+DEFINE_bool(enable_udf, false, "enable udf");
 
 namespace nebula {
 
 // static
 FunctionManager &FunctionManager::instance() {
   static FunctionManager instance;
+  if (FLAGS_enable_udf) {
+    static FunctionUdfManager udfManager;
+  }
   return instance;
 }
 
@@ -440,6 +447,9 @@ StatusOr<Value::Type> FunctionManager::getReturnType(const std::string &funcName
   }
   auto iter = typeSignature_.find(func);
   if (iter == typeSignature_.end()) {
+    if (FLAGS_enable_udf) {
+      return FunctionUdfManager::getUdfReturnType(funcName, argsType);
+    }
     return Status::Error("Function `%s' not defined", funcName.c_str());
   }
 
@@ -2930,6 +2940,9 @@ Status FunctionManager::find(const std::string &func, const size_t arity) {
   std::transform(func.begin(), func.end(), func.begin(), ::tolower);
   auto iter = functions_.find(func);
   if (iter == functions_.end()) {
+    if (FLAGS_enable_udf) {
+      return FunctionUdfManager::loadUdfFunction(func, arity);
+    }
     return Status::Error("Function `%s' not defined", func.c_str());
   }
   // check arity

src/common/function/FunctionManager.h

@@ -63,7 +63,6 @@ class FunctionManager final {
   static StatusOr<Value::Type> getReturnType(const std::string &funcName,
                                              const std::vector<Value::Type> &argsType);
 
- private:
   // The attributes of the function call
   struct FunctionAttributes final {
     size_t minArity_{0};
@@ -89,6 +88,7 @@ class FunctionManager final {
     }
   }
 
+ private:
   /**
    * FunctionManager functions as a singleton, since the dynamic loading is
    * process-wide.

src/common/function/FunctionUdfManager.cpp

@@ -0,0 +1,204 @@
+/* Copyright (c) 2020 vesoft inc. All rights reserved.
+ *
+ * This source code is licensed under Apache 2.0 License.
+ */
+
+#include "FunctionUdfManager.h"
+
+#include <dirent.h>
+#include <dlfcn.h>
+
+#include <cstring>
+#include <iostream>
+
+#include "graph/service/GraphFlags.h"
+
+DEFINE_string(udf_path, "lib/udf", "path to hold the udf");
+
+namespace nebula {
+
+static const char *dlsym_error;
+static std::unordered_map<std::string, Value::Type> udfFunReturnType_;
+static std::unordered_map<std::string, std::vector<std::vector<nebula::Value::Type>>>
+    udfFunInputType_;
+std::unordered_map<std::string, FunctionManager::FunctionAttributes> udfFunctions_;
+
+std::atomic<bool> expired_{};
+std::atomic<bool> try_to_expire_{};
+std::mutex mutex_;
+std::condition_variable expired_cond_;
+
+FunctionUdfManager &FunctionUdfManager::instance() {
+  static FunctionUdfManager instance;
+  return instance;
+}
+
+std::vector<std::string> getFilesList(const std::string &path, const char *ftype) {
+  std::vector<std::string> filenames;
+  DIR *pDir;
+  struct dirent *ptr;
+  if (!(pDir = opendir(path.c_str()))) {
+    LOG(ERROR) << "UDF Folder doesn't Exist!" << dlsym_error;
+    return filenames;
+  }
+  while ((ptr = readdir(pDir)) != 0) {
+    if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0 &&
+        strcmp((ptr->d_name) + strlen(ptr->d_name) - strlen(ftype), ftype) == 0) {
+      filenames.emplace_back(ptr->d_name);
+      LOG(INFO) << "Load UDF SO Name: " << ptr->d_name;
+    }
+  }
+  closedir(pDir);
+  return filenames;
+}
+
+FunctionUdfManager::create_f *FunctionUdfManager::getGraphFunctionClass(void *func_handle) {
+  auto *create_func = reinterpret_cast<create_f *>(dlsym(func_handle, "create"));
+  dlsym_error = dlerror();
+  if (dlsym_error) {
+    LOG(ERROR) << "Cannot load symbol create: " << dlsym_error;
+  }
+  return create_func;
+}
+
+FunctionUdfManager::destroy_f *FunctionUdfManager::deleteGraphFunctionClass(void *func_handle) {
+  auto *destroy_func = reinterpret_cast<destroy_f *>(dlsym(func_handle, "destroy"));
+  dlsym_error = dlerror();
+  if (dlsym_error) {
+    LOG(ERROR) << "Cannot load symbol destroy: " << dlsym_error;
+  }
+  return destroy_func;
+}
+
+FunctionUdfManager::FunctionUdfManager() {
+  initAndLoadSoFunction();
+  expired_ = true;
+  try_to_expire_ = false;
+
+  std::thread([this]() {
+    while (!try_to_expire_) {
+      std::this_thread::sleep_for(std::chrono::seconds(300));
+      initAndLoadSoFunction();
+    }
+    {
+      std::lock_guard<std::mutex> locker(mutex_);
+      expired_ = true;
+      expired_cond_.notify_one();
+    }
+  }).detach();
+}
+
+void FunctionUdfManager::initAndLoadSoFunction() {
+  auto udfPath = FLAGS_udf_path;
+  LOG(INFO) << "Load UDF so library: " << udfPath;
+  std::vector<std::string> files = getFilesList(udfPath, ".so");
+
+  for (auto &file : files) {
+    const std::string &path = udfPath;
+    std::string so_path_string = path + file;
+    const char *soPath = so_path_string.c_str();
+    try {
+      void *func_handle = dlopen(soPath, RTLD_LAZY);
+      if (!func_handle) {
+        LOG(ERROR) << "Cannot load udf library: " << dlerror();
+      }
+      dlerror();
+
+      create_f *create_func = getGraphFunctionClass(func_handle);
+      destroy_f *destroy_func = deleteGraphFunctionClass(func_handle);
+      if (create_func == nullptr || destroy_func == nullptr) {
+        LOG(ERROR) << "GraphFunction Create Or Destroy Error: " << soPath;
+        break;
+      }
+
+      GraphFunction *gf = create_func();
+      char *funName = gf->name();
+      udfFunInputType_.emplace(funName, gf->inputType());
+      udfFunReturnType_.emplace(funName, gf->returnType());
+      addSoUdfFunction(funName, soPath, gf->minArity(), gf->maxArity(), gf->isPure());
+
+      destroy_func(gf);
+      dlclose(func_handle);
+    } catch (...) {
+      LOG(ERROR) << "load So library Error: " << soPath;
+    }
+  }
+}
+
+StatusOr<Value::Type> FunctionUdfManager::getUdfReturnType(
+    std::string func, const std::vector<Value::Type> &argsType) {
+  if (udfFunReturnType_.find(func) != udfFunReturnType_.end()) {
+    if (udfFunInputType_.find(func) != udfFunInputType_.end()) {
+      auto iter = udfFunInputType_.find(func);
+      for (const auto &args : iter->second) {
+        if (argsType == args || args[0] == Value::Type::NULLVALUE ||
+            args[0] == Value::Type::__EMPTY__) {
+          return udfFunReturnType_[func];
+        }
+      }
+    }
+    return Status::Error("Parameter's type error");
+  }
+  return Status::Error("Function `%s' not defined", func.c_str());
+}
+
+StatusOr<const FunctionManager::FunctionAttributes> nebula::FunctionUdfManager::loadUdfFunction(
+    std::string func, size_t arity) {
+  auto iter = udfFunctions_.find(func);
+  if (iter == udfFunctions_.end()) {
+    return Status::Error("Function `%s' not defined", func.c_str());
+  }
+  auto minArity = iter->second.minArity_;
+  auto maxArity = iter->second.maxArity_;
+  if (arity < minArity || arity > maxArity) {
+    if (minArity == maxArity) {
+      return Status::Error(
+          "Arity not match for function `%s': "
+          "provided %lu but %lu expected.",
+          func.c_str(),
+          arity,
+          minArity);
+    } else {
+      return Status::Error(
+          "Arity not match for function `%s': "
+          "provided %lu but %lu-%lu expected.",
+          func.c_str(),
+          arity,
+          minArity,
+          maxArity);
+    }
+  }
+  return iter->second;
+}
+
+void FunctionUdfManager::addSoUdfFunction(
+    char *funName, const char *soPath, size_t minArity, size_t maxArity, bool isPure) {
+  auto &attr = udfFunctions_[funName];
+  attr.minArity_ = minArity;
+  attr.maxArity_ = maxArity;
+  attr.isAlwaysPure_ = isPure;
+  std::string path = soPath;
+  attr.body_ = [path](const auto &args) -> Value {
+    try {
+      char *soPath2 = const_cast<char *>(path.c_str());
+      void *func_handle = dlopen(soPath2, RTLD_LAZY);
+      if (!func_handle) {
+        LOG(ERROR) << "Cannot load udf library: " << dlerror();
+      }
+      dlerror();
+
+      create_f *create_func = getGraphFunctionClass(func_handle);
+      destroy_f *destroy_func = deleteGraphFunctionClass(func_handle);
+
+      GraphFunction *gf = create_func();
+      Value res = gf->body(args);
+      destroy_func(gf);
+      dlclose(func_handle);
+      return res;
+    } catch (...) {
+      return Value::kNullBadData;
+    }
+  };
+}
+
+}  // namespace nebula

src/common/function/FunctionUdfManager.h

@@ -0,0 +1,40 @@
+/* Copyright (c) 2020 vesoft inc. All rights reserved.
+ *
+ * This source code is licensed under Apache 2.0 License.
+ */
+
+#ifndef COMMON_FUNCTION_FUNCTIONUDFMANAGER_H_
+#define COMMON_FUNCTION_FUNCTIONUDFMANAGER_H_
+
+#include "FunctionManager.h"
+#include "GraphFunction.h"
+
+namespace nebula {
+
+class FunctionManager;
+
+class FunctionUdfManager {
+ public:
+  typedef GraphFunction *(create_f)();
+  typedef void(destroy_f)(GraphFunction *);
+
+  static StatusOr<Value::Type> getUdfReturnType(const std::string functionName,
+                                                const std::vector<Value::Type> &argsType);
+
+  static StatusOr<const FunctionManager::FunctionAttributes> loadUdfFunction(
+      std::string functionName, size_t arity);
+
+  static FunctionUdfManager &instance();
+
+  FunctionUdfManager();
+
+ private:
+  static create_f *getGraphFunctionClass(void *func_handle);
+  static destroy_f *deleteGraphFunctionClass(void *func_handle);
+
+  void addSoUdfFunction(char *funName, const char *soPath, size_t i, size_t i1, bool b);
+  void initAndLoadSoFunction();
+};
+
+}  // namespace nebula
+#endif  // COMMON_FUNCTION_FUNCTIONUDFMANAGER_H_

src/common/function/GraphFunction.h

@@ -0,0 +1,38 @@
+/* Copyright (c) 2020 vesoft inc. All rights reserved.
+ *
+ * This source code is licensed under Apache 2.0 License.
+ */
+
+#ifndef COMMON_FUNCTION_GRAPHFUNCTION_H
+#define COMMON_FUNCTION_GRAPHFUNCTION_H
+
+#include <vector>
+
+#include "common/datatypes/Value.h"
+
+class GraphFunction;
+
+extern "C" GraphFunction *create();
+extern "C" void destroy(GraphFunction *function);
+
+class GraphFunction {
+ public:
+  virtual ~GraphFunction() = default;
+
+  virtual char *name() = 0;
+
+  virtual std::vector<std::vector<nebula::Value::Type>> inputType() = 0;
+
+  virtual nebula::Value::Type returnType() = 0;
+
+  virtual size_t minArity() = 0;
+
+  virtual size_t maxArity() = 0;
+
+  virtual bool isPure() = 0;
+
+  virtual nebula::Value body(
+      const std::vector<std::reference_wrapper<const nebula::Value>> &args) = 0;
+};
+
+#endif  // COMMON_FUNCTION_GRAPHFUNCTION_H

src/graph/service/GraphFlags.h

@@ -22,6 +22,8 @@ DECLARE_int32(listen_backlog);
 DECLARE_string(listen_netdev);
 DECLARE_string(local_ip);
 DECLARE_string(pid_file);
+DECLARE_bool(enable_udf);
+DECLARE_string(udf_path);
 DECLARE_bool(local_config);
 DECLARE_bool(accept_partial_success);
 DECLARE_bool(disable_octal_escape_char);