inference c_api support std::string (#38667)

* c_api support std::string

* update

* update

* add NOTE

* fix delete error.

paddle/fluid/inference/capi_exp/pd_config.cc

@@ -459,12 +459,10 @@ __pd_give PD_OneDimArrayCstr* PD_ConfigAllPasses(
   std::vector<std::string> passes = config->pass_builder()->AllPasses();
   return paddle_infer::CvtVecToOneDimArrayCstr(passes);
 }
-const char* PD_ConfigSummary(__pd_keep PD_Config* pd_config) {
+__pd_give PD_Cstr* PD_ConfigSummary(__pd_keep PD_Config* pd_config) {
   CHECK_AND_CONVERT_PD_CONFIG;
   auto sum_str = config->Summary();
-  char* c = reinterpret_cast<char*>(malloc(sum_str.length() + 1));
-  snprintf(c, sum_str.length() + 1, "%s", sum_str.c_str());
-  return c;
+  return paddle_infer::CvtStrToCstr(sum_str);
 }
 
 }  // extern "C"

paddle/fluid/inference/capi_exp/pd_config.h

@@ -705,7 +705,7 @@ PADDLE_CAPI_EXPORT extern __pd_give PD_OneDimArrayCstr* PD_ConfigAllPasses(
 ///
 /// \return Return config info.
 ///
-PADDLE_CAPI_EXPORT extern const char* PD_ConfigSummary(
+PADDLE_CAPI_EXPORT extern __pd_give PD_Cstr* PD_ConfigSummary(
     __pd_keep PD_Config* pd_config);
 
 #ifdef __cplusplus

paddle/fluid/inference/capi_exp/pd_types.h

@@ -34,6 +34,11 @@ typedef struct PD_OneDimArrayCstr {
   char** data;
 } PD_OneDimArrayCstr;  // std::vector<std::string>
 
+typedef struct PD_Cstr {
+  size_t size;
+  char* data;
+} PD_Cstr;  // std::string
+
 typedef struct PD_TwoDimArraySize {
   size_t size;
   PD_OneDimArraySize** data;

paddle/fluid/inference/capi_exp/pd_utils.cc

@@ -78,6 +78,17 @@ void PD_OneDimArrayCstrDestroy(__pd_take PD_OneDimArrayCstr* array) {
     delete array;
   }
 }
+
+void PD_CstrDestroy(__pd_take PD_Cstr* cstr) {
+  if (cstr != NULL) {
+    if (cstr->size != 0) {
+      cstr->size = 0;
+      delete[] cstr->data;
+      cstr->data = NULL;
+    }
+    delete cstr;
+  }
+}
 namespace paddle_infer {
 
 __pd_give PD_OneDimArrayCstr* CvtVecToOneDimArrayCstr(
@@ -101,6 +112,18 @@ std::vector<std::string> CvtOneDimArrayToVecCstr(
   return vec;
 }
 
+__pd_give PD_Cstr* CvtStrToCstr(const std::string& str) {
+  PD_Cstr* cstr = new PD_Cstr;
+  if (str.empty()) {
+    cstr->size = 0;
+    cstr->data = NULL;
+  } else {
+    cstr->size = str.length() + 1;
+    cstr->data = new char[str.length() + 1];
+    memcpy(cstr->data, str.c_str(), str.length() + 1);
+  }
+  return cstr;
+}
 }  // namespace paddle_infer
 
 #define DESTROY_TWO_DIM_ARRAY(type)                                           \

paddle/fluid/inference/capi_exp/pd_utils.h

@@ -65,6 +65,15 @@ PADDLE_CAPI_EXPORT extern void PD_OneDimArraySizeDestroy(
 PADDLE_CAPI_EXPORT extern void PD_TwoDimArraySizeDestroy(
     __pd_take PD_TwoDimArraySize* array);
 
+///
+/// \brief Destroy the PD_Cstr object pointed to by the pointer.
+/// NOTE: if input string is empty, the return PD_Cstr's size is
+/// 0 and data is NULL.
+///
+/// \param[in] cstr pointer to the PD_Cstr object.
+///
+PADDLE_CAPI_EXPORT extern void PD_CstrDestroy(__pd_take PD_Cstr* cstr);
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif

paddle/fluid/inference/capi_exp/utils_internal.h

@@ -114,6 +114,14 @@ __pd_give PD_TwoDimArraySize* CvtVecToTwoDimArraySize(
 std::vector<std::vector<size_t>> CvtTwoDimArrayToVecSize(
     __pd_keep const PD_TwoDimArraySize* array);
 
+///
+/// \brief Convert the 'std::string' object to a 'PD_Cstr' object.
+///
+/// \param[in] vec source object.
+/// \return target object.
+///
+__pd_give PD_Cstr* CvtStrToCstr(const std::string& vec);
+
 ///
 /// \brief Convert the 'PD_PlaceType' object to a 'paddle_infer::PlaceType'
 /// object.

paddle/fluid/inference/goapi/config.go

@@ -833,7 +833,7 @@ func (config *Config) AllPasses() []string {
 ///
 func (config *Config) Summary() string {
 	cSummary := C.PD_ConfigSummary(config.c)
-	summary := C.GoString(cSummary)
-	C.free(unsafe.Pointer(cSummary))
+	summary := C.GoString(cSummary.data)
+	C.PD_CstrDestroy(cSummary)
 	return summary
 }

paddle/fluid/inference/tests/api/analyzer_capi_exp_tester.cc

@@ -18,7 +18,9 @@ limitations under the License. */
 #include <string>
 #include <vector>
 
+#include "paddle/fluid/inference/capi_exp/pd_config.h"
 #include "paddle/fluid/inference/capi_exp/pd_inference_api.h"
+#include "paddle/fluid/inference/capi_exp/pd_utils.h"
 #include "paddle/fluid/inference/tests/api/tester_helper.h"
 
 namespace paddle {
@@ -34,6 +36,8 @@ void predictor_run() {
   PD_ConfigSetCpuMathLibraryNumThreads(config, 10);
   PD_ConfigSwitchIrDebug(config, TRUE);
   PD_ConfigSetModel(config, prog_file.c_str(), params_file.c_str());
+  PD_Cstr *config_summary = PD_ConfigSummary(config);
+  LOG(INFO) << config_summary->data;
 
   PD_Predictor *predictor = PD_PredictorCreate(config);
   PD_Tensor *tensor = PD_PredictorGetInputHandle(predictor, "data");
@@ -51,6 +55,7 @@ void predictor_run() {
 
   delete[] input;
   PD_TensorDestroy(tensor);
+  PD_CstrDestroy(config_summary);
   PD_PredictorDestroy(predictor);
 }